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[2620:137:e000::1:20]) by mx.google.com with ESMTP id xb3-20020a170907070300b007c17efb64fcsi14007850ejb.639.2022.12.21.14.25.16; Wed, 21 Dec 2022 14:25:40 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=FN9cvFaF; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234956AbiLUWYj (ORCPT + 99 others); Wed, 21 Dec 2022 17:24:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234946AbiLUWYb (ORCPT ); Wed, 21 Dec 2022 17:24:31 -0500 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC4A52715F for ; Wed, 21 Dec 2022 14:24:27 -0800 (PST) Received: by mail-pj1-x1049.google.com with SMTP id pm5-20020a17090b3c4500b00219864a46f0so7490807pjb.7 for ; Wed, 21 Dec 2022 14:24:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=jqx+xXNPXyPMfyXZCg/z/s6ey1PJTXuwDa7ZZcqNa58=; b=FN9cvFaFQ0lDrnMfZlJ4Nw5QOVw0uGnDqGaQknumVRuppyrWoDHSBVuz6NL4ToY0RS 9vOuxkJ3/AofaX1iRjfpMBpMgUldPva9VTuxI+GzgvG3hUFpmFSghYUy2sJIfS9ttwfI XGhvxESKye6WvJLOGBgDYOxoD6CLBGJe+6xT4rDQG52AH4WnFl9PGc3AFw28vZayBBBn j9feajSJ2epeUE/GkU2rquziJiIxC8vdf+fWfieOmBNDpJ3ddN06FuqeOipY9Sg3aDoz XwJks6viAmjyebvL5gq7BHgmgh1daETNoQf/LVxOK/ho3WPukaLII5DxvdsU1/MnZ2Ma QC/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=jqx+xXNPXyPMfyXZCg/z/s6ey1PJTXuwDa7ZZcqNa58=; b=Eg8qZe86sz82txRsI9fFukjQmWUn+Ebs5pt4cy6fSXju7FBeGRMJB919xa7m/dOy/M kN6aDfaNjxrcALC4fXwDGq2RUiTBl97mgtBHvTe3SVeZsA8oy6qOc1AS7Uj7siG0oX0R m5v/HXG9j8rwghbw6Btsbowxxghtu6dF/LG2RinX42B5c8gdN/GkeD+FIyV6qT6w/khN udsyWxxqMd4TWB3y4iVGASqcAN+uooGwQ24hKDRE7iPs3S1Kgie6E8aVU8dKID+7D3P2 9+8INMZof+lV57NIDSZtoPzahU9F5IVPbtN27jYo73YvHjeVIqaNXML0Ttyf2h5V3kKE VZjg== X-Gm-Message-State: AFqh2kr82DhwZbCsYZkcGJHdprSiQiaHBrNQfM5X+U5zQmWGsdjzB4hD hWoyTTQLiXJa6AHTX2HzhS0JEelcKvtUNGKRfWq/b0sxB1EUUQozo9pic0kmdu0+wl/Yw+3LWBl pLGMM6Z7E2D20dPyf0tx1bJnlFBI6ox4i0CoW6GzyPXIgPHxTl0zpmBfSuO4w/ilniASghnrW X-Received: from sweer.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:e45]) (user=bgardon job=sendgmr) by 2002:a17:90a:4b03:b0:224:c5cb:ce1b with SMTP id g3-20020a17090a4b0300b00224c5cbce1bmr308212pjh.209.1671661467110; Wed, 21 Dec 2022 14:24:27 -0800 (PST) Date: Wed, 21 Dec 2022 22:24:07 +0000 In-Reply-To: <20221221222418.3307832-1-bgardon@google.com> Mime-Version: 1.0 References: <20221221222418.3307832-1-bgardon@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20221221222418.3307832-4-bgardon@google.com> Subject: [RFC 03/14] KVM: x86/MMU: Move the Shadow MMU implementation to shadow_mmu.c From: Ben Gardon To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Peter Xu , Sean Christopherson , David Matlack , Vipin Sharma , Nagareddy Reddy , Ben Gardon X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1752864171713612617?= X-GMAIL-MSGID: =?utf-8?q?1752864171713612617?= Cut and paste the implementation of the Shadow MMU to shadow_mmu.(c|h). This is a monsterously large commit, moving ~3500 lines. With such a large move, there's no way to make it easy. Do the move in one massive step to simplify dealing with merge conflicts and to make the git history a little easier to dig through. Several cleanup commits follow this one rather than preceed it so that their git history will remain easy to see. No functional change intended. Signed-off-by: Ben Gardon --- arch/x86/kvm/debugfs.c | 1 + arch/x86/kvm/mmu/mmu.c | 4526 ++++--------------------------- arch/x86/kvm/mmu/mmu_internal.h | 4 +- arch/x86/kvm/mmu/shadow_mmu.c | 3408 +++++++++++++++++++++++ arch/x86/kvm/mmu/shadow_mmu.h | 145 + 5 files changed, 4086 insertions(+), 3998 deletions(-) diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c index c1390357126a..e304243d2041 100644 --- a/arch/x86/kvm/debugfs.c +++ b/arch/x86/kvm/debugfs.c @@ -9,6 +9,7 @@ #include "lapic.h" #include "mmu.h" #include "mmu/mmu_internal.h" +#include "mmu/shadow_mmu.h" static int vcpu_get_timer_advance_ns(void *data, u64 *val) { diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 729a2799d4d7..bf14e181eb12 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -109,59 +109,12 @@ bool dbg = 0; module_param(dbg, bool, 0644); #endif -#define PTE_PREFETCH_NUM 8 - #include -/* make pte_list_desc fit well in cache lines */ -#define PTE_LIST_EXT 14 - -/* - * Slight optimization of cacheline layout, by putting `more' and `spte_count' - * at the start; then accessing it will only use one single cacheline for - * either full (entries==PTE_LIST_EXT) case or entries<=6. - */ -struct pte_list_desc { - struct pte_list_desc *more; - /* - * Stores number of entries stored in the pte_list_desc. No need to be - * u64 but just for easier alignment. When PTE_LIST_EXT, means full. - */ - u64 spte_count; - u64 *sptes[PTE_LIST_EXT]; -}; - -struct kvm_shadow_walk_iterator { - u64 addr; - hpa_t shadow_addr; - u64 *sptep; - int level; - unsigned index; -}; - -#define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \ - for (shadow_walk_init_using_root(&(_walker), (_vcpu), \ - (_root), (_addr)); \ - shadow_walk_okay(&(_walker)); \ - shadow_walk_next(&(_walker))) - -#define for_each_shadow_entry(_vcpu, _addr, _walker) \ - for (shadow_walk_init(&(_walker), _vcpu, _addr); \ - shadow_walk_okay(&(_walker)); \ - shadow_walk_next(&(_walker))) - -#define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \ - for (shadow_walk_init(&(_walker), _vcpu, _addr); \ - shadow_walk_okay(&(_walker)) && \ - ({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \ - __shadow_walk_next(&(_walker), spte)) - struct kmem_cache *pte_list_desc_cache; struct kmem_cache *mmu_page_header_cache; struct percpu_counter kvm_total_used_mmu_pages; -static void mmu_spte_set(u64 *sptep, u64 spte); - struct kvm_mmu_role_regs { const unsigned long cr0; const unsigned long cr4; @@ -257,15 +210,6 @@ void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, kvm_flush_remote_tlbs_with_range(kvm, &range); } -void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, - unsigned int access) -{ - u64 spte = make_mmio_spte(vcpu, gfn, access); - - trace_mark_mmio_spte(sptep, gfn, spte); - mmu_spte_set(sptep, spte); -} - static gfn_t get_mmio_spte_gfn(u64 spte) { u64 gpa = spte & shadow_nonpresent_or_rsvd_lower_gfn_mask; @@ -301,310 +245,6 @@ static int is_cpuid_PSE36(void) return 1; } -#ifdef CONFIG_X86_64 -static void __set_spte(u64 *sptep, u64 spte) -{ - WRITE_ONCE(*sptep, spte); -} - -static void __update_clear_spte_fast(u64 *sptep, u64 spte) -{ - WRITE_ONCE(*sptep, spte); -} - -static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) -{ - return xchg(sptep, spte); -} - -static u64 __get_spte_lockless(u64 *sptep) -{ - return READ_ONCE(*sptep); -} -#else -union split_spte { - struct { - u32 spte_low; - u32 spte_high; - }; - u64 spte; -}; - -static void count_spte_clear(u64 *sptep, u64 spte) -{ - struct kvm_mmu_page *sp = sptep_to_sp(sptep); - - if (is_shadow_present_pte(spte)) - return; - - /* Ensure the spte is completely set before we increase the count */ - smp_wmb(); - sp->clear_spte_count++; -} - -static void __set_spte(u64 *sptep, u64 spte) -{ - union split_spte *ssptep, sspte; - - ssptep = (union split_spte *)sptep; - sspte = (union split_spte)spte; - - ssptep->spte_high = sspte.spte_high; - - /* - * If we map the spte from nonpresent to present, We should store - * the high bits firstly, then set present bit, so cpu can not - * fetch this spte while we are setting the spte. - */ - smp_wmb(); - - WRITE_ONCE(ssptep->spte_low, sspte.spte_low); -} - -static void __update_clear_spte_fast(u64 *sptep, u64 spte) -{ - union split_spte *ssptep, sspte; - - ssptep = (union split_spte *)sptep; - sspte = (union split_spte)spte; - - WRITE_ONCE(ssptep->spte_low, sspte.spte_low); - - /* - * If we map the spte from present to nonpresent, we should clear - * present bit firstly to avoid vcpu fetch the old high bits. - */ - smp_wmb(); - - ssptep->spte_high = sspte.spte_high; - count_spte_clear(sptep, spte); -} - -static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) -{ - union split_spte *ssptep, sspte, orig; - - ssptep = (union split_spte *)sptep; - sspte = (union split_spte)spte; - - /* xchg acts as a barrier before the setting of the high bits */ - orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low); - orig.spte_high = ssptep->spte_high; - ssptep->spte_high = sspte.spte_high; - count_spte_clear(sptep, spte); - - return orig.spte; -} - -/* - * The idea using the light way get the spte on x86_32 guest is from - * gup_get_pte (mm/gup.c). - * - * An spte tlb flush may be pending, because kvm_set_pte_rmap - * coalesces them and we are running out of the MMU lock. Therefore - * we need to protect against in-progress updates of the spte. - * - * Reading the spte while an update is in progress may get the old value - * for the high part of the spte. The race is fine for a present->non-present - * change (because the high part of the spte is ignored for non-present spte), - * but for a present->present change we must reread the spte. - * - * All such changes are done in two steps (present->non-present and - * non-present->present), hence it is enough to count the number of - * present->non-present updates: if it changed while reading the spte, - * we might have hit the race. This is done using clear_spte_count. - */ -static u64 __get_spte_lockless(u64 *sptep) -{ - struct kvm_mmu_page *sp = sptep_to_sp(sptep); - union split_spte spte, *orig = (union split_spte *)sptep; - int count; - -retry: - count = sp->clear_spte_count; - smp_rmb(); - - spte.spte_low = orig->spte_low; - smp_rmb(); - - spte.spte_high = orig->spte_high; - smp_rmb(); - - if (unlikely(spte.spte_low != orig->spte_low || - count != sp->clear_spte_count)) - goto retry; - - return spte.spte; -} -#endif - -/* Rules for using mmu_spte_set: - * Set the sptep from nonpresent to present. - * Note: the sptep being assigned *must* be either not present - * or in a state where the hardware will not attempt to update - * the spte. - */ -static void mmu_spte_set(u64 *sptep, u64 new_spte) -{ - WARN_ON(is_shadow_present_pte(*sptep)); - __set_spte(sptep, new_spte); -} - -/* - * Update the SPTE (excluding the PFN), but do not track changes in its - * accessed/dirty status. - */ -static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) -{ - u64 old_spte = *sptep; - - WARN_ON(!is_shadow_present_pte(new_spte)); - check_spte_writable_invariants(new_spte); - - if (!is_shadow_present_pte(old_spte)) { - mmu_spte_set(sptep, new_spte); - return old_spte; - } - - if (!spte_has_volatile_bits(old_spte)) - __update_clear_spte_fast(sptep, new_spte); - else - old_spte = __update_clear_spte_slow(sptep, new_spte); - - WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); - - return old_spte; -} - -/* Rules for using mmu_spte_update: - * Update the state bits, it means the mapped pfn is not changed. - * - * Whenever an MMU-writable SPTE is overwritten with a read-only SPTE, remote - * TLBs must be flushed. Otherwise rmap_write_protect will find a read-only - * spte, even though the writable spte might be cached on a CPU's TLB. - * - * Returns true if the TLB needs to be flushed - */ -static bool mmu_spte_update(u64 *sptep, u64 new_spte) -{ - bool flush = false; - u64 old_spte = mmu_spte_update_no_track(sptep, new_spte); - - if (!is_shadow_present_pte(old_spte)) - return false; - - /* - * For the spte updated out of mmu-lock is safe, since - * we always atomically update it, see the comments in - * spte_has_volatile_bits(). - */ - if (is_mmu_writable_spte(old_spte) && - !is_writable_pte(new_spte)) - flush = true; - - /* - * Flush TLB when accessed/dirty states are changed in the page tables, - * to guarantee consistency between TLB and page tables. - */ - - if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) { - flush = true; - kvm_set_pfn_accessed(spte_to_pfn(old_spte)); - } - - if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) { - flush = true; - kvm_set_pfn_dirty(spte_to_pfn(old_spte)); - } - - return flush; -} - -/* - * Rules for using mmu_spte_clear_track_bits: - * It sets the sptep from present to nonpresent, and track the - * state bits, it is used to clear the last level sptep. - * Returns the old PTE. - */ -static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) -{ - kvm_pfn_t pfn; - u64 old_spte = *sptep; - int level = sptep_to_sp(sptep)->role.level; - struct page *page; - - if (!is_shadow_present_pte(old_spte) || - !spte_has_volatile_bits(old_spte)) - __update_clear_spte_fast(sptep, 0ull); - else - old_spte = __update_clear_spte_slow(sptep, 0ull); - - if (!is_shadow_present_pte(old_spte)) - return old_spte; - - kvm_update_page_stats(kvm, level, -1); - - pfn = spte_to_pfn(old_spte); - - /* - * KVM doesn't hold a reference to any pages mapped into the guest, and - * instead uses the mmu_notifier to ensure that KVM unmaps any pages - * before they are reclaimed. Sanity check that, if the pfn is backed - * by a refcounted page, the refcount is elevated. - */ - page = kvm_pfn_to_refcounted_page(pfn); - WARN_ON(page && !page_count(page)); - - if (is_accessed_spte(old_spte)) - kvm_set_pfn_accessed(pfn); - - if (is_dirty_spte(old_spte)) - kvm_set_pfn_dirty(pfn); - - return old_spte; -} - -/* - * Rules for using mmu_spte_clear_no_track: - * Directly clear spte without caring the state bits of sptep, - * it is used to set the upper level spte. - */ -static void mmu_spte_clear_no_track(u64 *sptep) -{ - __update_clear_spte_fast(sptep, 0ull); -} - -static u64 mmu_spte_get_lockless(u64 *sptep) -{ - return __get_spte_lockless(sptep); -} - -/* Returns the Accessed status of the PTE and resets it at the same time. */ -static bool mmu_spte_age(u64 *sptep) -{ - u64 spte = mmu_spte_get_lockless(sptep); - - if (!is_accessed_spte(spte)) - return false; - - if (spte_ad_enabled(spte)) { - clear_bit((ffs(shadow_accessed_mask) - 1), - (unsigned long *)sptep); - } else { - /* - * Capture the dirty status of the page, so that it doesn't get - * lost when the SPTE is marked for access tracking. - */ - if (is_writable_pte(spte)) - kvm_set_pfn_dirty(spte_to_pfn(spte)); - - spte = mark_spte_for_access_track(spte); - mmu_spte_update_no_track(sptep, spte); - } - - return true; -} - void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) { if (is_tdp_mmu(vcpu->arch.mmu)) { @@ -670,77 +310,6 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache); } -static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc) -{ - kmem_cache_free(pte_list_desc_cache, pte_list_desc); -} - -static bool sp_has_gptes(struct kvm_mmu_page *sp); - -static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index) -{ - if (sp->role.passthrough) - return sp->gfn; - - if (!sp->role.direct) - return sp->shadowed_translation[index] >> PAGE_SHIFT; - - return sp->gfn + (index << ((sp->role.level - 1) * SPTE_LEVEL_BITS)); -} - -/* - * For leaf SPTEs, fetch the *guest* access permissions being shadowed. Note - * that the SPTE itself may have a more constrained access permissions that - * what the guest enforces. For example, a guest may create an executable - * huge PTE but KVM may disallow execution to mitigate iTLB multihit. - */ -static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index) -{ - if (sp_has_gptes(sp)) - return sp->shadowed_translation[index] & ACC_ALL; - - /* - * For direct MMUs (e.g. TDP or non-paging guests) or passthrough SPs, - * KVM is not shadowing any guest page tables, so the "guest access - * permissions" are just ACC_ALL. - * - * For direct SPs in indirect MMUs (shadow paging), i.e. when KVM - * is shadowing a guest huge page with small pages, the guest access - * permissions being shadowed are the access permissions of the huge - * page. - * - * In both cases, sp->role.access contains the correct access bits. - */ - return sp->role.access; -} - -static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index, - gfn_t gfn, unsigned int access) -{ - if (sp_has_gptes(sp)) { - sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access; - return; - } - - WARN_ONCE(access != kvm_mmu_page_get_access(sp, index), - "access mismatch under %s page %llx (expected %u, got %u)\n", - sp->role.passthrough ? "passthrough" : "direct", - sp->gfn, kvm_mmu_page_get_access(sp, index), access); - - WARN_ONCE(gfn != kvm_mmu_page_get_gfn(sp, index), - "gfn mismatch under %s page %llx (expected %llx, got %llx)\n", - sp->role.passthrough ? "passthrough" : "direct", - sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn); -} - -static void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, - unsigned int access) -{ - gfn_t gfn = kvm_mmu_page_get_gfn(sp, index); - - kvm_mmu_page_set_translation(sp, index, gfn, access); -} - /* * Return the pointer to the large page information for a given gfn, * handling slots that are not large page aligned. @@ -777,28 +346,6 @@ void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn) update_gfn_disallow_lpage_count(slot, gfn, -1); } -static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) -{ - struct kvm_memslots *slots; - struct kvm_memory_slot *slot; - gfn_t gfn; - - kvm->arch.indirect_shadow_pages++; - gfn = sp->gfn; - slots = kvm_memslots_for_spte_role(kvm, sp->role); - slot = __gfn_to_memslot(slots, gfn); - - /* the non-leaf shadow pages are keeping readonly. */ - if (sp->role.level > PG_LEVEL_4K) - return kvm_slot_page_track_add_page(kvm, slot, gfn, - KVM_PAGE_TRACK_WRITE); - - kvm_mmu_gfn_disallow_lpage(slot, gfn); - - if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K)) - kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); -} - void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp) { /* @@ -826,23 +373,6 @@ void account_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp, track_possible_nx_huge_page(kvm, sp); } -static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) -{ - struct kvm_memslots *slots; - struct kvm_memory_slot *slot; - gfn_t gfn; - - kvm->arch.indirect_shadow_pages--; - gfn = sp->gfn; - slots = kvm_memslots_for_spte_role(kvm, sp->role); - slot = __gfn_to_memslot(slots, gfn); - if (sp->role.level > PG_LEVEL_4K) - return kvm_slot_page_track_remove_page(kvm, slot, gfn, - KVM_PAGE_TRACK_WRITE); - - kvm_mmu_gfn_allow_lpage(slot, gfn); -} - void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp) { if (list_empty(&sp->possible_nx_huge_page_link)) @@ -873,437 +403,51 @@ struct kvm_memory_slot *gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, return slot; } -/* - * About rmap_head encoding: +/** + * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages + * @kvm: kvm instance + * @slot: slot to protect + * @gfn_offset: start of the BITS_PER_LONG pages we care about + * @mask: indicates which pages we should protect * - * If the bit zero of rmap_head->val is clear, then it points to the only spte - * in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct - * pte_list_desc containing more mappings. - */ - -/* - * Returns the number of pointers in the rmap chain, not counting the new one. + * Used when we do not need to care about huge page mappings. */ -static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte, - struct kvm_rmap_head *rmap_head) -{ - struct pte_list_desc *desc; - int count = 0; - - if (!rmap_head->val) { - rmap_printk("%p %llx 0->1\n", spte, *spte); - rmap_head->val = (unsigned long)spte; - } else if (!(rmap_head->val & 1)) { - rmap_printk("%p %llx 1->many\n", spte, *spte); - desc = kvm_mmu_memory_cache_alloc(cache); - desc->sptes[0] = (u64 *)rmap_head->val; - desc->sptes[1] = spte; - desc->spte_count = 2; - rmap_head->val = (unsigned long)desc | 1; - ++count; - } else { - rmap_printk("%p %llx many->many\n", spte, *spte); - desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); - while (desc->spte_count == PTE_LIST_EXT) { - count += PTE_LIST_EXT; - if (!desc->more) { - desc->more = kvm_mmu_memory_cache_alloc(cache); - desc = desc->more; - desc->spte_count = 0; - break; - } - desc = desc->more; - } - count += desc->spte_count; - desc->sptes[desc->spte_count++] = spte; - } - return count; -} - -static void -pte_list_desc_remove_entry(struct kvm_rmap_head *rmap_head, - struct pte_list_desc *desc, int i, - struct pte_list_desc *prev_desc) +static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) { - int j = desc->spte_count - 1; + struct kvm_rmap_head *rmap_head; + + if (is_tdp_mmu_enabled(kvm)) + kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, + slot->base_gfn + gfn_offset, mask, true); - desc->sptes[i] = desc->sptes[j]; - desc->sptes[j] = NULL; - desc->spte_count--; - if (desc->spte_count) + if (!kvm_memslots_have_rmaps(kvm)) return; - if (!prev_desc && !desc->more) - rmap_head->val = 0; - else - if (prev_desc) - prev_desc->more = desc->more; - else - rmap_head->val = (unsigned long)desc->more | 1; - mmu_free_pte_list_desc(desc); -} -static void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head) -{ - struct pte_list_desc *desc; - struct pte_list_desc *prev_desc; - int i; + while (mask) { + rmap_head = gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), + PG_LEVEL_4K, slot); + rmap_write_protect(rmap_head, false); - if (!rmap_head->val) { - pr_err("%s: %p 0->BUG\n", __func__, spte); - BUG(); - } else if (!(rmap_head->val & 1)) { - rmap_printk("%p 1->0\n", spte); - if ((u64 *)rmap_head->val != spte) { - pr_err("%s: %p 1->BUG\n", __func__, spte); - BUG(); - } - rmap_head->val = 0; - } else { - rmap_printk("%p many->many\n", spte); - desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); - prev_desc = NULL; - while (desc) { - for (i = 0; i < desc->spte_count; ++i) { - if (desc->sptes[i] == spte) { - pte_list_desc_remove_entry(rmap_head, - desc, i, prev_desc); - return; - } - } - prev_desc = desc; - desc = desc->more; - } - pr_err("%s: %p many->many\n", __func__, spte); - BUG(); + /* clear the first set bit */ + mask &= mask - 1; } } -static void kvm_zap_one_rmap_spte(struct kvm *kvm, - struct kvm_rmap_head *rmap_head, u64 *sptep) -{ - mmu_spte_clear_track_bits(kvm, sptep); - pte_list_remove(sptep, rmap_head); -} - -/* Return true if at least one SPTE was zapped, false otherwise */ -static bool kvm_zap_all_rmap_sptes(struct kvm *kvm, - struct kvm_rmap_head *rmap_head) -{ - struct pte_list_desc *desc, *next; - int i; - - if (!rmap_head->val) - return false; - - if (!(rmap_head->val & 1)) { - mmu_spte_clear_track_bits(kvm, (u64 *)rmap_head->val); - goto out; - } - - desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); - - for (; desc; desc = next) { - for (i = 0; i < desc->spte_count; i++) - mmu_spte_clear_track_bits(kvm, desc->sptes[i]); - next = desc->more; - mmu_free_pte_list_desc(desc); - } -out: - /* rmap_head is meaningless now, remember to reset it */ - rmap_head->val = 0; - return true; -} - -unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) -{ - struct pte_list_desc *desc; - unsigned int count = 0; - - if (!rmap_head->val) - return 0; - else if (!(rmap_head->val & 1)) - return 1; - - desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); - - while (desc) { - count += desc->spte_count; - desc = desc->more; - } - - return count; -} - -static struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level, - const struct kvm_memory_slot *slot) -{ - unsigned long idx; - - idx = gfn_to_index(gfn, slot->base_gfn, level); - return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; -} - -static bool rmap_can_add(struct kvm_vcpu *vcpu) -{ - struct kvm_mmu_memory_cache *mc; - - mc = &vcpu->arch.mmu_pte_list_desc_cache; - return kvm_mmu_memory_cache_nr_free_objects(mc); -} - -static void rmap_remove(struct kvm *kvm, u64 *spte) -{ - struct kvm_memslots *slots; - struct kvm_memory_slot *slot; - struct kvm_mmu_page *sp; - gfn_t gfn; - struct kvm_rmap_head *rmap_head; - - sp = sptep_to_sp(spte); - gfn = kvm_mmu_page_get_gfn(sp, spte_index(spte)); - - /* - * Unlike rmap_add, rmap_remove does not run in the context of a vCPU - * so we have to determine which memslots to use based on context - * information in sp->role. - */ - slots = kvm_memslots_for_spte_role(kvm, sp->role); - - slot = __gfn_to_memslot(slots, gfn); - rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); - - pte_list_remove(spte, rmap_head); -} - -/* - * Used by the following functions to iterate through the sptes linked by a - * rmap. All fields are private and not assumed to be used outside. - */ -struct rmap_iterator { - /* private fields */ - struct pte_list_desc *desc; /* holds the sptep if not NULL */ - int pos; /* index of the sptep */ -}; - -/* - * Iteration must be started by this function. This should also be used after - * removing/dropping sptes from the rmap link because in such cases the - * information in the iterator may not be valid. - * - * Returns sptep if found, NULL otherwise. - */ -static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head, - struct rmap_iterator *iter) -{ - u64 *sptep; - - if (!rmap_head->val) - return NULL; - - if (!(rmap_head->val & 1)) { - iter->desc = NULL; - sptep = (u64 *)rmap_head->val; - goto out; - } - - iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); - iter->pos = 0; - sptep = iter->desc->sptes[iter->pos]; -out: - BUG_ON(!is_shadow_present_pte(*sptep)); - return sptep; -} - -/* - * Must be used with a valid iterator: e.g. after rmap_get_first(). - * - * Returns sptep if found, NULL otherwise. - */ -static u64 *rmap_get_next(struct rmap_iterator *iter) -{ - u64 *sptep; - - if (iter->desc) { - if (iter->pos < PTE_LIST_EXT - 1) { - ++iter->pos; - sptep = iter->desc->sptes[iter->pos]; - if (sptep) - goto out; - } - - iter->desc = iter->desc->more; - - if (iter->desc) { - iter->pos = 0; - /* desc->sptes[0] cannot be NULL */ - sptep = iter->desc->sptes[iter->pos]; - goto out; - } - } - - return NULL; -out: - BUG_ON(!is_shadow_present_pte(*sptep)); - return sptep; -} - -#define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \ - for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \ - _spte_; _spte_ = rmap_get_next(_iter_)) - -static void drop_spte(struct kvm *kvm, u64 *sptep) -{ - u64 old_spte = mmu_spte_clear_track_bits(kvm, sptep); - - if (is_shadow_present_pte(old_spte)) - rmap_remove(kvm, sptep); -} - -static void drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush) -{ - struct kvm_mmu_page *sp; - - sp = sptep_to_sp(sptep); - WARN_ON(sp->role.level == PG_LEVEL_4K); - - drop_spte(kvm, sptep); - - if (flush) - kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, - KVM_PAGES_PER_HPAGE(sp->role.level)); -} - -/* - * Write-protect on the specified @sptep, @pt_protect indicates whether - * spte write-protection is caused by protecting shadow page table. - * - * Note: write protection is difference between dirty logging and spte - * protection: - * - for dirty logging, the spte can be set to writable at anytime if - * its dirty bitmap is properly set. - * - for spte protection, the spte can be writable only after unsync-ing - * shadow page. - * - * Return true if tlb need be flushed. - */ -static bool spte_write_protect(u64 *sptep, bool pt_protect) -{ - u64 spte = *sptep; - - if (!is_writable_pte(spte) && - !(pt_protect && is_mmu_writable_spte(spte))) - return false; - - rmap_printk("spte %p %llx\n", sptep, *sptep); - - if (pt_protect) - spte &= ~shadow_mmu_writable_mask; - spte = spte & ~PT_WRITABLE_MASK; - - return mmu_spte_update(sptep, spte); -} - -static bool rmap_write_protect(struct kvm_rmap_head *rmap_head, - bool pt_protect) -{ - u64 *sptep; - struct rmap_iterator iter; - bool flush = false; - - for_each_rmap_spte(rmap_head, &iter, sptep) - flush |= spte_write_protect(sptep, pt_protect); - - return flush; -} - -static bool spte_clear_dirty(u64 *sptep) -{ - u64 spte = *sptep; - - rmap_printk("spte %p %llx\n", sptep, *sptep); - - MMU_WARN_ON(!spte_ad_enabled(spte)); - spte &= ~shadow_dirty_mask; - return mmu_spte_update(sptep, spte); -} - -static bool spte_wrprot_for_clear_dirty(u64 *sptep) -{ - bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, - (unsigned long *)sptep); - if (was_writable && !spte_ad_enabled(*sptep)) - kvm_set_pfn_dirty(spte_to_pfn(*sptep)); - - return was_writable; -} - -/* - * Gets the GFN ready for another round of dirty logging by clearing the - * - D bit on ad-enabled SPTEs, and - * - W bit on ad-disabled SPTEs. - * Returns true iff any D or W bits were cleared. - */ -static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - const struct kvm_memory_slot *slot) -{ - u64 *sptep; - struct rmap_iterator iter; - bool flush = false; - - for_each_rmap_spte(rmap_head, &iter, sptep) - if (spte_ad_need_write_protect(*sptep)) - flush |= spte_wrprot_for_clear_dirty(sptep); - else - flush |= spte_clear_dirty(sptep); - - return flush; -} - -/** - * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages - * @kvm: kvm instance - * @slot: slot to protect - * @gfn_offset: start of the BITS_PER_LONG pages we care about - * @mask: indicates which pages we should protect - * - * Used when we do not need to care about huge page mappings. - */ -static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, - struct kvm_memory_slot *slot, - gfn_t gfn_offset, unsigned long mask) -{ - struct kvm_rmap_head *rmap_head; - - if (is_tdp_mmu_enabled(kvm)) - kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, - slot->base_gfn + gfn_offset, mask, true); - - if (!kvm_memslots_have_rmaps(kvm)) - return; - - while (mask) { - rmap_head = gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), - PG_LEVEL_4K, slot); - rmap_write_protect(rmap_head, false); - - /* clear the first set bit */ - mask &= mask - 1; - } -} - -/** - * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write - * protect the page if the D-bit isn't supported. - * @kvm: kvm instance - * @slot: slot to clear D-bit - * @gfn_offset: start of the BITS_PER_LONG pages we care about - * @mask: indicates which pages we should clear D-bit - * - * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap. - */ -static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, - struct kvm_memory_slot *slot, - gfn_t gfn_offset, unsigned long mask) +/** + * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write + * protect the page if the D-bit isn't supported. + * @kvm: kvm instance + * @slot: slot to clear D-bit + * @gfn_offset: start of the BITS_PER_LONG pages we care about + * @mask: indicates which pages we should clear D-bit + * + * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap. + */ +static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) { struct kvm_rmap_head *rmap_head; @@ -1405,147 +549,6 @@ bool kvm_vcpu_write_protect_gfn(struct kvm_vcpu *vcpu, u64 gfn) return kvm_mmu_slot_gfn_write_protect(vcpu->kvm, slot, gfn, PG_LEVEL_4K); } -static bool __kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - const struct kvm_memory_slot *slot) -{ - return kvm_zap_all_rmap_sptes(kvm, rmap_head); -} - -static bool kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, int level, - pte_t unused) -{ - return __kvm_zap_rmap(kvm, rmap_head, slot); -} - -static bool kvm_set_pte_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, int level, - pte_t pte) -{ - u64 *sptep; - struct rmap_iterator iter; - bool need_flush = false; - u64 new_spte; - kvm_pfn_t new_pfn; - - WARN_ON(pte_huge(pte)); - new_pfn = pte_pfn(pte); - -restart: - for_each_rmap_spte(rmap_head, &iter, sptep) { - rmap_printk("spte %p %llx gfn %llx (%d)\n", - sptep, *sptep, gfn, level); - - need_flush = true; - - if (pte_write(pte)) { - kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); - goto restart; - } else { - new_spte = kvm_mmu_changed_pte_notifier_make_spte( - *sptep, new_pfn); - - mmu_spte_clear_track_bits(kvm, sptep); - mmu_spte_set(sptep, new_spte); - } - } - - if (need_flush && kvm_available_flush_tlb_with_range()) { - kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); - return false; - } - - return need_flush; -} - -struct slot_rmap_walk_iterator { - /* input fields. */ - const struct kvm_memory_slot *slot; - gfn_t start_gfn; - gfn_t end_gfn; - int start_level; - int end_level; - - /* output fields. */ - gfn_t gfn; - struct kvm_rmap_head *rmap; - int level; - - /* private field. */ - struct kvm_rmap_head *end_rmap; -}; - -static void -rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level) -{ - iterator->level = level; - iterator->gfn = iterator->start_gfn; - iterator->rmap = gfn_to_rmap(iterator->gfn, level, iterator->slot); - iterator->end_rmap = gfn_to_rmap(iterator->end_gfn, level, iterator->slot); -} - -static void -slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator, - const struct kvm_memory_slot *slot, int start_level, - int end_level, gfn_t start_gfn, gfn_t end_gfn) -{ - iterator->slot = slot; - iterator->start_level = start_level; - iterator->end_level = end_level; - iterator->start_gfn = start_gfn; - iterator->end_gfn = end_gfn; - - rmap_walk_init_level(iterator, iterator->start_level); -} - -static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator) -{ - return !!iterator->rmap; -} - -static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) -{ - while (++iterator->rmap <= iterator->end_rmap) { - iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level)); - - if (iterator->rmap->val) - return; - } - - if (++iterator->level > iterator->end_level) { - iterator->rmap = NULL; - return; - } - - rmap_walk_init_level(iterator, iterator->level); -} - -#define for_each_slot_rmap_range(_slot_, _start_level_, _end_level_, \ - _start_gfn, _end_gfn, _iter_) \ - for (slot_rmap_walk_init(_iter_, _slot_, _start_level_, \ - _end_level_, _start_gfn, _end_gfn); \ - slot_rmap_walk_okay(_iter_); \ - slot_rmap_walk_next(_iter_)) - -typedef bool (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, - int level, pte_t pte); - -static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm, - struct kvm_gfn_range *range, - rmap_handler_t handler) -{ - struct slot_rmap_walk_iterator iterator; - bool ret = false; - - for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, - range->start, range->end - 1, &iterator) - ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn, - iterator.level, range->pte); - - return ret; -} - bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) { bool flush = false; @@ -1572,2392 +575,596 @@ bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) return flush; } -static bool kvm_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, int level, - pte_t unused) +bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { - u64 *sptep; - struct rmap_iterator iter; - int young = 0; - - for_each_rmap_spte(rmap_head, &iter, sptep) - young |= mmu_spte_age(sptep); + bool young = false; - return young; -} + if (kvm_memslots_have_rmaps(kvm)) + young = kvm_handle_gfn_range(kvm, range, kvm_age_rmap); -static bool kvm_test_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, - int level, pte_t unused) -{ - u64 *sptep; - struct rmap_iterator iter; + if (is_tdp_mmu_enabled(kvm)) + young |= kvm_tdp_mmu_age_gfn_range(kvm, range); - for_each_rmap_spte(rmap_head, &iter, sptep) - if (is_accessed_spte(*sptep)) - return true; - return false; + return young; } -#define RMAP_RECYCLE_THRESHOLD 1000 - -static void __rmap_add(struct kvm *kvm, - struct kvm_mmu_memory_cache *cache, - const struct kvm_memory_slot *slot, - u64 *spte, gfn_t gfn, unsigned int access) +bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { - struct kvm_mmu_page *sp; - struct kvm_rmap_head *rmap_head; - int rmap_count; + bool young = false; - sp = sptep_to_sp(spte); - kvm_mmu_page_set_translation(sp, spte_index(spte), gfn, access); - kvm_update_page_stats(kvm, sp->role.level, 1); + if (kvm_memslots_have_rmaps(kvm)) + young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmap); - rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); - rmap_count = pte_list_add(cache, spte, rmap_head); + if (is_tdp_mmu_enabled(kvm)) + young |= kvm_tdp_mmu_test_age_gfn(kvm, range); - if (rmap_count > kvm->stat.max_mmu_rmap_size) - kvm->stat.max_mmu_rmap_size = rmap_count; - if (rmap_count > RMAP_RECYCLE_THRESHOLD) { - kvm_zap_all_rmap_sptes(kvm, rmap_head); - kvm_flush_remote_tlbs_with_address( - kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level)); - } + return young; } -static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot, - u64 *spte, gfn_t gfn, unsigned int access) +bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, struct list_head *invalid_list, + bool remote_flush) { - struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache; + if (!remote_flush && list_empty(invalid_list)) + return false; - __rmap_add(vcpu->kvm, cache, slot, spte, gfn, access); + if (!list_empty(invalid_list)) + kvm_mmu_commit_zap_page(kvm, invalid_list); + else + kvm_flush_remote_tlbs(kvm); + return true; } -bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) { - bool young = false; - - if (kvm_memslots_have_rmaps(kvm)) - young = kvm_handle_gfn_range(kvm, range, kvm_age_rmap); - - if (is_tdp_mmu_enabled(kvm)) - young |= kvm_tdp_mmu_age_gfn_range(kvm, range); + if (sp->role.invalid) + return true; - return young; + /* TDP MMU pages do not use the MMU generation. */ + return !sp->tdp_mmu_page && + unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen); } -bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +/* + * Lookup the mapping level for @gfn in the current mm. + * + * WARNING! Use of host_pfn_mapping_level() requires the caller and the end + * consumer to be tied into KVM's handlers for MMU notifier events! + * + * There are several ways to safely use this helper: + * + * - Check mmu_invalidate_retry_hva() after grabbing the mapping level, before + * consuming it. In this case, mmu_lock doesn't need to be held during the + * lookup, but it does need to be held while checking the MMU notifier. + * + * - Hold mmu_lock AND ensure there is no in-progress MMU notifier invalidation + * event for the hva. This can be done by explicit checking the MMU notifier + * or by ensuring that KVM already has a valid mapping that covers the hva. + * + * - Do not use the result to install new mappings, e.g. use the host mapping + * level only to decide whether or not to zap an entry. In this case, it's + * not required to hold mmu_lock (though it's highly likely the caller will + * want to hold mmu_lock anyways, e.g. to modify SPTEs). + * + * Note! The lookup can still race with modifications to host page tables, but + * the above "rules" ensure KVM will not _consume_ the result of the walk if a + * race with the primary MMU occurs. + */ +static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, + const struct kvm_memory_slot *slot) { - bool young = false; + int level = PG_LEVEL_4K; + unsigned long hva; + unsigned long flags; + pgd_t pgd; + p4d_t p4d; + pud_t pud; + pmd_t pmd; - if (kvm_memslots_have_rmaps(kvm)) - young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmap); + /* + * Note, using the already-retrieved memslot and __gfn_to_hva_memslot() + * is not solely for performance, it's also necessary to avoid the + * "writable" check in __gfn_to_hva_many(), which will always fail on + * read-only memslots due to gfn_to_hva() assuming writes. Earlier + * page fault steps have already verified the guest isn't writing a + * read-only memslot. + */ + hva = __gfn_to_hva_memslot(slot, gfn); - if (is_tdp_mmu_enabled(kvm)) - young |= kvm_tdp_mmu_test_age_gfn(kvm, range); + /* + * Disable IRQs to prevent concurrent tear down of host page tables, + * e.g. if the primary MMU promotes a P*D to a huge page and then frees + * the original page table. + */ + local_irq_save(flags); - return young; -} + /* + * Read each entry once. As above, a non-leaf entry can be promoted to + * a huge page _during_ this walk. Re-reading the entry could send the + * walk into the weeks, e.g. p*d_large() returns false (sees the old + * value) and then p*d_offset() walks into the target huge page instead + * of the old page table (sees the new value). + */ + pgd = READ_ONCE(*pgd_offset(kvm->mm, hva)); + if (pgd_none(pgd)) + goto out; -#ifdef MMU_DEBUG -static int is_empty_shadow_page(u64 *spt) -{ - u64 *pos; - u64 *end; + p4d = READ_ONCE(*p4d_offset(&pgd, hva)); + if (p4d_none(p4d) || !p4d_present(p4d)) + goto out; - for (pos = spt, end = pos + SPTE_ENT_PER_PAGE; pos != end; pos++) - if (is_shadow_present_pte(*pos)) { - printk(KERN_ERR "%s: %p %llx\n", __func__, - pos, *pos); - return 0; - } - return 1; -} -#endif + pud = READ_ONCE(*pud_offset(&p4d, hva)); + if (pud_none(pud) || !pud_present(pud)) + goto out; -/* - * This value is the sum of all of the kvm instances's - * kvm->arch.n_used_mmu_pages values. We need a global, - * aggregate version in order to make the slab shrinker - * faster - */ -static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr) -{ - kvm->arch.n_used_mmu_pages += nr; - percpu_counter_add(&kvm_total_used_mmu_pages, nr); -} + if (pud_large(pud)) { + level = PG_LEVEL_1G; + goto out; + } -static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) -{ - kvm_mod_used_mmu_pages(kvm, +1); - kvm_account_pgtable_pages((void *)sp->spt, +1); -} + pmd = READ_ONCE(*pmd_offset(&pud, hva)); + if (pmd_none(pmd) || !pmd_present(pmd)) + goto out; -static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) -{ - kvm_mod_used_mmu_pages(kvm, -1); - kvm_account_pgtable_pages((void *)sp->spt, -1); -} + if (pmd_large(pmd)) + level = PG_LEVEL_2M; -static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp) -{ - MMU_WARN_ON(!is_empty_shadow_page(sp->spt)); - hlist_del(&sp->hash_link); - list_del(&sp->link); - free_page((unsigned long)sp->spt); - if (!sp->role.direct) - free_page((unsigned long)sp->shadowed_translation); - kmem_cache_free(mmu_page_header_cache, sp); +out: + local_irq_restore(flags); + return level; } -static unsigned kvm_page_table_hashfn(gfn_t gfn) +int kvm_mmu_max_mapping_level(struct kvm *kvm, + const struct kvm_memory_slot *slot, gfn_t gfn, + int max_level) { - return hash_64(gfn, KVM_MMU_HASH_SHIFT); -} + struct kvm_lpage_info *linfo; + int host_level; -static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache, - struct kvm_mmu_page *sp, u64 *parent_pte) -{ - if (!parent_pte) - return; + max_level = min(max_level, max_huge_page_level); + for ( ; max_level > PG_LEVEL_4K; max_level--) { + linfo = lpage_info_slot(gfn, slot, max_level); + if (!linfo->disallow_lpage) + break; + } - pte_list_add(cache, parent_pte, &sp->parent_ptes); -} + if (max_level == PG_LEVEL_4K) + return PG_LEVEL_4K; -static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, - u64 *parent_pte) -{ - pte_list_remove(parent_pte, &sp->parent_ptes); + host_level = host_pfn_mapping_level(kvm, gfn, slot); + return min(host_level, max_level); } -static void drop_parent_pte(struct kvm_mmu_page *sp, - u64 *parent_pte) +void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { - mmu_page_remove_parent_pte(sp, parent_pte); - mmu_spte_clear_no_track(parent_pte); -} + struct kvm_memory_slot *slot = fault->slot; + kvm_pfn_t mask; -static void mark_unsync(u64 *spte); -static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) -{ - u64 *sptep; - struct rmap_iterator iter; + fault->huge_page_disallowed = fault->exec && fault->nx_huge_page_workaround_enabled; - for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) { - mark_unsync(sptep); - } -} + if (unlikely(fault->max_level == PG_LEVEL_4K)) + return; -static void mark_unsync(u64 *spte) -{ - struct kvm_mmu_page *sp; + if (is_error_noslot_pfn(fault->pfn)) + return; - sp = sptep_to_sp(spte); - if (__test_and_set_bit(spte_index(spte), sp->unsync_child_bitmap)) + if (kvm_slot_dirty_track_enabled(slot)) return; - if (sp->unsync_children++) + + /* + * Enforce the iTLB multihit workaround after capturing the requested + * level, which will be used to do precise, accurate accounting. + */ + fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, + fault->gfn, fault->max_level); + if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) return; - kvm_mmu_mark_parents_unsync(sp); -} -static int nonpaging_sync_page(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *sp) -{ - return -1; + /* + * mmu_invalidate_retry() was successful and mmu_lock is held, so + * the pmd can't be split from under us. + */ + fault->goal_level = fault->req_level; + mask = KVM_PAGES_PER_HPAGE(fault->goal_level) - 1; + VM_BUG_ON((fault->gfn & mask) != (fault->pfn & mask)); + fault->pfn &= ~mask; } -#define KVM_PAGE_ARRAY_NR 16 - -struct kvm_mmu_pages { - struct mmu_page_and_offset { - struct kvm_mmu_page *sp; - unsigned int idx; - } page[KVM_PAGE_ARRAY_NR]; - unsigned int nr; -}; - -static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp, - int idx) +void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level) { - int i; - - if (sp->unsync) - for (i=0; i < pvec->nr; i++) - if (pvec->page[i].sp == sp) - return 0; - - pvec->page[pvec->nr].sp = sp; - pvec->page[pvec->nr].idx = idx; - pvec->nr++; - return (pvec->nr == KVM_PAGE_ARRAY_NR); + if (cur_level > PG_LEVEL_4K && + cur_level == fault->goal_level && + is_shadow_present_pte(spte) && + !is_large_pte(spte) && + spte_to_child_sp(spte)->nx_huge_page_disallowed) { + /* + * A small SPTE exists for this pfn, but FNAME(fetch) + * and __direct_map would like to create a large PTE + * instead: just force them to go down another level, + * patching back for them into pfn the next 9 bits of + * the address. + */ + u64 page_mask = KVM_PAGES_PER_HPAGE(cur_level) - + KVM_PAGES_PER_HPAGE(cur_level - 1); + fault->pfn |= fault->gfn & page_mask; + fault->goal_level--; + } } -static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx) +static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk) { - --sp->unsync_children; - WARN_ON((int)sp->unsync_children < 0); - __clear_bit(idx, sp->unsync_child_bitmap); + send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, PAGE_SHIFT, tsk); } -static int __mmu_unsync_walk(struct kvm_mmu_page *sp, - struct kvm_mmu_pages *pvec) +static int kvm_handle_error_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) { - int i, ret, nr_unsync_leaf = 0; - - for_each_set_bit(i, sp->unsync_child_bitmap, 512) { - struct kvm_mmu_page *child; - u64 ent = sp->spt[i]; + if (is_sigpending_pfn(pfn)) { + kvm_handle_signal_exit(vcpu); + return -EINTR; + } - if (!is_shadow_present_pte(ent) || is_large_pte(ent)) { - clear_unsync_child_bit(sp, i); - continue; - } + /* + * Do not cache the mmio info caused by writing the readonly gfn + * into the spte otherwise read access on readonly gfn also can + * caused mmio page fault and treat it as mmio access. + */ + if (pfn == KVM_PFN_ERR_RO_FAULT) + return RET_PF_EMULATE; - child = spte_to_child_sp(ent); - - if (child->unsync_children) { - if (mmu_pages_add(pvec, child, i)) - return -ENOSPC; - - ret = __mmu_unsync_walk(child, pvec); - if (!ret) { - clear_unsync_child_bit(sp, i); - continue; - } else if (ret > 0) { - nr_unsync_leaf += ret; - } else - return ret; - } else if (child->unsync) { - nr_unsync_leaf++; - if (mmu_pages_add(pvec, child, i)) - return -ENOSPC; - } else - clear_unsync_child_bit(sp, i); + if (pfn == KVM_PFN_ERR_HWPOISON) { + kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current); + return RET_PF_RETRY; } - return nr_unsync_leaf; + return -EFAULT; } -#define INVALID_INDEX (-1) - -static int mmu_unsync_walk(struct kvm_mmu_page *sp, - struct kvm_mmu_pages *pvec) +static int handle_abnormal_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, + unsigned int access) { - pvec->nr = 0; - if (!sp->unsync_children) - return 0; + /* The pfn is invalid, report the error! */ + if (unlikely(is_error_pfn(fault->pfn))) + return kvm_handle_error_pfn(vcpu, fault->gfn, fault->pfn); - mmu_pages_add(pvec, sp, INVALID_INDEX); - return __mmu_unsync_walk(sp, pvec); -} + if (unlikely(!fault->slot)) { + gva_t gva = fault->is_tdp ? 0 : fault->addr; -static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) -{ - WARN_ON(!sp->unsync); - trace_kvm_mmu_sync_page(sp); - sp->unsync = 0; - --kvm->stat.mmu_unsync; -} + vcpu_cache_mmio_info(vcpu, gva, fault->gfn, + access & shadow_mmio_access_mask); + /* + * If MMIO caching is disabled, emulate immediately without + * touching the shadow page tables as attempting to install an + * MMIO SPTE will just be an expensive nop. Do not cache MMIO + * whose gfn is greater than host.MAXPHYADDR, any guest that + * generates such gfns is running nested and is being tricked + * by L0 userspace (you can observe gfn > L1.MAXPHYADDR if + * and only if L1's MAXPHYADDR is inaccurate with respect to + * the hardware's). + */ + if (unlikely(!enable_mmio_caching) || + unlikely(fault->gfn > kvm_mmu_max_gfn())) + return RET_PF_EMULATE; + } -static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, - struct list_head *invalid_list); -static void kvm_mmu_commit_zap_page(struct kvm *kvm, - struct list_head *invalid_list); + return RET_PF_CONTINUE; +} -static bool sp_has_gptes(struct kvm_mmu_page *sp) +static bool page_fault_can_be_fast(struct kvm_page_fault *fault) { - if (sp->role.direct) - return false; - - if (sp->role.passthrough) + /* + * Page faults with reserved bits set, i.e. faults on MMIO SPTEs, only + * reach the common page fault handler if the SPTE has an invalid MMIO + * generation number. Refreshing the MMIO generation needs to go down + * the slow path. Note, EPT Misconfigs do NOT set the PRESENT flag! + */ + if (fault->rsvd) return false; - return true; -} - -#define for_each_valid_sp(_kvm, _sp, _list) \ - hlist_for_each_entry(_sp, _list, hash_link) \ - if (is_obsolete_sp((_kvm), (_sp))) { \ - } else - -#define for_each_gfn_valid_sp_with_gptes(_kvm, _sp, _gfn) \ - for_each_valid_sp(_kvm, _sp, \ - &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ - if ((_sp)->gfn != (_gfn) || !sp_has_gptes(_sp)) {} else - -static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, - struct list_head *invalid_list) -{ - int ret = vcpu->arch.mmu->sync_page(vcpu, sp); + /* + * #PF can be fast if: + * + * 1. The shadow page table entry is not present and A/D bits are + * disabled _by KVM_, which could mean that the fault is potentially + * caused by access tracking (if enabled). If A/D bits are enabled + * by KVM, but disabled by L1 for L2, KVM is forced to disable A/D + * bits for L2 and employ access tracking, but the fast page fault + * mechanism only supports direct MMUs. + * 2. The shadow page table entry is present, the access is a write, + * and no reserved bits are set (MMIO SPTEs cannot be "fixed"), i.e. + * the fault was caused by a write-protection violation. If the + * SPTE is MMU-writable (determined later), the fault can be fixed + * by setting the Writable bit, which can be done out of mmu_lock. + */ + if (!fault->present) + return !kvm_ad_enabled(); - if (ret < 0) - kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list); - return ret; + /* + * Note, instruction fetches and writes are mutually exclusive, ignore + * the "exec" flag. + */ + return fault->write; } -bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, struct list_head *invalid_list, - bool remote_flush) +/* + * Returns true if the SPTE was fixed successfully. Otherwise, + * someone else modified the SPTE from its original value. + */ +static bool +fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, + u64 *sptep, u64 old_spte, u64 new_spte) { - if (!remote_flush && list_empty(invalid_list)) + /* + * Theoretically we could also set dirty bit (and flush TLB) here in + * order to eliminate unnecessary PML logging. See comments in + * set_spte. But fast_page_fault is very unlikely to happen with PML + * enabled, so we do not do this. This might result in the same GPA + * to be logged in PML buffer again when the write really happens, and + * eventually to be called by mark_page_dirty twice. But it's also no + * harm. This also avoids the TLB flush needed after setting dirty bit + * so non-PML cases won't be impacted. + * + * Compare with set_spte where instead shadow_dirty_mask is set. + */ + if (!try_cmpxchg64(sptep, &old_spte, new_spte)) return false; - if (!list_empty(invalid_list)) - kvm_mmu_commit_zap_page(kvm, invalid_list); - else - kvm_flush_remote_tlbs(kvm); - return true; -} - -bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) -{ - if (sp->role.invalid) - return true; + if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) + mark_page_dirty_in_slot(vcpu->kvm, fault->slot, fault->gfn); - /* TDP MMU pages do not use the MMU generation. */ - return !sp->tdp_mmu_page && - unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen); + return true; } -struct mmu_page_path { - struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL]; - unsigned int idx[PT64_ROOT_MAX_LEVEL]; -}; - -#define for_each_sp(pvec, sp, parents, i) \ - for (i = mmu_pages_first(&pvec, &parents); \ - i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \ - i = mmu_pages_next(&pvec, &parents, i)) - -static int mmu_pages_next(struct kvm_mmu_pages *pvec, - struct mmu_page_path *parents, - int i) +static bool is_access_allowed(struct kvm_page_fault *fault, u64 spte) { - int n; - - for (n = i+1; n < pvec->nr; n++) { - struct kvm_mmu_page *sp = pvec->page[n].sp; - unsigned idx = pvec->page[n].idx; - int level = sp->role.level; - - parents->idx[level-1] = idx; - if (level == PG_LEVEL_4K) - break; + if (fault->exec) + return is_executable_pte(spte); - parents->parent[level-2] = sp; - } + if (fault->write) + return is_writable_pte(spte); - return n; + /* Fault was on Read access */ + return spte & PT_PRESENT_MASK; } -static int mmu_pages_first(struct kvm_mmu_pages *pvec, - struct mmu_page_path *parents) +/* + * Returns one of RET_PF_INVALID, RET_PF_FIXED or RET_PF_SPURIOUS. + */ +static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { struct kvm_mmu_page *sp; - int level; - - if (pvec->nr == 0) - return 0; - - WARN_ON(pvec->page[0].idx != INVALID_INDEX); - - sp = pvec->page[0].sp; - level = sp->role.level; - WARN_ON(level == PG_LEVEL_4K); - - parents->parent[level-2] = sp; + int ret = RET_PF_INVALID; + u64 spte = 0ull; + u64 *sptep = NULL; + uint retry_count = 0; - /* Also set up a sentinel. Further entries in pvec are all - * children of sp, so this element is never overwritten. - */ - parents->parent[level-1] = NULL; - return mmu_pages_next(pvec, parents, 0); -} + if (!page_fault_can_be_fast(fault)) + return ret; -static void mmu_pages_clear_parents(struct mmu_page_path *parents) -{ - struct kvm_mmu_page *sp; - unsigned int level = 0; + walk_shadow_page_lockless_begin(vcpu); do { - unsigned int idx = parents->idx[level]; - sp = parents->parent[level]; - if (!sp) - return; - - WARN_ON(idx == INVALID_INDEX); - clear_unsync_child_bit(sp, idx); - level++; - } while (!sp->unsync_children); -} - -static int mmu_sync_children(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *parent, bool can_yield) -{ - int i; - struct kvm_mmu_page *sp; - struct mmu_page_path parents; - struct kvm_mmu_pages pages; - LIST_HEAD(invalid_list); - bool flush = false; - - while (mmu_unsync_walk(parent, &pages)) { - bool protected = false; - - for_each_sp(pages, sp, parents, i) - protected |= kvm_vcpu_write_protect_gfn(vcpu, sp->gfn); - - if (protected) { - kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, true); - flush = false; - } - - for_each_sp(pages, sp, parents, i) { - kvm_unlink_unsync_page(vcpu->kvm, sp); - flush |= kvm_sync_page(vcpu, sp, &invalid_list) > 0; - mmu_pages_clear_parents(&parents); - } - if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) { - kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); - if (!can_yield) { - kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); - return -EINTR; - } - - cond_resched_rwlock_write(&vcpu->kvm->mmu_lock); - flush = false; - } - } - - kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); - return 0; -} + u64 new_spte; -static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) -{ - atomic_set(&sp->write_flooding_count, 0); -} + if (is_tdp_mmu(vcpu->arch.mmu)) + sptep = kvm_tdp_mmu_fast_pf_get_last_sptep(vcpu, fault->addr, &spte); + else + sptep = fast_pf_get_last_sptep(vcpu, fault->addr, &spte); -static void clear_sp_write_flooding_count(u64 *spte) -{ - __clear_sp_write_flooding_count(sptep_to_sp(spte)); -} + if (!is_shadow_present_pte(spte)) + break; -/* - * The vCPU is required when finding indirect shadow pages; the shadow - * page may already exist and syncing it needs the vCPU pointer in - * order to read guest page tables. Direct shadow pages are never - * unsync, thus @vcpu can be NULL if @role.direct is true. - */ -static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm, - struct kvm_vcpu *vcpu, - gfn_t gfn, - struct hlist_head *sp_list, - union kvm_mmu_page_role role) -{ - struct kvm_mmu_page *sp; - int ret; - int collisions = 0; - LIST_HEAD(invalid_list); + sp = sptep_to_sp(sptep); + if (!is_last_spte(spte, sp->role.level)) + break; - for_each_valid_sp(kvm, sp, sp_list) { - if (sp->gfn != gfn) { - collisions++; - continue; + /* + * Check whether the memory access that caused the fault would + * still cause it if it were to be performed right now. If not, + * then this is a spurious fault caused by TLB lazily flushed, + * or some other CPU has already fixed the PTE after the + * current CPU took the fault. + * + * Need not check the access of upper level table entries since + * they are always ACC_ALL. + */ + if (is_access_allowed(fault, spte)) { + ret = RET_PF_SPURIOUS; + break; } - if (sp->role.word != role.word) { - /* - * If the guest is creating an upper-level page, zap - * unsync pages for the same gfn. While it's possible - * the guest is using recursive page tables, in all - * likelihood the guest has stopped using the unsync - * page and is installing a completely unrelated page. - * Unsync pages must not be left as is, because the new - * upper-level page will be write-protected. - */ - if (role.level > PG_LEVEL_4K && sp->unsync) - kvm_mmu_prepare_zap_page(kvm, sp, - &invalid_list); - continue; - } + new_spte = spte; - /* unsync and write-flooding only apply to indirect SPs. */ - if (sp->role.direct) - goto out; + /* + * KVM only supports fixing page faults outside of MMU lock for + * direct MMUs, nested MMUs are always indirect, and KVM always + * uses A/D bits for non-nested MMUs. Thus, if A/D bits are + * enabled, the SPTE can't be an access-tracked SPTE. + */ + if (unlikely(!kvm_ad_enabled()) && is_access_track_spte(spte)) + new_spte = restore_acc_track_spte(new_spte); - if (sp->unsync) { - if (KVM_BUG_ON(!vcpu, kvm)) - break; + /* + * To keep things simple, only SPTEs that are MMU-writable can + * be made fully writable outside of mmu_lock, e.g. only SPTEs + * that were write-protected for dirty-logging or access + * tracking are handled here. Don't bother checking if the + * SPTE is writable to prioritize running with A/D bits enabled. + * The is_access_allowed() check above handles the common case + * of the fault being spurious, and the SPTE is known to be + * shadow-present, i.e. except for access tracking restoration + * making the new SPTE writable, the check is wasteful. + */ + if (fault->write && is_mmu_writable_spte(spte)) { + new_spte |= PT_WRITABLE_MASK; /* - * The page is good, but is stale. kvm_sync_page does - * get the latest guest state, but (unlike mmu_unsync_children) - * it doesn't write-protect the page or mark it synchronized! - * This way the validity of the mapping is ensured, but the - * overhead of write protection is not incurred until the - * guest invalidates the TLB mapping. This allows multiple - * SPs for a single gfn to be unsync. + * Do not fix write-permission on the large spte when + * dirty logging is enabled. Since we only dirty the + * first page into the dirty-bitmap in + * fast_pf_fix_direct_spte(), other pages are missed + * if its slot has dirty logging enabled. * - * If the sync fails, the page is zapped. If so, break - * in order to rebuild it. + * Instead, we let the slow page fault path create a + * normal spte to fix the access. */ - ret = kvm_sync_page(vcpu, sp, &invalid_list); - if (ret < 0) + if (sp->role.level > PG_LEVEL_4K && + kvm_slot_dirty_track_enabled(fault->slot)) break; - - WARN_ON(!list_empty(&invalid_list)); - if (ret > 0) - kvm_flush_remote_tlbs(kvm); } - __clear_sp_write_flooding_count(sp); - - goto out; - } - - sp = NULL; - ++kvm->stat.mmu_cache_miss; - -out: - kvm_mmu_commit_zap_page(kvm, &invalid_list); - - if (collisions > kvm->stat.max_mmu_page_hash_collisions) - kvm->stat.max_mmu_page_hash_collisions = collisions; - return sp; -} - -/* Caches used when allocating a new shadow page. */ -struct shadow_page_caches { - struct kvm_mmu_memory_cache *page_header_cache; - struct kvm_mmu_memory_cache *shadow_page_cache; - struct kvm_mmu_memory_cache *shadowed_info_cache; -}; - -static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm, - struct shadow_page_caches *caches, - gfn_t gfn, - struct hlist_head *sp_list, - union kvm_mmu_page_role role) -{ - struct kvm_mmu_page *sp; - - sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache); - sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache); - if (!role.direct) - sp->shadowed_translation = kvm_mmu_memory_cache_alloc(caches->shadowed_info_cache); - - set_page_private(virt_to_page(sp->spt), (unsigned long)sp); - - INIT_LIST_HEAD(&sp->possible_nx_huge_page_link); - - /* - * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() - * depends on valid pages being added to the head of the list. See - * comments in kvm_zap_obsolete_pages(). - */ - sp->mmu_valid_gen = kvm->arch.mmu_valid_gen; - list_add(&sp->link, &kvm->arch.active_mmu_pages); - kvm_account_mmu_page(kvm, sp); - - sp->gfn = gfn; - sp->role = role; - hlist_add_head(&sp->hash_link, sp_list); - if (sp_has_gptes(sp)) - account_shadowed(kvm, sp); - - return sp; -} - -/* Note, @vcpu may be NULL if @role.direct is true; see kvm_mmu_find_shadow_page. */ -static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm, - struct kvm_vcpu *vcpu, - struct shadow_page_caches *caches, - gfn_t gfn, - union kvm_mmu_page_role role) -{ - struct hlist_head *sp_list; - struct kvm_mmu_page *sp; - bool created = false; - - sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]; - - sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role); - if (!sp) { - created = true; - sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role); - } - - trace_kvm_mmu_get_page(sp, created); - return sp; -} - -static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu, - gfn_t gfn, - union kvm_mmu_page_role role) -{ - struct shadow_page_caches caches = { - .page_header_cache = &vcpu->arch.mmu_page_header_cache, - .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache, - .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache, - }; - - return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role); -} - -static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, - unsigned int access) -{ - struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep); - union kvm_mmu_page_role role; + /* Verify that the fault can be handled in the fast path */ + if (new_spte == spte || + !is_access_allowed(fault, new_spte)) + break; - role = parent_sp->role; - role.level--; - role.access = access; - role.direct = direct; - role.passthrough = 0; + /* + * Currently, fast page fault only works for direct mapping + * since the gfn is not stable for indirect shadow page. See + * Documentation/virt/kvm/locking.rst to get more detail. + */ + if (fast_pf_fix_direct_spte(vcpu, fault, sptep, spte, new_spte)) { + ret = RET_PF_FIXED; + break; + } - /* - * If the guest has 4-byte PTEs then that means it's using 32-bit, - * 2-level, non-PAE paging. KVM shadows such guests with PAE paging - * (i.e. 8-byte PTEs). The difference in PTE size means that KVM must - * shadow each guest page table with multiple shadow page tables, which - * requires extra bookkeeping in the role. - * - * Specifically, to shadow the guest's page directory (which covers a - * 4GiB address space), KVM uses 4 PAE page directories, each mapping - * 1GiB of the address space. @role.quadrant encodes which quarter of - * the address space each maps. - * - * To shadow the guest's page tables (which each map a 4MiB region), KVM - * uses 2 PAE page tables, each mapping a 2MiB region. For these, - * @role.quadrant encodes which half of the region they map. - * - * Concretely, a 4-byte PDE consumes bits 31:22, while an 8-byte PDE - * consumes bits 29:21. To consume bits 31:30, KVM's uses 4 shadow - * PDPTEs; those 4 PAE page directories are pre-allocated and their - * quadrant is assigned in mmu_alloc_root(). A 4-byte PTE consumes - * bits 21:12, while an 8-byte PTE consumes bits 20:12. To consume - * bit 21 in the PTE (the child here), KVM propagates that bit to the - * quadrant, i.e. sets quadrant to '0' or '1'. The parent 8-byte PDE - * covers bit 21 (see above), thus the quadrant is calculated from the - * _least_ significant bit of the PDE index. - */ - if (role.has_4_byte_gpte) { - WARN_ON_ONCE(role.level != PG_LEVEL_4K); - role.quadrant = spte_index(sptep) & 1; - } - - return role; -} - -static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu, - u64 *sptep, gfn_t gfn, - bool direct, unsigned int access) -{ - union kvm_mmu_page_role role; - - if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) - return ERR_PTR(-EEXIST); - - role = kvm_mmu_child_role(sptep, direct, access); - return kvm_mmu_get_shadow_page(vcpu, gfn, role); -} - -static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator, - struct kvm_vcpu *vcpu, hpa_t root, - u64 addr) -{ - iterator->addr = addr; - iterator->shadow_addr = root; - iterator->level = vcpu->arch.mmu->root_role.level; - - if (iterator->level >= PT64_ROOT_4LEVEL && - vcpu->arch.mmu->cpu_role.base.level < PT64_ROOT_4LEVEL && - !vcpu->arch.mmu->root_role.direct) - iterator->level = PT32E_ROOT_LEVEL; - - if (iterator->level == PT32E_ROOT_LEVEL) { - /* - * prev_root is currently only used for 64-bit hosts. So only - * the active root_hpa is valid here. - */ - BUG_ON(root != vcpu->arch.mmu->root.hpa); - - iterator->shadow_addr - = vcpu->arch.mmu->pae_root[(addr >> 30) & 3]; - iterator->shadow_addr &= SPTE_BASE_ADDR_MASK; - --iterator->level; - if (!iterator->shadow_addr) - iterator->level = 0; - } -} - -static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator, - struct kvm_vcpu *vcpu, u64 addr) -{ - shadow_walk_init_using_root(iterator, vcpu, vcpu->arch.mmu->root.hpa, - addr); -} - -static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) -{ - if (iterator->level < PG_LEVEL_4K) - return false; - - iterator->index = SPTE_INDEX(iterator->addr, iterator->level); - iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index; - return true; -} - -static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, - u64 spte) -{ - if (!is_shadow_present_pte(spte) || is_last_spte(spte, iterator->level)) { - iterator->level = 0; - return; - } - - iterator->shadow_addr = spte & SPTE_BASE_ADDR_MASK; - --iterator->level; -} - -static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator) -{ - __shadow_walk_next(iterator, *iterator->sptep); -} - -static void __link_shadow_page(struct kvm *kvm, - struct kvm_mmu_memory_cache *cache, u64 *sptep, - struct kvm_mmu_page *sp, bool flush) -{ - u64 spte; - - BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); - - /* - * If an SPTE is present already, it must be a leaf and therefore - * a large one. Drop it, and flush the TLB if needed, before - * installing sp. - */ - if (is_shadow_present_pte(*sptep)) - drop_large_spte(kvm, sptep, flush); - - spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp)); - - mmu_spte_set(sptep, spte); - - mmu_page_add_parent_pte(cache, sp, sptep); - - if (sp->unsync_children || sp->unsync) - mark_unsync(sptep); -} - -static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, - struct kvm_mmu_page *sp) -{ - __link_shadow_page(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, sptep, sp, true); -} - -static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, - unsigned direct_access) -{ - if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { - struct kvm_mmu_page *child; - - /* - * For the direct sp, if the guest pte's dirty bit - * changed form clean to dirty, it will corrupt the - * sp's access: allow writable in the read-only sp, - * so we should update the spte at this point to get - * a new sp with the correct access. - */ - child = spte_to_child_sp(*sptep); - if (child->role.access == direct_access) - return; - - drop_parent_pte(child, sptep); - kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn, 1); - } -} - -/* Returns the number of zapped non-leaf child shadow pages. */ -static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, - u64 *spte, struct list_head *invalid_list) -{ - u64 pte; - struct kvm_mmu_page *child; - - pte = *spte; - if (is_shadow_present_pte(pte)) { - if (is_last_spte(pte, sp->role.level)) { - drop_spte(kvm, spte); - } else { - child = spte_to_child_sp(pte); - drop_parent_pte(child, spte); - - /* - * Recursively zap nested TDP SPs, parentless SPs are - * unlikely to be used again in the near future. This - * avoids retaining a large number of stale nested SPs. - */ - if (tdp_enabled && invalid_list && - child->role.guest_mode && !child->parent_ptes.val) - return kvm_mmu_prepare_zap_page(kvm, child, - invalid_list); - } - } else if (is_mmio_spte(pte)) { - mmu_spte_clear_no_track(spte); - } - return 0; -} - -static int kvm_mmu_page_unlink_children(struct kvm *kvm, - struct kvm_mmu_page *sp, - struct list_head *invalid_list) -{ - int zapped = 0; - unsigned i; - - for (i = 0; i < SPTE_ENT_PER_PAGE; ++i) - zapped += mmu_page_zap_pte(kvm, sp, sp->spt + i, invalid_list); - - return zapped; -} - -static void kvm_mmu_unlink_parents(struct kvm_mmu_page *sp) -{ - u64 *sptep; - struct rmap_iterator iter; - - while ((sptep = rmap_get_first(&sp->parent_ptes, &iter))) - drop_parent_pte(sp, sptep); -} - -static int mmu_zap_unsync_children(struct kvm *kvm, - struct kvm_mmu_page *parent, - struct list_head *invalid_list) -{ - int i, zapped = 0; - struct mmu_page_path parents; - struct kvm_mmu_pages pages; - - if (parent->role.level == PG_LEVEL_4K) - return 0; - - while (mmu_unsync_walk(parent, &pages)) { - struct kvm_mmu_page *sp; - - for_each_sp(pages, sp, parents, i) { - kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); - mmu_pages_clear_parents(&parents); - zapped++; - } - } - - return zapped; -} - -static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, - struct kvm_mmu_page *sp, - struct list_head *invalid_list, - int *nr_zapped) -{ - bool list_unstable, zapped_root = false; - - trace_kvm_mmu_prepare_zap_page(sp); - ++kvm->stat.mmu_shadow_zapped; - *nr_zapped = mmu_zap_unsync_children(kvm, sp, invalid_list); - *nr_zapped += kvm_mmu_page_unlink_children(kvm, sp, invalid_list); - kvm_mmu_unlink_parents(sp); - - /* Zapping children means active_mmu_pages has become unstable. */ - list_unstable = *nr_zapped; - - if (!sp->role.invalid && sp_has_gptes(sp)) - unaccount_shadowed(kvm, sp); - - if (sp->unsync) - kvm_unlink_unsync_page(kvm, sp); - if (!sp->root_count) { - /* Count self */ - (*nr_zapped)++; - - /* - * Already invalid pages (previously active roots) are not on - * the active page list. See list_del() in the "else" case of - * !sp->root_count. - */ - if (sp->role.invalid) - list_add(&sp->link, invalid_list); - else - list_move(&sp->link, invalid_list); - kvm_unaccount_mmu_page(kvm, sp); - } else { - /* - * Remove the active root from the active page list, the root - * will be explicitly freed when the root_count hits zero. - */ - list_del(&sp->link); - - /* - * Obsolete pages cannot be used on any vCPUs, see the comment - * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also - * treats invalid shadow pages as being obsolete. - */ - zapped_root = !is_obsolete_sp(kvm, sp); - } - - if (sp->nx_huge_page_disallowed) - unaccount_nx_huge_page(kvm, sp); - - sp->role.invalid = 1; - - /* - * Make the request to free obsolete roots after marking the root - * invalid, otherwise other vCPUs may not see it as invalid. - */ - if (zapped_root) - kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); - return list_unstable; -} - -static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, - struct list_head *invalid_list) -{ - int nr_zapped; - - __kvm_mmu_prepare_zap_page(kvm, sp, invalid_list, &nr_zapped); - return nr_zapped; -} - -static void kvm_mmu_commit_zap_page(struct kvm *kvm, - struct list_head *invalid_list) -{ - struct kvm_mmu_page *sp, *nsp; - - if (list_empty(invalid_list)) - return; - - /* - * We need to make sure everyone sees our modifications to - * the page tables and see changes to vcpu->mode here. The barrier - * in the kvm_flush_remote_tlbs() achieves this. This pairs - * with vcpu_enter_guest and walk_shadow_page_lockless_begin/end. - * - * In addition, kvm_flush_remote_tlbs waits for all vcpus to exit - * guest mode and/or lockless shadow page table walks. - */ - kvm_flush_remote_tlbs(kvm); - - list_for_each_entry_safe(sp, nsp, invalid_list, link) { - WARN_ON(!sp->role.invalid || sp->root_count); - kvm_mmu_free_shadow_page(sp); - } -} - -static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, - unsigned long nr_to_zap) -{ - unsigned long total_zapped = 0; - struct kvm_mmu_page *sp, *tmp; - LIST_HEAD(invalid_list); - bool unstable; - int nr_zapped; - - if (list_empty(&kvm->arch.active_mmu_pages)) - return 0; - -restart: - list_for_each_entry_safe_reverse(sp, tmp, &kvm->arch.active_mmu_pages, link) { - /* - * Don't zap active root pages, the page itself can't be freed - * and zapping it will just force vCPUs to realloc and reload. - */ - if (sp->root_count) - continue; - - unstable = __kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, - &nr_zapped); - total_zapped += nr_zapped; - if (total_zapped >= nr_to_zap) - break; - - if (unstable) - goto restart; - } - - kvm_mmu_commit_zap_page(kvm, &invalid_list); - - kvm->stat.mmu_recycled += total_zapped; - return total_zapped; -} - -static inline unsigned long kvm_mmu_available_pages(struct kvm *kvm) -{ - if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages) - return kvm->arch.n_max_mmu_pages - - kvm->arch.n_used_mmu_pages; - - return 0; -} - -static int make_mmu_pages_available(struct kvm_vcpu *vcpu) -{ - unsigned long avail = kvm_mmu_available_pages(vcpu->kvm); - - if (likely(avail >= KVM_MIN_FREE_MMU_PAGES)) - return 0; - - kvm_mmu_zap_oldest_mmu_pages(vcpu->kvm, KVM_REFILL_PAGES - avail); - - /* - * Note, this check is intentionally soft, it only guarantees that one - * page is available, while the caller may end up allocating as many as - * four pages, e.g. for PAE roots or for 5-level paging. Temporarily - * exceeding the (arbitrary by default) limit will not harm the host, - * being too aggressive may unnecessarily kill the guest, and getting an - * exact count is far more trouble than it's worth, especially in the - * page fault paths. - */ - if (!kvm_mmu_available_pages(vcpu->kvm)) - return -ENOSPC; - return 0; -} - -/* - * Changing the number of mmu pages allocated to the vm - * Note: if goal_nr_mmu_pages is too small, you will get dead lock - */ -void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) -{ - write_lock(&kvm->mmu_lock); - - if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { - kvm_mmu_zap_oldest_mmu_pages(kvm, kvm->arch.n_used_mmu_pages - - goal_nr_mmu_pages); - - goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; - } - - kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages; - - write_unlock(&kvm->mmu_lock); -} - -int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn) -{ - struct kvm_mmu_page *sp; - LIST_HEAD(invalid_list); - int r; - - pgprintk("%s: looking for gfn %llx\n", __func__, gfn); - r = 0; - write_lock(&kvm->mmu_lock); - for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { - pgprintk("%s: gfn %llx role %x\n", __func__, gfn, - sp->role.word); - r = 1; - kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); - } - kvm_mmu_commit_zap_page(kvm, &invalid_list); - write_unlock(&kvm->mmu_lock); - - return r; -} - -static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) -{ - gpa_t gpa; - int r; - - if (vcpu->arch.mmu->root_role.direct) - return 0; - - gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL); - - r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT); - - return r; -} - -static void kvm_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) -{ - trace_kvm_mmu_unsync_page(sp); - ++kvm->stat.mmu_unsync; - sp->unsync = 1; - - kvm_mmu_mark_parents_unsync(sp); -} - -/* - * Attempt to unsync any shadow pages that can be reached by the specified gfn, - * KVM is creating a writable mapping for said gfn. Returns 0 if all pages - * were marked unsync (or if there is no shadow page), -EPERM if the SPTE must - * be write-protected. - */ -int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, - gfn_t gfn, bool can_unsync, bool prefetch) -{ - struct kvm_mmu_page *sp; - bool locked = false; - - /* - * Force write-protection if the page is being tracked. Note, the page - * track machinery is used to write-protect upper-level shadow pages, - * i.e. this guards the role.level == 4K assertion below! - */ - if (kvm_slot_page_track_is_active(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE)) - return -EPERM; - - /* - * The page is not write-tracked, mark existing shadow pages unsync - * unless KVM is synchronizing an unsync SP (can_unsync = false). In - * that case, KVM must complete emulation of the guest TLB flush before - * allowing shadow pages to become unsync (writable by the guest). - */ - for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { - if (!can_unsync) - return -EPERM; - - if (sp->unsync) - continue; - - if (prefetch) - return -EEXIST; - - /* - * TDP MMU page faults require an additional spinlock as they - * run with mmu_lock held for read, not write, and the unsync - * logic is not thread safe. Take the spinklock regardless of - * the MMU type to avoid extra conditionals/parameters, there's - * no meaningful penalty if mmu_lock is held for write. - */ - if (!locked) { - locked = true; - spin_lock(&kvm->arch.mmu_unsync_pages_lock); - - /* - * Recheck after taking the spinlock, a different vCPU - * may have since marked the page unsync. A false - * positive on the unprotected check above is not - * possible as clearing sp->unsync _must_ hold mmu_lock - * for write, i.e. unsync cannot transition from 0->1 - * while this CPU holds mmu_lock for read (or write). - */ - if (READ_ONCE(sp->unsync)) - continue; - } - - WARN_ON(sp->role.level != PG_LEVEL_4K); - kvm_unsync_page(kvm, sp); - } - if (locked) - spin_unlock(&kvm->arch.mmu_unsync_pages_lock); - - /* - * We need to ensure that the marking of unsync pages is visible - * before the SPTE is updated to allow writes because - * kvm_mmu_sync_roots() checks the unsync flags without holding - * the MMU lock and so can race with this. If the SPTE was updated - * before the page had been marked as unsync-ed, something like the - * following could happen: - * - * CPU 1 CPU 2 - * --------------------------------------------------------------------- - * 1.2 Host updates SPTE - * to be writable - * 2.1 Guest writes a GPTE for GVA X. - * (GPTE being in the guest page table shadowed - * by the SP from CPU 1.) - * This reads SPTE during the page table walk. - * Since SPTE.W is read as 1, there is no - * fault. - * - * 2.2 Guest issues TLB flush. - * That causes a VM Exit. - * - * 2.3 Walking of unsync pages sees sp->unsync is - * false and skips the page. - * - * 2.4 Guest accesses GVA X. - * Since the mapping in the SP was not updated, - * so the old mapping for GVA X incorrectly - * gets used. - * 1.1 Host marks SP - * as unsync - * (sp->unsync = true) - * - * The write barrier below ensures that 1.1 happens before 1.2 and thus - * the situation in 2.4 does not arise. It pairs with the read barrier - * in is_unsync_root(), placed between 2.1's load of SPTE.W and 2.3. - */ - smp_wmb(); - - return 0; -} - -static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, - u64 *sptep, unsigned int pte_access, gfn_t gfn, - kvm_pfn_t pfn, struct kvm_page_fault *fault) -{ - struct kvm_mmu_page *sp = sptep_to_sp(sptep); - int level = sp->role.level; - int was_rmapped = 0; - int ret = RET_PF_FIXED; - bool flush = false; - bool wrprot; - u64 spte; - - /* Prefetching always gets a writable pfn. */ - bool host_writable = !fault || fault->map_writable; - bool prefetch = !fault || fault->prefetch; - bool write_fault = fault && fault->write; - - pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, - *sptep, write_fault, gfn); - - if (unlikely(is_noslot_pfn(pfn))) { - vcpu->stat.pf_mmio_spte_created++; - mark_mmio_spte(vcpu, sptep, gfn, pte_access); - return RET_PF_EMULATE; - } - - if (is_shadow_present_pte(*sptep)) { - /* - * If we overwrite a PTE page pointer with a 2MB PMD, unlink - * the parent of the now unreachable PTE. - */ - if (level > PG_LEVEL_4K && !is_large_pte(*sptep)) { - struct kvm_mmu_page *child; - u64 pte = *sptep; - - child = spte_to_child_sp(pte); - drop_parent_pte(child, sptep); - flush = true; - } else if (pfn != spte_to_pfn(*sptep)) { - pgprintk("hfn old %llx new %llx\n", - spte_to_pfn(*sptep), pfn); - drop_spte(vcpu->kvm, sptep); - flush = true; - } else - was_rmapped = 1; - } - - wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, - true, host_writable, &spte); - - if (*sptep == spte) { - ret = RET_PF_SPURIOUS; - } else { - flush |= mmu_spte_update(sptep, spte); - trace_kvm_mmu_set_spte(level, gfn, sptep); - } - - if (wrprot) { - if (write_fault) - ret = RET_PF_EMULATE; - } - - if (flush) - kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, - KVM_PAGES_PER_HPAGE(level)); - - pgprintk("%s: setting spte %llx\n", __func__, *sptep); - - if (!was_rmapped) { - WARN_ON_ONCE(ret == RET_PF_SPURIOUS); - rmap_add(vcpu, slot, sptep, gfn, pte_access); - } else { - /* Already rmapped but the pte_access bits may have changed. */ - kvm_mmu_page_set_access(sp, spte_index(sptep), pte_access); - } - - return ret; -} - -static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *sp, - u64 *start, u64 *end) -{ - struct page *pages[PTE_PREFETCH_NUM]; - struct kvm_memory_slot *slot; - unsigned int access = sp->role.access; - int i, ret; - gfn_t gfn; - - gfn = kvm_mmu_page_get_gfn(sp, spte_index(start)); - slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK); - if (!slot) - return -1; - - ret = gfn_to_page_many_atomic(slot, gfn, pages, end - start); - if (ret <= 0) - return -1; - - for (i = 0; i < ret; i++, gfn++, start++) { - mmu_set_spte(vcpu, slot, start, access, gfn, - page_to_pfn(pages[i]), NULL); - put_page(pages[i]); - } - - return 0; -} - -static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *sp, u64 *sptep) -{ - u64 *spte, *start = NULL; - int i; - - WARN_ON(!sp->role.direct); - - i = spte_index(sptep) & ~(PTE_PREFETCH_NUM - 1); - spte = sp->spt + i; - - for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { - if (is_shadow_present_pte(*spte) || spte == sptep) { - if (!start) - continue; - if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0) - return; - start = NULL; - } else if (!start) - start = spte; - } - if (start) - direct_pte_prefetch_many(vcpu, sp, start, spte); -} - -static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) -{ - struct kvm_mmu_page *sp; - - sp = sptep_to_sp(sptep); - - /* - * Without accessed bits, there's no way to distinguish between - * actually accessed translations and prefetched, so disable pte - * prefetch if accessed bits aren't available. - */ - if (sp_ad_disabled(sp)) - return; - - if (sp->role.level > PG_LEVEL_4K) - return; - - /* - * If addresses are being invalidated, skip prefetching to avoid - * accidentally prefetching those addresses. - */ - if (unlikely(vcpu->kvm->mmu_invalidate_in_progress)) - return; - - __direct_pte_prefetch(vcpu, sp, sptep); -} - -/* - * Lookup the mapping level for @gfn in the current mm. - * - * WARNING! Use of host_pfn_mapping_level() requires the caller and the end - * consumer to be tied into KVM's handlers for MMU notifier events! - * - * There are several ways to safely use this helper: - * - * - Check mmu_invalidate_retry_hva() after grabbing the mapping level, before - * consuming it. In this case, mmu_lock doesn't need to be held during the - * lookup, but it does need to be held while checking the MMU notifier. - * - * - Hold mmu_lock AND ensure there is no in-progress MMU notifier invalidation - * event for the hva. This can be done by explicit checking the MMU notifier - * or by ensuring that KVM already has a valid mapping that covers the hva. - * - * - Do not use the result to install new mappings, e.g. use the host mapping - * level only to decide whether or not to zap an entry. In this case, it's - * not required to hold mmu_lock (though it's highly likely the caller will - * want to hold mmu_lock anyways, e.g. to modify SPTEs). - * - * Note! The lookup can still race with modifications to host page tables, but - * the above "rules" ensure KVM will not _consume_ the result of the walk if a - * race with the primary MMU occurs. - */ -static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, - const struct kvm_memory_slot *slot) -{ - int level = PG_LEVEL_4K; - unsigned long hva; - unsigned long flags; - pgd_t pgd; - p4d_t p4d; - pud_t pud; - pmd_t pmd; - - /* - * Note, using the already-retrieved memslot and __gfn_to_hva_memslot() - * is not solely for performance, it's also necessary to avoid the - * "writable" check in __gfn_to_hva_many(), which will always fail on - * read-only memslots due to gfn_to_hva() assuming writes. Earlier - * page fault steps have already verified the guest isn't writing a - * read-only memslot. - */ - hva = __gfn_to_hva_memslot(slot, gfn); - - /* - * Disable IRQs to prevent concurrent tear down of host page tables, - * e.g. if the primary MMU promotes a P*D to a huge page and then frees - * the original page table. - */ - local_irq_save(flags); - - /* - * Read each entry once. As above, a non-leaf entry can be promoted to - * a huge page _during_ this walk. Re-reading the entry could send the - * walk into the weeks, e.g. p*d_large() returns false (sees the old - * value) and then p*d_offset() walks into the target huge page instead - * of the old page table (sees the new value). - */ - pgd = READ_ONCE(*pgd_offset(kvm->mm, hva)); - if (pgd_none(pgd)) - goto out; - - p4d = READ_ONCE(*p4d_offset(&pgd, hva)); - if (p4d_none(p4d) || !p4d_present(p4d)) - goto out; - - pud = READ_ONCE(*pud_offset(&p4d, hva)); - if (pud_none(pud) || !pud_present(pud)) - goto out; - - if (pud_large(pud)) { - level = PG_LEVEL_1G; - goto out; - } - - pmd = READ_ONCE(*pmd_offset(&pud, hva)); - if (pmd_none(pmd) || !pmd_present(pmd)) - goto out; - - if (pmd_large(pmd)) - level = PG_LEVEL_2M; - -out: - local_irq_restore(flags); - return level; -} - -int kvm_mmu_max_mapping_level(struct kvm *kvm, - const struct kvm_memory_slot *slot, gfn_t gfn, - int max_level) -{ - struct kvm_lpage_info *linfo; - int host_level; - - max_level = min(max_level, max_huge_page_level); - for ( ; max_level > PG_LEVEL_4K; max_level--) { - linfo = lpage_info_slot(gfn, slot, max_level); - if (!linfo->disallow_lpage) - break; - } - - if (max_level == PG_LEVEL_4K) - return PG_LEVEL_4K; - - host_level = host_pfn_mapping_level(kvm, gfn, slot); - return min(host_level, max_level); -} - -void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) -{ - struct kvm_memory_slot *slot = fault->slot; - kvm_pfn_t mask; - - fault->huge_page_disallowed = fault->exec && fault->nx_huge_page_workaround_enabled; - - if (unlikely(fault->max_level == PG_LEVEL_4K)) - return; - - if (is_error_noslot_pfn(fault->pfn)) - return; - - if (kvm_slot_dirty_track_enabled(slot)) - return; - - /* - * Enforce the iTLB multihit workaround after capturing the requested - * level, which will be used to do precise, accurate accounting. - */ - fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, - fault->gfn, fault->max_level); - if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) - return; - - /* - * mmu_invalidate_retry() was successful and mmu_lock is held, so - * the pmd can't be split from under us. - */ - fault->goal_level = fault->req_level; - mask = KVM_PAGES_PER_HPAGE(fault->goal_level) - 1; - VM_BUG_ON((fault->gfn & mask) != (fault->pfn & mask)); - fault->pfn &= ~mask; -} - -void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level) -{ - if (cur_level > PG_LEVEL_4K && - cur_level == fault->goal_level && - is_shadow_present_pte(spte) && - !is_large_pte(spte) && - spte_to_child_sp(spte)->nx_huge_page_disallowed) { - /* - * A small SPTE exists for this pfn, but FNAME(fetch) - * and __direct_map would like to create a large PTE - * instead: just force them to go down another level, - * patching back for them into pfn the next 9 bits of - * the address. - */ - u64 page_mask = KVM_PAGES_PER_HPAGE(cur_level) - - KVM_PAGES_PER_HPAGE(cur_level - 1); - fault->pfn |= fault->gfn & page_mask; - fault->goal_level--; - } -} - -static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) -{ - struct kvm_shadow_walk_iterator it; - struct kvm_mmu_page *sp; - int ret; - gfn_t base_gfn = fault->gfn; - - kvm_mmu_hugepage_adjust(vcpu, fault); - - trace_kvm_mmu_spte_requested(fault); - for_each_shadow_entry(vcpu, fault->addr, it) { - /* - * We cannot overwrite existing page tables with an NX - * large page, as the leaf could be executable. - */ - if (fault->nx_huge_page_workaround_enabled) - disallowed_hugepage_adjust(fault, *it.sptep, it.level); - - base_gfn = fault->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1); - if (it.level == fault->goal_level) - break; - - sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL); - if (sp == ERR_PTR(-EEXIST)) - continue; - - link_shadow_page(vcpu, it.sptep, sp); - if (fault->huge_page_disallowed) - account_nx_huge_page(vcpu->kvm, sp, - fault->req_level >= it.level); - } - - if (WARN_ON_ONCE(it.level != fault->goal_level)) - return -EFAULT; - - ret = mmu_set_spte(vcpu, fault->slot, it.sptep, ACC_ALL, - base_gfn, fault->pfn, fault); - if (ret == RET_PF_SPURIOUS) - return ret; - - direct_pte_prefetch(vcpu, it.sptep); - return ret; -} - -static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk) -{ - send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, PAGE_SHIFT, tsk); -} - -static int kvm_handle_error_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) -{ - if (is_sigpending_pfn(pfn)) { - kvm_handle_signal_exit(vcpu); - return -EINTR; - } - - /* - * Do not cache the mmio info caused by writing the readonly gfn - * into the spte otherwise read access on readonly gfn also can - * caused mmio page fault and treat it as mmio access. - */ - if (pfn == KVM_PFN_ERR_RO_FAULT) - return RET_PF_EMULATE; - - if (pfn == KVM_PFN_ERR_HWPOISON) { - kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current); - return RET_PF_RETRY; - } - - return -EFAULT; -} - -static int handle_abnormal_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, - unsigned int access) -{ - /* The pfn is invalid, report the error! */ - if (unlikely(is_error_pfn(fault->pfn))) - return kvm_handle_error_pfn(vcpu, fault->gfn, fault->pfn); - - if (unlikely(!fault->slot)) { - gva_t gva = fault->is_tdp ? 0 : fault->addr; - - vcpu_cache_mmio_info(vcpu, gva, fault->gfn, - access & shadow_mmio_access_mask); - /* - * If MMIO caching is disabled, emulate immediately without - * touching the shadow page tables as attempting to install an - * MMIO SPTE will just be an expensive nop. Do not cache MMIO - * whose gfn is greater than host.MAXPHYADDR, any guest that - * generates such gfns is running nested and is being tricked - * by L0 userspace (you can observe gfn > L1.MAXPHYADDR if - * and only if L1's MAXPHYADDR is inaccurate with respect to - * the hardware's). - */ - if (unlikely(!enable_mmio_caching) || - unlikely(fault->gfn > kvm_mmu_max_gfn())) - return RET_PF_EMULATE; - } - - return RET_PF_CONTINUE; -} - -static bool page_fault_can_be_fast(struct kvm_page_fault *fault) -{ - /* - * Page faults with reserved bits set, i.e. faults on MMIO SPTEs, only - * reach the common page fault handler if the SPTE has an invalid MMIO - * generation number. Refreshing the MMIO generation needs to go down - * the slow path. Note, EPT Misconfigs do NOT set the PRESENT flag! - */ - if (fault->rsvd) - return false; - - /* - * #PF can be fast if: - * - * 1. The shadow page table entry is not present and A/D bits are - * disabled _by KVM_, which could mean that the fault is potentially - * caused by access tracking (if enabled). If A/D bits are enabled - * by KVM, but disabled by L1 for L2, KVM is forced to disable A/D - * bits for L2 and employ access tracking, but the fast page fault - * mechanism only supports direct MMUs. - * 2. The shadow page table entry is present, the access is a write, - * and no reserved bits are set (MMIO SPTEs cannot be "fixed"), i.e. - * the fault was caused by a write-protection violation. If the - * SPTE is MMU-writable (determined later), the fault can be fixed - * by setting the Writable bit, which can be done out of mmu_lock. - */ - if (!fault->present) - return !kvm_ad_enabled(); - - /* - * Note, instruction fetches and writes are mutually exclusive, ignore - * the "exec" flag. - */ - return fault->write; -} - -/* - * Returns true if the SPTE was fixed successfully. Otherwise, - * someone else modified the SPTE from its original value. - */ -static bool -fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, - u64 *sptep, u64 old_spte, u64 new_spte) -{ - /* - * Theoretically we could also set dirty bit (and flush TLB) here in - * order to eliminate unnecessary PML logging. See comments in - * set_spte. But fast_page_fault is very unlikely to happen with PML - * enabled, so we do not do this. This might result in the same GPA - * to be logged in PML buffer again when the write really happens, and - * eventually to be called by mark_page_dirty twice. But it's also no - * harm. This also avoids the TLB flush needed after setting dirty bit - * so non-PML cases won't be impacted. - * - * Compare with set_spte where instead shadow_dirty_mask is set. - */ - if (!try_cmpxchg64(sptep, &old_spte, new_spte)) - return false; - - if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) - mark_page_dirty_in_slot(vcpu->kvm, fault->slot, fault->gfn); - - return true; -} - -static bool is_access_allowed(struct kvm_page_fault *fault, u64 spte) -{ - if (fault->exec) - return is_executable_pte(spte); - - if (fault->write) - return is_writable_pte(spte); - - /* Fault was on Read access */ - return spte & PT_PRESENT_MASK; -} - -/* - * Returns the last level spte pointer of the shadow page walk for the given - * gpa, and sets *spte to the spte value. This spte may be non-preset. If no - * walk could be performed, returns NULL and *spte does not contain valid data. - * - * Contract: - * - Must be called between walk_shadow_page_lockless_{begin,end}. - * - The returned sptep must not be used after walk_shadow_page_lockless_end. - */ -static u64 *fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte) -{ - struct kvm_shadow_walk_iterator iterator; - u64 old_spte; - u64 *sptep = NULL; - - for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) { - sptep = iterator.sptep; - *spte = old_spte; - } - - return sptep; -} - -/* - * Returns one of RET_PF_INVALID, RET_PF_FIXED or RET_PF_SPURIOUS. - */ -static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) -{ - struct kvm_mmu_page *sp; - int ret = RET_PF_INVALID; - u64 spte = 0ull; - u64 *sptep = NULL; - uint retry_count = 0; - - if (!page_fault_can_be_fast(fault)) - return ret; - - walk_shadow_page_lockless_begin(vcpu); - - do { - u64 new_spte; - - if (is_tdp_mmu(vcpu->arch.mmu)) - sptep = kvm_tdp_mmu_fast_pf_get_last_sptep(vcpu, fault->addr, &spte); - else - sptep = fast_pf_get_last_sptep(vcpu, fault->addr, &spte); - - if (!is_shadow_present_pte(spte)) - break; - - sp = sptep_to_sp(sptep); - if (!is_last_spte(spte, sp->role.level)) - break; - - /* - * Check whether the memory access that caused the fault would - * still cause it if it were to be performed right now. If not, - * then this is a spurious fault caused by TLB lazily flushed, - * or some other CPU has already fixed the PTE after the - * current CPU took the fault. - * - * Need not check the access of upper level table entries since - * they are always ACC_ALL. - */ - if (is_access_allowed(fault, spte)) { - ret = RET_PF_SPURIOUS; - break; - } - - new_spte = spte; - - /* - * KVM only supports fixing page faults outside of MMU lock for - * direct MMUs, nested MMUs are always indirect, and KVM always - * uses A/D bits for non-nested MMUs. Thus, if A/D bits are - * enabled, the SPTE can't be an access-tracked SPTE. - */ - if (unlikely(!kvm_ad_enabled()) && is_access_track_spte(spte)) - new_spte = restore_acc_track_spte(new_spte); - - /* - * To keep things simple, only SPTEs that are MMU-writable can - * be made fully writable outside of mmu_lock, e.g. only SPTEs - * that were write-protected for dirty-logging or access - * tracking are handled here. Don't bother checking if the - * SPTE is writable to prioritize running with A/D bits enabled. - * The is_access_allowed() check above handles the common case - * of the fault being spurious, and the SPTE is known to be - * shadow-present, i.e. except for access tracking restoration - * making the new SPTE writable, the check is wasteful. - */ - if (fault->write && is_mmu_writable_spte(spte)) { - new_spte |= PT_WRITABLE_MASK; - - /* - * Do not fix write-permission on the large spte when - * dirty logging is enabled. Since we only dirty the - * first page into the dirty-bitmap in - * fast_pf_fix_direct_spte(), other pages are missed - * if its slot has dirty logging enabled. - * - * Instead, we let the slow page fault path create a - * normal spte to fix the access. - */ - if (sp->role.level > PG_LEVEL_4K && - kvm_slot_dirty_track_enabled(fault->slot)) - break; - } - - /* Verify that the fault can be handled in the fast path */ - if (new_spte == spte || - !is_access_allowed(fault, new_spte)) - break; - - /* - * Currently, fast page fault only works for direct mapping - * since the gfn is not stable for indirect shadow page. See - * Documentation/virt/kvm/locking.rst to get more detail. - */ - if (fast_pf_fix_direct_spte(vcpu, fault, sptep, spte, new_spte)) { - ret = RET_PF_FIXED; - break; - } - - if (++retry_count > 4) { - printk_once(KERN_WARNING - "kvm: Fast #PF retrying more than 4 times.\n"); - break; - } - - } while (true); - - trace_fast_page_fault(vcpu, fault, sptep, spte, ret); - walk_shadow_page_lockless_end(vcpu); - - if (ret != RET_PF_INVALID) - vcpu->stat.pf_fast++; - - return ret; -} - -static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, - struct list_head *invalid_list) -{ - struct kvm_mmu_page *sp; - - if (!VALID_PAGE(*root_hpa)) - return; - - /* - * The "root" may be a special root, e.g. a PAE entry, treat it as a - * SPTE to ensure any non-PA bits are dropped. - */ - sp = spte_to_child_sp(*root_hpa); - if (WARN_ON(!sp)) - return; - - if (is_tdp_mmu_page(sp)) - kvm_tdp_mmu_put_root(kvm, sp, false); - else if (!--sp->root_count && sp->role.invalid) - kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); - - *root_hpa = INVALID_PAGE; -} - -/* roots_to_free must be some combination of the KVM_MMU_ROOT_* flags */ -void kvm_mmu_free_roots(struct kvm *kvm, struct kvm_mmu *mmu, - ulong roots_to_free) -{ - int i; - LIST_HEAD(invalid_list); - bool free_active_root; - - BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG); - - /* Before acquiring the MMU lock, see if we need to do any real work. */ - free_active_root = (roots_to_free & KVM_MMU_ROOT_CURRENT) - && VALID_PAGE(mmu->root.hpa); - - if (!free_active_root) { - for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) - if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) && - VALID_PAGE(mmu->prev_roots[i].hpa)) - break; - - if (i == KVM_MMU_NUM_PREV_ROOTS) - return; - } - - write_lock(&kvm->mmu_lock); - - for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) - if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) - mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa, - &invalid_list); - - if (free_active_root) { - if (to_shadow_page(mmu->root.hpa)) { - mmu_free_root_page(kvm, &mmu->root.hpa, &invalid_list); - } else if (mmu->pae_root) { - for (i = 0; i < 4; ++i) { - if (!IS_VALID_PAE_ROOT(mmu->pae_root[i])) - continue; - - mmu_free_root_page(kvm, &mmu->pae_root[i], - &invalid_list); - mmu->pae_root[i] = INVALID_PAE_ROOT; - } - } - mmu->root.hpa = INVALID_PAGE; - mmu->root.pgd = 0; - } - - kvm_mmu_commit_zap_page(kvm, &invalid_list); - write_unlock(&kvm->mmu_lock); -} -EXPORT_SYMBOL_GPL(kvm_mmu_free_roots); - -void kvm_mmu_free_guest_mode_roots(struct kvm *kvm, struct kvm_mmu *mmu) -{ - unsigned long roots_to_free = 0; - hpa_t root_hpa; - int i; - - /* - * This should not be called while L2 is active, L2 can't invalidate - * _only_ its own roots, e.g. INVVPID unconditionally exits. - */ - WARN_ON_ONCE(mmu->root_role.guest_mode); - - for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { - root_hpa = mmu->prev_roots[i].hpa; - if (!VALID_PAGE(root_hpa)) - continue; - - if (!to_shadow_page(root_hpa) || - to_shadow_page(root_hpa)->role.guest_mode) - roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); - } - - kvm_mmu_free_roots(kvm, mmu, roots_to_free); -} -EXPORT_SYMBOL_GPL(kvm_mmu_free_guest_mode_roots); - - -static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn) -{ - int ret = 0; - - if (!kvm_vcpu_is_visible_gfn(vcpu, root_gfn)) { - kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); - ret = 1; - } - - return ret; -} - -static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, - u8 level) -{ - union kvm_mmu_page_role role = vcpu->arch.mmu->root_role; - struct kvm_mmu_page *sp; - - role.level = level; - role.quadrant = quadrant; - - WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte); - WARN_ON_ONCE(role.direct && role.has_4_byte_gpte); - - sp = kvm_mmu_get_shadow_page(vcpu, gfn, role); - ++sp->root_count; - - return __pa(sp->spt); -} - -static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) -{ - struct kvm_mmu *mmu = vcpu->arch.mmu; - u8 shadow_root_level = mmu->root_role.level; - hpa_t root; - unsigned i; - int r; - - write_lock(&vcpu->kvm->mmu_lock); - r = make_mmu_pages_available(vcpu); - if (r < 0) - goto out_unlock; - - if (is_tdp_mmu_enabled(vcpu->kvm)) { - root = kvm_tdp_mmu_get_vcpu_root_hpa(vcpu); - mmu->root.hpa = root; - } else if (shadow_root_level >= PT64_ROOT_4LEVEL) { - root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level); - mmu->root.hpa = root; - } else if (shadow_root_level == PT32E_ROOT_LEVEL) { - if (WARN_ON_ONCE(!mmu->pae_root)) { - r = -EIO; - goto out_unlock; - } - - for (i = 0; i < 4; ++i) { - WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); - - root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0, - PT32_ROOT_LEVEL); - mmu->pae_root[i] = root | PT_PRESENT_MASK | - shadow_me_value; - } - mmu->root.hpa = __pa(mmu->pae_root); - } else { - WARN_ONCE(1, "Bad TDP root level = %d\n", shadow_root_level); - r = -EIO; - goto out_unlock; - } - - /* root.pgd is ignored for direct MMUs. */ - mmu->root.pgd = 0; -out_unlock: - write_unlock(&vcpu->kvm->mmu_lock); - return r; -} - -static int mmu_first_shadow_root_alloc(struct kvm *kvm) -{ - struct kvm_memslots *slots; - struct kvm_memory_slot *slot; - int r = 0, i, bkt; - - /* - * Check if this is the first shadow root being allocated before - * taking the lock. - */ - if (kvm_shadow_root_allocated(kvm)) - return 0; - - mutex_lock(&kvm->slots_arch_lock); - - /* Recheck, under the lock, whether this is the first shadow root. */ - if (kvm_shadow_root_allocated(kvm)) - goto out_unlock; - - /* - * Check if anything actually needs to be allocated, e.g. all metadata - * will be allocated upfront if TDP is disabled. - */ - if (kvm_memslots_have_rmaps(kvm) && - kvm_page_track_write_tracking_enabled(kvm)) - goto out_success; - - for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { - slots = __kvm_memslots(kvm, i); - kvm_for_each_memslot(slot, bkt, slots) { - /* - * Both of these functions are no-ops if the target is - * already allocated, so unconditionally calling both - * is safe. Intentionally do NOT free allocations on - * failure to avoid having to track which allocations - * were made now versus when the memslot was created. - * The metadata is guaranteed to be freed when the slot - * is freed, and will be kept/used if userspace retries - * KVM_RUN instead of killing the VM. - */ - r = memslot_rmap_alloc(slot, slot->npages); - if (r) - goto out_unlock; - r = kvm_page_track_write_tracking_alloc(slot); - if (r) - goto out_unlock; - } - } - - /* - * Ensure that shadow_root_allocated becomes true strictly after - * all the related pointers are set. - */ -out_success: - smp_store_release(&kvm->arch.shadow_root_allocated, true); - -out_unlock: - mutex_unlock(&kvm->slots_arch_lock); - return r; -} - -static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) -{ - struct kvm_mmu *mmu = vcpu->arch.mmu; - u64 pdptrs[4], pm_mask; - gfn_t root_gfn, root_pgd; - int quadrant, i, r; - hpa_t root; - - root_pgd = mmu->get_guest_pgd(vcpu); - root_gfn = root_pgd >> PAGE_SHIFT; - - if (mmu_check_root(vcpu, root_gfn)) - return 1; - - /* - * On SVM, reading PDPTRs might access guest memory, which might fault - * and thus might sleep. Grab the PDPTRs before acquiring mmu_lock. - */ - if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { - for (i = 0; i < 4; ++i) { - pdptrs[i] = mmu->get_pdptr(vcpu, i); - if (!(pdptrs[i] & PT_PRESENT_MASK)) - continue; - - if (mmu_check_root(vcpu, pdptrs[i] >> PAGE_SHIFT)) - return 1; - } - } - - r = mmu_first_shadow_root_alloc(vcpu->kvm); - if (r) - return r; - - write_lock(&vcpu->kvm->mmu_lock); - r = make_mmu_pages_available(vcpu); - if (r < 0) - goto out_unlock; - - /* - * Do we shadow a long mode page table? If so we need to - * write-protect the guests page table root. - */ - if (mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { - root = mmu_alloc_root(vcpu, root_gfn, 0, - mmu->root_role.level); - mmu->root.hpa = root; - goto set_root_pgd; - } - - if (WARN_ON_ONCE(!mmu->pae_root)) { - r = -EIO; - goto out_unlock; - } - - /* - * We shadow a 32 bit page table. This may be a legacy 2-level - * or a PAE 3-level page table. In either case we need to be aware that - * the shadow page table may be a PAE or a long mode page table. - */ - pm_mask = PT_PRESENT_MASK | shadow_me_value; - if (mmu->root_role.level >= PT64_ROOT_4LEVEL) { - pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; - - if (WARN_ON_ONCE(!mmu->pml4_root)) { - r = -EIO; - goto out_unlock; - } - mmu->pml4_root[0] = __pa(mmu->pae_root) | pm_mask; - - if (mmu->root_role.level == PT64_ROOT_5LEVEL) { - if (WARN_ON_ONCE(!mmu->pml5_root)) { - r = -EIO; - goto out_unlock; - } - mmu->pml5_root[0] = __pa(mmu->pml4_root) | pm_mask; - } - } - - for (i = 0; i < 4; ++i) { - WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); - - if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { - if (!(pdptrs[i] & PT_PRESENT_MASK)) { - mmu->pae_root[i] = INVALID_PAE_ROOT; - continue; - } - root_gfn = pdptrs[i] >> PAGE_SHIFT; - } - - /* - * If shadowing 32-bit non-PAE page tables, each PAE page - * directory maps one quarter of the guest's non-PAE page - * directory. Othwerise each PAE page direct shadows one guest - * PAE page directory so that quadrant should be 0. - */ - quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0; - - root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL); - mmu->pae_root[i] = root | pm_mask; - } - - if (mmu->root_role.level == PT64_ROOT_5LEVEL) - mmu->root.hpa = __pa(mmu->pml5_root); - else if (mmu->root_role.level == PT64_ROOT_4LEVEL) - mmu->root.hpa = __pa(mmu->pml4_root); - else - mmu->root.hpa = __pa(mmu->pae_root); - -set_root_pgd: - mmu->root.pgd = root_pgd; -out_unlock: - write_unlock(&vcpu->kvm->mmu_lock); - - return r; -} - -static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) -{ - struct kvm_mmu *mmu = vcpu->arch.mmu; - bool need_pml5 = mmu->root_role.level > PT64_ROOT_4LEVEL; - u64 *pml5_root = NULL; - u64 *pml4_root = NULL; - u64 *pae_root; - - /* - * When shadowing 32-bit or PAE NPT with 64-bit NPT, the PML4 and PDP - * tables are allocated and initialized at root creation as there is no - * equivalent level in the guest's NPT to shadow. Allocate the tables - * on demand, as running a 32-bit L1 VMM on 64-bit KVM is very rare. - */ - if (mmu->root_role.direct || - mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL || - mmu->root_role.level < PT64_ROOT_4LEVEL) - return 0; - - /* - * NPT, the only paging mode that uses this horror, uses a fixed number - * of levels for the shadow page tables, e.g. all MMUs are 4-level or - * all MMus are 5-level. Thus, this can safely require that pml5_root - * is allocated if the other roots are valid and pml5 is needed, as any - * prior MMU would also have required pml5. - */ - if (mmu->pae_root && mmu->pml4_root && (!need_pml5 || mmu->pml5_root)) - return 0; - - /* - * The special roots should always be allocated in concert. Yell and - * bail if KVM ends up in a state where only one of the roots is valid. - */ - if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root || - (need_pml5 && mmu->pml5_root))) - return -EIO; - - /* - * Unlike 32-bit NPT, the PDP table doesn't need to be in low mem, and - * doesn't need to be decrypted. - */ - pae_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); - if (!pae_root) - return -ENOMEM; - -#ifdef CONFIG_X86_64 - pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); - if (!pml4_root) - goto err_pml4; + if (++retry_count > 4) { + printk_once(KERN_WARNING + "kvm: Fast #PF retrying more than 4 times.\n"); + break; + } - if (need_pml5) { - pml5_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); - if (!pml5_root) - goto err_pml5; - } -#endif + } while (true); - mmu->pae_root = pae_root; - mmu->pml4_root = pml4_root; - mmu->pml5_root = pml5_root; + trace_fast_page_fault(vcpu, fault, sptep, spte, ret); + walk_shadow_page_lockless_end(vcpu); - return 0; + if (ret != RET_PF_INVALID) + vcpu->stat.pf_fast++; -#ifdef CONFIG_X86_64 -err_pml5: - free_page((unsigned long)pml4_root); -err_pml4: - free_page((unsigned long)pae_root); - return -ENOMEM; -#endif + return ret; } -static bool is_unsync_root(hpa_t root) +static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, + struct list_head *invalid_list) { struct kvm_mmu_page *sp; - if (!VALID_PAGE(root)) - return false; - - /* - * The read barrier orders the CPU's read of SPTE.W during the page table - * walk before the reads of sp->unsync/sp->unsync_children here. - * - * Even if another CPU was marking the SP as unsync-ed simultaneously, - * any guest page table changes are not guaranteed to be visible anyway - * until this VCPU issues a TLB flush strictly after those changes are - * made. We only need to ensure that the other CPU sets these flags - * before any actual changes to the page tables are made. The comments - * in mmu_try_to_unsync_pages() describe what could go wrong if this - * requirement isn't satisfied. - */ - smp_rmb(); - sp = to_shadow_page(root); + if (!VALID_PAGE(*root_hpa)) + return; /* - * PAE roots (somewhat arbitrarily) aren't backed by shadow pages, the - * PDPTEs for a given PAE root need to be synchronized individually. + * The "root" may be a special root, e.g. a PAE entry, treat it as a + * SPTE to ensure any non-PA bits are dropped. */ - if (WARN_ON_ONCE(!sp)) - return false; + sp = spte_to_child_sp(*root_hpa); + if (WARN_ON(!sp)) + return; - if (sp->unsync || sp->unsync_children) - return true; + if (is_tdp_mmu_page(sp)) + kvm_tdp_mmu_put_root(kvm, sp, false); + else if (!--sp->root_count && sp->role.invalid) + kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); - return false; + *root_hpa = INVALID_PAGE; } -void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu) +/* roots_to_free must be some combination of the KVM_MMU_ROOT_* flags */ +void kvm_mmu_free_roots(struct kvm *kvm, struct kvm_mmu *mmu, + ulong roots_to_free) { int i; - struct kvm_mmu_page *sp; - - if (vcpu->arch.mmu->root_role.direct) - return; + LIST_HEAD(invalid_list); + bool free_active_root; - if (!VALID_PAGE(vcpu->arch.mmu->root.hpa)) - return; + BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG); - vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); + /* Before acquiring the MMU lock, see if we need to do any real work. */ + free_active_root = (roots_to_free & KVM_MMU_ROOT_CURRENT) + && VALID_PAGE(mmu->root.hpa); - if (vcpu->arch.mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { - hpa_t root = vcpu->arch.mmu->root.hpa; - sp = to_shadow_page(root); + if (!free_active_root) { + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) && + VALID_PAGE(mmu->prev_roots[i].hpa)) + break; - if (!is_unsync_root(root)) + if (i == KVM_MMU_NUM_PREV_ROOTS) return; - - write_lock(&vcpu->kvm->mmu_lock); - mmu_sync_children(vcpu, sp, true); - write_unlock(&vcpu->kvm->mmu_lock); - return; } - write_lock(&vcpu->kvm->mmu_lock); + write_lock(&kvm->mmu_lock); + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) + mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa, + &invalid_list); - for (i = 0; i < 4; ++i) { - hpa_t root = vcpu->arch.mmu->pae_root[i]; + if (free_active_root) { + if (to_shadow_page(mmu->root.hpa)) { + mmu_free_root_page(kvm, &mmu->root.hpa, &invalid_list); + } else if (mmu->pae_root) { + for (i = 0; i < 4; ++i) { + if (!IS_VALID_PAE_ROOT(mmu->pae_root[i])) + continue; - if (IS_VALID_PAE_ROOT(root)) { - sp = spte_to_child_sp(root); - mmu_sync_children(vcpu, sp, true); + mmu_free_root_page(kvm, &mmu->pae_root[i], + &invalid_list); + mmu->pae_root[i] = INVALID_PAE_ROOT; + } } + mmu->root.hpa = INVALID_PAGE; + mmu->root.pgd = 0; } - write_unlock(&vcpu->kvm->mmu_lock); + kvm_mmu_commit_zap_page(kvm, &invalid_list); + write_unlock(&kvm->mmu_lock); } +EXPORT_SYMBOL_GPL(kvm_mmu_free_roots); -void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu) +static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) { - unsigned long roots_to_free = 0; - int i; + struct kvm_mmu *mmu = vcpu->arch.mmu; + u8 shadow_root_level = mmu->root_role.level; + hpa_t root; + unsigned i; + int r; - for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) - if (is_unsync_root(vcpu->arch.mmu->prev_roots[i].hpa)) - roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + write_lock(&vcpu->kvm->mmu_lock); + r = make_mmu_pages_available(vcpu); + if (r < 0) + goto out_unlock; + + if (is_tdp_mmu_enabled(vcpu->kvm)) { + root = kvm_tdp_mmu_get_vcpu_root_hpa(vcpu); + mmu->root.hpa = root; + } else if (shadow_root_level >= PT64_ROOT_4LEVEL) { + root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level); + mmu->root.hpa = root; + } else if (shadow_root_level == PT32E_ROOT_LEVEL) { + if (WARN_ON_ONCE(!mmu->pae_root)) { + r = -EIO; + goto out_unlock; + } + + for (i = 0; i < 4; ++i) { + WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); - /* sync prev_roots by simply freeing them */ - kvm_mmu_free_roots(vcpu->kvm, vcpu->arch.mmu, roots_to_free); + root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0, + PT32_ROOT_LEVEL); + mmu->pae_root[i] = root | PT_PRESENT_MASK | + shadow_me_value; + } + mmu->root.hpa = __pa(mmu->pae_root); + } else { + WARN_ONCE(1, "Bad TDP root level = %d\n", shadow_root_level); + r = -EIO; + goto out_unlock; + } + + /* root.pgd is ignored for direct MMUs. */ + mmu->root.pgd = 0; +out_unlock: + write_unlock(&vcpu->kvm->mmu_lock); + return r; } static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, @@ -3984,31 +1191,6 @@ static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct) return vcpu_match_mmio_gva(vcpu, addr); } -/* - * Return the level of the lowest level SPTE added to sptes. - * That SPTE may be non-present. - * - * Must be called between walk_shadow_page_lockless_{begin,end}. - */ -static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) -{ - struct kvm_shadow_walk_iterator iterator; - int leaf = -1; - u64 spte; - - for (shadow_walk_init(&iterator, vcpu, addr), - *root_level = iterator.level; - shadow_walk_okay(&iterator); - __shadow_walk_next(&iterator, spte)) { - leaf = iterator.level; - spte = mmu_spte_get_lockless(iterator.sptep); - - sptes[leaf] = spte; - } - - return leaf; -} - /* return true if reserved bit(s) are detected on a valid, non-MMIO SPTE. */ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) { @@ -4112,17 +1294,6 @@ static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu, return false; } -static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) -{ - struct kvm_shadow_walk_iterator iterator; - u64 spte; - - walk_shadow_page_lockless_begin(vcpu); - for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) - clear_sp_write_flooding_count(iterator.sptep); - walk_shadow_page_lockless_end(vcpu); -} - static u32 alloc_apf_token(struct kvm_vcpu *vcpu) { /* make sure the token value is not 0 */ @@ -5305,264 +2476,65 @@ void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu) vcpu->arch.nested_mmu.root_role.word = 0; vcpu->arch.root_mmu.cpu_role.ext.valid = 0; vcpu->arch.guest_mmu.cpu_role.ext.valid = 0; - vcpu->arch.nested_mmu.cpu_role.ext.valid = 0; - kvm_mmu_reset_context(vcpu); - - /* - * Changing guest CPUID after KVM_RUN is forbidden, see the comment in - * kvm_arch_vcpu_ioctl(). - */ - KVM_BUG_ON(vcpu->arch.last_vmentry_cpu != -1, vcpu->kvm); -} - -void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) -{ - kvm_mmu_unload(vcpu); - kvm_init_mmu(vcpu); -} -EXPORT_SYMBOL_GPL(kvm_mmu_reset_context); - -int kvm_mmu_load(struct kvm_vcpu *vcpu) -{ - int r; - - r = mmu_topup_memory_caches(vcpu, !vcpu->arch.mmu->root_role.direct); - if (r) - goto out; - r = mmu_alloc_special_roots(vcpu); - if (r) - goto out; - if (vcpu->arch.mmu->root_role.direct) - r = mmu_alloc_direct_roots(vcpu); - else - r = mmu_alloc_shadow_roots(vcpu); - if (r) - goto out; - - kvm_mmu_sync_roots(vcpu); - - kvm_mmu_load_pgd(vcpu); - - /* - * Flush any TLB entries for the new root, the provenance of the root - * is unknown. Even if KVM ensures there are no stale TLB entries - * for a freed root, in theory another hypervisor could have left - * stale entries. Flushing on alloc also allows KVM to skip the TLB - * flush when freeing a root (see kvm_tdp_mmu_put_root()). - */ - static_call(kvm_x86_flush_tlb_current)(vcpu); -out: - return r; -} - -void kvm_mmu_unload(struct kvm_vcpu *vcpu) -{ - struct kvm *kvm = vcpu->kvm; - - kvm_mmu_free_roots(kvm, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL); - WARN_ON(VALID_PAGE(vcpu->arch.root_mmu.root.hpa)); - kvm_mmu_free_roots(kvm, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); - WARN_ON(VALID_PAGE(vcpu->arch.guest_mmu.root.hpa)); - vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); -} - -static bool is_obsolete_root(struct kvm *kvm, hpa_t root_hpa) -{ - struct kvm_mmu_page *sp; - - if (!VALID_PAGE(root_hpa)) - return false; - - /* - * When freeing obsolete roots, treat roots as obsolete if they don't - * have an associated shadow page. This does mean KVM will get false - * positives and free roots that don't strictly need to be freed, but - * such false positives are relatively rare: - * - * (a) only PAE paging and nested NPT has roots without shadow pages - * (b) remote reloads due to a memslot update obsoletes _all_ roots - * (c) KVM doesn't track previous roots for PAE paging, and the guest - * is unlikely to zap an in-use PGD. - */ - sp = to_shadow_page(root_hpa); - return !sp || is_obsolete_sp(kvm, sp); -} - -static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu) -{ - unsigned long roots_to_free = 0; - int i; - - if (is_obsolete_root(kvm, mmu->root.hpa)) - roots_to_free |= KVM_MMU_ROOT_CURRENT; - - for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { - if (is_obsolete_root(kvm, mmu->prev_roots[i].hpa)) - roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); - } - - if (roots_to_free) - kvm_mmu_free_roots(kvm, mmu, roots_to_free); -} - -void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu) -{ - __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.root_mmu); - __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu); -} - -static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, - int *bytes) -{ - u64 gentry = 0; - int r; - - /* - * Assume that the pte write on a page table of the same type - * as the current vcpu paging mode since we update the sptes only - * when they have the same mode. - */ - if (is_pae(vcpu) && *bytes == 4) { - /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ - *gpa &= ~(gpa_t)7; - *bytes = 8; - } - - if (*bytes == 4 || *bytes == 8) { - r = kvm_vcpu_read_guest_atomic(vcpu, *gpa, &gentry, *bytes); - if (r) - gentry = 0; - } - - return gentry; -} - -/* - * If we're seeing too many writes to a page, it may no longer be a page table, - * or we may be forking, in which case it is better to unmap the page. - */ -static bool detect_write_flooding(struct kvm_mmu_page *sp) -{ - /* - * Skip write-flooding detected for the sp whose level is 1, because - * it can become unsync, then the guest page is not write-protected. - */ - if (sp->role.level == PG_LEVEL_4K) - return false; - - atomic_inc(&sp->write_flooding_count); - return atomic_read(&sp->write_flooding_count) >= 3; -} - -/* - * Misaligned accesses are too much trouble to fix up; also, they usually - * indicate a page is not used as a page table. - */ -static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, - int bytes) -{ - unsigned offset, pte_size, misaligned; - - pgprintk("misaligned: gpa %llx bytes %d role %x\n", - gpa, bytes, sp->role.word); - - offset = offset_in_page(gpa); - pte_size = sp->role.has_4_byte_gpte ? 4 : 8; + vcpu->arch.nested_mmu.cpu_role.ext.valid = 0; + kvm_mmu_reset_context(vcpu); /* - * Sometimes, the OS only writes the last one bytes to update status - * bits, for example, in linux, andb instruction is used in clear_bit(). + * Changing guest CPUID after KVM_RUN is forbidden, see the comment in + * kvm_arch_vcpu_ioctl(). */ - if (!(offset & (pte_size - 1)) && bytes == 1) - return false; - - misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); - misaligned |= bytes < 4; - - return misaligned; + KVM_BUG_ON(vcpu->arch.last_vmentry_cpu != -1, vcpu->kvm); } -static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) +void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) { - unsigned page_offset, quadrant; - u64 *spte; - int level; - - page_offset = offset_in_page(gpa); - level = sp->role.level; - *nspte = 1; - if (sp->role.has_4_byte_gpte) { - page_offset <<= 1; /* 32->64 */ - /* - * A 32-bit pde maps 4MB while the shadow pdes map - * only 2MB. So we need to double the offset again - * and zap two pdes instead of one. - */ - if (level == PT32_ROOT_LEVEL) { - page_offset &= ~7; /* kill rounding error */ - page_offset <<= 1; - *nspte = 2; - } - quadrant = page_offset >> PAGE_SHIFT; - page_offset &= ~PAGE_MASK; - if (quadrant != sp->role.quadrant) - return NULL; - } - - spte = &sp->spt[page_offset / sizeof(*spte)]; - return spte; + kvm_mmu_unload(vcpu); + kvm_init_mmu(vcpu); } +EXPORT_SYMBOL_GPL(kvm_mmu_reset_context); -static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, - const u8 *new, int bytes, - struct kvm_page_track_notifier_node *node) +int kvm_mmu_load(struct kvm_vcpu *vcpu) { - gfn_t gfn = gpa >> PAGE_SHIFT; - struct kvm_mmu_page *sp; - LIST_HEAD(invalid_list); - u64 entry, gentry, *spte; - int npte; - bool flush = false; - - /* - * If we don't have indirect shadow pages, it means no page is - * write-protected, so we can exit simply. - */ - if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) - return; - - pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes); + int r; - write_lock(&vcpu->kvm->mmu_lock); + r = mmu_topup_memory_caches(vcpu, !vcpu->arch.mmu->root_role.direct); + if (r) + goto out; + r = mmu_alloc_special_roots(vcpu); + if (r) + goto out; + if (vcpu->arch.mmu->root_role.direct) + r = mmu_alloc_direct_roots(vcpu); + else + r = mmu_alloc_shadow_roots(vcpu); + if (r) + goto out; - gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes); + kvm_mmu_sync_roots(vcpu); - ++vcpu->kvm->stat.mmu_pte_write; + kvm_mmu_load_pgd(vcpu); - for_each_gfn_valid_sp_with_gptes(vcpu->kvm, sp, gfn) { - if (detect_write_misaligned(sp, gpa, bytes) || - detect_write_flooding(sp)) { - kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list); - ++vcpu->kvm->stat.mmu_flooded; - continue; - } + /* + * Flush any TLB entries for the new root, the provenance of the root + * is unknown. Even if KVM ensures there are no stale TLB entries + * for a freed root, in theory another hypervisor could have left + * stale entries. Flushing on alloc also allows KVM to skip the TLB + * flush when freeing a root (see kvm_tdp_mmu_put_root()). + */ + static_call(kvm_x86_flush_tlb_current)(vcpu); +out: + return r; +} - spte = get_written_sptes(sp, gpa, &npte); - if (!spte) - continue; +void kvm_mmu_unload(struct kvm_vcpu *vcpu) +{ + struct kvm *kvm = vcpu->kvm; - while (npte--) { - entry = *spte; - mmu_page_zap_pte(vcpu->kvm, sp, spte, NULL); - if (gentry && sp->role.level != PG_LEVEL_4K) - ++vcpu->kvm->stat.mmu_pde_zapped; - if (is_shadow_present_pte(entry)) - flush = true; - ++spte; - } - } - kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); - write_unlock(&vcpu->kvm->mmu_lock); + kvm_mmu_free_roots(kvm, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL); + WARN_ON(VALID_PAGE(vcpu->arch.root_mmu.root.hpa)); + kvm_mmu_free_roots(kvm, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); + WARN_ON(VALID_PAGE(vcpu->arch.guest_mmu.root.hpa)); + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); } int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, @@ -5728,58 +2700,6 @@ void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, } EXPORT_SYMBOL_GPL(kvm_configure_mmu); -/* The return value indicates if tlb flush on all vcpus is needed. */ -typedef bool (*slot_level_handler) (struct kvm *kvm, - struct kvm_rmap_head *rmap_head, - const struct kvm_memory_slot *slot); - -/* The caller should hold mmu-lock before calling this function. */ -static __always_inline bool -slot_handle_level_range(struct kvm *kvm, const struct kvm_memory_slot *memslot, - slot_level_handler fn, int start_level, int end_level, - gfn_t start_gfn, gfn_t end_gfn, bool flush_on_yield, - bool flush) -{ - struct slot_rmap_walk_iterator iterator; - - for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn, - end_gfn, &iterator) { - if (iterator.rmap) - flush |= fn(kvm, iterator.rmap, memslot); - - if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { - if (flush && flush_on_yield) { - kvm_flush_remote_tlbs_with_address(kvm, - start_gfn, - iterator.gfn - start_gfn + 1); - flush = false; - } - cond_resched_rwlock_write(&kvm->mmu_lock); - } - } - - return flush; -} - -static __always_inline bool -slot_handle_level(struct kvm *kvm, const struct kvm_memory_slot *memslot, - slot_level_handler fn, int start_level, int end_level, - bool flush_on_yield) -{ - return slot_handle_level_range(kvm, memslot, fn, start_level, - end_level, memslot->base_gfn, - memslot->base_gfn + memslot->npages - 1, - flush_on_yield, false); -} - -static __always_inline bool -slot_handle_level_4k(struct kvm *kvm, const struct kvm_memory_slot *memslot, - slot_level_handler fn, bool flush_on_yield) -{ - return slot_handle_level(kvm, memslot, fn, PG_LEVEL_4K, - PG_LEVEL_4K, flush_on_yield); -} - static void free_mmu_pages(struct kvm_mmu *mmu) { if (!tdp_enabled && mmu->pae_root) @@ -5871,63 +2791,6 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu) return ret; } -#define BATCH_ZAP_PAGES 10 -static void kvm_zap_obsolete_pages(struct kvm *kvm) -{ - struct kvm_mmu_page *sp, *node; - int nr_zapped, batch = 0; - bool unstable; - -restart: - list_for_each_entry_safe_reverse(sp, node, - &kvm->arch.active_mmu_pages, link) { - /* - * No obsolete valid page exists before a newly created page - * since active_mmu_pages is a FIFO list. - */ - if (!is_obsolete_sp(kvm, sp)) - break; - - /* - * Invalid pages should never land back on the list of active - * pages. Skip the bogus page, otherwise we'll get stuck in an - * infinite loop if the page gets put back on the list (again). - */ - if (WARN_ON(sp->role.invalid)) - continue; - - /* - * No need to flush the TLB since we're only zapping shadow - * pages with an obsolete generation number and all vCPUS have - * loaded a new root, i.e. the shadow pages being zapped cannot - * be in active use by the guest. - */ - if (batch >= BATCH_ZAP_PAGES && - cond_resched_rwlock_write(&kvm->mmu_lock)) { - batch = 0; - goto restart; - } - - unstable = __kvm_mmu_prepare_zap_page(kvm, sp, - &kvm->arch.zapped_obsolete_pages, &nr_zapped); - batch += nr_zapped; - - if (unstable) - goto restart; - } - - /* - * Kick all vCPUs (via remote TLB flush) before freeing the page tables - * to ensure KVM is not in the middle of a lockless shadow page table - * walk, which may reference the pages. The remote TLB flush itself is - * not required and is simply a convenient way to kick vCPUs as needed. - * KVM performs a local TLB flush when allocating a new root (see - * kvm_mmu_load()), and the reload in the caller ensure no vCPUs are - * running with an obsolete MMU. - */ - kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); -} - /* * Fast invalidate all shadow pages and use lock-break technique * to zap obsolete pages. @@ -5988,11 +2851,6 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) kvm_tdp_mmu_zap_invalidated_roots(kvm); } -static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) -{ - return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); -} - static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, struct kvm_memory_slot *slot, struct kvm_page_track_notifier_node *node) @@ -6047,37 +2905,6 @@ void kvm_mmu_uninit_vm(struct kvm *kvm) mmu_free_vm_memory_caches(kvm); } -static bool kvm_rmap_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) -{ - const struct kvm_memory_slot *memslot; - struct kvm_memslots *slots; - struct kvm_memslot_iter iter; - bool flush = false; - gfn_t start, end; - int i; - - if (!kvm_memslots_have_rmaps(kvm)) - return flush; - - for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { - slots = __kvm_memslots(kvm, i); - - kvm_for_each_memslot_in_gfn_range(&iter, slots, gfn_start, gfn_end) { - memslot = iter.slot; - start = max(gfn_start, memslot->base_gfn); - end = min(gfn_end, memslot->base_gfn + memslot->npages); - if (WARN_ON_ONCE(start >= end)) - continue; - - flush = slot_handle_level_range(kvm, memslot, __kvm_zap_rmap, - PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, - start, end - 1, true, flush); - } - } - - return flush; -} - /* * Invalidate (zap) SPTEs that cover GFNs from gfn_start and up to gfn_end * (not including it) @@ -6111,13 +2938,6 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) write_unlock(&kvm->mmu_lock); } -static bool slot_rmap_write_protect(struct kvm *kvm, - struct kvm_rmap_head *rmap_head, - const struct kvm_memory_slot *slot) -{ - return rmap_write_protect(rmap_head, false); -} - void kvm_mmu_slot_remove_write_access(struct kvm *kvm, const struct kvm_memory_slot *memslot, int start_level) @@ -6189,183 +3009,6 @@ int topup_split_caches(struct kvm *kvm) return kvm_mmu_topup_memory_cache(&kvm->arch.split_shadow_page_cache, 1); } -static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep) -{ - struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); - struct shadow_page_caches caches = {}; - union kvm_mmu_page_role role; - unsigned int access; - gfn_t gfn; - - gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); - access = kvm_mmu_page_get_access(huge_sp, spte_index(huge_sptep)); - - /* - * Note, huge page splitting always uses direct shadow pages, regardless - * of whether the huge page itself is mapped by a direct or indirect - * shadow page, since the huge page region itself is being directly - * mapped with smaller pages. - */ - role = kvm_mmu_child_role(huge_sptep, /*direct=*/true, access); - - /* Direct SPs do not require a shadowed_info_cache. */ - caches.page_header_cache = &kvm->arch.split_page_header_cache; - caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache; - - /* Safe to pass NULL for vCPU since requesting a direct SP. */ - return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role); -} - -static void shadow_mmu_split_huge_page(struct kvm *kvm, - const struct kvm_memory_slot *slot, - u64 *huge_sptep) - -{ - struct kvm_mmu_memory_cache *cache = &kvm->arch.split_desc_cache; - u64 huge_spte = READ_ONCE(*huge_sptep); - struct kvm_mmu_page *sp; - bool flush = false; - u64 *sptep, spte; - gfn_t gfn; - int index; - - sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep); - - for (index = 0; index < SPTE_ENT_PER_PAGE; index++) { - sptep = &sp->spt[index]; - gfn = kvm_mmu_page_get_gfn(sp, index); - - /* - * The SP may already have populated SPTEs, e.g. if this huge - * page is aliased by multiple sptes with the same access - * permissions. These entries are guaranteed to map the same - * gfn-to-pfn translation since the SP is direct, so no need to - * modify them. - * - * However, if a given SPTE points to a lower level page table, - * that lower level page table may only be partially populated. - * Installing such SPTEs would effectively unmap a potion of the - * huge page. Unmapping guest memory always requires a TLB flush - * since a subsequent operation on the unmapped regions would - * fail to detect the need to flush. - */ - if (is_shadow_present_pte(*sptep)) { - flush |= !is_last_spte(*sptep, sp->role.level); - continue; - } - - spte = make_huge_page_split_spte(kvm, huge_spte, sp->role, index); - mmu_spte_set(sptep, spte); - __rmap_add(kvm, cache, slot, sptep, gfn, sp->role.access); - } - - __link_shadow_page(kvm, cache, huge_sptep, sp, flush); -} - -static int shadow_mmu_try_split_huge_page(struct kvm *kvm, - const struct kvm_memory_slot *slot, - u64 *huge_sptep) -{ - struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); - int level, r = 0; - gfn_t gfn; - u64 spte; - - /* Grab information for the tracepoint before dropping the MMU lock. */ - gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); - level = huge_sp->role.level; - spte = *huge_sptep; - - if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) { - r = -ENOSPC; - goto out; - } - - if (need_topup_split_caches_or_resched(kvm)) { - write_unlock(&kvm->mmu_lock); - cond_resched(); - /* - * If the topup succeeds, return -EAGAIN to indicate that the - * rmap iterator should be restarted because the MMU lock was - * dropped. - */ - r = topup_split_caches(kvm) ?: -EAGAIN; - write_lock(&kvm->mmu_lock); - goto out; - } - - shadow_mmu_split_huge_page(kvm, slot, huge_sptep); - -out: - trace_kvm_mmu_split_huge_page(gfn, spte, level, r); - return r; -} - -static bool shadow_mmu_try_split_huge_pages(struct kvm *kvm, - struct kvm_rmap_head *rmap_head, - const struct kvm_memory_slot *slot) -{ - struct rmap_iterator iter; - struct kvm_mmu_page *sp; - u64 *huge_sptep; - int r; - -restart: - for_each_rmap_spte(rmap_head, &iter, huge_sptep) { - sp = sptep_to_sp(huge_sptep); - - /* TDP MMU is enabled, so rmap only contains nested MMU SPs. */ - if (WARN_ON_ONCE(!sp->role.guest_mode)) - continue; - - /* The rmaps should never contain non-leaf SPTEs. */ - if (WARN_ON_ONCE(!is_large_pte(*huge_sptep))) - continue; - - /* SPs with level >PG_LEVEL_4K should never by unsync. */ - if (WARN_ON_ONCE(sp->unsync)) - continue; - - /* Don't bother splitting huge pages on invalid SPs. */ - if (sp->role.invalid) - continue; - - r = shadow_mmu_try_split_huge_page(kvm, slot, huge_sptep); - - /* - * The split succeeded or needs to be retried because the MMU - * lock was dropped. Either way, restart the iterator to get it - * back into a consistent state. - */ - if (!r || r == -EAGAIN) - goto restart; - - /* The split failed and shouldn't be retried (e.g. -ENOMEM). */ - break; - } - - return false; -} - -static void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm, - const struct kvm_memory_slot *slot, - gfn_t start, gfn_t end, - int target_level) -{ - int level; - - /* - * Split huge pages starting with KVM_MAX_HUGEPAGE_LEVEL and working - * down to the target level. This ensures pages are recursively split - * all the way to the target level. There's no need to split pages - * already at the target level. - */ - for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--) { - slot_handle_level_range(kvm, slot, shadow_mmu_try_split_huge_pages, - level, level, start, end - 1, true, false); - } -} - /* Must be called with the mmu_lock held in write-mode. */ void kvm_mmu_try_split_huge_pages(struct kvm *kvm, const struct kvm_memory_slot *memslot, @@ -6417,56 +3060,6 @@ void kvm_mmu_slot_try_split_huge_pages(struct kvm *kvm, */ } -static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, - struct kvm_rmap_head *rmap_head, - const struct kvm_memory_slot *slot) -{ - u64 *sptep; - struct rmap_iterator iter; - int need_tlb_flush = 0; - struct kvm_mmu_page *sp; - -restart: - for_each_rmap_spte(rmap_head, &iter, sptep) { - sp = sptep_to_sp(sptep); - - /* - * We cannot do huge page mapping for indirect shadow pages, - * which are found on the last rmap (level = 1) when not using - * tdp; such shadow pages are synced with the page table in - * the guest, and the guest page table is using 4K page size - * mapping if the indirect sp has level = 1. - */ - if (sp->role.direct && - sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn, - PG_LEVEL_NUM)) { - kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); - - if (kvm_available_flush_tlb_with_range()) - kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, - KVM_PAGES_PER_HPAGE(sp->role.level)); - else - need_tlb_flush = 1; - - goto restart; - } - } - - return need_tlb_flush; -} - -static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, - const struct kvm_memory_slot *slot) -{ - /* - * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap - * pages that are already mapped at the maximum hugepage level. - */ - if (slot_handle_level(kvm, slot, kvm_mmu_zap_collapsible_spte, - PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, true)) - kvm_arch_flush_remote_tlbs_memslot(kvm, slot); -} - void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, const struct kvm_memory_slot *slot) { @@ -6577,67 +3170,8 @@ void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) } } -static unsigned long -mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) -{ - struct kvm *kvm; - int nr_to_scan = sc->nr_to_scan; - unsigned long freed = 0; - - mutex_lock(&kvm_lock); - - list_for_each_entry(kvm, &vm_list, vm_list) { - int idx; - LIST_HEAD(invalid_list); - - /* - * Never scan more than sc->nr_to_scan VM instances. - * Will not hit this condition practically since we do not try - * to shrink more than one VM and it is very unlikely to see - * !n_used_mmu_pages so many times. - */ - if (!nr_to_scan--) - break; - /* - * n_used_mmu_pages is accessed without holding kvm->mmu_lock - * here. We may skip a VM instance errorneosly, but we do not - * want to shrink a VM that only started to populate its MMU - * anyway. - */ - if (!kvm->arch.n_used_mmu_pages && - !kvm_has_zapped_obsolete_pages(kvm)) - continue; - - idx = srcu_read_lock(&kvm->srcu); - write_lock(&kvm->mmu_lock); - - if (kvm_has_zapped_obsolete_pages(kvm)) { - kvm_mmu_commit_zap_page(kvm, - &kvm->arch.zapped_obsolete_pages); - goto unlock; - } - - freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan); - -unlock: - write_unlock(&kvm->mmu_lock); - srcu_read_unlock(&kvm->srcu, idx); - - /* - * unfair on small ones - * per-vm shrinkers cry out - * sadness comes quickly - */ - list_move_tail(&kvm->vm_list, &vm_list); - break; - } - - mutex_unlock(&kvm_lock); - return freed; -} - -static unsigned long -mmu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) +static unsigned long mmu_shrink_count(struct shrinker *shrink, + struct shrink_control *sc) { return percpu_counter_read_positive(&kvm_total_used_mmu_pages); } diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index 856e2e0a8420..74a99b67f09e 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -44,6 +44,8 @@ extern bool dbg; #define INVALID_PAE_ROOT 0 #define IS_VALID_PAE_ROOT(x) (!!(x)) +#define PTE_PREFETCH_NUM 8 + typedef u64 __rcu *tdp_ptep_t; struct kvm_mmu_page { @@ -168,8 +170,6 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, int min_level); void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, u64 start_gfn, u64 pages); -unsigned int pte_list_count(struct kvm_rmap_head *rmap_head); - extern int nx_huge_pages; static inline bool is_nx_huge_page_enabled(struct kvm *kvm) { diff --git a/arch/x86/kvm/mmu/shadow_mmu.c b/arch/x86/kvm/mmu/shadow_mmu.c index 7bce5ec52b2e..05d8f5be559d 100644 --- a/arch/x86/kvm/mmu/shadow_mmu.c +++ b/arch/x86/kvm/mmu/shadow_mmu.c @@ -19,3 +19,3411 @@ #include #include #include + +#define for_each_shadow_entry(_vcpu, _addr, _walker) \ + for (shadow_walk_init(&(_walker), _vcpu, _addr); \ + shadow_walk_okay(&(_walker)); \ + shadow_walk_next(&(_walker))) + +#define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \ + for (shadow_walk_init(&(_walker), _vcpu, _addr); \ + shadow_walk_okay(&(_walker)) && \ + ({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \ + __shadow_walk_next(&(_walker), spte)) + +static void mmu_spte_set(u64 *sptep, u64 spte); + +void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, + unsigned int access) +{ + u64 spte = make_mmio_spte(vcpu, gfn, access); + + trace_mark_mmio_spte(sptep, gfn, spte); + mmu_spte_set(sptep, spte); +} + +#ifdef CONFIG_X86_64 +static void __set_spte(u64 *sptep, u64 spte) +{ + WRITE_ONCE(*sptep, spte); +} + +static void __update_clear_spte_fast(u64 *sptep, u64 spte) +{ + WRITE_ONCE(*sptep, spte); +} + +static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) +{ + return xchg(sptep, spte); +} + +static u64 __get_spte_lockless(u64 *sptep) +{ + return READ_ONCE(*sptep); +} +#else +union split_spte { + struct { + u32 spte_low; + u32 spte_high; + }; + u64 spte; +}; + +static void count_spte_clear(u64 *sptep, u64 spte) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + + if (is_shadow_present_pte(spte)) + return; + + /* Ensure the spte is completely set before we increase the count */ + smp_wmb(); + sp->clear_spte_count++; +} + +static void __set_spte(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + ssptep->spte_high = sspte.spte_high; + + /* + * If we map the spte from nonpresent to present, We should store + * the high bits firstly, then set present bit, so cpu can not + * fetch this spte while we are setting the spte. + */ + smp_wmb(); + + WRITE_ONCE(ssptep->spte_low, sspte.spte_low); +} + +static void __update_clear_spte_fast(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + WRITE_ONCE(ssptep->spte_low, sspte.spte_low); + + /* + * If we map the spte from present to nonpresent, we should clear + * present bit firstly to avoid vcpu fetch the old high bits. + */ + smp_wmb(); + + ssptep->spte_high = sspte.spte_high; + count_spte_clear(sptep, spte); +} + +static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte, orig; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + /* xchg acts as a barrier before the setting of the high bits */ + orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low); + orig.spte_high = ssptep->spte_high; + ssptep->spte_high = sspte.spte_high; + count_spte_clear(sptep, spte); + + return orig.spte; +} + +/* + * The idea using the light way get the spte on x86_32 guest is from + * gup_get_pte (mm/gup.c). + * + * An spte tlb flush may be pending, because kvm_set_pte_rmap + * coalesces them and we are running out of the MMU lock. Therefore + * we need to protect against in-progress updates of the spte. + * + * Reading the spte while an update is in progress may get the old value + * for the high part of the spte. The race is fine for a present->non-present + * change (because the high part of the spte is ignored for non-present spte), + * but for a present->present change we must reread the spte. + * + * All such changes are done in two steps (present->non-present and + * non-present->present), hence it is enough to count the number of + * present->non-present updates: if it changed while reading the spte, + * we might have hit the race. This is done using clear_spte_count. + */ +static u64 __get_spte_lockless(u64 *sptep) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + union split_spte spte, *orig = (union split_spte *)sptep; + int count; + +retry: + count = sp->clear_spte_count; + smp_rmb(); + + spte.spte_low = orig->spte_low; + smp_rmb(); + + spte.spte_high = orig->spte_high; + smp_rmb(); + + if (unlikely(spte.spte_low != orig->spte_low || + count != sp->clear_spte_count)) + goto retry; + + return spte.spte; +} +#endif + +/* Rules for using mmu_spte_set: + * Set the sptep from nonpresent to present. + * Note: the sptep being assigned *must* be either not present + * or in a state where the hardware will not attempt to update + * the spte. + */ +static void mmu_spte_set(u64 *sptep, u64 new_spte) +{ + WARN_ON(is_shadow_present_pte(*sptep)); + __set_spte(sptep, new_spte); +} + +/* + * Update the SPTE (excluding the PFN), but do not track changes in its + * accessed/dirty status. + */ +static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) +{ + u64 old_spte = *sptep; + + WARN_ON(!is_shadow_present_pte(new_spte)); + check_spte_writable_invariants(new_spte); + + if (!is_shadow_present_pte(old_spte)) { + mmu_spte_set(sptep, new_spte); + return old_spte; + } + + if (!spte_has_volatile_bits(old_spte)) + __update_clear_spte_fast(sptep, new_spte); + else + old_spte = __update_clear_spte_slow(sptep, new_spte); + + WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); + + return old_spte; +} + +/* Rules for using mmu_spte_update: + * Update the state bits, it means the mapped pfn is not changed. + * + * Whenever an MMU-writable SPTE is overwritten with a read-only SPTE, remote + * TLBs must be flushed. Otherwise rmap_write_protect will find a read-only + * spte, even though the writable spte might be cached on a CPU's TLB. + * + * Returns true if the TLB needs to be flushed + */ +bool mmu_spte_update(u64 *sptep, u64 new_spte) +{ + bool flush = false; + u64 old_spte = mmu_spte_update_no_track(sptep, new_spte); + + if (!is_shadow_present_pte(old_spte)) + return false; + + /* + * For the spte updated out of mmu-lock is safe, since + * we always atomically update it, see the comments in + * spte_has_volatile_bits(). + */ + if (is_mmu_writable_spte(old_spte) && + !is_writable_pte(new_spte)) + flush = true; + + /* + * Flush TLB when accessed/dirty states are changed in the page tables, + * to guarantee consistency between TLB and page tables. + */ + + if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) { + flush = true; + kvm_set_pfn_accessed(spte_to_pfn(old_spte)); + } + + if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) { + flush = true; + kvm_set_pfn_dirty(spte_to_pfn(old_spte)); + } + + return flush; +} + +/* + * Rules for using mmu_spte_clear_track_bits: + * It sets the sptep from present to nonpresent, and track the + * state bits, it is used to clear the last level sptep. + * Returns the old PTE. + */ +static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) +{ + kvm_pfn_t pfn; + u64 old_spte = *sptep; + int level = sptep_to_sp(sptep)->role.level; + struct page *page; + + if (!is_shadow_present_pte(old_spte) || + !spte_has_volatile_bits(old_spte)) + __update_clear_spte_fast(sptep, 0ull); + else + old_spte = __update_clear_spte_slow(sptep, 0ull); + + if (!is_shadow_present_pte(old_spte)) + return old_spte; + + kvm_update_page_stats(kvm, level, -1); + + pfn = spte_to_pfn(old_spte); + + /* + * KVM doesn't hold a reference to any pages mapped into the guest, and + * instead uses the mmu_notifier to ensure that KVM unmaps any pages + * before they are reclaimed. Sanity check that, if the pfn is backed + * by a refcounted page, the refcount is elevated. + */ + page = kvm_pfn_to_refcounted_page(pfn); + WARN_ON(page && !page_count(page)); + + if (is_accessed_spte(old_spte)) + kvm_set_pfn_accessed(pfn); + + if (is_dirty_spte(old_spte)) + kvm_set_pfn_dirty(pfn); + + return old_spte; +} + +/* + * Rules for using mmu_spte_clear_no_track: + * Directly clear spte without caring the state bits of sptep, + * it is used to set the upper level spte. + */ +void mmu_spte_clear_no_track(u64 *sptep) +{ + __update_clear_spte_fast(sptep, 0ull); +} + +static u64 mmu_spte_get_lockless(u64 *sptep) +{ + return __get_spte_lockless(sptep); +} + +/* Returns the Accessed status of the PTE and resets it at the same time. */ +static bool mmu_spte_age(u64 *sptep) +{ + u64 spte = mmu_spte_get_lockless(sptep); + + if (!is_accessed_spte(spte)) + return false; + + if (spte_ad_enabled(spte)) { + clear_bit((ffs(shadow_accessed_mask) - 1), + (unsigned long *)sptep); + } else { + /* + * Capture the dirty status of the page, so that it doesn't get + * lost when the SPTE is marked for access tracking. + */ + if (is_writable_pte(spte)) + kvm_set_pfn_dirty(spte_to_pfn(spte)); + + spte = mark_spte_for_access_track(spte); + mmu_spte_update_no_track(sptep, spte); + } + + return true; +} + +static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc) +{ + kmem_cache_free(pte_list_desc_cache, pte_list_desc); +} + +static bool sp_has_gptes(struct kvm_mmu_page *sp); + +gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index) +{ + if (sp->role.passthrough) + return sp->gfn; + + if (!sp->role.direct) + return sp->shadowed_translation[index] >> PAGE_SHIFT; + + return sp->gfn + (index << ((sp->role.level - 1) * SPTE_LEVEL_BITS)); +} + +/* + * For leaf SPTEs, fetch the *guest* access permissions being shadowed. Note + * that the SPTE itself may have a more constrained access permissions that + * what the guest enforces. For example, a guest may create an executable + * huge PTE but KVM may disallow execution to mitigate iTLB multihit. + */ +static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index) +{ + if (sp_has_gptes(sp)) + return sp->shadowed_translation[index] & ACC_ALL; + + /* + * For direct MMUs (e.g. TDP or non-paging guests) or passthrough SPs, + * KVM is not shadowing any guest page tables, so the "guest access + * permissions" are just ACC_ALL. + * + * For direct SPs in indirect MMUs (shadow paging), i.e. when KVM + * is shadowing a guest huge page with small pages, the guest access + * permissions being shadowed are the access permissions of the huge + * page. + * + * In both cases, sp->role.access contains the correct access bits. + */ + return sp->role.access; +} + +static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index, + gfn_t gfn, unsigned int access) +{ + if (sp_has_gptes(sp)) { + sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access; + return; + } + + WARN_ONCE(access != kvm_mmu_page_get_access(sp, index), + "access mismatch under %s page %llx (expected %u, got %u)\n", + sp->role.passthrough ? "passthrough" : "direct", + sp->gfn, kvm_mmu_page_get_access(sp, index), access); + + WARN_ONCE(gfn != kvm_mmu_page_get_gfn(sp, index), + "gfn mismatch under %s page %llx (expected %llx, got %llx)\n", + sp->role.passthrough ? "passthrough" : "direct", + sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn); +} + +void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, + unsigned int access) +{ + gfn_t gfn = kvm_mmu_page_get_gfn(sp, index); + + kvm_mmu_page_set_translation(sp, index, gfn, access); +} + +static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + gfn_t gfn; + + kvm->arch.indirect_shadow_pages++; + gfn = sp->gfn; + slots = kvm_memslots_for_spte_role(kvm, sp->role); + slot = __gfn_to_memslot(slots, gfn); + + /* the non-leaf shadow pages are keeping readonly. */ + if (sp->role.level > PG_LEVEL_4K) + return kvm_slot_page_track_add_page(kvm, slot, gfn, + KVM_PAGE_TRACK_WRITE); + + kvm_mmu_gfn_disallow_lpage(slot, gfn); + + if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K)) + kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); +} + +static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + gfn_t gfn; + + kvm->arch.indirect_shadow_pages--; + gfn = sp->gfn; + slots = kvm_memslots_for_spte_role(kvm, sp->role); + slot = __gfn_to_memslot(slots, gfn); + if (sp->role.level > PG_LEVEL_4K) + return kvm_slot_page_track_remove_page(kvm, slot, gfn, + KVM_PAGE_TRACK_WRITE); + + kvm_mmu_gfn_allow_lpage(slot, gfn); +} + +/* + * About rmap_head encoding: + * + * If the bit zero of rmap_head->val is clear, then it points to the only spte + * in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct + * pte_list_desc containing more mappings. + */ + +/* + * Returns the number of pointers in the rmap chain, not counting the new one. + */ +static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte, + struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc; + int count = 0; + + if (!rmap_head->val) { + rmap_printk("%p %llx 0->1\n", spte, *spte); + rmap_head->val = (unsigned long)spte; + } else if (!(rmap_head->val & 1)) { + rmap_printk("%p %llx 1->many\n", spte, *spte); + desc = kvm_mmu_memory_cache_alloc(cache); + desc->sptes[0] = (u64 *)rmap_head->val; + desc->sptes[1] = spte; + desc->spte_count = 2; + rmap_head->val = (unsigned long)desc | 1; + ++count; + } else { + rmap_printk("%p %llx many->many\n", spte, *spte); + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + while (desc->spte_count == PTE_LIST_EXT) { + count += PTE_LIST_EXT; + if (!desc->more) { + desc->more = kvm_mmu_memory_cache_alloc(cache); + desc = desc->more; + desc->spte_count = 0; + break; + } + desc = desc->more; + } + count += desc->spte_count; + desc->sptes[desc->spte_count++] = spte; + } + return count; +} + +static void +pte_list_desc_remove_entry(struct kvm_rmap_head *rmap_head, + struct pte_list_desc *desc, int i, + struct pte_list_desc *prev_desc) +{ + int j = desc->spte_count - 1; + + desc->sptes[i] = desc->sptes[j]; + desc->sptes[j] = NULL; + desc->spte_count--; + if (desc->spte_count) + return; + if (!prev_desc && !desc->more) + rmap_head->val = 0; + else + if (prev_desc) + prev_desc->more = desc->more; + else + rmap_head->val = (unsigned long)desc->more | 1; + mmu_free_pte_list_desc(desc); +} + +static void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc; + struct pte_list_desc *prev_desc; + int i; + + if (!rmap_head->val) { + pr_err("%s: %p 0->BUG\n", __func__, spte); + BUG(); + } else if (!(rmap_head->val & 1)) { + rmap_printk("%p 1->0\n", spte); + if ((u64 *)rmap_head->val != spte) { + pr_err("%s: %p 1->BUG\n", __func__, spte); + BUG(); + } + rmap_head->val = 0; + } else { + rmap_printk("%p many->many\n", spte); + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + prev_desc = NULL; + while (desc) { + for (i = 0; i < desc->spte_count; ++i) { + if (desc->sptes[i] == spte) { + pte_list_desc_remove_entry(rmap_head, + desc, i, prev_desc); + return; + } + } + prev_desc = desc; + desc = desc->more; + } + pr_err("%s: %p many->many\n", __func__, spte); + BUG(); + } +} + +static void kvm_zap_one_rmap_spte(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, u64 *sptep) +{ + mmu_spte_clear_track_bits(kvm, sptep); + pte_list_remove(sptep, rmap_head); +} + +/* Return true if at least one SPTE was zapped, false otherwise */ +static bool kvm_zap_all_rmap_sptes(struct kvm *kvm, + struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc, *next; + int i; + + if (!rmap_head->val) + return false; + + if (!(rmap_head->val & 1)) { + mmu_spte_clear_track_bits(kvm, (u64 *)rmap_head->val); + goto out; + } + + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + + for (; desc; desc = next) { + for (i = 0; i < desc->spte_count; i++) + mmu_spte_clear_track_bits(kvm, desc->sptes[i]); + next = desc->more; + mmu_free_pte_list_desc(desc); + } +out: + /* rmap_head is meaningless now, remember to reset it */ + rmap_head->val = 0; + return true; +} + +unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc; + unsigned int count = 0; + + if (!rmap_head->val) + return 0; + else if (!(rmap_head->val & 1)) + return 1; + + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + + while (desc) { + count += desc->spte_count; + desc = desc->more; + } + + return count; +} + +struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level, + const struct kvm_memory_slot *slot) +{ + unsigned long idx; + + idx = gfn_to_index(gfn, slot->base_gfn, level); + return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; +} + +bool rmap_can_add(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_memory_cache *mc; + + mc = &vcpu->arch.mmu_pte_list_desc_cache; + return kvm_mmu_memory_cache_nr_free_objects(mc); +} + +static void rmap_remove(struct kvm *kvm, u64 *spte) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + struct kvm_mmu_page *sp; + gfn_t gfn; + struct kvm_rmap_head *rmap_head; + + sp = sptep_to_sp(spte); + gfn = kvm_mmu_page_get_gfn(sp, spte_index(spte)); + + /* + * Unlike rmap_add, rmap_remove does not run in the context of a vCPU + * so we have to determine which memslots to use based on context + * information in sp->role. + */ + slots = kvm_memslots_for_spte_role(kvm, sp->role); + + slot = __gfn_to_memslot(slots, gfn); + rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); + + pte_list_remove(spte, rmap_head); +} + +/* + * Used by the following functions to iterate through the sptes linked by a + * rmap. All fields are private and not assumed to be used outside. + */ +struct rmap_iterator { + /* private fields */ + struct pte_list_desc *desc; /* holds the sptep if not NULL */ + int pos; /* index of the sptep */ +}; + +/* + * Iteration must be started by this function. This should also be used after + * removing/dropping sptes from the rmap link because in such cases the + * information in the iterator may not be valid. + * + * Returns sptep if found, NULL otherwise. + */ +static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head, + struct rmap_iterator *iter) +{ + u64 *sptep; + + if (!rmap_head->val) + return NULL; + + if (!(rmap_head->val & 1)) { + iter->desc = NULL; + sptep = (u64 *)rmap_head->val; + goto out; + } + + iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + iter->pos = 0; + sptep = iter->desc->sptes[iter->pos]; +out: + BUG_ON(!is_shadow_present_pte(*sptep)); + return sptep; +} + +/* + * Must be used with a valid iterator: e.g. after rmap_get_first(). + * + * Returns sptep if found, NULL otherwise. + */ +static u64 *rmap_get_next(struct rmap_iterator *iter) +{ + u64 *sptep; + + if (iter->desc) { + if (iter->pos < PTE_LIST_EXT - 1) { + ++iter->pos; + sptep = iter->desc->sptes[iter->pos]; + if (sptep) + goto out; + } + + iter->desc = iter->desc->more; + + if (iter->desc) { + iter->pos = 0; + /* desc->sptes[0] cannot be NULL */ + sptep = iter->desc->sptes[iter->pos]; + goto out; + } + } + + return NULL; +out: + BUG_ON(!is_shadow_present_pte(*sptep)); + return sptep; +} + +#define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \ + for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \ + _spte_; _spte_ = rmap_get_next(_iter_)) + +void drop_spte(struct kvm *kvm, u64 *sptep) +{ + u64 old_spte = mmu_spte_clear_track_bits(kvm, sptep); + + if (is_shadow_present_pte(old_spte)) + rmap_remove(kvm, sptep); +} + +static void drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(sptep); + WARN_ON(sp->role.level == PG_LEVEL_4K); + + drop_spte(kvm, sptep); + + if (flush) + kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, + KVM_PAGES_PER_HPAGE(sp->role.level)); +} + +/* + * Write-protect on the specified @sptep, @pt_protect indicates whether + * spte write-protection is caused by protecting shadow page table. + * + * Note: write protection is difference between dirty logging and spte + * protection: + * - for dirty logging, the spte can be set to writable at anytime if + * its dirty bitmap is properly set. + * - for spte protection, the spte can be writable only after unsync-ing + * shadow page. + * + * Return true if tlb need be flushed. + */ +static bool spte_write_protect(u64 *sptep, bool pt_protect) +{ + u64 spte = *sptep; + + if (!is_writable_pte(spte) && + !(pt_protect && is_mmu_writable_spte(spte))) + return false; + + rmap_printk("spte %p %llx\n", sptep, *sptep); + + if (pt_protect) + spte &= ~shadow_mmu_writable_mask; + spte = spte & ~PT_WRITABLE_MASK; + + return mmu_spte_update(sptep, spte); +} + +bool rmap_write_protect(struct kvm_rmap_head *rmap_head, bool pt_protect) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) + flush |= spte_write_protect(sptep, pt_protect); + + return flush; +} + +static bool spte_clear_dirty(u64 *sptep) +{ + u64 spte = *sptep; + + rmap_printk("spte %p %llx\n", sptep, *sptep); + + MMU_WARN_ON(!spte_ad_enabled(spte)); + spte &= ~shadow_dirty_mask; + return mmu_spte_update(sptep, spte); +} + +static bool spte_wrprot_for_clear_dirty(u64 *sptep) +{ + bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, + (unsigned long *)sptep); + if (was_writable && !spte_ad_enabled(*sptep)) + kvm_set_pfn_dirty(spte_to_pfn(*sptep)); + + return was_writable; +} + +/* + * Gets the GFN ready for another round of dirty logging by clearing the + * - D bit on ad-enabled SPTEs, and + * - W bit on ad-disabled SPTEs. + * Returns true iff any D or W bits were cleared. + */ +bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) + if (spte_ad_need_write_protect(*sptep)) + flush |= spte_wrprot_for_clear_dirty(sptep); + else + flush |= spte_clear_dirty(sptep); + + return flush; +} + +static bool __kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + return kvm_zap_all_rmap_sptes(kvm, rmap_head); +} + +bool kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t unused) +{ + return __kvm_zap_rmap(kvm, rmap_head, slot); +} + +bool kvm_set_pte_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t pte) +{ + u64 *sptep; + struct rmap_iterator iter; + bool need_flush = false; + u64 new_spte; + kvm_pfn_t new_pfn; + + WARN_ON(pte_huge(pte)); + new_pfn = pte_pfn(pte); + +restart: + for_each_rmap_spte(rmap_head, &iter, sptep) { + rmap_printk("spte %p %llx gfn %llx (%d)\n", + sptep, *sptep, gfn, level); + + need_flush = true; + + if (pte_write(pte)) { + kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); + goto restart; + } else { + new_spte = kvm_mmu_changed_pte_notifier_make_spte( + *sptep, new_pfn); + + mmu_spte_clear_track_bits(kvm, sptep); + mmu_spte_set(sptep, new_spte); + } + } + + if (need_flush && kvm_available_flush_tlb_with_range()) { + kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); + return false; + } + + return need_flush; +} + +struct slot_rmap_walk_iterator { + /* input fields. */ + const struct kvm_memory_slot *slot; + gfn_t start_gfn; + gfn_t end_gfn; + int start_level; + int end_level; + + /* output fields. */ + gfn_t gfn; + struct kvm_rmap_head *rmap; + int level; + + /* private field. */ + struct kvm_rmap_head *end_rmap; +}; + +static void +rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level) +{ + iterator->level = level; + iterator->gfn = iterator->start_gfn; + iterator->rmap = gfn_to_rmap(iterator->gfn, level, iterator->slot); + iterator->end_rmap = gfn_to_rmap(iterator->end_gfn, level, iterator->slot); +} + +static void +slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator, + const struct kvm_memory_slot *slot, int start_level, + int end_level, gfn_t start_gfn, gfn_t end_gfn) +{ + iterator->slot = slot; + iterator->start_level = start_level; + iterator->end_level = end_level; + iterator->start_gfn = start_gfn; + iterator->end_gfn = end_gfn; + + rmap_walk_init_level(iterator, iterator->start_level); +} + +static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator) +{ + return !!iterator->rmap; +} + +static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) +{ + while (++iterator->rmap <= iterator->end_rmap) { + iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level)); + + if (iterator->rmap->val) + return; + } + + if (++iterator->level > iterator->end_level) { + iterator->rmap = NULL; + return; + } + + rmap_walk_init_level(iterator, iterator->level); +} + +#define for_each_slot_rmap_range(_slot_, _start_level_, _end_level_, \ + _start_gfn, _end_gfn, _iter_) \ + for (slot_rmap_walk_init(_iter_, _slot_, _start_level_, \ + _end_level_, _start_gfn, _end_gfn); \ + slot_rmap_walk_okay(_iter_); \ + slot_rmap_walk_next(_iter_)) + +__always_inline bool kvm_handle_gfn_range(struct kvm *kvm, + struct kvm_gfn_range *range, + rmap_handler_t handler) +{ + struct slot_rmap_walk_iterator iterator; + bool ret = false; + + for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, + range->start, range->end - 1, &iterator) + ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn, + iterator.level, range->pte); + + return ret; +} + +bool kvm_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t unused) +{ + u64 *sptep; + struct rmap_iterator iter; + int young = 0; + + for_each_rmap_spte(rmap_head, &iter, sptep) + young |= mmu_spte_age(sptep); + + return young; +} + +bool kvm_test_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, + int level, pte_t unused) +{ + u64 *sptep; + struct rmap_iterator iter; + + for_each_rmap_spte(rmap_head, &iter, sptep) + if (is_accessed_spte(*sptep)) + return true; + return false; +} + +#define RMAP_RECYCLE_THRESHOLD 1000 + +static void __rmap_add(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, + const struct kvm_memory_slot *slot, + u64 *spte, gfn_t gfn, unsigned int access) +{ + struct kvm_mmu_page *sp; + struct kvm_rmap_head *rmap_head; + int rmap_count; + + sp = sptep_to_sp(spte); + kvm_mmu_page_set_translation(sp, spte_index(spte), gfn, access); + kvm_update_page_stats(kvm, sp->role.level, 1); + + rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); + rmap_count = pte_list_add(cache, spte, rmap_head); + + if (rmap_count > kvm->stat.max_mmu_rmap_size) + kvm->stat.max_mmu_rmap_size = rmap_count; + if (rmap_count > RMAP_RECYCLE_THRESHOLD) { + kvm_zap_all_rmap_sptes(kvm, rmap_head); + kvm_flush_remote_tlbs_with_address( + kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level)); + } +} + +static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot, + u64 *spte, gfn_t gfn, unsigned int access) +{ + struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache; + + __rmap_add(vcpu->kvm, cache, slot, spte, gfn, access); +} + +#ifdef MMU_DEBUG +static int is_empty_shadow_page(u64 *spt) +{ + u64 *pos; + u64 *end; + + for (pos = spt, end = pos + SPTE_ENT_PER_PAGE; pos != end; pos++) + if (is_shadow_present_pte(*pos)) { + printk(KERN_ERR "%s: %p %llx\n", __func__, + pos, *pos); + return 0; + } + return 1; +} +#endif + +/* + * This value is the sum of all of the kvm instances's + * kvm->arch.n_used_mmu_pages values. We need a global, + * aggregate version in order to make the slab shrinker + * faster + */ +static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr) +{ + kvm->arch.n_used_mmu_pages += nr; + percpu_counter_add(&kvm_total_used_mmu_pages, nr); +} + +static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_mod_used_mmu_pages(kvm, +1); + kvm_account_pgtable_pages((void *)sp->spt, +1); +} + +static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_mod_used_mmu_pages(kvm, -1); + kvm_account_pgtable_pages((void *)sp->spt, -1); +} + +static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp) +{ + MMU_WARN_ON(!is_empty_shadow_page(sp->spt)); + hlist_del(&sp->hash_link); + list_del(&sp->link); + free_page((unsigned long)sp->spt); + if (!sp->role.direct) + free_page((unsigned long)sp->shadowed_translation); + kmem_cache_free(mmu_page_header_cache, sp); +} + +static unsigned kvm_page_table_hashfn(gfn_t gfn) +{ + return hash_64(gfn, KVM_MMU_HASH_SHIFT); +} + +static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache, + struct kvm_mmu_page *sp, u64 *parent_pte) +{ + if (!parent_pte) + return; + + pte_list_add(cache, parent_pte, &sp->parent_ptes); +} + +static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, + u64 *parent_pte) +{ + pte_list_remove(parent_pte, &sp->parent_ptes); +} + +void drop_parent_pte(struct kvm_mmu_page *sp, u64 *parent_pte) +{ + mmu_page_remove_parent_pte(sp, parent_pte); + mmu_spte_clear_no_track(parent_pte); +} + +static void mark_unsync(u64 *spte); +static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) +{ + u64 *sptep; + struct rmap_iterator iter; + + for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) { + mark_unsync(sptep); + } +} + +static void mark_unsync(u64 *spte) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(spte); + if (__test_and_set_bit(spte_index(spte), sp->unsync_child_bitmap)) + return; + if (sp->unsync_children++) + return; + kvm_mmu_mark_parents_unsync(sp); +} + +int nonpaging_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) +{ + return -1; +} + +#define KVM_PAGE_ARRAY_NR 16 + +struct kvm_mmu_pages { + struct mmu_page_and_offset { + struct kvm_mmu_page *sp; + unsigned int idx; + } page[KVM_PAGE_ARRAY_NR]; + unsigned int nr; +}; + +static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp, + int idx) +{ + int i; + + if (sp->unsync) + for (i=0; i < pvec->nr; i++) + if (pvec->page[i].sp == sp) + return 0; + + pvec->page[pvec->nr].sp = sp; + pvec->page[pvec->nr].idx = idx; + pvec->nr++; + return (pvec->nr == KVM_PAGE_ARRAY_NR); +} + +static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx) +{ + --sp->unsync_children; + WARN_ON((int)sp->unsync_children < 0); + __clear_bit(idx, sp->unsync_child_bitmap); +} + +static int __mmu_unsync_walk(struct kvm_mmu_page *sp, + struct kvm_mmu_pages *pvec) +{ + int i, ret, nr_unsync_leaf = 0; + + for_each_set_bit(i, sp->unsync_child_bitmap, 512) { + struct kvm_mmu_page *child; + u64 ent = sp->spt[i]; + + if (!is_shadow_present_pte(ent) || is_large_pte(ent)) { + clear_unsync_child_bit(sp, i); + continue; + } + + child = spte_to_child_sp(ent); + + if (child->unsync_children) { + if (mmu_pages_add(pvec, child, i)) + return -ENOSPC; + + ret = __mmu_unsync_walk(child, pvec); + if (!ret) { + clear_unsync_child_bit(sp, i); + continue; + } else if (ret > 0) { + nr_unsync_leaf += ret; + } else + return ret; + } else if (child->unsync) { + nr_unsync_leaf++; + if (mmu_pages_add(pvec, child, i)) + return -ENOSPC; + } else + clear_unsync_child_bit(sp, i); + } + + return nr_unsync_leaf; +} + +#define INVALID_INDEX (-1) + +static int mmu_unsync_walk(struct kvm_mmu_page *sp, + struct kvm_mmu_pages *pvec) +{ + pvec->nr = 0; + if (!sp->unsync_children) + return 0; + + mmu_pages_add(pvec, sp, INVALID_INDEX); + return __mmu_unsync_walk(sp, pvec); +} + +static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + WARN_ON(!sp->unsync); + trace_kvm_mmu_sync_page(sp); + sp->unsync = 0; + --kvm->stat.mmu_unsync; +} + +static bool sp_has_gptes(struct kvm_mmu_page *sp) +{ + if (sp->role.direct) + return false; + + if (sp->role.passthrough) + return false; + + return true; +} + +#define for_each_valid_sp(_kvm, _sp, _list) \ + hlist_for_each_entry(_sp, _list, hash_link) \ + if (is_obsolete_sp((_kvm), (_sp))) { \ + } else + +#define for_each_gfn_valid_sp_with_gptes(_kvm, _sp, _gfn) \ + for_each_valid_sp(_kvm, _sp, \ + &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ + if ((_sp)->gfn != (_gfn) || !sp_has_gptes(_sp)) {} else + +static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int ret = vcpu->arch.mmu->sync_page(vcpu, sp); + + if (ret < 0) + kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list); + return ret; +} + +struct mmu_page_path { + struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL]; + unsigned int idx[PT64_ROOT_MAX_LEVEL]; +}; + +#define for_each_sp(pvec, sp, parents, i) \ + for (i = mmu_pages_first(&pvec, &parents); \ + i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \ + i = mmu_pages_next(&pvec, &parents, i)) + +static int mmu_pages_next(struct kvm_mmu_pages *pvec, + struct mmu_page_path *parents, + int i) +{ + int n; + + for (n = i+1; n < pvec->nr; n++) { + struct kvm_mmu_page *sp = pvec->page[n].sp; + unsigned idx = pvec->page[n].idx; + int level = sp->role.level; + + parents->idx[level-1] = idx; + if (level == PG_LEVEL_4K) + break; + + parents->parent[level-2] = sp; + } + + return n; +} + +static int mmu_pages_first(struct kvm_mmu_pages *pvec, + struct mmu_page_path *parents) +{ + struct kvm_mmu_page *sp; + int level; + + if (pvec->nr == 0) + return 0; + + WARN_ON(pvec->page[0].idx != INVALID_INDEX); + + sp = pvec->page[0].sp; + level = sp->role.level; + WARN_ON(level == PG_LEVEL_4K); + + parents->parent[level-2] = sp; + + /* Also set up a sentinel. Further entries in pvec are all + * children of sp, so this element is never overwritten. + */ + parents->parent[level-1] = NULL; + return mmu_pages_next(pvec, parents, 0); +} + +static void mmu_pages_clear_parents(struct mmu_page_path *parents) +{ + struct kvm_mmu_page *sp; + unsigned int level = 0; + + do { + unsigned int idx = parents->idx[level]; + sp = parents->parent[level]; + if (!sp) + return; + + WARN_ON(idx == INVALID_INDEX); + clear_unsync_child_bit(sp, idx); + level++; + } while (!sp->unsync_children); +} + +int mmu_sync_children(struct kvm_vcpu *vcpu, struct kvm_mmu_page *parent, + bool can_yield) +{ + int i; + struct kvm_mmu_page *sp; + struct mmu_page_path parents; + struct kvm_mmu_pages pages; + LIST_HEAD(invalid_list); + bool flush = false; + + while (mmu_unsync_walk(parent, &pages)) { + bool protected = false; + + for_each_sp(pages, sp, parents, i) + protected |= kvm_vcpu_write_protect_gfn(vcpu, sp->gfn); + + if (protected) { + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, true); + flush = false; + } + + for_each_sp(pages, sp, parents, i) { + kvm_unlink_unsync_page(vcpu->kvm, sp); + flush |= kvm_sync_page(vcpu, sp, &invalid_list) > 0; + mmu_pages_clear_parents(&parents); + } + if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) { + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + if (!can_yield) { + kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); + return -EINTR; + } + + cond_resched_rwlock_write(&vcpu->kvm->mmu_lock); + flush = false; + } + } + + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + return 0; +} + +void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) +{ + atomic_set(&sp->write_flooding_count, 0); +} + +void clear_sp_write_flooding_count(u64 *spte) +{ + __clear_sp_write_flooding_count(sptep_to_sp(spte)); +} + +/* + * The vCPU is required when finding indirect shadow pages; the shadow + * page may already exist and syncing it needs the vCPU pointer in + * order to read guest page tables. Direct shadow pages are never + * unsync, thus @vcpu can be NULL if @role.direct is true. + */ +static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm, + struct kvm_vcpu *vcpu, + gfn_t gfn, + struct hlist_head *sp_list, + union kvm_mmu_page_role role) +{ + struct kvm_mmu_page *sp; + int ret; + int collisions = 0; + LIST_HEAD(invalid_list); + + for_each_valid_sp(kvm, sp, sp_list) { + if (sp->gfn != gfn) { + collisions++; + continue; + } + + if (sp->role.word != role.word) { + /* + * If the guest is creating an upper-level page, zap + * unsync pages for the same gfn. While it's possible + * the guest is using recursive page tables, in all + * likelihood the guest has stopped using the unsync + * page and is installing a completely unrelated page. + * Unsync pages must not be left as is, because the new + * upper-level page will be write-protected. + */ + if (role.level > PG_LEVEL_4K && sp->unsync) + kvm_mmu_prepare_zap_page(kvm, sp, + &invalid_list); + continue; + } + + /* unsync and write-flooding only apply to indirect SPs. */ + if (sp->role.direct) + goto out; + + if (sp->unsync) { + if (KVM_BUG_ON(!vcpu, kvm)) + break; + + /* + * The page is good, but is stale. kvm_sync_page does + * get the latest guest state, but (unlike mmu_unsync_children) + * it doesn't write-protect the page or mark it synchronized! + * This way the validity of the mapping is ensured, but the + * overhead of write protection is not incurred until the + * guest invalidates the TLB mapping. This allows multiple + * SPs for a single gfn to be unsync. + * + * If the sync fails, the page is zapped. If so, break + * in order to rebuild it. + */ + ret = kvm_sync_page(vcpu, sp, &invalid_list); + if (ret < 0) + break; + + WARN_ON(!list_empty(&invalid_list)); + if (ret > 0) + kvm_flush_remote_tlbs(kvm); + } + + __clear_sp_write_flooding_count(sp); + + goto out; + } + + sp = NULL; + ++kvm->stat.mmu_cache_miss; + +out: + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + if (collisions > kvm->stat.max_mmu_page_hash_collisions) + kvm->stat.max_mmu_page_hash_collisions = collisions; + return sp; +} + +/* Caches used when allocating a new shadow page. */ +struct shadow_page_caches { + struct kvm_mmu_memory_cache *page_header_cache; + struct kvm_mmu_memory_cache *shadow_page_cache; + struct kvm_mmu_memory_cache *shadowed_info_cache; +}; + +static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm, + struct shadow_page_caches *caches, + gfn_t gfn, + struct hlist_head *sp_list, + union kvm_mmu_page_role role) +{ + struct kvm_mmu_page *sp; + + sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache); + sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache); + if (!role.direct) + sp->shadowed_translation = kvm_mmu_memory_cache_alloc(caches->shadowed_info_cache); + + set_page_private(virt_to_page(sp->spt), (unsigned long)sp); + + INIT_LIST_HEAD(&sp->possible_nx_huge_page_link); + + /* + * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() + * depends on valid pages being added to the head of the list. See + * comments in kvm_zap_obsolete_pages(). + */ + sp->mmu_valid_gen = kvm->arch.mmu_valid_gen; + list_add(&sp->link, &kvm->arch.active_mmu_pages); + kvm_account_mmu_page(kvm, sp); + + sp->gfn = gfn; + sp->role = role; + hlist_add_head(&sp->hash_link, sp_list); + if (sp_has_gptes(sp)) + account_shadowed(kvm, sp); + + return sp; +} + +/* Note, @vcpu may be NULL if @role.direct is true; see kvm_mmu_find_shadow_page. */ +static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm, + struct kvm_vcpu *vcpu, + struct shadow_page_caches *caches, + gfn_t gfn, + union kvm_mmu_page_role role) +{ + struct hlist_head *sp_list; + struct kvm_mmu_page *sp; + bool created = false; + + sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]; + + sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role); + if (!sp) { + created = true; + sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role); + } + + trace_kvm_mmu_get_page(sp, created); + return sp; +} + +static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu, + gfn_t gfn, + union kvm_mmu_page_role role) +{ + struct shadow_page_caches caches = { + .page_header_cache = &vcpu->arch.mmu_page_header_cache, + .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache, + .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache, + }; + + return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role); +} + +static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, + unsigned int access) +{ + struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep); + union kvm_mmu_page_role role; + + role = parent_sp->role; + role.level--; + role.access = access; + role.direct = direct; + role.passthrough = 0; + + /* + * If the guest has 4-byte PTEs then that means it's using 32-bit, + * 2-level, non-PAE paging. KVM shadows such guests with PAE paging + * (i.e. 8-byte PTEs). The difference in PTE size means that KVM must + * shadow each guest page table with multiple shadow page tables, which + * requires extra bookkeeping in the role. + * + * Specifically, to shadow the guest's page directory (which covers a + * 4GiB address space), KVM uses 4 PAE page directories, each mapping + * 1GiB of the address space. @role.quadrant encodes which quarter of + * the address space each maps. + * + * To shadow the guest's page tables (which each map a 4MiB region), KVM + * uses 2 PAE page tables, each mapping a 2MiB region. For these, + * @role.quadrant encodes which half of the region they map. + * + * Concretely, a 4-byte PDE consumes bits 31:22, while an 8-byte PDE + * consumes bits 29:21. To consume bits 31:30, KVM's uses 4 shadow + * PDPTEs; those 4 PAE page directories are pre-allocated and their + * quadrant is assigned in mmu_alloc_root(). A 4-byte PTE consumes + * bits 21:12, while an 8-byte PTE consumes bits 20:12. To consume + * bit 21 in the PTE (the child here), KVM propagates that bit to the + * quadrant, i.e. sets quadrant to '0' or '1'. The parent 8-byte PDE + * covers bit 21 (see above), thus the quadrant is calculated from the + * _least_ significant bit of the PDE index. + */ + if (role.has_4_byte_gpte) { + WARN_ON_ONCE(role.level != PG_LEVEL_4K); + role.quadrant = spte_index(sptep) & 1; + } + + return role; +} + +struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu, u64 *sptep, + gfn_t gfn, bool direct, + unsigned int access) +{ + union kvm_mmu_page_role role; + + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) + return ERR_PTR(-EEXIST); + + role = kvm_mmu_child_role(sptep, direct, access); + return kvm_mmu_get_shadow_page(vcpu, gfn, role); +} + +void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator, + struct kvm_vcpu *vcpu, hpa_t root, u64 addr) +{ + iterator->addr = addr; + iterator->shadow_addr = root; + iterator->level = vcpu->arch.mmu->root_role.level; + + if (iterator->level >= PT64_ROOT_4LEVEL && + vcpu->arch.mmu->cpu_role.base.level < PT64_ROOT_4LEVEL && + !vcpu->arch.mmu->root_role.direct) + iterator->level = PT32E_ROOT_LEVEL; + + if (iterator->level == PT32E_ROOT_LEVEL) { + /* + * prev_root is currently only used for 64-bit hosts. So only + * the active root_hpa is valid here. + */ + BUG_ON(root != vcpu->arch.mmu->root.hpa); + + iterator->shadow_addr + = vcpu->arch.mmu->pae_root[(addr >> 30) & 3]; + iterator->shadow_addr &= SPTE_BASE_ADDR_MASK; + --iterator->level; + if (!iterator->shadow_addr) + iterator->level = 0; + } +} + +void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator, + struct kvm_vcpu *vcpu, u64 addr) +{ + shadow_walk_init_using_root(iterator, vcpu, vcpu->arch.mmu->root.hpa, + addr); +} + +bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) +{ + if (iterator->level < PG_LEVEL_4K) + return false; + + iterator->index = SPTE_INDEX(iterator->addr, iterator->level); + iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index; + return true; +} + +static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, + u64 spte) +{ + if (!is_shadow_present_pte(spte) || is_last_spte(spte, iterator->level)) { + iterator->level = 0; + return; + } + + iterator->shadow_addr = spte & SPTE_BASE_ADDR_MASK; + --iterator->level; +} + +void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator) +{ + __shadow_walk_next(iterator, *iterator->sptep); +} + +static void __link_shadow_page(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, u64 *sptep, + struct kvm_mmu_page *sp, bool flush) +{ + u64 spte; + + BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); + + /* + * If an SPTE is present already, it must be a leaf and therefore + * a large one. Drop it, and flush the TLB if needed, before + * installing sp. + */ + if (is_shadow_present_pte(*sptep)) + drop_large_spte(kvm, sptep, flush); + + spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp)); + + mmu_spte_set(sptep, spte); + + mmu_page_add_parent_pte(cache, sp, sptep); + + if (sp->unsync_children || sp->unsync) + mark_unsync(sptep); +} + +void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, struct kvm_mmu_page *sp) +{ + __link_shadow_page(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, sptep, sp, true); +} + +void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, + unsigned direct_access) +{ + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + + /* + * For the direct sp, if the guest pte's dirty bit + * changed form clean to dirty, it will corrupt the + * sp's access: allow writable in the read-only sp, + * so we should update the spte at this point to get + * a new sp with the correct access. + */ + child = spte_to_child_sp(*sptep); + if (child->role.access == direct_access) + return; + + drop_parent_pte(child, sptep); + kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn, 1); + } +} + +/* Returns the number of zapped non-leaf child shadow pages. */ +int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *spte, + struct list_head *invalid_list) +{ + u64 pte; + struct kvm_mmu_page *child; + + pte = *spte; + if (is_shadow_present_pte(pte)) { + if (is_last_spte(pte, sp->role.level)) { + drop_spte(kvm, spte); + } else { + child = spte_to_child_sp(pte); + drop_parent_pte(child, spte); + + /* + * Recursively zap nested TDP SPs, parentless SPs are + * unlikely to be used again in the near future. This + * avoids retaining a large number of stale nested SPs. + */ + if (tdp_enabled && invalid_list && + child->role.guest_mode && !child->parent_ptes.val) + return kvm_mmu_prepare_zap_page(kvm, child, + invalid_list); + } + } else if (is_mmio_spte(pte)) { + mmu_spte_clear_no_track(spte); + } + return 0; +} + +static int kvm_mmu_page_unlink_children(struct kvm *kvm, + struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int zapped = 0; + unsigned i; + + for (i = 0; i < SPTE_ENT_PER_PAGE; ++i) + zapped += mmu_page_zap_pte(kvm, sp, sp->spt + i, invalid_list); + + return zapped; +} + +static void kvm_mmu_unlink_parents(struct kvm_mmu_page *sp) +{ + u64 *sptep; + struct rmap_iterator iter; + + while ((sptep = rmap_get_first(&sp->parent_ptes, &iter))) + drop_parent_pte(sp, sptep); +} + +static int mmu_zap_unsync_children(struct kvm *kvm, + struct kvm_mmu_page *parent, + struct list_head *invalid_list) +{ + int i, zapped = 0; + struct mmu_page_path parents; + struct kvm_mmu_pages pages; + + if (parent->role.level == PG_LEVEL_4K) + return 0; + + while (mmu_unsync_walk(parent, &pages)) { + struct kvm_mmu_page *sp; + + for_each_sp(pages, sp, parents, i) { + kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); + mmu_pages_clear_parents(&parents); + zapped++; + } + } + + return zapped; +} + +bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list, + int *nr_zapped) +{ + bool list_unstable, zapped_root = false; + + trace_kvm_mmu_prepare_zap_page(sp); + ++kvm->stat.mmu_shadow_zapped; + *nr_zapped = mmu_zap_unsync_children(kvm, sp, invalid_list); + *nr_zapped += kvm_mmu_page_unlink_children(kvm, sp, invalid_list); + kvm_mmu_unlink_parents(sp); + + /* Zapping children means active_mmu_pages has become unstable. */ + list_unstable = *nr_zapped; + + if (!sp->role.invalid && sp_has_gptes(sp)) + unaccount_shadowed(kvm, sp); + + if (sp->unsync) + kvm_unlink_unsync_page(kvm, sp); + if (!sp->root_count) { + /* Count self */ + (*nr_zapped)++; + + /* + * Already invalid pages (previously active roots) are not on + * the active page list. See list_del() in the "else" case of + * !sp->root_count. + */ + if (sp->role.invalid) + list_add(&sp->link, invalid_list); + else + list_move(&sp->link, invalid_list); + kvm_unaccount_mmu_page(kvm, sp); + } else { + /* + * Remove the active root from the active page list, the root + * will be explicitly freed when the root_count hits zero. + */ + list_del(&sp->link); + + /* + * Obsolete pages cannot be used on any vCPUs, see the comment + * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also + * treats invalid shadow pages as being obsolete. + */ + zapped_root = !is_obsolete_sp(kvm, sp); + } + + if (sp->nx_huge_page_disallowed) + unaccount_nx_huge_page(kvm, sp); + + sp->role.invalid = 1; + + /* + * Make the request to free obsolete roots after marking the root + * invalid, otherwise other vCPUs may not see it as invalid. + */ + if (zapped_root) + kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); + return list_unstable; +} + +bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int nr_zapped; + + __kvm_mmu_prepare_zap_page(kvm, sp, invalid_list, &nr_zapped); + return nr_zapped; +} + +void kvm_mmu_commit_zap_page(struct kvm *kvm, struct list_head *invalid_list) +{ + struct kvm_mmu_page *sp, *nsp; + + if (list_empty(invalid_list)) + return; + + /* + * We need to make sure everyone sees our modifications to + * the page tables and see changes to vcpu->mode here. The barrier + * in the kvm_flush_remote_tlbs() achieves this. This pairs + * with vcpu_enter_guest and walk_shadow_page_lockless_begin/end. + * + * In addition, kvm_flush_remote_tlbs waits for all vcpus to exit + * guest mode and/or lockless shadow page table walks. + */ + kvm_flush_remote_tlbs(kvm); + + list_for_each_entry_safe(sp, nsp, invalid_list, link) { + WARN_ON(!sp->role.invalid || sp->root_count); + kvm_mmu_free_shadow_page(sp); + } +} + +static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, + unsigned long nr_to_zap) +{ + unsigned long total_zapped = 0; + struct kvm_mmu_page *sp, *tmp; + LIST_HEAD(invalid_list); + bool unstable; + int nr_zapped; + + if (list_empty(&kvm->arch.active_mmu_pages)) + return 0; + +restart: + list_for_each_entry_safe_reverse(sp, tmp, &kvm->arch.active_mmu_pages, link) { + /* + * Don't zap active root pages, the page itself can't be freed + * and zapping it will just force vCPUs to realloc and reload. + */ + if (sp->root_count) + continue; + + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, + &nr_zapped); + total_zapped += nr_zapped; + if (total_zapped >= nr_to_zap) + break; + + if (unstable) + goto restart; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + kvm->stat.mmu_recycled += total_zapped; + return total_zapped; +} + +static inline unsigned long kvm_mmu_available_pages(struct kvm *kvm) +{ + if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages) + return kvm->arch.n_max_mmu_pages - + kvm->arch.n_used_mmu_pages; + + return 0; +} + +int make_mmu_pages_available(struct kvm_vcpu *vcpu) +{ + unsigned long avail = kvm_mmu_available_pages(vcpu->kvm); + + if (likely(avail >= KVM_MIN_FREE_MMU_PAGES)) + return 0; + + kvm_mmu_zap_oldest_mmu_pages(vcpu->kvm, KVM_REFILL_PAGES - avail); + + /* + * Note, this check is intentionally soft, it only guarantees that one + * page is available, while the caller may end up allocating as many as + * four pages, e.g. for PAE roots or for 5-level paging. Temporarily + * exceeding the (arbitrary by default) limit will not harm the host, + * being too aggressive may unnecessarily kill the guest, and getting an + * exact count is far more trouble than it's worth, especially in the + * page fault paths. + */ + if (!kvm_mmu_available_pages(vcpu->kvm)) + return -ENOSPC; + return 0; +} + +/* + * Changing the number of mmu pages allocated to the vm + * Note: if goal_nr_mmu_pages is too small, you will get dead lock + */ +void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) +{ + write_lock(&kvm->mmu_lock); + + if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { + kvm_mmu_zap_oldest_mmu_pages(kvm, kvm->arch.n_used_mmu_pages - + goal_nr_mmu_pages); + + goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; + } + + kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages; + + write_unlock(&kvm->mmu_lock); +} + +int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn) +{ + struct kvm_mmu_page *sp; + LIST_HEAD(invalid_list); + int r; + + pgprintk("%s: looking for gfn %llx\n", __func__, gfn); + r = 0; + write_lock(&kvm->mmu_lock); + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { + pgprintk("%s: gfn %llx role %x\n", __func__, gfn, + sp->role.word); + r = 1; + kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); + } + kvm_mmu_commit_zap_page(kvm, &invalid_list); + write_unlock(&kvm->mmu_lock); + + return r; +} + +int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) +{ + gpa_t gpa; + int r; + + if (vcpu->arch.mmu->root_role.direct) + return 0; + + gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL); + + r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT); + + return r; +} + +static void kvm_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + trace_kvm_mmu_unsync_page(sp); + ++kvm->stat.mmu_unsync; + sp->unsync = 1; + + kvm_mmu_mark_parents_unsync(sp); +} + +/* + * Attempt to unsync any shadow pages that can be reached by the specified gfn, + * KVM is creating a writable mapping for said gfn. Returns 0 if all pages + * were marked unsync (or if there is no shadow page), -EPERM if the SPTE must + * be write-protected. + */ +int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, + gfn_t gfn, bool can_unsync, bool prefetch) +{ + struct kvm_mmu_page *sp; + bool locked = false; + + /* + * Force write-protection if the page is being tracked. Note, the page + * track machinery is used to write-protect upper-level shadow pages, + * i.e. this guards the role.level == 4K assertion below! + */ + if (kvm_slot_page_track_is_active(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE)) + return -EPERM; + + /* + * The page is not write-tracked, mark existing shadow pages unsync + * unless KVM is synchronizing an unsync SP (can_unsync = false). In + * that case, KVM must complete emulation of the guest TLB flush before + * allowing shadow pages to become unsync (writable by the guest). + */ + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { + if (!can_unsync) + return -EPERM; + + if (sp->unsync) + continue; + + if (prefetch) + return -EEXIST; + + /* + * TDP MMU page faults require an additional spinlock as they + * run with mmu_lock held for read, not write, and the unsync + * logic is not thread safe. Take the spinklock regardless of + * the MMU type to avoid extra conditionals/parameters, there's + * no meaningful penalty if mmu_lock is held for write. + */ + if (!locked) { + locked = true; + spin_lock(&kvm->arch.mmu_unsync_pages_lock); + + /* + * Recheck after taking the spinlock, a different vCPU + * may have since marked the page unsync. A false + * positive on the unprotected check above is not + * possible as clearing sp->unsync _must_ hold mmu_lock + * for write, i.e. unsync cannot transition from 0->1 + * while this CPU holds mmu_lock for read (or write). + */ + if (READ_ONCE(sp->unsync)) + continue; + } + + WARN_ON(sp->role.level != PG_LEVEL_4K); + kvm_unsync_page(kvm, sp); + } + if (locked) + spin_unlock(&kvm->arch.mmu_unsync_pages_lock); + + /* + * We need to ensure that the marking of unsync pages is visible + * before the SPTE is updated to allow writes because + * kvm_mmu_sync_roots() checks the unsync flags without holding + * the MMU lock and so can race with this. If the SPTE was updated + * before the page had been marked as unsync-ed, something like the + * following could happen: + * + * CPU 1 CPU 2 + * --------------------------------------------------------------------- + * 1.2 Host updates SPTE + * to be writable + * 2.1 Guest writes a GPTE for GVA X. + * (GPTE being in the guest page table shadowed + * by the SP from CPU 1.) + * This reads SPTE during the page table walk. + * Since SPTE.W is read as 1, there is no + * fault. + * + * 2.2 Guest issues TLB flush. + * That causes a VM Exit. + * + * 2.3 Walking of unsync pages sees sp->unsync is + * false and skips the page. + * + * 2.4 Guest accesses GVA X. + * Since the mapping in the SP was not updated, + * so the old mapping for GVA X incorrectly + * gets used. + * 1.1 Host marks SP + * as unsync + * (sp->unsync = true) + * + * The write barrier below ensures that 1.1 happens before 1.2 and thus + * the situation in 2.4 does not arise. It pairs with the read barrier + * in is_unsync_root(), placed between 2.1's load of SPTE.W and 2.3. + */ + smp_wmb(); + + return 0; +} + +int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, + u64 *sptep, unsigned int pte_access, gfn_t gfn, + kvm_pfn_t pfn, struct kvm_page_fault *fault) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + int level = sp->role.level; + int was_rmapped = 0; + int ret = RET_PF_FIXED; + bool flush = false; + bool wrprot; + u64 spte; + + /* Prefetching always gets a writable pfn. */ + bool host_writable = !fault || fault->map_writable; + bool prefetch = !fault || fault->prefetch; + bool write_fault = fault && fault->write; + + pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, + *sptep, write_fault, gfn); + + if (unlikely(is_noslot_pfn(pfn))) { + vcpu->stat.pf_mmio_spte_created++; + mark_mmio_spte(vcpu, sptep, gfn, pte_access); + return RET_PF_EMULATE; + } + + if (is_shadow_present_pte(*sptep)) { + /* + * If we overwrite a PTE page pointer with a 2MB PMD, unlink + * the parent of the now unreachable PTE. + */ + if (level > PG_LEVEL_4K && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + u64 pte = *sptep; + + child = spte_to_child_sp(pte); + drop_parent_pte(child, sptep); + flush = true; + } else if (pfn != spte_to_pfn(*sptep)) { + pgprintk("hfn old %llx new %llx\n", + spte_to_pfn(*sptep), pfn); + drop_spte(vcpu->kvm, sptep); + flush = true; + } else + was_rmapped = 1; + } + + wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, + true, host_writable, &spte); + + if (*sptep == spte) { + ret = RET_PF_SPURIOUS; + } else { + flush |= mmu_spte_update(sptep, spte); + trace_kvm_mmu_set_spte(level, gfn, sptep); + } + + if (wrprot) { + if (write_fault) + ret = RET_PF_EMULATE; + } + + if (flush) + kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, + KVM_PAGES_PER_HPAGE(level)); + + pgprintk("%s: setting spte %llx\n", __func__, *sptep); + + if (!was_rmapped) { + WARN_ON_ONCE(ret == RET_PF_SPURIOUS); + rmap_add(vcpu, slot, sptep, gfn, pte_access); + } else { + /* Already rmapped but the pte_access bits may have changed. */ + kvm_mmu_page_set_access(sp, spte_index(sptep), pte_access); + } + + return ret; +} + +static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *sp, + u64 *start, u64 *end) +{ + struct page *pages[PTE_PREFETCH_NUM]; + struct kvm_memory_slot *slot; + unsigned int access = sp->role.access; + int i, ret; + gfn_t gfn; + + gfn = kvm_mmu_page_get_gfn(sp, spte_index(start)); + slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK); + if (!slot) + return -1; + + ret = gfn_to_page_many_atomic(slot, gfn, pages, end - start); + if (ret <= 0) + return -1; + + for (i = 0; i < ret; i++, gfn++, start++) { + mmu_set_spte(vcpu, slot, start, access, gfn, + page_to_pfn(pages[i]), NULL); + put_page(pages[i]); + } + + return 0; +} + +void __direct_pte_prefetch(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + u64 *sptep) +{ + u64 *spte, *start = NULL; + int i; + + WARN_ON(!sp->role.direct); + + i = spte_index(sptep) & ~(PTE_PREFETCH_NUM - 1); + spte = sp->spt + i; + + for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { + if (is_shadow_present_pte(*spte) || spte == sptep) { + if (!start) + continue; + if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0) + return; + start = NULL; + } else if (!start) + start = spte; + } + if (start) + direct_pte_prefetch_many(vcpu, sp, start, spte); +} + +static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(sptep); + + /* + * Without accessed bits, there's no way to distinguish between + * actually accessed translations and prefetched, so disable pte + * prefetch if accessed bits aren't available. + */ + if (sp_ad_disabled(sp)) + return; + + if (sp->role.level > PG_LEVEL_4K) + return; + + /* + * If addresses are being invalidated, skip prefetching to avoid + * accidentally prefetching those addresses. + */ + if (unlikely(vcpu->kvm->mmu_invalidate_in_progress)) + return; + + __direct_pte_prefetch(vcpu, sp, sptep); +} + +int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_shadow_walk_iterator it; + struct kvm_mmu_page *sp; + int ret; + gfn_t base_gfn = fault->gfn; + + kvm_mmu_hugepage_adjust(vcpu, fault); + + trace_kvm_mmu_spte_requested(fault); + for_each_shadow_entry(vcpu, fault->addr, it) { + /* + * We cannot overwrite existing page tables with an NX + * large page, as the leaf could be executable. + */ + if (fault->nx_huge_page_workaround_enabled) + disallowed_hugepage_adjust(fault, *it.sptep, it.level); + + base_gfn = fault->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1); + if (it.level == fault->goal_level) + break; + + sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL); + if (sp == ERR_PTR(-EEXIST)) + continue; + + link_shadow_page(vcpu, it.sptep, sp); + if (fault->huge_page_disallowed) + account_nx_huge_page(vcpu->kvm, sp, + fault->req_level >= it.level); + } + + if (WARN_ON_ONCE(it.level != fault->goal_level)) + return -EFAULT; + + ret = mmu_set_spte(vcpu, fault->slot, it.sptep, ACC_ALL, + base_gfn, fault->pfn, fault); + if (ret == RET_PF_SPURIOUS) + return ret; + + direct_pte_prefetch(vcpu, it.sptep); + return ret; +} + +/* + * Returns the last level spte pointer of the shadow page walk for the given + * gpa, and sets *spte to the spte value. This spte may be non-preset. If no + * walk could be performed, returns NULL and *spte does not contain valid data. + * + * Contract: + * - Must be called between walk_shadow_page_lockless_{begin,end}. + * - The returned sptep must not be used after walk_shadow_page_lockless_end. + */ +u64 *fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte) +{ + struct kvm_shadow_walk_iterator iterator; + u64 old_spte; + u64 *sptep = NULL; + + for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) { + sptep = iterator.sptep; + *spte = old_spte; + } + + return sptep; +} + +void kvm_mmu_free_guest_mode_roots(struct kvm *kvm, struct kvm_mmu *mmu) +{ + unsigned long roots_to_free = 0; + hpa_t root_hpa; + int i; + + /* + * This should not be called while L2 is active, L2 can't invalidate + * _only_ its own roots, e.g. INVVPID unconditionally exits. + */ + WARN_ON_ONCE(mmu->root_role.guest_mode); + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + root_hpa = mmu->prev_roots[i].hpa; + if (!VALID_PAGE(root_hpa)) + continue; + + if (!to_shadow_page(root_hpa) || + to_shadow_page(root_hpa)->role.guest_mode) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + } + + kvm_mmu_free_roots(kvm, mmu, roots_to_free); +} +EXPORT_SYMBOL_GPL(kvm_mmu_free_guest_mode_roots); + + +static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn) +{ + int ret = 0; + + if (!kvm_vcpu_is_visible_gfn(vcpu, root_gfn)) { + kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); + ret = 1; + } + + return ret; +} + +hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, u8 level) +{ + union kvm_mmu_page_role role = vcpu->arch.mmu->root_role; + struct kvm_mmu_page *sp; + + role.level = level; + role.quadrant = quadrant; + + WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte); + WARN_ON_ONCE(role.direct && role.has_4_byte_gpte); + + sp = kvm_mmu_get_shadow_page(vcpu, gfn, role); + ++sp->root_count; + + return __pa(sp->spt); +} + +static int mmu_first_shadow_root_alloc(struct kvm *kvm) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + int r = 0, i, bkt; + + /* + * Check if this is the first shadow root being allocated before + * taking the lock. + */ + if (kvm_shadow_root_allocated(kvm)) + return 0; + + mutex_lock(&kvm->slots_arch_lock); + + /* Recheck, under the lock, whether this is the first shadow root. */ + if (kvm_shadow_root_allocated(kvm)) + goto out_unlock; + + /* + * Check if anything actually needs to be allocated, e.g. all metadata + * will be allocated upfront if TDP is disabled. + */ + if (kvm_memslots_have_rmaps(kvm) && + kvm_page_track_write_tracking_enabled(kvm)) + goto out_success; + + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { + slots = __kvm_memslots(kvm, i); + kvm_for_each_memslot(slot, bkt, slots) { + /* + * Both of these functions are no-ops if the target is + * already allocated, so unconditionally calling both + * is safe. Intentionally do NOT free allocations on + * failure to avoid having to track which allocations + * were made now versus when the memslot was created. + * The metadata is guaranteed to be freed when the slot + * is freed, and will be kept/used if userspace retries + * KVM_RUN instead of killing the VM. + */ + r = memslot_rmap_alloc(slot, slot->npages); + if (r) + goto out_unlock; + r = kvm_page_track_write_tracking_alloc(slot); + if (r) + goto out_unlock; + } + } + + /* + * Ensure that shadow_root_allocated becomes true strictly after + * all the related pointers are set. + */ +out_success: + smp_store_release(&kvm->arch.shadow_root_allocated, true); + +out_unlock: + mutex_unlock(&kvm->slots_arch_lock); + return r; +} + +int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + u64 pdptrs[4], pm_mask; + gfn_t root_gfn, root_pgd; + int quadrant, i, r; + hpa_t root; + + root_pgd = mmu->get_guest_pgd(vcpu); + root_gfn = root_pgd >> PAGE_SHIFT; + + if (mmu_check_root(vcpu, root_gfn)) + return 1; + + /* + * On SVM, reading PDPTRs might access guest memory, which might fault + * and thus might sleep. Grab the PDPTRs before acquiring mmu_lock. + */ + if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { + for (i = 0; i < 4; ++i) { + pdptrs[i] = mmu->get_pdptr(vcpu, i); + if (!(pdptrs[i] & PT_PRESENT_MASK)) + continue; + + if (mmu_check_root(vcpu, pdptrs[i] >> PAGE_SHIFT)) + return 1; + } + } + + r = mmu_first_shadow_root_alloc(vcpu->kvm); + if (r) + return r; + + write_lock(&vcpu->kvm->mmu_lock); + r = make_mmu_pages_available(vcpu); + if (r < 0) + goto out_unlock; + + /* + * Do we shadow a long mode page table? If so we need to + * write-protect the guests page table root. + */ + if (mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { + root = mmu_alloc_root(vcpu, root_gfn, 0, + mmu->root_role.level); + mmu->root.hpa = root; + goto set_root_pgd; + } + + if (WARN_ON_ONCE(!mmu->pae_root)) { + r = -EIO; + goto out_unlock; + } + + /* + * We shadow a 32 bit page table. This may be a legacy 2-level + * or a PAE 3-level page table. In either case we need to be aware that + * the shadow page table may be a PAE or a long mode page table. + */ + pm_mask = PT_PRESENT_MASK | shadow_me_value; + if (mmu->root_role.level >= PT64_ROOT_4LEVEL) { + pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; + + if (WARN_ON_ONCE(!mmu->pml4_root)) { + r = -EIO; + goto out_unlock; + } + mmu->pml4_root[0] = __pa(mmu->pae_root) | pm_mask; + + if (mmu->root_role.level == PT64_ROOT_5LEVEL) { + if (WARN_ON_ONCE(!mmu->pml5_root)) { + r = -EIO; + goto out_unlock; + } + mmu->pml5_root[0] = __pa(mmu->pml4_root) | pm_mask; + } + } + + for (i = 0; i < 4; ++i) { + WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); + + if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { + if (!(pdptrs[i] & PT_PRESENT_MASK)) { + mmu->pae_root[i] = INVALID_PAE_ROOT; + continue; + } + root_gfn = pdptrs[i] >> PAGE_SHIFT; + } + + /* + * If shadowing 32-bit non-PAE page tables, each PAE page + * directory maps one quarter of the guest's non-PAE page + * directory. Othwerise each PAE page direct shadows one guest + * PAE page directory so that quadrant should be 0. + */ + quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0; + + root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL); + mmu->pae_root[i] = root | pm_mask; + } + + if (mmu->root_role.level == PT64_ROOT_5LEVEL) + mmu->root.hpa = __pa(mmu->pml5_root); + else if (mmu->root_role.level == PT64_ROOT_4LEVEL) + mmu->root.hpa = __pa(mmu->pml4_root); + else + mmu->root.hpa = __pa(mmu->pae_root); + +set_root_pgd: + mmu->root.pgd = root_pgd; +out_unlock: + write_unlock(&vcpu->kvm->mmu_lock); + + return r; +} + +int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + bool need_pml5 = mmu->root_role.level > PT64_ROOT_4LEVEL; + u64 *pml5_root = NULL; + u64 *pml4_root = NULL; + u64 *pae_root; + + /* + * When shadowing 32-bit or PAE NPT with 64-bit NPT, the PML4 and PDP + * tables are allocated and initialized at root creation as there is no + * equivalent level in the guest's NPT to shadow. Allocate the tables + * on demand, as running a 32-bit L1 VMM on 64-bit KVM is very rare. + */ + if (mmu->root_role.direct || + mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL || + mmu->root_role.level < PT64_ROOT_4LEVEL) + return 0; + + /* + * NPT, the only paging mode that uses this horror, uses a fixed number + * of levels for the shadow page tables, e.g. all MMUs are 4-level or + * all MMus are 5-level. Thus, this can safely require that pml5_root + * is allocated if the other roots are valid and pml5 is needed, as any + * prior MMU would also have required pml5. + */ + if (mmu->pae_root && mmu->pml4_root && (!need_pml5 || mmu->pml5_root)) + return 0; + + /* + * The special roots should always be allocated in concert. Yell and + * bail if KVM ends up in a state where only one of the roots is valid. + */ + if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root || + (need_pml5 && mmu->pml5_root))) + return -EIO; + + /* + * Unlike 32-bit NPT, the PDP table doesn't need to be in low mem, and + * doesn't need to be decrypted. + */ + pae_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pae_root) + return -ENOMEM; + +#ifdef CONFIG_X86_64 + pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pml4_root) + goto err_pml4; + + if (need_pml5) { + pml5_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pml5_root) + goto err_pml5; + } +#endif + + mmu->pae_root = pae_root; + mmu->pml4_root = pml4_root; + mmu->pml5_root = pml5_root; + + return 0; + +#ifdef CONFIG_X86_64 +err_pml5: + free_page((unsigned long)pml4_root); +err_pml4: + free_page((unsigned long)pae_root); + return -ENOMEM; +#endif +} + +static bool is_unsync_root(hpa_t root) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root)) + return false; + + /* + * The read barrier orders the CPU's read of SPTE.W during the page table + * walk before the reads of sp->unsync/sp->unsync_children here. + * + * Even if another CPU was marking the SP as unsync-ed simultaneously, + * any guest page table changes are not guaranteed to be visible anyway + * until this VCPU issues a TLB flush strictly after those changes are + * made. We only need to ensure that the other CPU sets these flags + * before any actual changes to the page tables are made. The comments + * in mmu_try_to_unsync_pages() describe what could go wrong if this + * requirement isn't satisfied. + */ + smp_rmb(); + sp = to_shadow_page(root); + + /* + * PAE roots (somewhat arbitrarily) aren't backed by shadow pages, the + * PDPTEs for a given PAE root need to be synchronized individually. + */ + if (WARN_ON_ONCE(!sp)) + return false; + + if (sp->unsync || sp->unsync_children) + return true; + + return false; +} + +void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu) +{ + int i; + struct kvm_mmu_page *sp; + + if (vcpu->arch.mmu->root_role.direct) + return; + + if (!VALID_PAGE(vcpu->arch.mmu->root.hpa)) + return; + + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); + + if (vcpu->arch.mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { + hpa_t root = vcpu->arch.mmu->root.hpa; + sp = to_shadow_page(root); + + if (!is_unsync_root(root)) + return; + + write_lock(&vcpu->kvm->mmu_lock); + mmu_sync_children(vcpu, sp, true); + write_unlock(&vcpu->kvm->mmu_lock); + return; + } + + write_lock(&vcpu->kvm->mmu_lock); + + for (i = 0; i < 4; ++i) { + hpa_t root = vcpu->arch.mmu->pae_root[i]; + + if (IS_VALID_PAE_ROOT(root)) { + sp = spte_to_child_sp(root); + mmu_sync_children(vcpu, sp, true); + } + } + + write_unlock(&vcpu->kvm->mmu_lock); +} + +void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu) +{ + unsigned long roots_to_free = 0; + int i; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (is_unsync_root(vcpu->arch.mmu->prev_roots[i].hpa)) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + + /* sync prev_roots by simply freeing them */ + kvm_mmu_free_roots(vcpu->kvm, vcpu->arch.mmu, roots_to_free); +} + +/* + * Return the level of the lowest level SPTE added to sptes. + * That SPTE may be non-present. + * + * Must be called between walk_shadow_page_lockless_{begin,end}. + */ +int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) +{ + struct kvm_shadow_walk_iterator iterator; + int leaf = -1; + u64 spte; + + for (shadow_walk_init(&iterator, vcpu, addr), + *root_level = iterator.level; + shadow_walk_okay(&iterator); + __shadow_walk_next(&iterator, spte)) { + leaf = iterator.level; + spte = mmu_spte_get_lockless(iterator.sptep); + + sptes[leaf] = spte; + } + + return leaf; +} + +void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) +{ + struct kvm_shadow_walk_iterator iterator; + u64 spte; + + walk_shadow_page_lockless_begin(vcpu); + for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) + clear_sp_write_flooding_count(iterator.sptep); + walk_shadow_page_lockless_end(vcpu); +} + +static bool is_obsolete_root(struct kvm *kvm, hpa_t root_hpa) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root_hpa)) + return false; + + /* + * When freeing obsolete roots, treat roots as obsolete if they don't + * have an associated shadow page. This does mean KVM will get false + * positives and free roots that don't strictly need to be freed, but + * such false positives are relatively rare: + * + * (a) only PAE paging and nested NPT has roots without shadow pages + * (b) remote reloads due to a memslot update obsoletes _all_ roots + * (c) KVM doesn't track previous roots for PAE paging, and the guest + * is unlikely to zap an in-use PGD. + */ + sp = to_shadow_page(root_hpa); + return !sp || is_obsolete_sp(kvm, sp); +} + +static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu) +{ + unsigned long roots_to_free = 0; + int i; + + if (is_obsolete_root(kvm, mmu->root.hpa)) + roots_to_free |= KVM_MMU_ROOT_CURRENT; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + if (is_obsolete_root(kvm, mmu->prev_roots[i].hpa)) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + } + + if (roots_to_free) + kvm_mmu_free_roots(kvm, mmu, roots_to_free); +} + +void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu) +{ + __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.root_mmu); + __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu); +} + +static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, + int *bytes) +{ + u64 gentry = 0; + int r; + + /* + * Assume that the pte write on a page table of the same type + * as the current vcpu paging mode since we update the sptes only + * when they have the same mode. + */ + if (is_pae(vcpu) && *bytes == 4) { + /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ + *gpa &= ~(gpa_t)7; + *bytes = 8; + } + + if (*bytes == 4 || *bytes == 8) { + r = kvm_vcpu_read_guest_atomic(vcpu, *gpa, &gentry, *bytes); + if (r) + gentry = 0; + } + + return gentry; +} + +/* + * If we're seeing too many writes to a page, it may no longer be a page table, + * or we may be forking, in which case it is better to unmap the page. + */ +static bool detect_write_flooding(struct kvm_mmu_page *sp) +{ + /* + * Skip write-flooding detected for the sp whose level is 1, because + * it can become unsync, then the guest page is not write-protected. + */ + if (sp->role.level == PG_LEVEL_4K) + return false; + + atomic_inc(&sp->write_flooding_count); + return atomic_read(&sp->write_flooding_count) >= 3; +} + +/* + * Misaligned accesses are too much trouble to fix up; also, they usually + * indicate a page is not used as a page table. + */ +static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, + int bytes) +{ + unsigned offset, pte_size, misaligned; + + pgprintk("misaligned: gpa %llx bytes %d role %x\n", + gpa, bytes, sp->role.word); + + offset = offset_in_page(gpa); + pte_size = sp->role.has_4_byte_gpte ? 4 : 8; + + /* + * Sometimes, the OS only writes the last one bytes to update status + * bits, for example, in linux, andb instruction is used in clear_bit(). + */ + if (!(offset & (pte_size - 1)) && bytes == 1) + return false; + + misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); + misaligned |= bytes < 4; + + return misaligned; +} + +static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) +{ + unsigned page_offset, quadrant; + u64 *spte; + int level; + + page_offset = offset_in_page(gpa); + level = sp->role.level; + *nspte = 1; + if (sp->role.has_4_byte_gpte) { + page_offset <<= 1; /* 32->64 */ + /* + * A 32-bit pde maps 4MB while the shadow pdes map + * only 2MB. So we need to double the offset again + * and zap two pdes instead of one. + */ + if (level == PT32_ROOT_LEVEL) { + page_offset &= ~7; /* kill rounding error */ + page_offset <<= 1; + *nspte = 2; + } + quadrant = page_offset >> PAGE_SHIFT; + page_offset &= ~PAGE_MASK; + if (quadrant != sp->role.quadrant) + return NULL; + } + + spte = &sp->spt[page_offset / sizeof(*spte)]; + return spte; +} + +void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, + int bytes, struct kvm_page_track_notifier_node *node) +{ + gfn_t gfn = gpa >> PAGE_SHIFT; + struct kvm_mmu_page *sp; + LIST_HEAD(invalid_list); + u64 entry, gentry, *spte; + int npte; + bool flush = false; + + /* + * If we don't have indirect shadow pages, it means no page is + * write-protected, so we can exit simply. + */ + if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) + return; + + pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes); + + write_lock(&vcpu->kvm->mmu_lock); + + gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes); + + ++vcpu->kvm->stat.mmu_pte_write; + + for_each_gfn_valid_sp_with_gptes(vcpu->kvm, sp, gfn) { + if (detect_write_misaligned(sp, gpa, bytes) || + detect_write_flooding(sp)) { + kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list); + ++vcpu->kvm->stat.mmu_flooded; + continue; + } + + spte = get_written_sptes(sp, gpa, &npte); + if (!spte) + continue; + + while (npte--) { + entry = *spte; + mmu_page_zap_pte(vcpu->kvm, sp, spte, NULL); + if (gentry && sp->role.level != PG_LEVEL_4K) + ++vcpu->kvm->stat.mmu_pde_zapped; + if (is_shadow_present_pte(entry)) + flush = true; + ++spte; + } + } + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + write_unlock(&vcpu->kvm->mmu_lock); +} + +/* The caller should hold mmu-lock before calling this function. */ +static __always_inline bool +slot_handle_level_range(struct kvm *kvm, const struct kvm_memory_slot *memslot, + slot_level_handler fn, int start_level, int end_level, + gfn_t start_gfn, gfn_t end_gfn, bool flush_on_yield, + bool flush) +{ + struct slot_rmap_walk_iterator iterator; + + for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn, + end_gfn, &iterator) { + if (iterator.rmap) + flush |= fn(kvm, iterator.rmap, memslot); + + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { + if (flush && flush_on_yield) { + kvm_flush_remote_tlbs_with_address(kvm, + start_gfn, + iterator.gfn - start_gfn + 1); + flush = false; + } + cond_resched_rwlock_write(&kvm->mmu_lock); + } + } + + return flush; +} + +__always_inline bool slot_handle_level(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + slot_level_handler fn, int start_level, + int end_level, bool flush_on_yield) +{ + return slot_handle_level_range(kvm, memslot, fn, start_level, + end_level, memslot->base_gfn, + memslot->base_gfn + memslot->npages - 1, + flush_on_yield, false); +} + +__always_inline bool slot_handle_level_4k(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + slot_level_handler fn, + bool flush_on_yield) +{ + return slot_handle_level(kvm, memslot, fn, PG_LEVEL_4K, + PG_LEVEL_4K, flush_on_yield); +} + +#define BATCH_ZAP_PAGES 10 +void kvm_zap_obsolete_pages(struct kvm *kvm) +{ + struct kvm_mmu_page *sp, *node; + int nr_zapped, batch = 0; + bool unstable; + +restart: + list_for_each_entry_safe_reverse(sp, node, + &kvm->arch.active_mmu_pages, link) { + /* + * No obsolete valid page exists before a newly created page + * since active_mmu_pages is a FIFO list. + */ + if (!is_obsolete_sp(kvm, sp)) + break; + + /* + * Invalid pages should never land back on the list of active + * pages. Skip the bogus page, otherwise we'll get stuck in an + * infinite loop if the page gets put back on the list (again). + */ + if (WARN_ON(sp->role.invalid)) + continue; + + /* + * No need to flush the TLB since we're only zapping shadow + * pages with an obsolete generation number and all vCPUS have + * loaded a new root, i.e. the shadow pages being zapped cannot + * be in active use by the guest. + */ + if (batch >= BATCH_ZAP_PAGES && + cond_resched_rwlock_write(&kvm->mmu_lock)) { + batch = 0; + goto restart; + } + + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, + &kvm->arch.zapped_obsolete_pages, &nr_zapped); + batch += nr_zapped; + + if (unstable) + goto restart; + } + + /* + * Kick all vCPUs (via remote TLB flush) before freeing the page tables + * to ensure KVM is not in the middle of a lockless shadow page table + * walk, which may reference the pages. The remote TLB flush itself is + * not required and is simply a convenient way to kick vCPUs as needed. + * KVM performs a local TLB flush when allocating a new root (see + * kvm_mmu_load()), and the reload in the caller ensure no vCPUs are + * running with an obsolete MMU. + */ + kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); +} + +static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) +{ + return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); +} + +bool kvm_rmap_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) +{ + const struct kvm_memory_slot *memslot; + struct kvm_memslots *slots; + struct kvm_memslot_iter iter; + bool flush = false; + gfn_t start, end; + int i; + + if (!kvm_memslots_have_rmaps(kvm)) + return flush; + + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { + slots = __kvm_memslots(kvm, i); + + kvm_for_each_memslot_in_gfn_range(&iter, slots, gfn_start, gfn_end) { + memslot = iter.slot; + start = max(gfn_start, memslot->base_gfn); + end = min(gfn_end, memslot->base_gfn + memslot->npages); + if (WARN_ON_ONCE(start >= end)) + continue; + + flush = slot_handle_level_range(kvm, memslot, __kvm_zap_rmap, + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, + start, end - 1, true, flush); + } + } + + return flush; +} + +bool slot_rmap_write_protect(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + return rmap_write_protect(rmap_head, false); +} + +static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep) +{ + struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); + struct shadow_page_caches caches = {}; + union kvm_mmu_page_role role; + unsigned int access; + gfn_t gfn; + + gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); + access = kvm_mmu_page_get_access(huge_sp, spte_index(huge_sptep)); + + /* + * Note, huge page splitting always uses direct shadow pages, regardless + * of whether the huge page itself is mapped by a direct or indirect + * shadow page, since the huge page region itself is being directly + * mapped with smaller pages. + */ + role = kvm_mmu_child_role(huge_sptep, /*direct=*/true, access); + + /* Direct SPs do not require a shadowed_info_cache. */ + caches.page_header_cache = &kvm->arch.split_page_header_cache; + caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache; + + /* Safe to pass NULL for vCPU since requesting a direct SP. */ + return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role); +} + +static void shadow_mmu_split_huge_page(struct kvm *kvm, + const struct kvm_memory_slot *slot, + u64 *huge_sptep) + +{ + struct kvm_mmu_memory_cache *cache = &kvm->arch.split_desc_cache; + u64 huge_spte = READ_ONCE(*huge_sptep); + struct kvm_mmu_page *sp; + bool flush = false; + u64 *sptep, spte; + gfn_t gfn; + int index; + + sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep); + + for (index = 0; index < SPTE_ENT_PER_PAGE; index++) { + sptep = &sp->spt[index]; + gfn = kvm_mmu_page_get_gfn(sp, index); + + /* + * The SP may already have populated SPTEs, e.g. if this huge + * page is aliased by multiple sptes with the same access + * permissions. These entries are guaranteed to map the same + * gfn-to-pfn translation since the SP is direct, so no need to + * modify them. + * + * However, if a given SPTE points to a lower level page table, + * that lower level page table may only be partially populated. + * Installing such SPTEs would effectively unmap a potion of the + * huge page. Unmapping guest memory always requires a TLB flush + * since a subsequent operation on the unmapped regions would + * fail to detect the need to flush. + */ + if (is_shadow_present_pte(*sptep)) { + flush |= !is_last_spte(*sptep, sp->role.level); + continue; + } + + spte = make_huge_page_split_spte(kvm, huge_spte, sp->role, index); + mmu_spte_set(sptep, spte); + __rmap_add(kvm, cache, slot, sptep, gfn, sp->role.access); + } + + __link_shadow_page(kvm, cache, huge_sptep, sp, flush); +} + +static int shadow_mmu_try_split_huge_page(struct kvm *kvm, + const struct kvm_memory_slot *slot, + u64 *huge_sptep) +{ + struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); + int level, r = 0; + gfn_t gfn; + u64 spte; + + /* Grab information for the tracepoint before dropping the MMU lock. */ + gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); + level = huge_sp->role.level; + spte = *huge_sptep; + + if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) { + r = -ENOSPC; + goto out; + } + + if (need_topup_split_caches_or_resched(kvm)) { + write_unlock(&kvm->mmu_lock); + cond_resched(); + /* + * If the topup succeeds, return -EAGAIN to indicate that the + * rmap iterator should be restarted because the MMU lock was + * dropped. + */ + r = topup_split_caches(kvm) ?: -EAGAIN; + write_lock(&kvm->mmu_lock); + goto out; + } + + shadow_mmu_split_huge_page(kvm, slot, huge_sptep); + +out: + trace_kvm_mmu_split_huge_page(gfn, spte, level, r); + return r; +} + +static bool shadow_mmu_try_split_huge_pages(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + struct rmap_iterator iter; + struct kvm_mmu_page *sp; + u64 *huge_sptep; + int r; + +restart: + for_each_rmap_spte(rmap_head, &iter, huge_sptep) { + sp = sptep_to_sp(huge_sptep); + + /* TDP MMU is enabled, so rmap only contains nested MMU SPs. */ + if (WARN_ON_ONCE(!sp->role.guest_mode)) + continue; + + /* The rmaps should never contain non-leaf SPTEs. */ + if (WARN_ON_ONCE(!is_large_pte(*huge_sptep))) + continue; + + /* SPs with level >PG_LEVEL_4K should never by unsync. */ + if (WARN_ON_ONCE(sp->unsync)) + continue; + + /* Don't bother splitting huge pages on invalid SPs. */ + if (sp->role.invalid) + continue; + + r = shadow_mmu_try_split_huge_page(kvm, slot, huge_sptep); + + /* + * The split succeeded or needs to be retried because the MMU + * lock was dropped. Either way, restart the iterator to get it + * back into a consistent state. + */ + if (!r || r == -EAGAIN) + goto restart; + + /* The split failed and shouldn't be retried (e.g. -ENOMEM). */ + break; + } + + return false; +} + +void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t start, gfn_t end, + int target_level) +{ + int level; + + /* + * Split huge pages starting with KVM_MAX_HUGEPAGE_LEVEL and working + * down to the target level. This ensures pages are recursively split + * all the way to the target level. There's no need to split pages + * already at the target level. + */ + for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--) { + slot_handle_level_range(kvm, slot, shadow_mmu_try_split_huge_pages, + level, level, start, end - 1, true, false); + } +} + +static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + u64 *sptep; + struct rmap_iterator iter; + int need_tlb_flush = 0; + struct kvm_mmu_page *sp; + +restart: + for_each_rmap_spte(rmap_head, &iter, sptep) { + sp = sptep_to_sp(sptep); + + /* + * We cannot do huge page mapping for indirect shadow pages, + * which are found on the last rmap (level = 1) when not using + * tdp; such shadow pages are synced with the page table in + * the guest, and the guest page table is using 4K page size + * mapping if the indirect sp has level = 1. + */ + if (sp->role.direct && + sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn, + PG_LEVEL_NUM)) { + kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); + + if (kvm_available_flush_tlb_with_range()) + kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, + KVM_PAGES_PER_HPAGE(sp->role.level)); + else + need_tlb_flush = 1; + + goto restart; + } + } + + return need_tlb_flush; +} + +void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ + /* + * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap + * pages that are already mapped at the maximum hugepage level. + */ + if (slot_handle_level(kvm, slot, kvm_mmu_zap_collapsible_spte, + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, true)) + kvm_arch_flush_remote_tlbs_memslot(kvm, slot); +} + +unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) +{ + struct kvm *kvm; + int nr_to_scan = sc->nr_to_scan; + unsigned long freed = 0; + + mutex_lock(&kvm_lock); + + list_for_each_entry(kvm, &vm_list, vm_list) { + int idx; + LIST_HEAD(invalid_list); + + /* + * Never scan more than sc->nr_to_scan VM instances. + * Will not hit this condition practically since we do not try + * to shrink more than one VM and it is very unlikely to see + * !n_used_mmu_pages so many times. + */ + if (!nr_to_scan--) + break; + /* + * n_used_mmu_pages is accessed without holding kvm->mmu_lock + * here. We may skip a VM instance errorneosly, but we do not + * want to shrink a VM that only started to populate its MMU + * anyway. + */ + if (!kvm->arch.n_used_mmu_pages && + !kvm_has_zapped_obsolete_pages(kvm)) + continue; + + idx = srcu_read_lock(&kvm->srcu); + write_lock(&kvm->mmu_lock); + + if (kvm_has_zapped_obsolete_pages(kvm)) { + kvm_mmu_commit_zap_page(kvm, + &kvm->arch.zapped_obsolete_pages); + goto unlock; + } + + freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan); + +unlock: + write_unlock(&kvm->mmu_lock); + srcu_read_unlock(&kvm->srcu, idx); + + /* + * unfair on small ones + * per-vm shrinkers cry out + * sadness comes quickly + */ + list_move_tail(&kvm->vm_list, &vm_list); + break; + } + + mutex_unlock(&kvm_lock); + return freed; +} diff --git a/arch/x86/kvm/mmu/shadow_mmu.h b/arch/x86/kvm/mmu/shadow_mmu.h index 719b10f6c403..83876047c1f5 100644 --- a/arch/x86/kvm/mmu/shadow_mmu.h +++ b/arch/x86/kvm/mmu/shadow_mmu.h @@ -5,4 +5,149 @@ #include +/* make pte_list_desc fit well in cache lines */ +#define PTE_LIST_EXT 14 + +/* + * Slight optimization of cacheline layout, by putting `more' and `spte_count' + * at the start; then accessing it will only use one single cacheline for + * either full (entries==PTE_LIST_EXT) case or entries<=6. + */ +struct pte_list_desc { + struct pte_list_desc *more; + /* + * Stores number of entries stored in the pte_list_desc. No need to be + * u64 but just for easier alignment. When PTE_LIST_EXT, means full. + */ + u64 spte_count; + u64 *sptes[PTE_LIST_EXT]; +}; + +unsigned int pte_list_count(struct kvm_rmap_head *rmap_head); + +struct kvm_shadow_walk_iterator { + u64 addr; + hpa_t shadow_addr; + u64 *sptep; + int level; + unsigned index; +}; + +#define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \ + for (shadow_walk_init_using_root(&(_walker), (_vcpu), \ + (_root), (_addr)); \ + shadow_walk_okay(&(_walker)); \ + shadow_walk_next(&(_walker))) + +bool mmu_spte_update(u64 *sptep, u64 new_spte); +void mmu_spte_clear_no_track(u64 *sptep); +gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index); +void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, + unsigned int access); + +struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level, + const struct kvm_memory_slot *slot); +bool rmap_can_add(struct kvm_vcpu *vcpu); +void drop_spte(struct kvm *kvm, u64 *sptep); +bool rmap_write_protect(struct kvm_rmap_head *rmap_head, bool pt_protect); +bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot); +bool kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t unused); +bool kvm_set_pte_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t pte); + +typedef bool (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, + int level, pte_t pte); +bool kvm_handle_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, + rmap_handler_t handler); + +bool kvm_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t unused); +bool kvm_test_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, + int level, pte_t unused); + +void drop_parent_pte(struct kvm_mmu_page *sp, u64 *parent_pte); +int nonpaging_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp); +int mmu_sync_children(struct kvm_vcpu *vcpu, struct kvm_mmu_page *parent, + bool can_yield); +void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp); +void clear_sp_write_flooding_count(u64 *spte); + +struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu, u64 *sptep, + gfn_t gfn, bool direct, + unsigned int access); + +void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator, + struct kvm_vcpu *vcpu, hpa_t root, u64 addr); +void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator, + struct kvm_vcpu *vcpu, u64 addr); +bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator); +void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator); + +void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, struct kvm_mmu_page *sp); + +void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, + unsigned direct_access); + +int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *spte, + struct list_head *invalid_list); +bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list, + int *nr_zapped); +bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list); +void kvm_mmu_commit_zap_page(struct kvm *kvm, struct list_head *invalid_list); + +int make_mmu_pages_available(struct kvm_vcpu *vcpu); + +int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva); + +int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, + u64 *sptep, unsigned int pte_access, gfn_t gfn, + kvm_pfn_t pfn, struct kvm_page_fault *fault); +void __direct_pte_prefetch(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + u64 *sptep); +int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); +u64 *fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte); + +hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, u8 level); +int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu); +int mmu_alloc_special_roots(struct kvm_vcpu *vcpu); + +int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level); + +void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr); +void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, + int bytes, struct kvm_page_track_notifier_node *node); + +/* The return value indicates if tlb flush on all vcpus is needed. */ +typedef bool (*slot_level_handler) (struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot); +bool slot_handle_level(struct kvm *kvm, const struct kvm_memory_slot *memslot, + slot_level_handler fn, int start_level, int end_level, + bool flush_on_yield); +bool slot_handle_level_4k(struct kvm *kvm, const struct kvm_memory_slot *memslot, + slot_level_handler fn, bool flush_on_yield); + +void kvm_zap_obsolete_pages(struct kvm *kvm); +bool kvm_rmap_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end); + +bool slot_rmap_write_protect(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot); + +void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t start, gfn_t end, + int target_level); +void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot); + +unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc); #endif /* __KVM_X86_MMU_SHADOW_MMU_H */