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[2620:137:e000::1:20]) by mx.google.com with ESMTP id bv4-20020a632e04000000b00536b4c4b695si4790989pgb.136.2023.05.26.16.45.59; Fri, 26 May 2023 16:46:13 -0700 (PDT) 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=20221208 header.b=cWUN3P8r; 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 S237735AbjEZXpF (ORCPT + 99 others); Fri, 26 May 2023 19:45:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237722AbjEZXou (ORCPT ); Fri, 26 May 2023 19:44:50 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0EA51B1 for ; Fri, 26 May 2023 16:44:46 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-565c380565dso13130087b3.1 for ; Fri, 26 May 2023 16:44:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685144686; x=1687736686; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=9t4P2GvyPz5aecPxpWswvlll2je3r362Snycxj82bkU=; b=cWUN3P8rM/d3APcGkGsw1zxYbzC0SLP23YWYAHvNkl8en24zIhenJIzsgauwSrM86L GtpWgjW+9PaIY51P7YD5ERtfy398MWWnA2qbOrXT+m6cJHuvmS8It0VeeYLeOMql5pG+ oF4R8PaA47tg1/M/GaUTjyQPHdY2Yt35bMOgs0yeO0A95+MuHExqrRIRhATT/aSAcAvS DuZIw+jQWwcC1PbwFYK5fVCc5aYJ2bcpXcCLA842C0fEFJDU8WE3MLQI6mTQVW9b35Gn iKpM9XslaKQGwLt7gqMS0LD/fBOZjhpB3/6lsoxW54UOFTglxZ15DmEhLn/Wm52Z8EKo 74zA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685144686; x=1687736686; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=9t4P2GvyPz5aecPxpWswvlll2je3r362Snycxj82bkU=; b=EItzyLIKZLFukFZGPsAhE7DC4qH4gDmT7ymSVkCQaxFZBX8cSchjBKQ1VAXkvihJnk tpfrz8K62TEWIRQOetQ8LD/WbLkATpBo7MswmOYD+fxE38HOlMG0mZwIFhWKWKl9texk utcAxYqhK3R/a7QP87VFA9/jwpOIYKX7nbQZZJsAeUlf4hF9s6f7mev0QO9+eH7lIqKo 4aQvJr6EAZmZhdtUC9wCX8VI1nOY1EujLDPuTqChueNZN26A7ribtwLxfE0DYZ7IwVcC 3ESfW0wkVk5yCsCp/d9Rv6SmEVrB9GkPtBFfPLeQE8Evsk6z1fpaWvXzfGD+fjFo/PFj RPpA== X-Gm-Message-State: AC+VfDyIgD9Gq2Wk/KMGj24S2SIN7agucTDkWuGbH/fbuydDIyxESxQi WdDnkAAvxAc+oeKIybKTmZiUoOWgNmQ= X-Received: from yuzhao.bld.corp.google.com ([2620:15c:183:200:910f:8a15:592b:2087]) (user=yuzhao job=sendgmr) by 2002:a81:b627:0:b0:559:d859:d749 with SMTP id u39-20020a81b627000000b00559d859d749mr437593ywh.5.1685144686225; Fri, 26 May 2023 16:44:46 -0700 (PDT) Date: Fri, 26 May 2023 17:44:29 -0600 In-Reply-To: <20230526234435.662652-1-yuzhao@google.com> Message-Id: <20230526234435.662652-5-yuzhao@google.com> Mime-Version: 1.0 References: <20230526234435.662652-1-yuzhao@google.com> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Subject: [PATCH mm-unstable v2 04/10] kvm/arm64: make stage2 page tables RCU safe From: Yu Zhao To: Andrew Morton , Paolo Bonzini Cc: Alistair Popple , Anup Patel , Ben Gardon , Borislav Petkov , Catalin Marinas , Chao Peng , Christophe Leroy , Dave Hansen , Fabiano Rosas , Gaosheng Cui , Gavin Shan , "H. Peter Anvin" , Ingo Molnar , James Morse , "Jason A. Donenfeld" , Jason Gunthorpe , Jonathan Corbet , Marc Zyngier , Masami Hiramatsu , Michael Ellerman , Michael Larabel , Mike Rapoport , Nicholas Piggin , Oliver Upton , Paul Mackerras , Peter Xu , Sean Christopherson , Steven Rostedt , Suzuki K Poulose , Thomas Gleixner , Thomas Huth , Will Deacon , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, linux-mm@google.com, Yu Zhao 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,T_SCC_BODY_TEXT_LINE,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?1767002366385337344?= X-GMAIL-MSGID: =?utf-8?q?1767002366385337344?= Stage2 page tables are currently not RCU safe against unmapping or VM destruction. The previous mmu_notifier_ops members rely on kvm->mmu_lock to synchronize with those operations. However, the new mmu_notifier_ops member test_clear_young() provides a fast path that does not take kvm->mmu_lock. To implement kvm_arch_test_clear_young() for that path, unmapped page tables need to be freed by RCU and kvm_free_stage2_pgd() needs to be after mmu_notifier_unregister(). Remapping, specifically stage2_free_removed_table(), is already RCU safe. Signed-off-by: Yu Zhao --- arch/arm64/include/asm/kvm_pgtable.h | 2 ++ arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/hyp/pgtable.c | 8 ++++++-- arch/arm64/kvm/mmu.c | 17 ++++++++++++++++- 4 files changed, 25 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index ff520598b62c..5cab52e3a35f 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -153,6 +153,7 @@ static inline bool kvm_level_supports_block_mapping(u32 level) * @put_page: Decrement the refcount on a page. When the * refcount reaches 0 the page is automatically * freed. + * @put_page_rcu: RCU variant of the above. * @page_count: Return the refcount of a page. * @phys_to_virt: Convert a physical address into a virtual * address mapped in the current context. @@ -170,6 +171,7 @@ struct kvm_pgtable_mm_ops { void (*free_removed_table)(void *addr, u32 level); void (*get_page)(void *addr); void (*put_page)(void *addr); + void (*put_page_rcu)(void *addr); int (*page_count)(void *addr); void* (*phys_to_virt)(phys_addr_t phys); phys_addr_t (*virt_to_phys)(void *addr); diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 14391826241c..ee93271035d9 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -191,6 +191,7 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) */ void kvm_arch_destroy_vm(struct kvm *kvm) { + kvm_free_stage2_pgd(&kvm->arch.mmu); bitmap_free(kvm->arch.pmu_filter); free_cpumask_var(kvm->arch.supported_cpus); diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 24678ccba76a..dbace4c6a841 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -988,8 +988,12 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx, mm_ops->dcache_clean_inval_poc(kvm_pte_follow(ctx->old, mm_ops), kvm_granule_size(ctx->level)); - if (childp) - mm_ops->put_page(childp); + if (childp) { + if (mm_ops->put_page_rcu) + mm_ops->put_page_rcu(childp); + else + mm_ops->put_page(childp); + } return 0; } diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 3b9d4d24c361..c3b3e2afe26f 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -172,6 +172,21 @@ static int kvm_host_page_count(void *addr) return page_count(virt_to_page(addr)); } +static void kvm_s2_rcu_put_page(struct rcu_head *head) +{ + put_page(container_of(head, struct page, rcu_head)); +} + +static void kvm_s2_put_page_rcu(void *addr) +{ + struct page *page = virt_to_page(addr); + + if (kvm_host_page_count(addr) == 1) + kvm_account_pgtable_pages(addr, -1); + + call_rcu(&page->rcu_head, kvm_s2_rcu_put_page); +} + static phys_addr_t kvm_host_pa(void *addr) { return __pa(addr); @@ -704,6 +719,7 @@ static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = { .free_removed_table = stage2_free_removed_table, .get_page = kvm_host_get_page, .put_page = kvm_s2_put_page, + .put_page_rcu = kvm_s2_put_page_rcu, .page_count = kvm_host_page_count, .phys_to_virt = kvm_host_va, .virt_to_phys = kvm_host_pa, @@ -1877,7 +1893,6 @@ void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen) void kvm_arch_flush_shadow_all(struct kvm *kvm) { - kvm_free_stage2_pgd(&kvm->arch.mmu); } void kvm_arch_flush_shadow_memslot(struct kvm *kvm,