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[2003:f6:af34:4e00:7f5e:5982:a136:b54e]) by smtp.gmail.com with ESMTPSA id w11-20020a1709067c8b00b009231714b3d4sm6356260ejo.151.2023.03.21.18.34.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 18:34:27 -0700 (PDT) From: Mathias Krause To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Mathias Krause Subject: [PATCH v4 1/6] KVM: x86/mmu: Avoid indirect call for get_cr3 Date: Wed, 22 Mar 2023 02:37:26 +0100 Message-Id: <20230322013731.102955-2-minipli@grsecurity.net> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322013731.102955-1-minipli@grsecurity.net> References: <20230322013731.102955-1-minipli@grsecurity.net> MIME-Version: 1.0 X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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?1761029853697858427?= X-GMAIL-MSGID: =?utf-8?q?1761029853697858427?= From: Paolo Bonzini Most of the time, calls to get_guest_pgd result in calling kvm_read_cr3 (the exception is only nested TDP). Hardcode the default instead of using the get_cr3 function, avoiding a retpoline if they are enabled. Signed-off-by: Paolo Bonzini Signed-off-by: Mathias Krause --- arch/x86/kvm/mmu/mmu.c | 31 ++++++++++++++++++++----------- arch/x86/kvm/mmu/paging_tmpl.h | 2 +- 2 files changed, 21 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 144c5a01cd77..9046a892998e 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -242,6 +242,20 @@ static struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu) return regs; } +static unsigned long get_guest_cr3(struct kvm_vcpu *vcpu) +{ + return kvm_read_cr3(vcpu); +} + +static inline unsigned long kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + if (IS_ENABLED(CONFIG_RETPOLINE) && mmu->get_guest_pgd == get_guest_cr3) + return kvm_read_cr3(vcpu); + + return mmu->get_guest_pgd(vcpu); +} + static inline bool kvm_available_flush_tlb_with_range(void) { return kvm_x86_ops.tlb_remote_flush_with_range; @@ -3731,7 +3745,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) int quadrant, i, r; hpa_t root; - root_pgd = mmu->get_guest_pgd(vcpu); + root_pgd = kvm_mmu_get_guest_pgd(vcpu, mmu); root_gfn = root_pgd >> PAGE_SHIFT; if (mmu_check_root(vcpu, root_gfn)) @@ -4181,7 +4195,7 @@ static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, arch.token = alloc_apf_token(vcpu); arch.gfn = gfn; arch.direct_map = vcpu->arch.mmu->root_role.direct; - arch.cr3 = vcpu->arch.mmu->get_guest_pgd(vcpu); + arch.cr3 = kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu); return kvm_setup_async_pf(vcpu, cr2_or_gpa, kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); @@ -4200,7 +4214,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) return; if (!vcpu->arch.mmu->root_role.direct && - work->arch.cr3 != vcpu->arch.mmu->get_guest_pgd(vcpu)) + work->arch.cr3 != kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu)) return; kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true, NULL); @@ -4604,11 +4618,6 @@ void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd) } EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd); -static unsigned long get_cr3(struct kvm_vcpu *vcpu) -{ - return kvm_read_cr3(vcpu); -} - static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, unsigned int access) { @@ -5159,7 +5168,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu, context->page_fault = kvm_tdp_page_fault; context->sync_page = nonpaging_sync_page; context->invlpg = NULL; - context->get_guest_pgd = get_cr3; + context->get_guest_pgd = get_guest_cr3; context->get_pdptr = kvm_pdptr_read; context->inject_page_fault = kvm_inject_page_fault; @@ -5309,7 +5318,7 @@ static void init_kvm_softmmu(struct kvm_vcpu *vcpu, kvm_init_shadow_mmu(vcpu, cpu_role); - context->get_guest_pgd = get_cr3; + context->get_guest_pgd = get_guest_cr3; context->get_pdptr = kvm_pdptr_read; context->inject_page_fault = kvm_inject_page_fault; } @@ -5323,7 +5332,7 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, return; g_context->cpu_role.as_u64 = new_mode.as_u64; - g_context->get_guest_pgd = get_cr3; + g_context->get_guest_pgd = get_guest_cr3; g_context->get_pdptr = kvm_pdptr_read; g_context->inject_page_fault = kvm_inject_page_fault; diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index a056f2773dd9..8417ecbc3887 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -324,7 +324,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker, trace_kvm_mmu_pagetable_walk(addr, access); retry_walk: walker->level = mmu->cpu_role.base.level; - pte = mmu->get_guest_pgd(vcpu); + pte = kvm_mmu_get_guest_pgd(vcpu, mmu); have_ad = PT_HAVE_ACCESSED_DIRTY(mmu); #if PTTYPE == 64 From patchwork Wed Mar 22 01:37:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathias Krause X-Patchwork-Id: 73150 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:604a:0:0:0:0:0 with SMTP id j10csp2111620wrt; Tue, 21 Mar 2023 18:53:38 -0700 (PDT) X-Google-Smtp-Source: AK7set/VDRsXhzh567zHwo1m877oIuF0PMJixd+0aUpN31PAi4K+OYm/5BaVeymq0WmgdnfnK5su X-Received: by 2002:a17:906:6dcc:b0:932:aa80:406 with SMTP id j12-20020a1709066dcc00b00932aa800406mr5716900ejt.32.1679450018414; 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[2003:f6:af34:4e00:7f5e:5982:a136:b54e]) by smtp.gmail.com with ESMTPSA id w11-20020a1709067c8b00b009231714b3d4sm6356260ejo.151.2023.03.21.18.34.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 18:34:28 -0700 (PDT) From: Mathias Krause To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Mathias Krause Subject: [PATCH v4 2/6] KVM: x86: Do not unload MMU roots when only toggling CR0.WP with TDP enabled Date: Wed, 22 Mar 2023 02:37:27 +0100 Message-Id: <20230322013731.102955-3-minipli@grsecurity.net> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322013731.102955-1-minipli@grsecurity.net> References: <20230322013731.102955-1-minipli@grsecurity.net> MIME-Version: 1.0 X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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?1761030982584513119?= X-GMAIL-MSGID: =?utf-8?q?1761030982584513119?= There is no need to unload the MMU roots with TDP enabled when only CR0.WP has changed -- the paging structures are still valid, only the permission bitmap needs to be updated. One heavy user of toggling CR0.WP is grsecurity's KERNEXEC feature to implement kernel W^X. The optimization brings a huge performance gain for this case as the following micro-benchmark running 'ssdd 10 50000' from rt-tests[1] on a grsecurity L1 VM shows (runtime in seconds, lower is better): legacy TDP shadow kvm-x86/next@d8708b 8.43s 9.45s 70.3s +patch 5.39s 5.63s 70.2s For legacy MMU this is ~36% faster, for TTP MMU even ~40% faster. Also TDP and legacy MMU now both have a similar runtime which vanishes the need to disable TDP MMU for grsecurity. Shadow MMU sees no measurable difference and is still slow, as expected. [1] https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git Co-developed-by: Sean Christopherson Signed-off-by: Mathias Krause --- arch/x86/kvm/x86.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 237c483b1230..c6d909778b2c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -906,6 +906,18 @@ EXPORT_SYMBOL_GPL(load_pdptrs); void kvm_post_set_cr0(struct kvm_vcpu *vcpu, unsigned long old_cr0, unsigned long cr0) { + /* + * CR0.WP is incorporated into the MMU role, but only for non-nested, + * indirect shadow MMUs. If TDP is enabled, the MMU's metadata needs + * to be updated, e.g. so that emulating guest translations does the + * right thing, but there's no need to unload the root as CR0.WP + * doesn't affect SPTEs. + */ + if (tdp_enabled && (cr0 ^ old_cr0) == X86_CR0_WP) { + kvm_init_mmu(vcpu); + return; + } + if ((cr0 ^ old_cr0) & X86_CR0_PG) { kvm_clear_async_pf_completion_queue(vcpu); kvm_async_pf_hash_reset(vcpu); From patchwork Wed Mar 22 01:37:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathias Krause X-Patchwork-Id: 73147 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:604a:0:0:0:0:0 with SMTP id j10csp2110513wrt; Tue, 21 Mar 2023 18:49:26 -0700 (PDT) X-Google-Smtp-Source: AK7set/fdU/MOd90qmIHx4j4UguKDZovV8G3u+OnWcKKpOSmUu+Iqgydt9Qa2v6oiNCIFixMuiI3 X-Received: by 2002:a17:906:b309:b0:933:c052:a277 with SMTP id n9-20020a170906b30900b00933c052a277mr5009255ejz.12.1679449766334; Tue, 21 Mar 2023 18:49:26 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1679449766; cv=none; d=google.com; s=arc-20160816; b=l4Mjnl/wyQLPGlhOBzllAui2/7mTkLT2pfo5sjHJk2TurDgcvOhn5XWz0gILUS489C 9g4AluDVKzF14nHOQA38MGddh7VAwdJOukW5Za2KpFV327A9w5WP/Uf/Q1jeWnpBt2Xn ya0Hm7rhY5m3ypdLdDjZhxn5pJ8RQx9XSxItvYPPK95RUCJpTCy2MWl9+5vGVg4Et8Yw dCitxCcFSxJ83a/iwtk/E7elWSBCwIAZVQKV563qRYWfuF1pzQDXXLFmLXMK0hjUZXC0 aRUP/NNAJwmLZRUZyVdXqnNKVzPb+82Ug0gIPiddD1pqaqiCyPlwUMQoAA6ATT3N4Qvc YW9g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=xKfWyPdWdSRYOzolgK9AgL1vcMAf7TEF7SLZEQ3lWXY=; b=bvQWk4ETmLT/b4jAVVmy6JNRmtrmlTEiL9FK3AsCYtAqsRHC5xES2kxVnkkieyutF+ wVEvqNQMyV58dh2Qg/4Rk35Sa/DJk1/ernus7o2EV5xEwGEk4Nucb/AH+yoSoOS8ixuy 9JXcviFZYGdCTySs0lYLjzAxAnDdVJ0V1A4Owc5+B6UEMNjL83udsCHgZkKCR+hAVY/o ohkVYmww1nIfOtaKpmEz2lXz1tI5ZQKDxYZCoFyL+ZiPMPyB42slyjbT2P/UgTTd7MxN QyhrNck9EKu8yrsEjYe63YAgBsJXfSjD1cs2zuB3gLU70pIpUQDryDhwL/NTZZ6K4w/W zezA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@grsecurity.net header.s=grsec header.b=n43NCSzm; 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=NONE sp=NONE dis=NONE) header.from=grsecurity.net Received: from out1.vger.email (out1.vger.email. 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[2003:f6:af34:4e00:7f5e:5982:a136:b54e]) by smtp.gmail.com with ESMTPSA id w11-20020a1709067c8b00b009231714b3d4sm6356260ejo.151.2023.03.21.18.34.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 18:34:29 -0700 (PDT) From: Mathias Krause To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Mathias Krause Subject: [PATCH v4 3/6] KVM: x86: Ignore CR0.WP toggles in non-paging mode Date: Wed, 22 Mar 2023 02:37:28 +0100 Message-Id: <20230322013731.102955-4-minipli@grsecurity.net> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322013731.102955-1-minipli@grsecurity.net> References: <20230322013731.102955-1-minipli@grsecurity.net> MIME-Version: 1.0 X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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?1761030717888626567?= X-GMAIL-MSGID: =?utf-8?q?1761030717888626567?= If paging is disabled, there are no permission bits to emulate. Micro-optimize this case to avoid unnecessary work. Suggested-and-co-developed-by: Sean Christopherson Signed-off-by: Mathias Krause --- arch/x86/kvm/x86.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c6d909778b2c..8a66ac7a4878 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -908,14 +908,20 @@ void kvm_post_set_cr0(struct kvm_vcpu *vcpu, unsigned long old_cr0, unsigned lon { /* * CR0.WP is incorporated into the MMU role, but only for non-nested, - * indirect shadow MMUs. If TDP is enabled, the MMU's metadata needs - * to be updated, e.g. so that emulating guest translations does the - * right thing, but there's no need to unload the root as CR0.WP - * doesn't affect SPTEs. + * indirect shadow MMUs. If paging is disabled, no updates are needed + * as there are no permission bits to emulate. If TDP is enabled, the + * MMU's metadata needs to be updated, e.g. so that emulating guest + * translations does the right thing, but there's no need to unload the + * root as CR0.WP doesn't affect SPTEs. */ - if (tdp_enabled && (cr0 ^ old_cr0) == X86_CR0_WP) { - kvm_init_mmu(vcpu); - return; + if ((cr0 ^ old_cr0) == X86_CR0_WP) { + if (!(cr0 & X86_CR0_PG)) + return; + + if (tdp_enabled) { + kvm_init_mmu(vcpu); + return; + } } if ((cr0 ^ old_cr0) & X86_CR0_PG) { From patchwork Wed Mar 22 01:37:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathias Krause X-Patchwork-Id: 73146 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:604a:0:0:0:0:0 with SMTP id j10csp2108876wrt; Tue, 21 Mar 2023 18:44:10 -0700 (PDT) X-Google-Smtp-Source: AK7set/KGhXy9NWtgy83sGLguF82uPJK2+eHpkHvbd9FJzsV1+HB3yeE9dE6EV7N2jhPh8YUNjum X-Received: by 2002:a17:903:1249:b0:19e:3caa:804e with SMTP id u9-20020a170903124900b0019e3caa804emr1326686plh.6.1679449450281; Tue, 21 Mar 2023 18:44:10 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1679449450; cv=none; d=google.com; s=arc-20160816; b=M/Gh/5Gh+a76Ti+yAn6WNTQwhqKCQKvIs9NT+17BaCY/PscgPuKufsKOdVDTFWC9ll JzOPqQ3SfjLAnPYN6Xn1jpHrrPNai9z5uTxXmQNK3THbtwN55s88Kcm6RLBFrWydmNX/ PuV9qI5U82dM6KM5QUo9a46jMuN9lA5gPDfm0cIOxpmSEDbnIGdlBgIC08WJ79RmEvV9 Ko4wPj6IG9cbr4uqrhdpybydqs94tmn4VKtqJGreeAMeTw47RyL89brRgmL/L1rEV4eA GLAI+ejvEsxzQhaao/2T4A1pLZw77x/03tNLrimHoI57s1DO5P3mlx7d/KFcVWU0DqWd aXVw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=+bcoTADskNJyZKsi62570ynPgg29dBb9TzGC3hyekEs=; b=ejlxCYuGY7y6wX7GJogKSDV7B99MLKEjbf3ZBVyEGrZGdTfXelmMbGsjBhR3x8GedL Hm9m20HsqfeThFz7WLn+W7tVmXSR7y7MiXKQoiFaVvNjJpLoW3iDYkB+tXgs8OdThDot 4leCVTIddQGrJ9c96Kl0R1r85/wf9H2tX2yb3EVZxCApnQmRZJ+LYBZTNLiOHuxrvSA1 HaUsci1VFcazOBpFA5dJ7leG4RKfFjvgOQ4TqMmD7/sjWdKTJw/O/SffgzYncV8JB3LV jgJUrRXdDKQAbhjetMI7YOEYHQvJMVRyPmJzrd4KnfqfOEn7y8hK+j1XvXmqQGulVDsk V0Jg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@grsecurity.net header.s=grsec header.b=MLpGqNNZ; 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=NONE sp=NONE dis=NONE) header.from=grsecurity.net Received: from out1.vger.email (out1.vger.email. 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[2003:f6:af34:4e00:7f5e:5982:a136:b54e]) by smtp.gmail.com with ESMTPSA id w11-20020a1709067c8b00b009231714b3d4sm6356260ejo.151.2023.03.21.18.34.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 18:34:30 -0700 (PDT) From: Mathias Krause To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Mathias Krause Subject: [PATCH v4 4/6] KVM: x86: Make use of kvm_read_cr*_bits() when testing bits Date: Wed, 22 Mar 2023 02:37:29 +0100 Message-Id: <20230322013731.102955-5-minipli@grsecurity.net> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322013731.102955-1-minipli@grsecurity.net> References: <20230322013731.102955-1-minipli@grsecurity.net> MIME-Version: 1.0 X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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?1761030386630101015?= X-GMAIL-MSGID: =?utf-8?q?1761030386630101015?= Make use of the kvm_read_cr{0,4}_bits() helper functions when we only want to know the state of certain bits instead of the whole register. This not only makes the intent cleaner, it also avoids a potential VMREAD in case the tested bits aren't guest owned. Signed-off-by: Mathias Krause --- arch/x86/kvm/pmu.c | 4 ++-- arch/x86/kvm/vmx/vmx.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 612e6c70ce2e..f4aa170b5b97 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -540,9 +540,9 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data) if (!pmc) return 1; - if (!(kvm_read_cr4(vcpu) & X86_CR4_PCE) && + if (!(kvm_read_cr4_bits(vcpu, X86_CR4_PCE)) && (static_call(kvm_x86_get_cpl)(vcpu) != 0) && - (kvm_read_cr0(vcpu) & X86_CR0_PE)) + (kvm_read_cr0_bits(vcpu, X86_CR0_PE))) return 1; *data = pmc_read_counter(pmc) & mask; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d7bf14abdba1..8fc1a0c7856f 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5517,7 +5517,7 @@ static int handle_cr(struct kvm_vcpu *vcpu) break; case 3: /* lmsw */ val = (exit_qualification >> LMSW_SOURCE_DATA_SHIFT) & 0x0f; - trace_kvm_cr_write(0, (kvm_read_cr0(vcpu) & ~0xful) | val); + trace_kvm_cr_write(0, (kvm_read_cr0_bits(vcpu, ~0xful) | val)); kvm_lmsw(vcpu, val); return kvm_skip_emulated_instruction(vcpu); @@ -7575,7 +7575,7 @@ static u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) if (!kvm_arch_has_noncoherent_dma(vcpu->kvm)) return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT; - if (kvm_read_cr0(vcpu) & X86_CR0_CD) { + if (kvm_read_cr0_bits(vcpu, X86_CR0_CD)) { if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED)) cache = MTRR_TYPE_WRBACK; else From patchwork Wed Mar 22 01:37:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathias Krause X-Patchwork-Id: 73141 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:604a:0:0:0:0:0 with SMTP id j10csp2106844wrt; Tue, 21 Mar 2023 18:36:39 -0700 (PDT) X-Google-Smtp-Source: AK7set+hsxte5H08/9oO6YTqLO0sfzhEEIdzcUAFhp6cmVN4cNnxcC+mW/TiB8rC53kEz94yt4eP X-Received: by 2002:aa7:d14b:0:b0:4fb:2296:30af with SMTP id r11-20020aa7d14b000000b004fb229630afmr5299319edo.20.1679448999406; Tue, 21 Mar 2023 18:36:39 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1679448999; cv=none; d=google.com; s=arc-20160816; b=QEdzAQlJ7u1bSQxF9bHCBOTkpvqo0xw/Vj18/wSDgJlOhzyjXPbqNJEVtBD54p0Tkq XveZLKtGStkOJwffsDrudVH7BEo//1fy2rOgaqPTbZD/FpJWb6ZTNlewPhkM77aAP1xV hur4gD7cYSFdYTedDkjYImYqhyX0EOV3qLcAPznEgYi+Yo4WXcSH8BsIj5wwUX7wuREr dgiNFoNHblpB2vIPQq8vEni/7JjNLWhFLYxK/agJM5zmng4grXL/7y+/IU5ZbKrxwpfw NFBO/bqi4B+8RfFQFrV2rOpzlOeyNFBX8bhOrkwTp/nEs5t1POYWq3Hlm7JK1iY+GsfE +R0A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=9S6DLSaz+uk2ZH/3jWZtx5Az5bSp7as8qYLxRe1iiAg=; b=IrSxyC/HgVSCz298V5RTM0myW9txajUOIXEB6uBdLSXyJ4A46O0IYs/rciBf5yOCXD uCO6uI9LRC5AdcGapMQ2iTduTk52/OSzqtCUtvZ+5ZWlR5f+VI+QaUxCpYSFWp7JD3Ud LT1zvn12y4zT86M05c8qb4DMB/wWbII4Jh83RCGPLNc3f5im1x+ODQ0jrKbPL1fmd67z 05Ko+5RFWSmr1Zuk7D/9nE4p8albq3Pqf1OCtQTtnrllP0Rni4rsWyw+FRtsnDrBCNZY 9bpKCTi+QdRD5I3/5IndFje/Tl30VFtsbOjcQVtIxO6R4Gu0mmYaYQYc/5vgiMS2teKf mA/g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@grsecurity.net header.s=grsec header.b=wJWLjVUh; 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=NONE sp=NONE dis=NONE) header.from=grsecurity.net Received: from out1.vger.email (out1.vger.email. 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[2003:f6:af34:4e00:7f5e:5982:a136:b54e]) by smtp.gmail.com with ESMTPSA id w11-20020a1709067c8b00b009231714b3d4sm6356260ejo.151.2023.03.21.18.34.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 18:34:31 -0700 (PDT) From: Mathias Krause To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Mathias Krause Subject: [PATCH v4 5/6] KVM: x86/mmu: Fix comment typo Date: Wed, 22 Mar 2023 02:37:30 +0100 Message-Id: <20230322013731.102955-6-minipli@grsecurity.net> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322013731.102955-1-minipli@grsecurity.net> References: <20230322013731.102955-1-minipli@grsecurity.net> MIME-Version: 1.0 X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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?1761029913861030347?= X-GMAIL-MSGID: =?utf-8?q?1761029913861030347?= Fix a small comment typo in make_spte(). Signed-off-by: Mathias Krause --- arch/x86/kvm/mmu/spte.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index c15bfca3ed15..cf2c6426a6fc 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -164,7 +164,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, /* * For simplicity, enforce the NX huge page mitigation even if not * strictly necessary. KVM could ignore the mitigation if paging is - * disabled in the guest, as the guest doesn't have an page tables to + * disabled in the guest, as the guest doesn't have any page tables to * abuse. But to safely ignore the mitigation, KVM would have to * ensure a new MMU is loaded (or all shadow pages zapped) when CR0.PG * is toggled on, and that's a net negative for performance when TDP is From patchwork Wed Mar 22 01:37:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathias Krause X-Patchwork-Id: 73142 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:604a:0:0:0:0:0 with SMTP id j10csp2106970wrt; Tue, 21 Mar 2023 18:37:10 -0700 (PDT) X-Google-Smtp-Source: AK7set8cq+WhS9scJgjwysUXNRZAdrpJ+8O9i6bj2cDbw4FSbv3fI8Z6QCvrzJY0NXmok/bvzV8p X-Received: by 2002:a17:906:4e0a:b0:931:6921:bdb7 with SMTP id z10-20020a1709064e0a00b009316921bdb7mr4588558eju.60.1679449030616; Tue, 21 Mar 2023 18:37:10 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1679449030; cv=none; d=google.com; s=arc-20160816; b=nuTwX791kN6KbHDtq7tGt+CdZWuRWYg9bQoVK5Rv8E5Hdtg84sQtZ8790PH8LZF8cd snSSA5qwYowfeDhVl6Dfdtm0afsaNNQk5WtMTcyw9NU6hgdSvWyaiEZBv35o0Nqfpn/6 3RLG/O+nsySnLmlR5AEBL8UxX+bpyi7NipMeRyLPQHO5Q3PPdHkKTYNXaYnwFckZMLg9 jwO/NeTRHOYKOUDNNZBOWchfbJANlSrcg8u0Yr5jC6MgXJyrNQXasokIznNMs9dZP6UU x5IfP7ZmsAqy1ss7YEYzrIrB0dcXD2887zBXSVtq0LHvFJ5FQxA2mMLNi3ScDt6/29/j El2Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=61LlI0wVrzyKbUKk1uZrrjDNEa+G+M4L4TNEr5FBml0=; b=i0h/lKcoS+GI36+5sIpX6yxBrXjVjEdfUBlS1OrvlUaO/xvubc1v/pgHCVP7edaIrW skVIIIS44jrN1iiCoG1lVz7YAxlcseW0sR6fkt+gAFoRJBJ7FIUnKlr8GYe+5rdKw/Sj 0WTzE88rXAGXgukhNuSjp12nGcekgHer7nexI1sgm5hxRLfvxUXHaZ6ER6uw3RLX7CHb Wh45U4i5PnDA61xbP32gQhqrk17VpmqAIklra7qOb9ovhGrlGWXhcmPbXdf8mG+GgN1w 25uDQSznoSPlqR0SHQ7TALZGcXKDxF5mfkJma2Jj8II603cgNq2GVmBQUJC+YcUGg3Q5 UfRQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@grsecurity.net header.s=grsec header.b=uH52rgmz; 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=NONE sp=NONE dis=NONE) header.from=grsecurity.net Received: from out1.vger.email (out1.vger.email. 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[2003:f6:af34:4e00:7f5e:5982:a136:b54e]) by smtp.gmail.com with ESMTPSA id w11-20020a1709067c8b00b009231714b3d4sm6356260ejo.151.2023.03.21.18.34.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 18:34:32 -0700 (PDT) From: Mathias Krause To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Mathias Krause Subject: [PATCH v4 6/6] KVM: VMX: Make CR0.WP a guest owned bit Date: Wed, 22 Mar 2023 02:37:31 +0100 Message-Id: <20230322013731.102955-7-minipli@grsecurity.net> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322013731.102955-1-minipli@grsecurity.net> References: <20230322013731.102955-1-minipli@grsecurity.net> MIME-Version: 1.0 X-Spam-Status: No, score=0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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?1761029946442123552?= X-GMAIL-MSGID: =?utf-8?q?1761029946442123552?= Guests like grsecurity that make heavy use of CR0.WP to implement kernel level W^X will suffer from the implied VMEXITs. With EPT there is no need to intercept a guest change of CR0.WP, so simply make it a guest owned bit if we can do so. This implies that a read of a guest's CR0.WP bit might need a VMREAD. However, the only potentially affected user seems to be kvm_init_mmu() which is a heavy operation to begin with. But also most callers already cache the full value of CR0 anyway, so no additional VMREAD is needed. The only exception is nested_vmx_load_cr3(). This change is VMX-specific, as SVM has no such fine grained control register intercept control. Suggested-and-co-developed-by: Sean Christopherson Signed-off-by: Mathias Krause --- arch/x86/kvm/kvm_cache_regs.h | 2 +- arch/x86/kvm/vmx/nested.c | 4 ++-- arch/x86/kvm/vmx/vmx.c | 2 +- arch/x86/kvm/vmx/vmx.h | 18 ++++++++++++++++++ 4 files changed, 22 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h index 4c91f626c058..e50d353b5c1c 100644 --- a/arch/x86/kvm/kvm_cache_regs.h +++ b/arch/x86/kvm/kvm_cache_regs.h @@ -4,7 +4,7 @@ #include -#define KVM_POSSIBLE_CR0_GUEST_BITS X86_CR0_TS +#define KVM_POSSIBLE_CR0_GUEST_BITS (X86_CR0_TS | X86_CR0_WP) #define KVM_POSSIBLE_CR4_GUEST_BITS \ (X86_CR4_PVI | X86_CR4_DE | X86_CR4_PCE | X86_CR4_OSFXSR \ | X86_CR4_OSXMMEXCPT | X86_CR4_PGE | X86_CR4_TSD | X86_CR4_FSGSBASE) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index f63b28f46a71..61d940fc91ba 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -4481,7 +4481,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, * CR0_GUEST_HOST_MASK is already set in the original vmcs01 * (KVM doesn't change it); */ - vcpu->arch.cr0_guest_owned_bits = KVM_POSSIBLE_CR0_GUEST_BITS; + vcpu->arch.cr0_guest_owned_bits = vmx_l1_guest_owned_cr0_bits(); vmx_set_cr0(vcpu, vmcs12->host_cr0); /* Same as above - no reason to call set_cr4_guest_host_mask(). */ @@ -4632,7 +4632,7 @@ static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu) */ vmx_set_efer(vcpu, nested_vmx_get_vmcs01_guest_efer(vmx)); - vcpu->arch.cr0_guest_owned_bits = KVM_POSSIBLE_CR0_GUEST_BITS; + vcpu->arch.cr0_guest_owned_bits = vmx_l1_guest_owned_cr0_bits(); vmx_set_cr0(vcpu, vmcs_readl(CR0_READ_SHADOW)); vcpu->arch.cr4_guest_owned_bits = ~vmcs_readl(CR4_GUEST_HOST_MASK); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 8fc1a0c7856f..e501f6864a72 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4790,7 +4790,7 @@ static void init_vmcs(struct vcpu_vmx *vmx) /* 22.2.1, 20.8.1 */ vm_entry_controls_set(vmx, vmx_vmentry_ctrl()); - vmx->vcpu.arch.cr0_guest_owned_bits = KVM_POSSIBLE_CR0_GUEST_BITS; + vmx->vcpu.arch.cr0_guest_owned_bits = vmx_l1_guest_owned_cr0_bits(); vmcs_writel(CR0_GUEST_HOST_MASK, ~vmx->vcpu.arch.cr0_guest_owned_bits); set_cr4_guest_host_mask(vmx); diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 2acdc54bc34b..423e9d3c9c40 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -640,6 +640,24 @@ BUILD_CONTROLS_SHADOW(tertiary_exec, TERTIARY_VM_EXEC_CONTROL, 64) (1 << VCPU_EXREG_EXIT_INFO_1) | \ (1 << VCPU_EXREG_EXIT_INFO_2)) +static inline unsigned long vmx_l1_guest_owned_cr0_bits(void) +{ + unsigned long bits = KVM_POSSIBLE_CR0_GUEST_BITS; + + /* + * CR0.WP needs to be intercepted when KVM is shadowing legacy paging + * in order to construct shadow PTEs with the correct protections. + * Note! CR0.WP technically can be passed through to the guest if + * paging is disabled, but checking CR0.PG would generate a cyclical + * dependency of sorts due to forcing the caller to ensure CR0 holds + * the correct value prior to determining which CR0 bits can be owned + * by L1. Keep it simple and limit the optimization to EPT. + */ + if (!enable_ept) + bits &= ~X86_CR0_WP; + return bits; +} + static __always_inline struct kvm_vmx *to_kvm_vmx(struct kvm *kvm) { return container_of(kvm, struct kvm_vmx, kvm);