From: David Matlack <dmatlack@google.com> To: Paolo Bonzini <pbonzini@redhat.com> Cc: Marc Zyngier <maz@kernel.org>, Huacai Chen <chenhuacai@kernel.org>, Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>, Anup Patel <anup@brainfault.org>, Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, Sean Christopherson <seanjc@google.com>, Andrew Jones <drjones@redhat.com>, Ben Gardon <bgardon@google.com>, Peter Xu <peterx@redhat.com>, maciej.szmigiero@oracle.com, "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" <kvmarm@lists.cs.columbia.edu>, "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" <linux-mips@vger.kernel.org>, "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" <kvm@vger.kernel.org>, "open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)" <kvm-riscv@lists.infradead.org>, Peter Feiner <pfeiner@google.com>, Lai Jiangshan <jiangshanlai@gmail.com>, David Matlack <dmatlack@google.com> Subject: [PATCH v6 01/22] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs Date: Mon, 16 May 2022 23:21:17 +0000 [thread overview] Message-ID: <20220516232138.1783324-2-dmatlack@google.com> (raw) In-Reply-To: <20220516232138.1783324-1-dmatlack@google.com> Commit fb58a9c345f6 ("KVM: x86/mmu: Optimize MMU page cache lookup for fully direct MMUs") skipped the unsync checks and write flood clearing for full direct MMUs. We can extend this further to skip the checks for all direct shadow pages. Direct shadow pages in indirect MMUs (i.e. shadow paging) are used when shadowing a guest huge page with smaller pages. Such direct shadow pages, like their counterparts in fully direct MMUs, are never marked unsynced or have a non-zero write-flooding count. Checking sp->role.direct also generates better code than checking direct_map because, due to register pressure, direct_map has to get shoved onto the stack and then pulled back off. No functional change intended. Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: David Matlack <dmatlack@google.com> --- arch/x86/kvm/mmu/mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index efe5a3dca1e0..774810d8a2ed 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2026,7 +2026,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, int direct, unsigned int access) { - bool direct_mmu = vcpu->arch.mmu->root_role.direct; union kvm_mmu_page_role role; struct hlist_head *sp_list; unsigned quadrant; @@ -2070,7 +2069,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, continue; } - if (direct_mmu) + /* unsync and write-flooding only apply to indirect SPs. */ + if (sp->role.direct) goto trace_get_page; if (sp->unsync) { -- 2.36.0.550.gb090851708-goog
WARNING: multiple messages have this Message-ID (diff)
From: David Matlack <dmatlack@google.com> To: Paolo Bonzini <pbonzini@redhat.com> Cc: Albert Ou <aou@eecs.berkeley.edu>, "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" <kvm@vger.kernel.org>, Marc Zyngier <maz@kernel.org>, Huacai Chen <chenhuacai@kernel.org>, Lai Jiangshan <jiangshanlai@gmail.com>, "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" <linux-mips@vger.kernel.org>, David Matlack <dmatlack@google.com>, Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>, Palmer Dabbelt <palmer@dabbelt.com>, "open list:KERNEL VIRTUAL MACHINE FOR RISC-V \(KVM/riscv\)" <kvm-riscv@lists.infradead.org>, Paul Walmsley <paul.walmsley@sifive.com>, Ben Gardon <bgardon@google.com>, maciej.szmigiero@oracle.com, "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 \(KVM/arm64\)" <kvmarm@lists.cs.columbia.edu>, Peter Feiner <pfeiner@google.com> Subject: [PATCH v6 01/22] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs Date: Mon, 16 May 2022 23:21:17 +0000 [thread overview] Message-ID: <20220516232138.1783324-2-dmatlack@google.com> (raw) In-Reply-To: <20220516232138.1783324-1-dmatlack@google.com> Commit fb58a9c345f6 ("KVM: x86/mmu: Optimize MMU page cache lookup for fully direct MMUs") skipped the unsync checks and write flood clearing for full direct MMUs. We can extend this further to skip the checks for all direct shadow pages. Direct shadow pages in indirect MMUs (i.e. shadow paging) are used when shadowing a guest huge page with smaller pages. Such direct shadow pages, like their counterparts in fully direct MMUs, are never marked unsynced or have a non-zero write-flooding count. Checking sp->role.direct also generates better code than checking direct_map because, due to register pressure, direct_map has to get shoved onto the stack and then pulled back off. No functional change intended. Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: David Matlack <dmatlack@google.com> --- arch/x86/kvm/mmu/mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index efe5a3dca1e0..774810d8a2ed 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2026,7 +2026,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, int direct, unsigned int access) { - bool direct_mmu = vcpu->arch.mmu->root_role.direct; union kvm_mmu_page_role role; struct hlist_head *sp_list; unsigned quadrant; @@ -2070,7 +2069,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, continue; } - if (direct_mmu) + /* unsync and write-flooding only apply to indirect SPs. */ + if (sp->role.direct) goto trace_get_page; if (sp->unsync) { -- 2.36.0.550.gb090851708-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2022-05-16 23:21 UTC|newest] Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-16 23:21 [PATCH v6 00/22] KVM: Extend Eager Page Splitting to the shadow MMU David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` David Matlack [this message] 2022-05-16 23:21 ` [PATCH v6 01/22] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs David Matlack 2022-05-16 23:21 ` [PATCH v6 02/22] KVM: x86/mmu: Use a bool for direct David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` [PATCH v6 03/22] KVM: x86/mmu: Stop passing @direct to mmu_alloc_root() David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-16 18:47 ` Sean Christopherson 2022-06-16 18:47 ` Sean Christopherson 2022-06-22 14:06 ` Paolo Bonzini 2022-06-22 14:06 ` Paolo Bonzini 2022-06-22 14:19 ` Sean Christopherson 2022-06-22 14:19 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 04/22] KVM: x86/mmu: Derive shadow MMU page role from parent David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 1:19 ` Sean Christopherson 2022-06-17 1:19 ` Sean Christopherson 2022-06-17 15:12 ` Sean Christopherson 2022-06-17 15:12 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 05/22] KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 15:20 ` Sean Christopherson 2022-06-17 15:20 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 06/22] KVM: x86/mmu: Decompose kvm_mmu_get_page() into separate functions David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` [PATCH v6 07/22] KVM: x86/mmu: Consolidate shadow page allocation and initialization David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` [PATCH v6 08/22] KVM: x86/mmu: Rename shadow MMU functions that deal with shadow pages David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` [PATCH v6 09/22] KVM: x86/mmu: Move guest PT write-protection to account_shadowed() David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` [PATCH v6 10/22] KVM: x86/mmu: Pass memory caches to allocate SPs separately David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 15:01 ` Sean Christopherson 2022-06-17 15:01 ` Sean Christopherson 2022-06-21 17:06 ` David Matlack 2022-06-21 17:06 ` David Matlack 2022-06-21 17:27 ` Sean Christopherson 2022-06-21 17:27 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 11/22] KVM: x86/mmu: Replace vcpu with kvm in kvm_mmu_alloc_shadow_page() David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` [PATCH v6 12/22] KVM: x86/mmu: Pass kvm pointer separately from vcpu to kvm_mmu_find_shadow_page() David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-16 23:21 ` [PATCH v6 13/22] KVM: x86/mmu: Allow NULL @vcpu in kvm_mmu_find_shadow_page() David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 15:28 ` Sean Christopherson 2022-06-17 15:28 ` Sean Christopherson 2022-06-22 14:26 ` Paolo Bonzini 2022-06-22 14:26 ` Paolo Bonzini 2022-05-16 23:21 ` [PATCH v6 14/22] KVM: x86/mmu: Pass const memslot to rmap_add() David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 15:30 ` Sean Christopherson 2022-06-17 15:30 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 15/22] KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 16:39 ` Sean Christopherson 2022-06-17 16:39 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 16/22] KVM: x86/mmu: Update page stats in __rmap_add() David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 16:40 ` Sean Christopherson 2022-06-17 16:40 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 17/22] KVM: x86/mmu: Cache the access bits of shadowed translations David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 16:53 ` Sean Christopherson 2022-06-17 16:53 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 18/22] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 16:56 ` Sean Christopherson 2022-06-17 16:56 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 19/22] KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible levels David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 17:01 ` Sean Christopherson 2022-06-17 17:01 ` Sean Christopherson 2022-06-21 17:24 ` David Matlack 2022-06-21 17:24 ` David Matlack 2022-06-21 17:59 ` Sean Christopherson 2022-06-21 17:59 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 20/22] KVM: x86/mmu: Refactor drop_large_spte() David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-17 17:11 ` Sean Christopherson 2022-06-17 17:11 ` Sean Christopherson 2022-06-22 16:13 ` Paolo Bonzini 2022-06-22 16:13 ` Paolo Bonzini 2022-06-22 16:50 ` Paolo Bonzini 2022-06-22 16:50 ` Paolo Bonzini 2022-05-16 23:21 ` [PATCH v6 21/22] KVM: Allow for different capacities in kvm_mmu_memory_cache structs David Matlack 2022-05-16 23:21 ` David Matlack 2022-05-19 15:33 ` Anup Patel 2022-05-19 15:33 ` Anup Patel 2022-05-20 23:21 ` Mingwei Zhang 2022-05-23 17:37 ` Sean Christopherson 2022-05-23 17:37 ` Sean Christopherson 2022-05-23 17:44 ` David Matlack 2022-05-23 17:44 ` David Matlack 2022-05-23 18:13 ` Mingwei Zhang 2022-05-23 18:13 ` Mingwei Zhang 2022-05-23 18:22 ` David Matlack 2022-05-23 18:22 ` David Matlack 2022-05-23 23:53 ` David Matlack 2022-05-23 23:53 ` David Matlack 2022-06-17 17:41 ` Sean Christopherson 2022-06-17 17:41 ` Sean Christopherson 2022-06-17 18:34 ` Sean Christopherson 2022-06-17 18:34 ` Sean Christopherson 2022-05-16 23:21 ` [PATCH v6 22/22] KVM: x86/mmu: Extend Eager Page Splitting to nested MMUs David Matlack 2022-05-16 23:21 ` David Matlack 2022-06-01 21:50 ` Ricardo Koller 2022-06-01 21:50 ` Ricardo Koller 2022-06-17 19:08 ` Sean Christopherson 2022-06-17 19:08 ` Sean Christopherson
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