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 v5 01/21] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs Date: Fri, 13 May 2022 20:27:59 +0000 [thread overview] Message-ID: <20220513202819.829591-2-dmatlack@google.com> (raw) In-Reply-To: <20220513202819.829591-1-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 v5 01/21] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs Date: Fri, 13 May 2022 20:27:59 +0000 [thread overview] Message-ID: <20220513202819.829591-2-dmatlack@google.com> (raw) In-Reply-To: <20220513202819.829591-1-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:[~2022-05-13 20:28 UTC|newest] Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-13 20:27 [PATCH v5 00/21] KVM: Extend Eager Page Splitting to the shadow MMU David Matlack 2022-05-13 20:27 ` David Matlack 2022-05-13 20:27 ` David Matlack [this message] 2022-05-13 20:27 ` [PATCH v5 01/21] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs David Matlack 2022-05-13 20:28 ` [PATCH v5 02/21] KVM: x86/mmu: Use a bool for direct David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-16 6:54 ` Lai Jiangshan 2022-05-16 6:54 ` Lai Jiangshan 2022-05-16 21:38 ` David Matlack 2022-05-16 21:38 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 04/21] KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 05/21] KVM: x86/mmu: Decompose kvm_mmu_get_page() into separate functions David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 06/21] KVM: x86/mmu: Consolidate shadow page allocation and initialization David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 07/21] KVM: x86/mmu: Rename shadow MMU functions that deal with shadow pages David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 08/21] KVM: x86/mmu: Move guest PT write-protection to account_shadowed() David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 09/21] KVM: x86/mmu: Pass memory caches to allocate SPs separately David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 10/21] KVM: x86/mmu: Replace vcpu with kvm in kvm_mmu_alloc_shadow_page() David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 11/21] KVM: x86/mmu: Pass kvm pointer separately from vcpu to kvm_mmu_find_shadow_page() David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 12/21] KVM: x86/mmu: Allow NULL @vcpu in kvm_mmu_find_shadow_page() David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 13/21] KVM: x86/mmu: Pass const memslot to rmap_add() David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 14/21] KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 15/21] KVM: x86/mmu: Update page stats in __rmap_add() David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 16/21] KVM: x86/mmu: Cache the access bits of shadowed translations David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 17/21] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 18/21] KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible levels David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 19/21] KVM: x86/mmu: Refactor drop_large_spte() David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-13 20:28 ` [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs David Matlack 2022-05-13 20:28 ` David Matlack 2022-05-15 11:42 ` Marc Zyngier 2022-05-15 11:42 ` Marc Zyngier 2022-05-16 3:31 ` Anup Patel 2022-05-16 3:31 ` Anup Patel 2022-05-16 23:23 ` David Matlack 2022-05-16 23:23 ` David Matlack 2022-05-16 14:49 ` Sean Christopherson 2022-05-16 14:49 ` Sean Christopherson 2022-05-16 16:39 ` David Matlack 2022-05-16 16:39 ` David Matlack 2022-05-16 17:53 ` Sean Christopherson 2022-05-16 17:53 ` Sean Christopherson 2022-05-13 20:28 ` [PATCH v5 21/21] KVM: x86/mmu: Extend Eager Page Splitting to nested MMUs David Matlack 2022-05-13 20:28 ` David Matlack
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