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 18/22] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU Date: Mon, 16 May 2022 23:21:34 +0000 [thread overview] Message-ID: <20220516232138.1783324-19-dmatlack@google.com> (raw) In-Reply-To: <20220516232138.1783324-1-dmatlack@google.com> Currently make_huge_page_split_spte() assumes execute permissions can be granted to any 4K SPTE when splitting huge pages. This is true for the TDP MMU but is not necessarily true for the shadow MMU, since KVM may be shadowing a non-executable huge page. To fix this, pass in the role of the child shadow page where the huge page will be split and derive the execution permission from that. This is correct because huge pages are always split with direct shadow page and thus the shadow page role contains the correct access permissions. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> --- arch/x86/kvm/mmu/spte.c | 16 ++++++++-------- arch/x86/kvm/mmu/spte.h | 2 +- arch/x86/kvm/mmu/tdp_mmu.c | 2 +- 3 files changed, 10 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index b5960bbde7f7..237e8dc12993 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -244,10 +244,10 @@ static u64 make_spte_executable(u64 spte) * This is used during huge page splitting to build the SPTEs that make up the * new page table. */ -u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index) +u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role, + int index) { u64 child_spte; - int child_level; if (WARN_ON_ONCE(!is_shadow_present_pte(huge_spte))) return 0; @@ -256,23 +256,23 @@ u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index) return 0; child_spte = huge_spte; - child_level = huge_level - 1; /* * The child_spte already has the base address of the huge page being * split. So we just have to OR in the offset to the page at the next * lower level for the given index. */ - child_spte |= (index * KVM_PAGES_PER_HPAGE(child_level)) << PAGE_SHIFT; + child_spte |= (index * KVM_PAGES_PER_HPAGE(role.level)) << PAGE_SHIFT; - if (child_level == PG_LEVEL_4K) { + if (role.level == PG_LEVEL_4K) { child_spte &= ~PT_PAGE_SIZE_MASK; /* - * When splitting to a 4K page, mark the page executable as the - * NX hugepage mitigation no longer applies. + * When splitting to a 4K page where execution is allowed, mark + * the page executable as the NX hugepage mitigation no longer + * applies. */ - if (is_nx_huge_page_enabled()) + if ((role.access & ACC_EXEC_MASK) && is_nx_huge_page_enabled()) child_spte = make_spte_executable(child_spte); } diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index 0127bb6e3c7d..3dada44cc066 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -425,7 +425,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, u64 old_spte, bool prefetch, bool can_unsync, bool host_writable, u64 *new_spte); -u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index); +u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role, int index); u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled); u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access); u64 mark_spte_for_access_track(u64 spte); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 841feaa48be5..a5472ee56080 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1488,7 +1488,7 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter, * not been linked in yet and thus is not reachable from any other CPU. */ for (i = 0; i < PT64_ENT_PER_PAGE; i++) - sp->spt[i] = make_huge_page_split_spte(huge_spte, level, i); + sp->spt[i] = make_huge_page_split_spte(huge_spte, sp->role, i); /* * Replace the huge spte with a pointer to the populated lower level -- 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 18/22] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU Date: Mon, 16 May 2022 23:21:34 +0000 [thread overview] Message-ID: <20220516232138.1783324-19-dmatlack@google.com> (raw) In-Reply-To: <20220516232138.1783324-1-dmatlack@google.com> Currently make_huge_page_split_spte() assumes execute permissions can be granted to any 4K SPTE when splitting huge pages. This is true for the TDP MMU but is not necessarily true for the shadow MMU, since KVM may be shadowing a non-executable huge page. To fix this, pass in the role of the child shadow page where the huge page will be split and derive the execution permission from that. This is correct because huge pages are always split with direct shadow page and thus the shadow page role contains the correct access permissions. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> --- arch/x86/kvm/mmu/spte.c | 16 ++++++++-------- arch/x86/kvm/mmu/spte.h | 2 +- arch/x86/kvm/mmu/tdp_mmu.c | 2 +- 3 files changed, 10 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index b5960bbde7f7..237e8dc12993 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -244,10 +244,10 @@ static u64 make_spte_executable(u64 spte) * This is used during huge page splitting to build the SPTEs that make up the * new page table. */ -u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index) +u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role, + int index) { u64 child_spte; - int child_level; if (WARN_ON_ONCE(!is_shadow_present_pte(huge_spte))) return 0; @@ -256,23 +256,23 @@ u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index) return 0; child_spte = huge_spte; - child_level = huge_level - 1; /* * The child_spte already has the base address of the huge page being * split. So we just have to OR in the offset to the page at the next * lower level for the given index. */ - child_spte |= (index * KVM_PAGES_PER_HPAGE(child_level)) << PAGE_SHIFT; + child_spte |= (index * KVM_PAGES_PER_HPAGE(role.level)) << PAGE_SHIFT; - if (child_level == PG_LEVEL_4K) { + if (role.level == PG_LEVEL_4K) { child_spte &= ~PT_PAGE_SIZE_MASK; /* - * When splitting to a 4K page, mark the page executable as the - * NX hugepage mitigation no longer applies. + * When splitting to a 4K page where execution is allowed, mark + * the page executable as the NX hugepage mitigation no longer + * applies. */ - if (is_nx_huge_page_enabled()) + if ((role.access & ACC_EXEC_MASK) && is_nx_huge_page_enabled()) child_spte = make_spte_executable(child_spte); } diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index 0127bb6e3c7d..3dada44cc066 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -425,7 +425,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, u64 old_spte, bool prefetch, bool can_unsync, bool host_writable, u64 *new_spte); -u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index); +u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role, int index); u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled); u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access); u64 mark_spte_for_access_track(u64 spte); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 841feaa48be5..a5472ee56080 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1488,7 +1488,7 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter, * not been linked in yet and thus is not reachable from any other CPU. */ for (i = 0; i < PT64_ENT_PER_PAGE; i++) - sp->spt[i] = make_huge_page_split_spte(huge_spte, level, i); + sp->spt[i] = make_huge_page_split_spte(huge_spte, sp->role, i); /* * Replace the huge spte with a pointer to the populated lower level -- 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 23:22 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 ` [PATCH v6 01/22] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs David Matlack 2022-05-16 23:21 ` 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 ` David Matlack [this message] 2022-05-16 23:21 ` [PATCH v6 18/22] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU David Matlack 2022-06-17 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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