From 8569992d64b8f750e34b7858eac5d7daaf0f80fd Mon Sep 17 00:00:00 2001 From: Chao Peng Date: Fri, 27 Oct 2023 11:21:45 -0700 Subject: KVM: Use gfn instead of hva for mmu_notifier_retry Currently in mmu_notifier invalidate path, hva range is recorded and then checked against by mmu_invalidate_retry_hva() in the page fault handling path. However, for the soon-to-be-introduced private memory, a page fault may not have a hva associated, checking gfn(gpa) makes more sense. For existing hva based shared memory, gfn is expected to also work. The only downside is when aliasing multiple gfns to a single hva, the current algorithm of checking multiple ranges could result in a much larger range being rejected. Such aliasing should be uncommon, so the impact is expected small. Suggested-by: Sean Christopherson Cc: Xu Yilun Signed-off-by: Chao Peng Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba [sean: convert vmx_set_apic_access_page_addr() to gfn-based API] Signed-off-by: Sean Christopherson Reviewed-by: Paolo Bonzini Reviewed-by: Xu Yilun Message-Id: <20231027182217.3615211-4-seanjc@google.com> Reviewed-by: Kai Huang Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 10 ++++++---- arch/x86/kvm/vmx/vmx.c | 11 +++++------ 2 files changed, 11 insertions(+), 10 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index b0f01d605617..b2d916f786ca 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3056,7 +3056,7 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) * * There are several ways to safely use this helper: * - * - Check mmu_invalidate_retry_hva() after grabbing the mapping level, before + * - Check mmu_invalidate_retry_gfn() after grabbing the mapping level, before * consuming it. In this case, mmu_lock doesn't need to be held during the * lookup, but it does need to be held while checking the MMU notifier. * @@ -4366,7 +4366,7 @@ static bool is_page_fault_stale(struct kvm_vcpu *vcpu, return true; return fault->slot && - mmu_invalidate_retry_hva(vcpu->kvm, fault->mmu_seq, fault->hva); + mmu_invalidate_retry_gfn(vcpu->kvm, fault->mmu_seq, fault->gfn); } static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) @@ -6260,7 +6260,9 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) write_lock(&kvm->mmu_lock); - kvm_mmu_invalidate_begin(kvm, 0, -1ul); + kvm_mmu_invalidate_begin(kvm); + + kvm_mmu_invalidate_range_add(kvm, gfn_start, gfn_end); flush = kvm_rmap_zap_gfn_range(kvm, gfn_start, gfn_end); @@ -6270,7 +6272,7 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) if (flush) kvm_flush_remote_tlbs_range(kvm, gfn_start, gfn_end - gfn_start); - kvm_mmu_invalidate_end(kvm, 0, -1ul); + kvm_mmu_invalidate_end(kvm); write_unlock(&kvm->mmu_lock); } diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index be20a60047b1..40e3780d73ae 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6757,10 +6757,10 @@ static void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu) return; /* - * Grab the memslot so that the hva lookup for the mmu_notifier retry - * is guaranteed to use the same memslot as the pfn lookup, i.e. rely - * on the pfn lookup's validation of the memslot to ensure a valid hva - * is used for the retry check. + * Explicitly grab the memslot using KVM's internal slot ID to ensure + * KVM doesn't unintentionally grab a userspace memslot. It _should_ + * be impossible for userspace to create a memslot for the APIC when + * APICv is enabled, but paranoia won't hurt in this case. */ slot = id_to_memslot(slots, APIC_ACCESS_PAGE_PRIVATE_MEMSLOT); if (!slot || slot->flags & KVM_MEMSLOT_INVALID) @@ -6785,8 +6785,7 @@ static void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu) return; read_lock(&vcpu->kvm->mmu_lock); - if (mmu_invalidate_retry_hva(kvm, mmu_seq, - gfn_to_hva_memslot(slot, gfn))) { + if (mmu_invalidate_retry_gfn(kvm, mmu_seq, gfn)) { kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu); read_unlock(&vcpu->kvm->mmu_lock); goto out; -- cgit v1.2.3