| Message ID | 20240507155817.3951344-11-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/mmu: Page fault and MMIO cleanups | expand |
On 5/7/2024 11:58 PM, Paolo Bonzini wrote: > From: Sean Christopherson <seanjc@google.com> > > Prioritize private vs. shared gfn attribute checks above slot validity > checks to ensure a consistent userspace ABI. E.g. as is, KVM will exit to > userspace if there is no memslot, but emulate accesses to the APIC access > page even if the attributes mismatch. > > Fixes: 8dd2eee9d526 ("KVM: x86/mmu: Handle page fault for private memory") > Cc: Yu Zhang <yu.c.zhang@linux.intel.com> > Cc: Chao Peng <chao.p.peng@linux.intel.com> > Cc: Fuad Tabba <tabba@google.com> > Cc: Michael Roth <michael.roth@amd.com> > Cc: Isaku Yamahata <isaku.yamahata@intel.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > Reviewed-by: Kai Huang <kai.huang@intel.com> > Message-ID: <20240228024147.41573-10-seanjc@google.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com> > --- > arch/x86/kvm/mmu/mmu.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 0d884d0b0f35..ba50b93e93ed 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4317,11 +4317,6 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > return RET_PF_EMULATE; > } > > - if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { > - kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > - return -EFAULT; > - } > - > if (fault->is_private) > return kvm_faultin_pfn_private(vcpu, fault); > > @@ -4359,9 +4354,24 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, > { > int ret; > > + /* > + * Note that the mmu_invalidate_seq also serves to detect a concurrent > + * change in attributes. is_page_fault_stale() will detect an > + * invalidation relate to fault->fn and resume the guest without s/fault->fn/fault->gfn/ > + * installing a mapping in the page tables. > + */ > fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq; > smp_rmb(); > > + /* > + * Now that we have a snapshot of mmu_invalidate_seq we can check for a > + * private vs. shared mismatch. > + */ > + if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { > + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > + return -EFAULT; > + } > + > /* > * Check for a relevant mmu_notifier invalidation event before getting > * the pfn from the primary MMU, and before acquiring mmu_lock.
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 0d884d0b0f35..ba50b93e93ed 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4317,11 +4317,6 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault return RET_PF_EMULATE; } - if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { - kvm_mmu_prepare_memory_fault_exit(vcpu, fault); - return -EFAULT; - } - if (fault->is_private) return kvm_faultin_pfn_private(vcpu, fault); @@ -4359,9 +4354,24 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, { int ret; + /* + * Note that the mmu_invalidate_seq also serves to detect a concurrent + * change in attributes. is_page_fault_stale() will detect an + * invalidation relate to fault->fn and resume the guest without + * installing a mapping in the page tables. + */ fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq; smp_rmb(); + /* + * Now that we have a snapshot of mmu_invalidate_seq we can check for a + * private vs. shared mismatch. + */ + if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); + return -EFAULT; + } + /* * Check for a relevant mmu_notifier invalidation event before getting * the pfn from the primary MMU, and before acquiring mmu_lock.