| Message ID | 20240507155817.3951344-2-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New |
| 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> > > Exit to userspace with -EFAULT / KVM_EXIT_MEMORY_FAULT if a private fault > triggers emulation of any kind, as KVM doesn't currently support emulating > access to guest private memory. Practically speaking, private faults and > emulation are already mutually exclusive, but there are many flow that > can result in KVM returning RET_PF_EMULATE, and adding one last check > to harden against weird, unexpected combinations and/or KVM bugs is > inexpensive. > > Suggested-by: Yan Zhao <yan.y.zhao@intel.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > Message-ID: <20240228024147.41573-2-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 | 8 -------- > arch/x86/kvm/mmu/mmu_internal.h | 19 +++++++++++++++++++ > 2 files changed, 19 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 45b6d8f9e359..c72a2033ca96 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4257,14 +4257,6 @@ static inline u8 kvm_max_level_for_order(int order) > return PG_LEVEL_4K; > } > > -static void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, > - struct kvm_page_fault *fault) > -{ > - kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, > - PAGE_SIZE, fault->write, fault->exec, > - fault->is_private); > -} > - > static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, > struct kvm_page_fault *fault) > { > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h > index 5390a591a571..61f49967047a 100644 > --- a/arch/x86/kvm/mmu/mmu_internal.h > +++ b/arch/x86/kvm/mmu/mmu_internal.h > @@ -279,6 +279,14 @@ enum { > RET_PF_SPURIOUS, > }; > > +static inline void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, > + struct kvm_page_fault *fault) > +{ > + kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, > + PAGE_SIZE, fault->write, fault->exec, > + fault->is_private); > +} > + > static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > u32 err, bool prefetch, int *emulation_type) > { > @@ -320,6 +328,17 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > else > r = vcpu->arch.mmu->page_fault(vcpu, &fault); > > + /* > + * Not sure what's happening, but punt to userspace and hope that > + * they can fix it by changing memory to shared, or they can > + * provide a better error. > + */ > + if (r == RET_PF_EMULATE && fault.is_private) { > + pr_warn_ratelimited("kvm: unexpected emulation request on private memory\n"); > + kvm_mmu_prepare_memory_fault_exit(vcpu, &fault); > + return -EFAULT; > + } > + > if (fault.write_fault_to_shadow_pgtable && emulation_type) > *emulation_type |= EMULTYPE_WRITE_PF_TO_SP; >
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 45b6d8f9e359..c72a2033ca96 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4257,14 +4257,6 @@ static inline u8 kvm_max_level_for_order(int order) return PG_LEVEL_4K; } -static void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, - struct kvm_page_fault *fault) -{ - kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, - PAGE_SIZE, fault->write, fault->exec, - fault->is_private); -} - static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index 5390a591a571..61f49967047a 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -279,6 +279,14 @@ enum { RET_PF_SPURIOUS, }; +static inline void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, + PAGE_SIZE, fault->write, fault->exec, + fault->is_private); +} + static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u32 err, bool prefetch, int *emulation_type) { @@ -320,6 +328,17 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, else r = vcpu->arch.mmu->page_fault(vcpu, &fault); + /* + * Not sure what's happening, but punt to userspace and hope that + * they can fix it by changing memory to shared, or they can + * provide a better error. + */ + if (r == RET_PF_EMULATE && fault.is_private) { + pr_warn_ratelimited("kvm: unexpected emulation request on private memory\n"); + kvm_mmu_prepare_memory_fault_exit(vcpu, &fault); + return -EFAULT; + } + if (fault.write_fault_to_shadow_pgtable && emulation_type) *emulation_type |= EMULTYPE_WRITE_PF_TO_SP;