| Message ID | 20240416201935.3525739-11-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: MMU changes for confidential computing | expand |
On 4/17/2024 4:19 AM, Paolo Bonzini wrote: > Right now the error code is not used when an async page fault is completed. > This is not a problem in the current code, but it is untidy. For protected > VMs, we will also need to check that the page attributes match the current > state of the page, because asynchronous page faults can only occur on > shared pages (private pages go through kvm_faultin_pfn_private() instead of > __gfn_to_pfn_memslot()). > > Start by piping the error code from kvm_arch_setup_async_pf() to > kvm_arch_async_page_ready() via the architecture-specific async page > fault data. It is missed in this patch ... > For now, it can be used to assert that there are no > async page faults on private memory. > > Extracted from a patch by Isaku Yamahata. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/mmu/mmu.c | 17 ++++++++++------- > 2 files changed, 11 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 7c73952b6f4e..57ec96bd4221 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1850,6 +1850,7 @@ struct kvm_arch_async_pf { > gfn_t gfn; > unsigned long cr3; > bool direct_map; > + u64 error_code; > }; > > extern u32 __read_mostly kvm_nr_uret_msrs; > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 33aea47dce8b..402d04aa5423 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4207,24 +4207,27 @@ static u32 alloc_apf_token(struct kvm_vcpu *vcpu) > return (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; > } > > -static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > - gfn_t gfn) > +static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, > + struct kvm_page_fault *fault) > { > struct kvm_arch_async_pf arch; > > arch.token = alloc_apf_token(vcpu); > - arch.gfn = gfn; > + arch.gfn = fault->gfn; > arch.direct_map = vcpu->arch.mmu->root_role.direct; > arch.cr3 = kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu); + arch.error_code = fault->error_code; > > - return kvm_setup_async_pf(vcpu, cr2_or_gpa, > - kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); > + return kvm_setup_async_pf(vcpu, fault->addr, > + kvm_vcpu_gfn_to_hva(vcpu, fault->gfn), &arch); > } > > void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) > { > int r; > > + if (WARN_ON_ONCE(work->arch.error_code & PFERR_GUEST_ENC_MASK)) > + return; > + > if ((vcpu->arch.mmu->root_role.direct != work->arch.direct_map) || > work->wakeup_all) > return; > @@ -4237,7 +4240,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) > work->arch.cr3 != kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu)) > return; > > - kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true, NULL); > + kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, work->arch.error_code, true, NULL); > } > > static inline u8 kvm_max_level_for_order(int order) > @@ -4342,7 +4345,7 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > trace_kvm_async_pf_repeated_fault(fault->addr, fault->gfn); > kvm_make_request(KVM_REQ_APF_HALT, vcpu); > return RET_PF_RETRY; > - } else if (kvm_arch_setup_async_pf(vcpu, fault->addr, fault->gfn)) { > + } else if (kvm_arch_setup_async_pf(vcpu, fault)) { > return RET_PF_RETRY; > } > }
On Fri, Apr 19, 2024 at 9:35 AM Xiaoyao Li <xiaoyao.li@intel.com> wrote: > > On 4/17/2024 4:19 AM, Paolo Bonzini wrote: > > Right now the error code is not used when an async page fault is completed. > > This is not a problem in the current code, but it is untidy. For protected > > VMs, we will also need to check that the page attributes match the current > > state of the page, because asynchronous page faults can only occur on > > shared pages (private pages go through kvm_faultin_pfn_private() instead of > > __gfn_to_pfn_memslot()). > > > > Start by piping the error code from kvm_arch_setup_async_pf() to > > kvm_arch_async_page_ready() via the architecture-specific async page > > fault data. > > It is missed in this patch ... Ugh, thanks Xiaoyao! Paolo
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 7c73952b6f4e..57ec96bd4221 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1850,6 +1850,7 @@ struct kvm_arch_async_pf { gfn_t gfn; unsigned long cr3; bool direct_map; + u64 error_code; }; extern u32 __read_mostly kvm_nr_uret_msrs; diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 33aea47dce8b..402d04aa5423 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4207,24 +4207,27 @@ static u32 alloc_apf_token(struct kvm_vcpu *vcpu) return (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; } -static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, - gfn_t gfn) +static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) { struct kvm_arch_async_pf arch; arch.token = alloc_apf_token(vcpu); - arch.gfn = gfn; + arch.gfn = fault->gfn; arch.direct_map = vcpu->arch.mmu->root_role.direct; arch.cr3 = kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu); - return kvm_setup_async_pf(vcpu, cr2_or_gpa, - kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); + return kvm_setup_async_pf(vcpu, fault->addr, + kvm_vcpu_gfn_to_hva(vcpu, fault->gfn), &arch); } void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) { int r; + if (WARN_ON_ONCE(work->arch.error_code & PFERR_GUEST_ENC_MASK)) + return; + if ((vcpu->arch.mmu->root_role.direct != work->arch.direct_map) || work->wakeup_all) return; @@ -4237,7 +4240,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) work->arch.cr3 != kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu)) return; - kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true, NULL); + kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, work->arch.error_code, true, NULL); } static inline u8 kvm_max_level_for_order(int order) @@ -4342,7 +4345,7 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault trace_kvm_async_pf_repeated_fault(fault->addr, fault->gfn); kvm_make_request(KVM_REQ_APF_HALT, vcpu); return RET_PF_RETRY; - } else if (kvm_arch_setup_async_pf(vcpu, fault->addr, fault->gfn)) { + } else if (kvm_arch_setup_async_pf(vcpu, fault)) { return RET_PF_RETRY; } }
Right now the error code is not used when an async page fault is completed. This is not a problem in the current code, but it is untidy. For protected VMs, we will also need to check that the page attributes match the current state of the page, because asynchronous page faults can only occur on shared pages (private pages go through kvm_faultin_pfn_private() instead of __gfn_to_pfn_memslot()). Start by piping the error code from kvm_arch_setup_async_pf() to kvm_arch_async_page_ready() via the architecture-specific async page fault data. For now, it can be used to assert that there are no async page faults on private memory. Extracted from a patch by Isaku Yamahata. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu/mmu.c | 17 ++++++++++------- 2 files changed, 11 insertions(+), 7 deletions(-)