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KVM: x86: Tell ->inject_page_fault() whether or a fault came from hardware

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When injecting a page fault (including nested TDP faults into L1), tell the
injection routine whether or not the fault originated in hardware, i.e. if
KVM is effectively forwarding a fault it intercept.  For nested TDP fault
injection, KVM needs to grab PAGE_WALK vs. GUEST_FINAL information from the
VMCB/VMCS, _if_ the fault originated in hardware.

Note, simply checking whether or not the original exit was due a #NPF or
EPT Violation isn't sufficient/correct, as the fault being synthesized for
L1 may or may not be the "same" fault that triggered a VM-Exit from L2.
E.g. if access to emulated MMIO in L2 hits a !PRESENT fault (EPT Violation
or #NPF), e.g. because MMIO caching is disabled or it's the first time the
GPA has been accessed by L2, then KVM will enter the emulator.  If
emulating the MMIO instruction then hits a nested TDP fault, e.g. because
L2 was accessing MMIO with a MOVSQ (memory-to-memory move), or because L1
has since unmapped the code stream, then the TDP fault synthesized to L1
will not be the same emulated fault the triggered the VM-Exit.

No functional change intended (nothing uses the new param, yet...).

Link: https://patch.msgid.link/20260522232701.3671446-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2026-05-22 16:26:58 -07:00
parent bb24edbb67
commit fe0b872d75
5 changed files with 28 additions and 14 deletions
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18
arch/x86/include/asm/kvm_host.h
View File

@ -484,7 +484,8 @@ struct kvm_mmu {
u64 (*get_pdptr)(struct kvm_vcpu *vcpu, int index);
int (*page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
void (*inject_page_fault)(struct kvm_vcpu *vcpu,
struct x86_exception *fault);
struct x86_exception *fault,
bool from_hardware);
gpa_t (*gva_to_gpa)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
gpa_t gva_or_gpa, u64 access,
struct x86_exception *exception);
@ -2304,9 +2305,18 @@ void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr, unsigned long payload);
void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned int nr,
bool has_error_code, u32 error_code);
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault);
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault,
bool from_hardware);
void __kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault,
bool from_hardware);
static inline void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault)
{
__kvm_inject_emulated_page_fault(vcpu, fault, false);
}
bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
bool kvm_require_dr(struct kvm_vcpu *vcpu, int dr);

2
arch/x86/kvm/mmu/paging_tmpl.h
View File

@ -813,7 +813,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
*/
if (!r) {
if (!fault->prefetch)
kvm_inject_emulated_page_fault(vcpu, &walker.fault);
__kvm_inject_emulated_page_fault(vcpu, &walker.fault, true);
return RET_PF_RETRY;
}

3
arch/x86/kvm/svm/nested.c
View File

@ -34,7 +34,8 @@
#define CC KVM_NESTED_VMENTER_CONSISTENCY_CHECK
static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu,
struct x86_exception *fault)
struct x86_exception *fault,
bool from_hardware)
{
struct vcpu_svm *svm = to_svm(vcpu);
struct vmcb *vmcb = svm->vmcb;

3
arch/x86/kvm/vmx/nested.c
View File

@ -411,7 +411,8 @@ static void nested_ept_invalidate_addr(struct kvm_vcpu *vcpu, gpa_t eptp,
}
static void nested_ept_inject_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault)
struct x86_exception *fault,
bool from_hardware)
{
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
struct vcpu_vmx *vmx = to_vmx(vcpu);

16
arch/x86/kvm/x86.c
View File

@ -969,7 +969,8 @@ static int complete_emulated_insn_gp(struct kvm_vcpu *vcpu, int err)
EMULTYPE_COMPLETE_USER_EXIT);
}
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault,
bool from_hardware)
{
++vcpu->stat.pf_guest;
@ -986,8 +987,9 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
fault->address);
}
void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault)
void __kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault,
bool from_hardware)
{
struct kvm_mmu *fault_mmu;
WARN_ON_ONCE(fault->vector != PF_VECTOR);
@ -1004,9 +1006,9 @@ void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
kvm_mmu_invalidate_addr(vcpu, fault_mmu, fault->address,
KVM_MMU_ROOT_CURRENT);
fault_mmu->inject_page_fault(vcpu, fault);
fault_mmu->inject_page_fault(vcpu, fault, from_hardware);
}
EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_inject_emulated_page_fault);
EXPORT_SYMBOL_FOR_KVM_INTERNAL(__kvm_inject_emulated_page_fault);
void kvm_inject_nmi(struct kvm_vcpu *vcpu)
{
@ -14058,7 +14060,7 @@ bool kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
fault.nested_page_fault = false;
fault.address = work->arch.token;
fault.async_page_fault = true;
kvm_inject_page_fault(vcpu, &fault);
kvm_inject_page_fault(vcpu, &fault, false);
return true;
} else {
/*
@ -14229,7 +14231,7 @@ void kvm_fixup_and_inject_pf_error(struct kvm_vcpu *vcpu, gva_t gva, u16 error_c
fault.address = gva;
fault.async_page_fault = false;
}
vcpu->arch.walk_mmu->inject_page_fault(vcpu, &fault);
vcpu->arch.walk_mmu->inject_page_fault(vcpu, &fault, true);
}
EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_fixup_and_inject_pf_error);