Add has_emulator_context to kvm_queued_exception to record whether a queued exception VM-Exit originated from the current emulator exception. This provenance allows nested virtualization code to determine whether the emulator decode state can be used for a nested #PF VM-Exit.
Explicit provenance is needed because a matching emulator RIP does not prove that the fetch cache describes the faulting instruction. For example, completing pending emulated I/O can advance RIP while leaving the fetch cache populated with the completed instruction. Determine provenance in kvm_inject_page_fault() and carry it through exception queueing so that it is stored as part of the nested VM-Exit event. Userspace-injected and other unrelated exceptions leave the flag clear. Signed-off-by: Tina Zhang <[email protected]> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 33 ++++++++++++++++++++++----------- 2 files changed, 23 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 7a258831616f..8466a17cd046 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -688,6 +688,7 @@ struct kvm_queued_exception { bool pending; bool injected; bool has_error_code; + bool has_emulator_context; u8 vector; u32 error_code; unsigned long payload; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0f1a829032c0..e7aff420d6c6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -444,7 +444,8 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_deliver_exception_payload); static void kvm_queue_exception_vmexit(struct kvm_vcpu *vcpu, unsigned int vector, bool has_error_code, u32 error_code, - bool has_payload, unsigned long payload) + bool has_payload, unsigned long payload, + bool has_emulator_context) { struct kvm_queued_exception *ex = &vcpu->arch.exception_vmexit; @@ -452,6 +453,7 @@ static void kvm_queue_exception_vmexit(struct kvm_vcpu *vcpu, unsigned int vecto ex->injected = false; ex->pending = true; ex->has_error_code = has_error_code; + ex->has_emulator_context = has_emulator_context; ex->error_code = error_code; ex->has_payload = has_payload; ex->payload = payload; @@ -459,7 +461,8 @@ static void kvm_queue_exception_vmexit(struct kvm_vcpu *vcpu, unsigned int vecto static void kvm_multiple_exception(struct kvm_vcpu *vcpu, unsigned int nr, bool has_error, u32 error_code, - bool has_payload, unsigned long payload) + bool has_payload, unsigned long payload, + bool has_emulator_context) { u32 prev_nr; int class1, class2; @@ -473,7 +476,8 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu, unsigned int nr, if (is_guest_mode(vcpu) && kvm_nested_call(is_exception_vmexit)(vcpu, nr, error_code)) { kvm_queue_exception_vmexit(vcpu, nr, has_error, error_code, - has_payload, payload); + has_payload, payload, + has_emulator_context); return; } @@ -519,7 +523,7 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu, unsigned int nr, void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr) { - kvm_multiple_exception(vcpu, nr, false, 0, false, 0); + kvm_multiple_exception(vcpu, nr, false, 0, false, 0, false); } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_queue_exception); @@ -527,14 +531,16 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_queue_exception); void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr, unsigned long payload) { - kvm_multiple_exception(vcpu, nr, false, 0, true, payload); + kvm_multiple_exception(vcpu, nr, false, 0, true, payload, false); } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_queue_exception_p); static void kvm_queue_exception_e_p(struct kvm_vcpu *vcpu, unsigned nr, - u32 error_code, unsigned long payload) + u32 error_code, unsigned long payload, + bool has_emulator_context) { - kvm_multiple_exception(vcpu, nr, true, error_code, true, payload); + kvm_multiple_exception(vcpu, nr, true, error_code, true, payload, + has_emulator_context); } void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned int nr, @@ -580,6 +586,9 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_complete_insn_gp); void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault, bool from_hardware) { + struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt; + bool has_emulator_context = ctxt && fault == &ctxt->exception; + ++vcpu->stat.pf_guest; /* @@ -589,10 +598,12 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault, if (is_guest_mode(vcpu) && fault->async_page_fault) kvm_queue_exception_vmexit(vcpu, PF_VECTOR, true, fault->error_code, - true, fault->address); + true, fault->address, + has_emulator_context); else kvm_queue_exception_e_p(vcpu, PF_VECTOR, fault->error_code, - fault->address); + fault->address, + has_emulator_context); } void __kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu, @@ -627,7 +638,7 @@ void kvm_inject_nmi(struct kvm_vcpu *vcpu) void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code) { - kvm_multiple_exception(vcpu, nr, true, error_code, false, 0); + kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, false); } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_queue_exception_e); @@ -8949,7 +8960,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) kvm_nested_call(is_exception_vmexit)(vcpu, ex->vector, ex->error_code)) { kvm_queue_exception_vmexit(vcpu, ex->vector, ex->has_error_code, ex->error_code, - ex->has_payload, ex->payload); + ex->has_payload, ex->payload, false); ex->injected = false; ex->pending = false; } -- 2.43.7
