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KVM: x86: skip writeback on injection of nested exception

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If a nested page fault happens during emulation, we will inject a vmexit,
not a page fault.  However because writeback happens after the injection,
we will write ctxt->eip from L2 into the L1 EIP.  We do not write back
if an instruction caused an interception vmexit---do the same for page
faults.

Suggested-by: Gleb Natapov <gleb@kernel.org>
Reviewed-by: Gleb Natapov <gleb@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-09-04 19:46:15 +02:00
parent 5e35251951
commit ef54bcfeea
2 changed files with 10 additions and 6 deletions
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1
arch/x86/include/asm/kvm_host.h
View File

@ -893,7 +893,6 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
gfn_t gfn, void *data, int offset, int len, gfn_t gfn, void *data, int offset, int len,
u32 access); u32 access);
void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl); bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
static inline int __kvm_irq_line_state(unsigned long *irq_state, static inline int __kvm_irq_line_state(unsigned long *irq_state,

15
arch/x86/kvm/x86.c
View File

@ -408,12 +408,14 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
} }
EXPORT_SYMBOL_GPL(kvm_inject_page_fault); EXPORT_SYMBOL_GPL(kvm_inject_page_fault);
void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault) static bool kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
{ {
if (mmu_is_nested(vcpu) && !fault->nested_page_fault) if (mmu_is_nested(vcpu) && !fault->nested_page_fault)
vcpu->arch.nested_mmu.inject_page_fault(vcpu, fault); vcpu->arch.nested_mmu.inject_page_fault(vcpu, fault);
else else
vcpu->arch.mmu.inject_page_fault(vcpu, fault); vcpu->arch.mmu.inject_page_fault(vcpu, fault);
return fault->nested_page_fault;
} }
void kvm_inject_nmi(struct kvm_vcpu *vcpu) void kvm_inject_nmi(struct kvm_vcpu *vcpu)
@ -4929,16 +4931,18 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
} }
} }
static void inject_emulated_exception(struct kvm_vcpu *vcpu) static bool inject_emulated_exception(struct kvm_vcpu *vcpu)
{ {
struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt; struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt;
if (ctxt->exception.vector == PF_VECTOR) if (ctxt->exception.vector == PF_VECTOR)
kvm_propagate_fault(vcpu, &ctxt->exception); return kvm_propagate_fault(vcpu, &ctxt->exception);
else if (ctxt->exception.error_code_valid)
if (ctxt->exception.error_code_valid)
kvm_queue_exception_e(vcpu, ctxt->exception.vector, kvm_queue_exception_e(vcpu, ctxt->exception.vector,
ctxt->exception.error_code); ctxt->exception.error_code);
else else
kvm_queue_exception(vcpu, ctxt->exception.vector); kvm_queue_exception(vcpu, ctxt->exception.vector);
return false;
} }
static void init_emulate_ctxt(struct kvm_vcpu *vcpu) static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
@ -5300,8 +5304,9 @@ restart:
} }
if (ctxt->have_exception) { if (ctxt->have_exception) {
inject_emulated_exception(vcpu);
r = EMULATE_DONE; r = EMULATE_DONE;
if (inject_emulated_exception(vcpu))
return r;
} else if (vcpu->arch.pio.count) { } else if (vcpu->arch.pio.count) {
if (!vcpu->arch.pio.in) { if (!vcpu->arch.pio.in) {
/* FIXME: return into emulator if single-stepping. */ /* FIXME: return into emulator if single-stepping. */