Il 04/09/2014 17:05, Gleb Natapov ha scritto:
>> >
>> > If you do that, KVM gets down to the "if (writeback)" and writes the
>> > ctxt->eip from L2 into the L1 EIP.
> Heh, that's a bummer. We should not write back if an instruction caused a
> vmexit.
>
You're right, that works.
Paolo
-------------- 8< -------------
Subject: [PATCH] KVM: x86: skip writeback on injection of nested exception
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.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 1 -
arch/x86/kvm/x86.c | 15 ++++++++++-----
2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 08cc299..c989651 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -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,
gfn_t gfn, void *data, int offset, int len,
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);
static inline int __kvm_irq_line_state(unsigned long *irq_state,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e4ed85e..3541946 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -408,12 +408,14 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct
x86_exception *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)
vcpu->arch.nested_mmu.inject_page_fault(vcpu, fault);
else
vcpu->arch.mmu.inject_page_fault(vcpu, fault);
+
+ return fault->nested_page_fault;
}
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;
if (ctxt->exception.vector == PF_VECTOR)
- kvm_propagate_fault(vcpu, &ctxt->exception);
- else if (ctxt->exception.error_code_valid)
+ return kvm_propagate_fault(vcpu, &ctxt->exception);
+
+ if (ctxt->exception.error_code_valid)
kvm_queue_exception_e(vcpu, ctxt->exception.vector,
ctxt->exception.error_code);
else
kvm_queue_exception(vcpu, ctxt->exception.vector);
+ return false;
}
static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
@@ -5300,8 +5304,9 @@ restart:
}
if (ctxt->have_exception) {
- inject_emulated_exception(vcpu);
r = EMULATE_DONE;
+ if (inject_emulated_exception(vcpu))
+ return r;
} else if (vcpu->arch.pio.count) {
if (!vcpu->arch.pio.in) {
/* FIXME: return into emulator if single-stepping. */
--
1.9.3
--
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