| Message ID | 1409670830-14544-4-git-send-email-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Sep 02, 2014 at 05:13:49PM +0200, Paolo Bonzini wrote: > This is required for the following patch to work correctly. If a nested page > fault happens during emulation, we must inject a vmexit, not a page fault. > Luckily we already have the required machinery: it is enough to return > X86EMUL_INTERCEPTED instead of X86EMUL_PROPAGATE_FAULT. > I wonder why this patch is needed. X86EMUL_PROPAGATE_FAULT causes ctxt->have_exception to be set to true in x86_emulate_insn(). x86_emulate_instruction() checks ctxt->have_exception and calls inject_emulated_exception() if it is true. inject_emulated_exception() calls kvm_propagate_fault() where we check if the fault was nested and generate vmexit or a page fault accordingly. > Reported-by: Valentine Sinitsyn <valentine.sinitsyn@gmail.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/kvm/x86.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index e4ed85e07a01..9e3b74c044ed 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -416,6 +416,16 @@ void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault) > vcpu->arch.mmu.inject_page_fault(vcpu, fault); > } > > +static inline int kvm_propagate_or_intercept(struct kvm_vcpu *vcpu, > + struct x86_exception *exception) > +{ > + if (likely(!exception->nested_page_fault)) > + return X86EMUL_PROPAGATE_FAULT; > + > + vcpu->arch.mmu.inject_page_fault(vcpu, exception); > + return X86EMUL_INTERCEPTED; > +} > + > void kvm_inject_nmi(struct kvm_vcpu *vcpu) > { > atomic_inc(&vcpu->arch.nmi_queued); > @@ -4122,7 +4132,7 @@ static int kvm_read_guest_virt_helper(gva_t addr, void *val, unsigned int bytes, > int ret; > > if (gpa == UNMAPPED_GVA) > - return X86EMUL_PROPAGATE_FAULT; > + return kvm_propagate_or_intercept(vcpu, exception); > ret = kvm_read_guest_page(vcpu->kvm, gpa >> PAGE_SHIFT, data, > offset, toread); > if (ret < 0) { > @@ -4152,7 +4162,7 @@ static int kvm_fetch_guest_virt(struct x86_emulate_ctxt *ctxt, > gpa_t gpa = vcpu->arch.walk_mmu->gva_to_gpa(vcpu, addr, access|PFERR_FETCH_MASK, > exception); > if (unlikely(gpa == UNMAPPED_GVA)) > - return X86EMUL_PROPAGATE_FAULT; > + return kvm_propagate_or_intercept(vcpu, exception); > > offset = addr & (PAGE_SIZE-1); > if (WARN_ON(offset + bytes > PAGE_SIZE)) > @@ -4203,7 +4213,7 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt, > int ret; > > if (gpa == UNMAPPED_GVA) > - return X86EMUL_PROPAGATE_FAULT; > + return kvm_propagate_or_intercept(vcpu, exception); > ret = kvm_write_guest(vcpu->kvm, gpa, data, towrite); > if (ret < 0) { > r = X86EMUL_IO_NEEDED; > @@ -4350,7 +4360,7 @@ static int emulator_read_write_onepage(unsigned long addr, void *val, > ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write); > > if (ret < 0) > - return X86EMUL_PROPAGATE_FAULT; > + return kvm_propagate_or_intercept(vcpu, exception); > > /* For APIC access vmexit */ > if (ret) > -- > 1.8.3.1 > > -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e4ed85e07a01..9e3b74c044ed 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -416,6 +416,16 @@ void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault) vcpu->arch.mmu.inject_page_fault(vcpu, fault); } +static inline int kvm_propagate_or_intercept(struct kvm_vcpu *vcpu, + struct x86_exception *exception) +{ + if (likely(!exception->nested_page_fault)) + return X86EMUL_PROPAGATE_FAULT; + + vcpu->arch.mmu.inject_page_fault(vcpu, exception); + return X86EMUL_INTERCEPTED; +} + void kvm_inject_nmi(struct kvm_vcpu *vcpu) { atomic_inc(&vcpu->arch.nmi_queued); @@ -4122,7 +4132,7 @@ static int kvm_read_guest_virt_helper(gva_t addr, void *val, unsigned int bytes, int ret; if (gpa == UNMAPPED_GVA) - return X86EMUL_PROPAGATE_FAULT; + return kvm_propagate_or_intercept(vcpu, exception); ret = kvm_read_guest_page(vcpu->kvm, gpa >> PAGE_SHIFT, data, offset, toread); if (ret < 0) { @@ -4152,7 +4162,7 @@ static int kvm_fetch_guest_virt(struct x86_emulate_ctxt *ctxt, gpa_t gpa = vcpu->arch.walk_mmu->gva_to_gpa(vcpu, addr, access|PFERR_FETCH_MASK, exception); if (unlikely(gpa == UNMAPPED_GVA)) - return X86EMUL_PROPAGATE_FAULT; + return kvm_propagate_or_intercept(vcpu, exception); offset = addr & (PAGE_SIZE-1); if (WARN_ON(offset + bytes > PAGE_SIZE)) @@ -4203,7 +4213,7 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt, int ret; if (gpa == UNMAPPED_GVA) - return X86EMUL_PROPAGATE_FAULT; + return kvm_propagate_or_intercept(vcpu, exception); ret = kvm_write_guest(vcpu->kvm, gpa, data, towrite); if (ret < 0) { r = X86EMUL_IO_NEEDED; @@ -4350,7 +4360,7 @@ static int emulator_read_write_onepage(unsigned long addr, void *val, ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write); if (ret < 0) - return X86EMUL_PROPAGATE_FAULT; + return kvm_propagate_or_intercept(vcpu, exception); /* For APIC access vmexit */ if (ret)
This is required for the following patch to work correctly. If a nested page fault happens during emulation, we must inject a vmexit, not a page fault. Luckily we already have the required machinery: it is enough to return X86EMUL_INTERCEPTED instead of X86EMUL_PROPAGATE_FAULT. Reported-by: Valentine Sinitsyn <valentine.sinitsyn@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/x86.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)