| Message ID | jpg4mmevkya.fsf@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/06/2015 08:05, Bandan Das wrote: > > If hardware doesn't support DecodeAssist - a feature that provides > more information about the intercept in the VMCB, KVM decodes the > instruction and then updates the next_rip vmcb control field. > However, NRIP support itself depends on cpuid Fn8000_000A_EDX[NRIPS]. > Since skip_emulated_instruction() doesn't verify nrip support > before accepting control.next_rip as valid, avoid writing this > field if support isn't present. > > Signed-off-by: Bandan Das <bsd@redhat.com> > --- > arch/x86/kvm/svm.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 9afa233..4911bf1 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -511,8 +511,10 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu) > { > struct vcpu_svm *svm = to_svm(vcpu); > > - if (svm->vmcb->control.next_rip != 0) > + if (svm->vmcb->control.next_rip != 0) { > + WARN_ON(!static_cpu_has(X86_FEATURE_NRIPS)); > svm->next_rip = svm->vmcb->control.next_rip; > + } > > if (!svm->next_rip) { > if (emulate_instruction(vcpu, EMULTYPE_SKIP) != > @@ -4317,7 +4319,9 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, > break; > } > > - vmcb->control.next_rip = info->next_rip; > + /* TODO: Advertise NRIPS to guest hypervisor unconditionally */ > + if (static_cpu_has(X86_FEATURE_NRIPS)) > + vmcb->control.next_rip = info->next_rip; > vmcb->control.exit_code = icpt_info.exit_code; > vmexit = nested_svm_exit_handled(svm); > > Applied, thanks. paolo -- 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/svm.c b/arch/x86/kvm/svm.c index 9afa233..4911bf1 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -511,8 +511,10 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); - if (svm->vmcb->control.next_rip != 0) + if (svm->vmcb->control.next_rip != 0) { + WARN_ON(!static_cpu_has(X86_FEATURE_NRIPS)); svm->next_rip = svm->vmcb->control.next_rip; + } if (!svm->next_rip) { if (emulate_instruction(vcpu, EMULTYPE_SKIP) != @@ -4317,7 +4319,9 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, break; } - vmcb->control.next_rip = info->next_rip; + /* TODO: Advertise NRIPS to guest hypervisor unconditionally */ + if (static_cpu_has(X86_FEATURE_NRIPS)) + vmcb->control.next_rip = info->next_rip; vmcb->control.exit_code = icpt_info.exit_code; vmexit = nested_svm_exit_handled(svm);
If hardware doesn't support DecodeAssist - a feature that provides more information about the intercept in the VMCB, KVM decodes the instruction and then updates the next_rip vmcb control field. However, NRIP support itself depends on cpuid Fn8000_000A_EDX[NRIPS]. Since skip_emulated_instruction() doesn't verify nrip support before accepting control.next_rip as valid, avoid writing this field if support isn't present. Signed-off-by: Bandan Das <bsd@redhat.com> --- arch/x86/kvm/svm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)