| Message ID | 1444384276-23732-1-git-send-email-joro@8bytes.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/10/2015 11:51, Joerg Roedel wrote: > From: Joerg Roedel <jroedel@suse.de> > > Currently we always write the next_rip of the shadow vmcb to > the guests vmcb when we emulate a vmexit. This could confuse > the guest when its cpuid indicated no support for the > next_rip feature. > > Fix this by only propagating next_rip if the guest actually > supports it. > > Cc: Bandan Das <bsd@redhat.com> > Cc: Dirk Mueller <dmueller@suse.com> > Tested-by: Dirk Mueller <dmueller@suse.com> > Signed-off-by: Joerg Roedel <jroedel@suse.de> > --- > arch/x86/kvm/cpuid.h | 21 +++++++++++++++++++++ > arch/x86/kvm/svm.c | 4 +++- > 2 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h > index dd05b9c..effca1f 100644 > --- a/arch/x86/kvm/cpuid.h > +++ b/arch/x86/kvm/cpuid.h > @@ -133,4 +133,25 @@ static inline bool guest_cpuid_has_mpx(struct kvm_vcpu *vcpu) > best = kvm_find_cpuid_entry(vcpu, 7, 0); > return best && (best->ebx & bit(X86_FEATURE_MPX)); > } > + > +/* > + * NRIPS is provided through cpuidfn 0x8000000a.edx bit 3 > + */ > +#define BIT_NRIPS 3 > + > +static inline bool guest_cpuid_has_nrips(struct kvm_vcpu *vcpu) > +{ > + struct kvm_cpuid_entry2 *best; > + > + best = kvm_find_cpuid_entry(vcpu, 0x8000000a, 0); > + > + /* > + * NRIPS is a scattered cpuid feature, so we can't use > + * X86_FEATURE_NRIPS here (X86_FEATURE_NRIPS would be bit > + * position 8, not 3). > + */ > + return best && (best->edx & bit(BIT_NRIPS)); > +} > +#undef BIT_NRIPS > + > #endif > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 2f9ed1f..4084b33 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -2365,7 +2365,9 @@ static int nested_svm_vmexit(struct vcpu_svm *svm) > nested_vmcb->control.exit_info_2 = vmcb->control.exit_info_2; > nested_vmcb->control.exit_int_info = vmcb->control.exit_int_info; > nested_vmcb->control.exit_int_info_err = vmcb->control.exit_int_info_err; > - nested_vmcb->control.next_rip = vmcb->control.next_rip; > + > + if (guest_cpuid_has_nrips(&svm->vcpu)) This could be a bit expensive to do on every vmexit. Can you benchmark it with kvm-unit-tests, or just cache the result in struct vcpu_svm? Thanks, Paolo > + nested_vmcb->control.next_rip = vmcb->control.next_rip; > > /* > * If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we have > -- 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/cpuid.h b/arch/x86/kvm/cpuid.h index dd05b9c..effca1f 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -133,4 +133,25 @@ static inline bool guest_cpuid_has_mpx(struct kvm_vcpu *vcpu) best = kvm_find_cpuid_entry(vcpu, 7, 0); return best && (best->ebx & bit(X86_FEATURE_MPX)); } + +/* + * NRIPS is provided through cpuidfn 0x8000000a.edx bit 3 + */ +#define BIT_NRIPS 3 + +static inline bool guest_cpuid_has_nrips(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best; + + best = kvm_find_cpuid_entry(vcpu, 0x8000000a, 0); + + /* + * NRIPS is a scattered cpuid feature, so we can't use + * X86_FEATURE_NRIPS here (X86_FEATURE_NRIPS would be bit + * position 8, not 3). + */ + return best && (best->edx & bit(BIT_NRIPS)); +} +#undef BIT_NRIPS + #endif diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 2f9ed1f..4084b33 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2365,7 +2365,9 @@ static int nested_svm_vmexit(struct vcpu_svm *svm) nested_vmcb->control.exit_info_2 = vmcb->control.exit_info_2; nested_vmcb->control.exit_int_info = vmcb->control.exit_int_info; nested_vmcb->control.exit_int_info_err = vmcb->control.exit_int_info_err; - nested_vmcb->control.next_rip = vmcb->control.next_rip; + + if (guest_cpuid_has_nrips(&svm->vcpu)) + nested_vmcb->control.next_rip = vmcb->control.next_rip; /* * If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we have