diff options
| author | Joerg Roedel <joro@8bytes.org> | 2015-10-14 15:10:54 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-10-16 10:32:17 +0200 |
| commit | 6092d3d3e6db983048469d424a8f2221915a8dd3 (patch) | |
| tree | ba6b6b6bc3fc5359267dfe695d7fcd13420b2f22 /arch/x86 | |
| parent | KVM: x86: manually unroll bad_mt_xwr loop (diff) | |
| download | linux-6092d3d3e6db983048469d424a8f2221915a8dd3.tar.xz linux-6092d3d3e6db983048469d424a8f2221915a8dd3.zip | |
kvm: svm: Only propagate next_rip when guest supports it
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>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/cpuid.h | 21 | ||||
| -rw-r--r-- | arch/x86/kvm/svm.c | 11 |
2 files changed, 31 insertions, 1 deletions
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index d434ee952b00..06332cb7e7d1 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -149,4 +149,25 @@ static inline bool guest_cpuid_has_rdtscp(struct kvm_vcpu *vcpu) best = kvm_find_cpuid_entry(vcpu, 0x80000001, 0); return best && (best->edx & bit(X86_FEATURE_RDTSCP)); } + +/* + * 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 54a86183e5d3..cd8659cfc632 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -159,6 +159,9 @@ struct vcpu_svm { u32 apf_reason; u64 tsc_ratio; + + /* cached guest cpuid flags for faster access */ + bool nrips_enabled : 1; }; static DEFINE_PER_CPU(u64, current_tsc_ratio); @@ -2365,7 +2368,9 @@ 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 (svm->nrips_enabled) + nested_vmcb->control.next_rip = vmcb->control.next_rip; /* * If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we have @@ -4085,6 +4090,10 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) static void svm_cpuid_update(struct kvm_vcpu *vcpu) { + struct vcpu_svm *svm = to_svm(vcpu); + + /* Update nrips enabled cache */ + svm->nrips_enabled = !!guest_cpuid_has_nrips(&svm->vcpu); } static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) |