On Wed, Dec 05, 2018 at 05:19:56PM -0200, Eduardo Habkost wrote:
> Months ago, we have added code to allow direct access to MSR_IA32_SPEC_CTRL
> to the guest, which makes STIBP available to guests. This was implemented
> by commits d28b387fb74d ("KVM/VMX: Allow direct access to
> MSR_IA32_SPEC_CTRL") and b2ac58f90540 ("KVM/SVM: Allow direct access to
> MSR_IA32_SPEC_CTRL").
>
> However, we never updated GET_SUPPORTED_CPUID to let userspace know that
> STIBP can be enabled in CPUID. Fix that by updating
Ooops!
> kvm_cpuid_8000_0008_ebx_x86_features and kvm_cpuid_7_0_edx_x86_features.
Shouldn't there also be a patch in QEMU to use it? (aka, +stibp).
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Thank you!
> Signed-off-by: Eduardo Habkost <ehabkost@xxxxxxxxxx>
> ---
> arch/x86/kvm/cpuid.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 7bcfa61375c0..cc6dd65828a4 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -381,7 +381,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> /* cpuid 0x80000008.ebx */
> const u32 kvm_cpuid_8000_0008_ebx_x86_features =
> F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
> - F(AMD_SSB_NO);
> + F(AMD_SSB_NO) | F(AMD_STIBP);
>
> /* cpuid 0xC0000001.edx */
> const u32 kvm_cpuid_C000_0001_edx_x86_features =
> @@ -411,7 +411,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> /* cpuid 7.0.edx*/
> const u32 kvm_cpuid_7_0_edx_x86_features =
> F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
> - F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES);
> + F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP);
>
> /* all calls to cpuid_count() should be made on the same cpu */
> get_cpu();
> --
> 2.18.0.rc1.1.g3f1ff2140
>
