Messages in this thread | | | Subject | Re: [PATCH 1/7] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors | From | Paolo Bonzini <> | Date | Tue, 9 Jan 2018 12:18:25 +0100 |
| |
On 09/01/2018 12:14, David Hildenbrand wrote: >> >> +/* These are scattered features in cpufeatures.h. */ >> +#define KVM_CPUID_BIT_AVX512_4VNNIW 2 >> +#define KVM_CPUID_BIT_AVX512_4FMAPS 3 >> +#define KVM_CPUID_BIT_SPEC_CTRL 26 >> +#define KVM_CPUID_BIT_STIBP 27 > I can see that STIBP is never checked in KVM code but only forwarded to > the guest if available. > > I am wondering if we would have to check against that, too, before > issuing a FEATURE_SET_IBPB.
STIBP is "single-threaded indirect branch prediction". SPEC_CTRL always implies that FEATURE_SET_IBPB is available.
Paolo
| |