On 16/08/19 23:45, Jim Mattson wrote: > On Thu, Aug 15, 2019 at 12:41 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: >> >> The AMD_* bits have to be set from the vendor-independent >> feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care >> about the vendor and they should be set on Intel processors as well. >> On top of this, SSBD, STIBP and AMD_SSB_NO bit were not set, and >> VIRT_SSBD does not have to be added manually because it is a >> cpufeature that comes directly from the host's CPUID bit. >> >> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > On AMD systems, aren't AMD_SSBD, AMD_STIBP, and AMD_SSB_NO set by > inheritance from the host: > > /* cpuid 0x80000008.ebx */ > const u32 kvm_cpuid_8000_0008_ebx_x86_features = > F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) | > F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON); > > I am curious why the cross-vendor settings go only one way. For > example, you set AMD_STIBP on Intel processors that have STIBP, but > you do not set INTEL_STIBP on AMD processors that have STIBP? > Similarly, you set AMD_SSB_NO for Intel processors that are immune to > SSB, but you do not set IA32_ARCH_CAPABILITIES.SSB_NO for AMD > processors that are immune to SSB? > > Perhaps there is another patch coming for reporting Intel bits on AMD? I wasn't going to work on it but yes, they should be. This patch just fixed what was half-implemented. Paolo
