On Wed, Dec 9, 2020 at 2:39 PM Babu Moger <babu.moger@xxxxxxx> wrote: > > > > On 12/7/20 5:22 PM, Jim Mattson wrote: > > On Mon, Dec 7, 2020 at 2:38 PM Babu Moger <babu.moger@xxxxxxx> wrote: > >> > >> Newer AMD processors have a feature to virtualize the use of the SPEC_CTRL > >> MSR. This feature is identified via CPUID 0x8000000A_EDX[20]. When present, > >> the SPEC_CTRL MSR is automatically virtualized and no longer requires > >> hypervisor intervention. > >> > >> Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > >> --- > >> arch/x86/include/asm/cpufeatures.h | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h > >> index dad350d42ecf..d649ac5ed7c7 100644 > >> --- a/arch/x86/include/asm/cpufeatures.h > >> +++ b/arch/x86/include/asm/cpufeatures.h > >> @@ -335,6 +335,7 @@ > >> #define X86_FEATURE_AVIC (15*32+13) /* Virtual Interrupt Controller */ > >> #define X86_FEATURE_V_VMSAVE_VMLOAD (15*32+15) /* Virtual VMSAVE VMLOAD */ > >> #define X86_FEATURE_VGIF (15*32+16) /* Virtual GIF */ > >> +#define X86_FEATURE_V_SPEC_CTRL (15*32+20) /* Virtual SPEC_CTRL */ > > > > Shouldn't this bit be reported by KVM_GET_SUPPORTED_CPUID when it's > > enumerated on the host? > > Jim, I am not sure if this needs to be reported by > KVM_GET_SUPPORTED_CPUID. I dont see V_VMSAVE_VMLOAD or VGIF being reported > via KVM_GET_SUPPORTED_CPUID. Do you see the need for that? Every little bit helps. No, it isn't *needed*. But then again, this entire patchset isn't *needed*, is it?
