On Wed, Aug 28, 2024, Colton Lewis wrote:
> Hi Mingwei, thanks for reviewing!
>
> Mingwei Zhang <mizhang@xxxxxxxxxx> writes:
>
> > On Tue, Aug 13, 2024, Colton Lewis wrote:
> > > This defined the CPUID calls to determine what extensions and
> > > properties are available. AMD reference manual names listed below.
>
> > > * PerfCtrExtCore (six core counters instead of four)
> > > * PerfCtrExtNB (four counters for northbridge events)
> > > * PerfCtrExtL2I (four counters for L2 cache events)
> > > * PerfMonV2 (support for registers to control multiple
> > > counters with a single register write)
> > > * LbrAndPmcFreeze (support for freezing last branch recorded stack on
> > > performance counter overflow)
> > > * NumPerfCtrCore (number of core counters)
> > > * NumPerfCtrNB (number of northbridge counters)
>
> > > Signed-off-by: Colton Lewis <coltonlewis@xxxxxxxxxx>
> > > ---
> > > tools/testing/selftests/kvm/include/x86_64/processor.h | 7 +++++++
> > > 1 file changed, 7 insertions(+)
>
> > > diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h
> > > b/tools/testing/selftests/kvm/include/x86_64/processor.h
> > > index a0c1440017bb..9d87b5f8974f 100644
> > > --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> > > +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> > > @@ -183,6 +183,9 @@ struct kvm_x86_cpu_feature {
> > > #define X86_FEATURE_GBPAGES KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 26)
> > > #define X86_FEATURE_RDTSCP KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 27)
> > > #define X86_FEATURE_LM KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 29)
> > > +#define X86_FEATURE_PERF_CTR_EXT_CORE KVM_X86_CPU_FEATURE(0x80000001,
> > > 0, ECX, 23)
> > > +#define X86_FEATURE_PERF_CTR_EXT_NB KVM_X86_CPU_FEATURE(0x80000001,
> > > 0, ECX, 24)
> > > +#define X86_FEATURE_PERF_CTR_EXT_L2I KVM_X86_CPU_FEATURE(0x80000001,
> > > 0, ECX, 28)
>
> > You won't be testing Northbridge counters and L2I counters, so these two
> > could be optional to the patch.
>
> That's correct. Since it was a small thing to include I thought it best
> to include and save someone in the future from digging through the
> reference manual again.
+1. They're defines, i.e. have no meaningful cost. And anything that *might*
save me from having to find CPUID entries in the SDM/APM is worth adding.
