Messages in this thread | | | Date | Mon, 6 Feb 2023 19:47:13 +0800 | Subject | Re: [PATCH v3 5/8] KVM: x86/cpuid: Add X86_FEATURE_AMD_PMU_V2 as a KVM-only leaf entry | From | Like Xu <> |
| |
On 25/1/2023 3:47 am, Sean Christopherson wrote: > On Fri, Nov 11, 2022, Like Xu wrote: >> From: Like Xu <likexu@tencent.com> >> >> Alias X86_FEATURE_AMD_PMU_V2 for feature AMD_PMU_V2 in KVM-only leafs that >> aren't scattered by cpufeatures.h so that it can be used in KVM, e.g. to >> query guest CPUID. As a bonus, no translation is needed for these features >> in __feature_translate(). >> >> Suggested-by: Sean Christopherson <seanjc@google.com> >> Signed-off-by: Like Xu <likexu@tencent.com> >> --- >> arch/x86/kvm/reverse_cpuid.h | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h >> index a19d473d0184..7cfedb3e47c0 100644 >> --- a/arch/x86/kvm/reverse_cpuid.h >> +++ b/arch/x86/kvm/reverse_cpuid.h >> @@ -13,6 +13,7 @@ >> */ >> enum kvm_only_cpuid_leafs { >> CPUID_12_EAX = NCAPINTS, >> + CPUID_8000_0022_EAX, >> NR_KVM_CPU_CAPS, >> >> NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, >> @@ -23,7 +24,15 @@ enum kvm_only_cpuid_leafs { >> /* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */ >> #define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0) >> #define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1) >> +#define KVM_X86_FEATURE_AMD_PMU_V2 KVM_X86_FEATURE(CPUID_8000_0022_EAX, 0) >> >> +/* >> + * Alias X86_FEATURE_* to the KVM variant for features in KVM-only leafs that >> + * aren't scattered by cpufeatures.h so that X86_FEATURE_* can be used in KVM, >> + * e.g. to query guest CPUID. As a bonus, no translation is needed for these >> + * features in __feature_translate(). >> + */ >> +#define X86_FEATURE_AMD_PMU_V2 KVM_X86_FEATURE_AMD_PMU_V2 > > I gave you bad input earlier, for purely KVM-defined flags there's no need for an > intermediate KVM_X86_FEATURE_AMD_PMU_V2, this could simply be: > > #define X86_FEATURE_AMD_PMU_V2 KVM_X86_FEATURE(CPUID_8000_0022_EAX, 0) > > That's a moot point though because, after much searching because I had a very hard > time believing the kernel wouldn't want to know about this flag, I found commit > > d6d0c7f681fd ("x86/cpufeatures: Add PerfMonV2 feature bit") > > from nearly a year ago. I.e. to avoid confusiong, this needs to be a scattered > flag, not a purely KVM flag. > > --- > arch/x86/kvm/reverse_cpuid.h | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h > index 4945456fd646..333e28b0a13c 100644 > --- a/arch/x86/kvm/reverse_cpuid.h > +++ b/arch/x86/kvm/reverse_cpuid.h > @@ -15,6 +15,7 @@ enum kvm_only_cpuid_leafs { > CPUID_12_EAX = NCAPINTS, > CPUID_7_1_EDX, > CPUID_8000_0007_EDX, > + CPUID_8000_0022_EAX, > NR_KVM_CPU_CAPS, > > NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, > @@ -47,6 +48,9 @@ enum kvm_only_cpuid_leafs { > /* CPUID level 0x80000007 (EDX). */ > #define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8) > > +/* CPUID level 0x80000022 (EAX) */ > +#define KVM_X86_FEATURE_PERFMON_V2 KVM_X86_FEATURE(CPUID_8000_0022_EAX, 0)
I'm very confused and is this the usage you want to see:
kvm_cpu_cap_set(KVM_X86_FEATURE_PERFMON_V2) kvm_cpu_cap_has(KVM_X86_FEATURE_PERFMON_V2) guest_cpuid_has(vcpu, X86_FEATURE_PERFMON_V2)
? then what about X86_FEATURE_PERFMON_V2 ?
> + > struct cpuid_reg { > u32 function; > u32 index; > @@ -73,6 +77,7 @@ static const struct cpuid_reg reverse_cpuid[] = { > [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX}, > [CPUID_7_1_EDX] = { 7, 1, CPUID_EDX}, > [CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX}, > + [CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX}, > }; > > /* > @@ -107,6 +112,8 @@ static __always_inline u32 __feature_translate(int x86_feature) > return KVM_X86_FEATURE_SGX_EDECCSSA; > else if (x86_feature == X86_FEATURE_CONSTANT_TSC) > return KVM_X86_FEATURE_CONSTANT_TSC; > + else if (x86_feature == X86_FEATURE_PERFMON_V2) > + return KVM_X86_FEATURE_PERFMON_V2; > > return x86_feature; > } > > base-commit: 5f3f3cc1279cd5cd52d301b97844bd3ce40c8020
| |