[PATCH V5 08/10] KVM: x86/cpuid: Add a KVM-only leaf to redirect AMD PerfMonV2 flag

From: Like Xu
Date: Mon Apr 10 2023 - 06:52:12 EST


From: Like Xu <likexu@xxxxxxxxxxx>

A KVM-only leaf for AMD's PerfMonV2 feature flag is defined to redirect
the kernel's scattered version to its architectural location, e.g. so that
KVM can query guest support via guest_cpuid_has().

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
---
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 a5717282bb9c..56cbdb24400a 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)
+
struct cpuid_reg {
u32 function;
u32 index;
@@ -74,6 +78,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
[CPUID_7_1_EDX] = { 7, 1, CPUID_EDX},
[CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
[CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
+ [CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
};

/*
@@ -108,6 +113,8 @@ 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;
}
--
2.40.0