[RFC PATCH 09/22] KVM: x86: Introduce KVM_X86_FEATURE_APERFMPERF

Mingwei Zhang
2024-11-21T18:53:33Z

The APERFMPERF feature bit appears in CPUID.6H:ECX[0], but is exposed to
Linux via X86_FEATURE_APERFMPERF in a Linux-defined feature word. To
enable KVM's reverse CPUID functionality for this feature, define a KVM
feature word matching the hardware CPUID leaf that contains the APERFMPERF
bit.

This patch only adds the feature definition - enabling and advertising
the feature to guests will be handled in later patches.

Signed-off-by: Mingwei Zhang <mizhang@google.com>
Co-developed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
---
arch/x86/kvm/reverse_cpuid.h | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 0d17d6b706396..d12e5d9ab2251 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -18,6 +18,7 @@ enum kvm_only_cpuid_leafs {
CPUID_8000_0022_EAX,
CPUID_7_2_EDX,
CPUID_24_0_EBX,
+ CPUID_6_ECX,
NR_KVM_CPU_CAPS,

NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
@@ -42,6 +43,9 @@ enum kvm_only_cpuid_leafs {
#define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1)
#define KVM_X86_FEATURE_SGX_EDECCSSA KVM_X86_FEATURE(CPUID_12_EAX, 11)

+/* Intel-defined sub-features, CPUID level 0x00000006 (ECX) */
+#define KVM_X86_FEATURE_APERFMPERF KVM_X86_FEATURE(CPUID_6_ECX, 0)
+
/* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */
#define X86_FEATURE_AVX_VNNI_INT8 KVM_X86_FEATURE(CPUID_7_1_EDX, 4)
#define X86_FEATURE_AVX_NE_CONVERT KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
@@ -98,6 +102,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
[CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
[CPUID_7_2_EDX] = { 7, 2, CPUID_EDX},
[CPUID_24_0_EBX] = { 0x24, 0, CPUID_EBX},
+ [CPUID_6_ECX] = { 6, 0, CPUID_ECX},
};

/*
@@ -135,6 +140,7 @@ static __always_inline u32 __feature_translate(int x86_feature)
KVM_X86_TRANSLATE_FEATURE(SGX_EDECCSSA);
KVM_X86_TRANSLATE_FEATURE(CONSTANT_TSC);
KVM_X86_TRANSLATE_FEATURE(PERFMON_V2);
+ KVM_X86_TRANSLATE_FEATURE(APERFMPERF);
KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL);
KVM_X86_TRANSLATE_FEATURE(BHI_CTRL);
default:
--
2.47.0.371.ga323438b13-goog