[Patch v3 02/13] KVM: x86: Add a KVM-only leaf for CPUID_8000_0007_EDX

Vipin Sharma
2022-12-05T19:15:33Z

From: Vitaly Kuznetsov <vkuznets@redhat.com>

CPUID_8000_0007_EDX may come handy when X86_FEATURE_CONSTANT_TSC
needs to be checked.

No functional change intended.

Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/cpuid.c | 8 ++++++--
arch/x86/kvm/reverse_cpuid.h | 7 +++++++
2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 723502181a3a..42913695fedd 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -701,6 +701,10 @@ void kvm_set_cpu_caps(void)
if (!tdp_enabled && IS_ENABLED(CONFIG_X86_64))
kvm_cpu_cap_set(X86_FEATURE_GBPAGES);

+ kvm_cpu_cap_init_kvm_defined(CPUID_8000_0007_EDX,
+ SF(CONSTANT_TSC)
+ );
+
kvm_cpu_cap_mask(CPUID_8000_0008_EBX,
F(CLZERO) | F(XSAVEERPTR) |
F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
@@ -1153,8 +1157,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->edx &= ~GENMASK(17, 16);
break;
case 0x80000007: /* Advanced power management */
- /* invariant TSC is CPUID.80000007H:EDX[8] */
- entry->edx &= (1 << 8);
+ cpuid_entry_override(entry, CPUID_8000_0007_EDX);
+
/* mask against host */
entry->edx &= boot_cpu_data.x86_power;
entry->eax = entry->ebx = entry->ecx = 0;
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 203fdad07bae..25b9b51abb20 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -14,6 +14,7 @@
enum kvm_only_cpuid_leafs {
CPUID_12_EAX = NCAPINTS,
CPUID_7_1_EDX,
+ CPUID_8000_0007_EDX,
NR_KVM_CPU_CAPS,

NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
@@ -42,6 +43,9 @@ enum kvm_only_cpuid_leafs {
#define X86_FEATURE_AVX_NE_CONVERT KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
#define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14)

+/* CPUID level 0x80000007 (EDX). */
+#define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
+
struct cpuid_reg {
u32 function;
u32 index;
@@ -67,6 +71,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
[CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX},
[CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
[CPUID_7_1_EDX] = { 7, 1, CPUID_EDX},
+ [CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
};

/*
@@ -97,6 +102,8 @@ static __always_inline u32 __feature_translate(int x86_feature)
return KVM_X86_FEATURE_SGX1;
else if (x86_feature == X86_FEATURE_SGX2)
return KVM_X86_FEATURE_SGX2;
+ else if (x86_feature == X86_FEATURE_CONSTANT_TSC)
+ return KVM_X86_FEATURE_CONSTANT_TSC;

return x86_feature;