linux-kernel - [Patch v3 02/13] KVM: x86: Add a KVM-only leaf for CPUID_8000_0007

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Message-ID: <20221205191430.2455108-3-vipinsh@google.com>
Date:   Mon,  5 Dec 2022 11:14:19 -0800
From:   Vipin Sharma <vipinsh@...gle.com>
To:     seanjc@...gle.com, pbonzini@...hat.com, vkuznets@...hat.com,
        dmatlack@...gle.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [Patch v3 02/13] KVM: x86: Add a KVM-only leaf for CPUID_8000_0007_EDX

From: Vitaly Kuznetsov <vkuznets@...hat.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@...gle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.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;
 }
-- 
2.39.0.rc0.267.gcb52ba06e7-goog