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From:   Kim Phillips <kim.phillips@amd.com>
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Subject: [PATCH v5 4/7] x86/cpu, kvm: Move CPUID 0x80000021 EAX feature bits propagation to kvm_set_cpu_caps()
Date:   Mon, 5 Dec 2022 17:32:32 -0600
Message-ID: <20221205233235.622491-5-kim.phillips@amd.com>
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Move CPUID 0x80000021 EAX feature bits guest propagation to
kvm_set_cpu_caps() instead of open-coding them in __do_cpuid_func().
Drop the bit description comments now the code is more self-describing.

Whilst there, switch to using the more efficient cpu_feature_enabled()
instead of static_cpu_has().

Signed-off-by: Kim Phillips <kim.phillips@amd.com>
---
 arch/x86/kvm/cpuid.c         | 25 ++++++++++---------------
 arch/x86/kvm/reverse_cpuid.h | 22 ++++++++++++++++------
 2 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index c92c49a0b35b..dd0fe79521eb 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -730,6 +730,15 @@ void kvm_set_cpu_caps(void)
 		0 /* SME */ | F(SEV) | 0 /* VM_PAGE_FLUSH */ | F(SEV_ES) |
 		F(SME_COHERENT));
 
+	kvm_cpu_cap_init_scattered(CPUID_8000_0021_EAX,
+		SF(NO_NESTED_DATA_BP) | SF(LFENCE_RDTSC) | 0 /* SmmPgCfgLock */ |
+		SF(NULL_SEL_CLR_BASE) | 0 /* PrefetchCtlMsr */
+	);
+	if (cpu_feature_enabled(X86_FEATURE_LFENCE_RDTSC))
+		kvm_cpu_cap_set(X86_FEATURE_LFENCE_RDTSC);
+	if (!static_cpu_has_bug(X86_BUG_NULL_SEG))
+		kvm_cpu_cap_set(X86_FEATURE_NULL_SEL_CLR_BASE);
+
 	kvm_cpu_cap_mask(CPUID_C000_0001_EDX,
 		F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |
 		F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) |
@@ -1211,21 +1220,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 		break;
 	case 0x80000021:
 		entry->ebx = entry->ecx = entry->edx = 0;
-		/*
-		 * Pass down these bits:
-		 *    EAX      0      NNDBP, Processor ignores nested data breakpoints
-		 *    EAX      2      LAS, LFENCE always serializing
-		 *    EAX      6      NSCB, Null selector clear base
-		 *
-		 * Other defined bits are for MSRs that KVM does not expose:
-		 *   EAX      3      SPCL, SMM page configuration lock
-		 *   EAX      13     PCMSR, Prefetch control MSR
-		 */
-		entry->eax &= BIT(0) | BIT(2) | BIT(6);
-		if (static_cpu_has(X86_FEATURE_LFENCE_RDTSC))
-			entry->eax |= BIT(2);
-		if (!static_cpu_has_bug(X86_BUG_NULL_SEG))
-			entry->eax |= BIT(6);
+		cpuid_entry_override(entry, CPUID_8000_0021_EAX);
 		break;
 	/*Add support for Centaur's CPUID instruction*/
 	case 0xC0000000:
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 4e5b8444f161..184614e27d5b 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_0021_EAX,
 	NR_KVM_CPU_CAPS,
 
 	NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
@@ -25,6 +26,11 @@ 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)
 
+/* AMD-defined Extended Feature 2 EAX, CPUID level 0x80000021 (EAX) */
+#define KVM_X86_FEATURE_NO_NESTED_DATA_BP	KVM_X86_FEATURE(CPUID_8000_0021_EAX, 0)
+#define KVM_X86_FEATURE_LFENCE_RDTSC		KVM_X86_FEATURE(CPUID_8000_0021_EAX, 2)
+#define KVM_X86_FEATURE_NULL_SEL_CLR_BASE	KVM_X86_FEATURE(CPUID_8000_0021_EAX, 6)
+
 struct cpuid_reg {
 	u32 function;
 	u32 index;
@@ -49,6 +55,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
 	[CPUID_7_1_EAX]       = {         7, 1, CPUID_EAX},
 	[CPUID_12_EAX]        = {0x00000012, 0, CPUID_EAX},
 	[CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
+	[CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
 };
 
 /*
@@ -75,12 +82,15 @@ static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
  */
 static __always_inline u32 __feature_translate(int x86_feature)
 {
-	if (x86_feature == X86_FEATURE_SGX1)
-		return KVM_X86_FEATURE_SGX1;
-	else if (x86_feature == X86_FEATURE_SGX2)
-		return KVM_X86_FEATURE_SGX2;
-	else if (x86_feature == X86_FEATURE_SGX_EDECCSSA)
-		return KVM_X86_FEATURE_SGX_EDECCSSA;
+	switch (x86_feature) {
+	case X86_FEATURE_SGX1:			return KVM_X86_FEATURE_SGX1;
+	case X86_FEATURE_SGX2:			return KVM_X86_FEATURE_SGX2;
+	case X86_FEATURE_SGX_EDECCSSA:		return KVM_X86_FEATURE_SGX_EDECCSSA;
+	case X86_FEATURE_NO_NESTED_DATA_BP:	return KVM_X86_FEATURE_NO_NESTED_DATA_BP;
+	case X86_FEATURE_LFENCE_RDTSC:		return KVM_X86_FEATURE_LFENCE_RDTSC;
+	case X86_FEATURE_NULL_SEL_CLR_BASE:	return KVM_X86_FEATURE_NULL_SEL_CLR_BASE;
+	default: break;
+	}
 
 	return x86_feature;
 }
-- 
2.34.1