[v6,5/7] x86/cpu, kvm: Add the SMM_CTL MSR not present feature

Commit Message

Kim Phillips Jan. 10, 2023, 10:46 p.m. UTC

The SMM_CTL MSR not present feature was being open-coded for KVM in
__do_cpuid_func().  Add it to its newly added CPUID leaf 0x80000021 EAX
proper, and propagate it in kvm_set_cpu_caps() instead.

Also drop the bit description comments now the code is more
self-describing, and retain the SmmPgCfgLock and PrefetchCtlMsr feature
bit comments at the kvm_cpu_cap_mask() callsite.

Signed-off-by: Kim Phillips <[e-mail]>
---
 arch/x86/include/asm/cpufeatures.h |  1 +
 arch/x86/kvm/cpuid.c               | 13 +++----------
 2 files changed, 4 insertions(+), 10 deletions(-)

Patch

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 8237c4cc4010..da42d799d405 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -430,6 +430,7 @@ 
 #define X86_FEATURE_NO_NESTED_DATA_BP	(20*32+ 0) /* "" AMD No Nested Data Breakpoints */
 #define X86_FEATURE_LFENCE_RDTSC	(20*32+ 2) /* "" LFENCE always serializing / synchronizes RDTSC */
 #define X86_FEATURE_NULL_SEL_CLR_BASE	(20*32+ 6) /* "" AMD Null Selector Clears Base */
+#define X86_FEATURE_NO_SMM_CTL_MSR	(20*32+ 9) /* "" AMD SMM_CTL MSR is not present */
 
 /*
  * BUG word(s)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 04f2f4879d69..56f00d9cc5c5 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -742,12 +742,14 @@  void kvm_set_cpu_caps(void)
 		F(SME_COHERENT));
 
 	kvm_cpu_cap_mask(CPUID_8000_0021_EAX,
-		F(NO_NESTED_DATA_BP) | F(LFENCE_RDTSC) | F(NULL_SEL_CLR_BASE)
+		F(NO_NESTED_DATA_BP) | F(LFENCE_RDTSC) | 0 /* SmmPgCfgLock */ |
+		F(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_set(X86_FEATURE_NO_SMM_CTL_MSR);
 
 	kvm_cpu_cap_mask(CPUID_C000_0001_EDX,
 		F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |
@@ -1231,15 +1233,6 @@  static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 	case 0x80000021:
 		entry->ebx = entry->ecx = entry->edx = 0;
 		cpuid_entry_override(entry, CPUID_8000_0021_EAX);
-		/*
-		 * Other defined bits are for MSRs that KVM does not expose:
-		 *   EAX      3      SPCL, SMM page configuration lock
-		 *   EAX      13     PCMSR, Prefetch control MSR
-		 *
-		 * KVM doesn't support SMM_CTL.
-		 *   EAX       9     SMM_CTL MSR is not supported
-		 */
-		entry->eax |= BIT(9);
 		break;
 	/*Add support for Centaur's CPUID instruction*/
 	case 0xC0000000: