[v5,5/7] x86/cpu: Define a scattered AMD Automatic IBRS feature bit

Commit Message

Kim Phillips Dec. 5, 2022, 11:32 p.m. UTC

It's bit 8 of the hardware CPUID 0x80000021 EAX leaf.

Signed-off-by: Kim Phillips <[e-mail]>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/scattered.c    | 1 +
 2 files changed, 2 insertions(+)

Patch

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 5ddde18c1ae8..961eb49532b7 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -309,6 +309,7 @@ 
 #define X86_FEATURE_MSR_TSX_CTRL	(11*32+20) /* "" MSR IA32_TSX_CTRL (Intel) implemented */
 #define X86_FEATURE_NO_NESTED_DATA_BP	(11*32+21) /* "" AMD No Nested Data Breakpoints */
 #define X86_FEATURE_NULL_SEL_CLR_BASE	(11*32+22) /* "" AMD Null Selector Clears Base */
+#define X86_FEATURE_AUTOIBRS		(11*32+23) /* AMD Automatic IBRS */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index caa03466cd9e..7ae7203cd410 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -48,6 +48,7 @@  static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_NO_NESTED_DATA_BP,CPUID_EAX,  0, 0x80000021, 0 },
 	{ X86_FEATURE_LFENCE_RDTSC,	CPUID_EAX,  2, 0x80000021, 0 },
 	{ X86_FEATURE_NULL_SEL_CLR_BASE,CPUID_EAX,  6, 0x80000021, 0 },
+	{ X86_FEATURE_AUTOIBRS,		CPUID_EAX,  8, 0x80000021, 0 },
 	{ X86_FEATURE_PERFMON_V2,	CPUID_EAX,  0, 0x80000022, 0 },
 	{ X86_FEATURE_AMD_LBR_V2,	CPUID_EAX,  1, 0x80000022, 0 },
 	{ 0, 0, 0, 0, 0 }