[PATCH v12 1/5] x86/cpufeatures: Add X86_FEATURE_RMPOPT feature flag

From: Ashish Kalra <[email protected]>

Add a flag indicating whether RMPOPT instruction is supported.

RMPOPT is a new instruction that reduces the performance overhead of RMP
checks for the hypervisor and non-SNP guests by allowing those checks to be
skipped when 1-GB memory regions are known to contain no SEV-SNP guest memory.

For more information on the RMPOPT instruction, see the AMD64 RMPOPT
technical documentation.

  [ bp: Zap respective tools/ change. ]

Suggested-by: Borislav Petkov (AMD) <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Reviewed-by: Dave Hansen <[email protected]>
Reviewed-by: Ackerley Tng <[email protected]>
Link: https://patch.msgid.link/39e9ee269a572c516a3f4e937bfe12d00697d5e6.1782841284.git.ashish.kalra@amd.com
---
 arch/x86/include/asm/cpufeatures.h | 2 +-
 arch/x86/kernel/cpu/scattered.c    | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 3d0940a3b9f3..dbccde9ee5cd 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -76,7 +76,7 @@
 #define X86_FEATURE_K8			( 3*32+ 4) /* Opteron, Athlon64 */
 #define X86_FEATURE_ZEN5		( 3*32+ 5) /* CPU based on Zen5 microarchitecture */
 #define X86_FEATURE_ZEN6		( 3*32+ 6) /* CPU based on Zen6 microarchitecture */
-/* Free                                 ( 3*32+ 7) */
+#define X86_FEATURE_RMPOPT		( 3*32+ 7) /* Support for AMD RMPOPT instruction */
 #define X86_FEATURE_CONSTANT_TSC	( 3*32+ 8) /* "constant_tsc" TSC ticks at a constant rate */
 /* free: was #define X86_FEATURE_UP	( 3*32+ 9) * "up" SMP kernel running on UP */
 #define X86_FEATURE_ART			( 3*32+10) /* "art" Always running timer (ART) */
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 937129ce6a96..021c0bf22de2 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -67,6 +67,7 @@ static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_PERFMON_V2,		CPUID_EAX,  0, 0x80000022, 0 },
 	{ X86_FEATURE_AMD_LBR_V2,		CPUID_EAX,  1, 0x80000022, 0 },
 	{ X86_FEATURE_AMD_LBR_PMC_FREEZE,	CPUID_EAX,  2, 0x80000022, 0 },
+	{ X86_FEATURE_RMPOPT,			CPUID_EDX,  0, 0x80000025, 0 },
 	{ X86_FEATURE_AMD_HTR_CORES,		CPUID_EAX, 30, 0x80000026, 0 },
 	{ 0, 0, 0, 0, 0 }
 };
-- 
2.43.0