[tip: x86/sev] x86/cpufeatures: Add X86_FEATURE_RMPOPT feature flag
From: tip-bot2 for Ashish Kalra
Date: Fri Sep 18 2026 - 20:13:27 EST
The following commit has been merged into the x86/sev branch of tip:
Commit-ID: 1ee97d0f7b20e1f71bdb9edf5950c8751538180a
Gitweb: https://git.kernel.org/tip/1ee97d0f7b20e1f71bdb9edf5950c8751538180a
Author: Ashish Kalra <ashish.kalra@xxxxxxx>
AuthorDate: Mon, 10 Aug 2026 19:21:17
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Fri, 18 Sep 2026 15:50:58 -07:00
x86/cpufeatures: Add X86_FEATURE_RMPOPT feature flag
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) <bp@xxxxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Link: https://patch.msgid.link/39e9ee269a572c516a3f4e937bfe12d00697d5e6.1782841284.git.ashish.kalra@xxxxxxx
---
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 f70ee74..3b5b32d 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 8665a64..d1795ce 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 }
};