[PATCH v14 1/5] x86/cpufeatures: Add X86_FEATURE_RMPOPT feature flag
From: Ashish Kalra <Ashish.Kalra@amd.com>
Date: 2026-09-10 21:59:36
Also in:
kvm, linux-crypto, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Ashish Kalra <ashish.kalra@amd.com> 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@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Ackerley Tng <redacted> 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 f70ee74b5f92..3b5b32d3391b 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 8665a6474806..d1795ce219da 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