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From:   Xin Li <xin3.li@intel.com>
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Subject: [PATCH v12 08/37] x86/cpufeatures: Add the cpu feature bit for FRED
Date:   Mon,  2 Oct 2023 23:24:29 -0700
Message-Id: <20231003062458.23552-9-xin3.li@intel.com>
In-Reply-To: <20231003062458.23552-1-xin3.li@intel.com>
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From: "H. Peter Anvin (Intel)" <hpa@zytor.com>

Any FRED CPU will always have the following features as its baseline:
  1) LKGS, load attributes of the GS segment but the base address into
     the IA32_KERNEL_GS_BASE MSR instead of the GS segment’s descriptor
     cache.
  2) WRMSRNS, non-serializing WRMSR for faster MSR writes.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Tested-by: Shan Kang <shan.kang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
---
 arch/x86/include/asm/cpufeatures.h       | 1 +
 arch/x86/kernel/cpu/cpuid-deps.c         | 2 ++
 tools/arch/x86/include/asm/cpufeatures.h | 1 +
 3 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 330876d34b68..57ae93dc1e52 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -321,6 +321,7 @@
 #define X86_FEATURE_FZRM		(12*32+10) /* "" Fast zero-length REP MOVSB */
 #define X86_FEATURE_FSRS		(12*32+11) /* "" Fast short REP STOSB */
 #define X86_FEATURE_FSRC		(12*32+12) /* "" Fast short REP {CMPSB,SCASB} */
+#define X86_FEATURE_FRED		(12*32+17) /* Flexible Return and Event Delivery */
 #define X86_FEATURE_LKGS		(12*32+18) /* "" Load "kernel" (userspace) GS */
 #define X86_FEATURE_WRMSRNS		(12*32+19) /* "" Non-Serializing Write to Model Specific Register instruction */
 #define X86_FEATURE_AMX_FP16		(12*32+21) /* "" AMX fp16 Support */
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index e462c1d3800a..b7174209d855 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -82,6 +82,8 @@ static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_XFD,			X86_FEATURE_XGETBV1   },
 	{ X86_FEATURE_AMX_TILE,			X86_FEATURE_XFD       },
 	{ X86_FEATURE_SHSTK,			X86_FEATURE_XSAVES    },
+	{ X86_FEATURE_FRED,			X86_FEATURE_LKGS      },
+	{ X86_FEATURE_FRED,			X86_FEATURE_WRMSRNS   },
 	{}
 };
 
diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
index 1b9d86ba5bc2..18bab7987d7f 100644
--- a/tools/arch/x86/include/asm/cpufeatures.h
+++ b/tools/arch/x86/include/asm/cpufeatures.h
@@ -317,6 +317,7 @@
 #define X86_FEATURE_FZRM		(12*32+10) /* "" Fast zero-length REP MOVSB */
 #define X86_FEATURE_FSRS		(12*32+11) /* "" Fast short REP STOSB */
 #define X86_FEATURE_FSRC		(12*32+12) /* "" Fast short REP {CMPSB,SCASB} */
+#define X86_FEATURE_FRED		(12*32+17) /* Flexible Return and Event Delivery */
 #define X86_FEATURE_LKGS		(12*32+18) /* "" Load "kernel" (userspace) GS */
 #define X86_FEATURE_WRMSRNS		(12*32+19) /* "" Non-Serializing Write to Model Specific Register instruction */
 #define X86_FEATURE_AMX_FP16		(12*32+21) /* "" AMX fp16 Support */
-- 
2.34.1