[PATCH] x86: Detect Extended Feature Disable (XFD)

[H.J. Lu]

An extension called extended feature disable (XFD) is an extension added
for Intel AMX to the XSAVE feature set that allows an operating system
to enable a feature while preventing specific user threads from using
the feature.
---
 sysdeps/x86/cpu-features.h         | 3 +++
 sysdeps/x86/tst-get-cpu-features.c | 1 +
 2 files changed, 4 insertions(+)

diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
index f25df778cc..bc425462d6 100644
--- a/sysdeps/x86/cpu-features.h
+++ b/sysdeps/x86/cpu-features.h
@@ -393,6 +393,7 @@ extern const struct cpu_features *__get_cpu_features (void)
 #define bit_cpu_XSAVEC		(1u << 1)
 #define bit_cpu_XGETBV_ECX_1	(1u << 2)
 #define bit_cpu_XSAVES		(1u << 3)
+#define bit_cpu_XFD		(1u << 4)
 
 /* COMMON_CPUID_INDEX_80000007.  */
 
@@ -578,6 +579,7 @@ extern const struct cpu_features *__get_cpu_features (void)
 #define index_cpu_XSAVEC	COMMON_CPUID_INDEX_D_ECX_1
 #define index_cpu_XGETBV_ECX_1	COMMON_CPUID_INDEX_D_ECX_1
 #define index_cpu_XSAVES	COMMON_CPUID_INDEX_D_ECX_1
+#define index_cpu_XFD		COMMON_CPUID_INDEX_D_ECX_1
 
 /* COMMON_CPUID_INDEX_80000007.  */
 
@@ -763,6 +765,7 @@ extern const struct cpu_features *__get_cpu_features (void)
 #define reg_XSAVEC		eax
 #define reg_XGETBV_ECX_1	eax
 #define reg_XSAVES		eax
+#define reg_XFD			eax
 
 /* COMMON_CPUID_INDEX_80000007.  */
 
diff --git a/sysdeps/x86/tst-get-cpu-features.c b/sysdeps/x86/tst-get-cpu-features.c
index dafd66434c..2cff2e86ba 100644
--- a/sysdeps/x86/tst-get-cpu-features.c
+++ b/sysdeps/x86/tst-get-cpu-features.c
@@ -214,6 +214,7 @@ do_test (void)
   CHECK_CPU_FEATURE (XSAVEC);
   CHECK_CPU_FEATURE (XGETBV_ECX_1);
   CHECK_CPU_FEATURE (XSAVES);
+  CHECK_CPU_FEATURE (XFD);
   CHECK_CPU_FEATURE (INVARIANT_TSC);
   CHECK_CPU_FEATURE (WBNOINVD);
   CHECK_CPU_FEATURE (AVX512_BF16);
-- 
2.26.2