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

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

Sourceware - libc-alpha mailing list
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

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

Sourceware - libc-alpha mailing list
On Mon, Jul 6, 2020 at 7:05 AM H.J. Lu <[hidden email]> wrote:

>
> 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
>

I checked it in.

--
H.J.