[PATCH] KVM: x86: Remove AMX-TF32 enumeration

[PATCH] KVM: x86: Remove AMX-TF32 enumeration

[Chang S. Bae]

AMX-TF32 enumeration was added based on the Intel documentation [1]. The
recent update removed the feature, indicating that the feature is no
longer planned for hardware implementation.

[1] Intel Architecture Instruction Set Extensions and Future Features

Cc: Zhao Liu <zhao1.liu@intel.com>
Cc: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
---
Note: The feature first appeared in the September 2025 revision of the
document and was removed in the June 2026 revision.
---
 arch/x86/kvm/cpuid.c         | 1 -
 arch/x86/kvm/reverse_cpuid.h | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 591d2294acd7..759a1c557080 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1082,7 +1082,6 @@ void kvm_initialize_cpu_caps(void)
 		F(AMX_COMPLEX_ALIAS),
 		F(AMX_FP16_ALIAS),
 		F(AMX_FP8),
-		F(AMX_TF32),
 		F(AMX_AVX512),
 		F(AMX_MOVRS),
 	);
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 2ad25781cefb..1bb13903c5b2 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -56,7 +56,6 @@
 #define X86_FEATURE_AMX_COMPLEX_ALIAS	KVM_X86_FEATURE(CPUID_1E_1_EAX, 2)
 #define X86_FEATURE_AMX_FP16_ALIAS	KVM_X86_FEATURE(CPUID_1E_1_EAX, 3)
 #define X86_FEATURE_AMX_FP8		KVM_X86_FEATURE(CPUID_1E_1_EAX, 4)
-#define X86_FEATURE_AMX_TF32		KVM_X86_FEATURE(CPUID_1E_1_EAX, 6)
 #define X86_FEATURE_AMX_AVX512		KVM_X86_FEATURE(CPUID_1E_1_EAX, 7)
 #define X86_FEATURE_AMX_MOVRS		KVM_X86_FEATURE(CPUID_1E_1_EAX, 8)
 
-- 
2.53.0

Re: [PATCH] KVM: x86: Remove AMX-TF32 enumeration

[Xiaoyao Li]

On 7/9/2026 5:01 AM, Chang S. Bae wrote:
> AMX-TF32 enumeration was added based on the Intel documentation [1]. The
> recent update removed the feature, indicating that the feature is no
> longer planned for hardware implementation.

Patch looks good to me.

BTW, I think the bit cannot be assigned for new other usage in the 
future and becomes reserved forever, right?

> [1] Intel Architecture Instruction Set Extensions and Future Features
> 
> Cc: Zhao Liu <zhao1.liu@intel.com>
> Cc: Binbin Wu <binbin.wu@linux.intel.com>
> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
> ---
> Note: The feature first appeared in the September 2025 revision of the
> document and was removed in the June 2026 revision.
> ---
>   arch/x86/kvm/cpuid.c         | 1 -
>   arch/x86/kvm/reverse_cpuid.h | 1 -
>   2 files changed, 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 591d2294acd7..759a1c557080 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -1082,7 +1082,6 @@ void kvm_initialize_cpu_caps(void)
>   		F(AMX_COMPLEX_ALIAS),
>   		F(AMX_FP16_ALIAS),
>   		F(AMX_FP8),
> -		F(AMX_TF32),
>   		F(AMX_AVX512),
>   		F(AMX_MOVRS),
>   	);
> diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
> index 2ad25781cefb..1bb13903c5b2 100644
> --- a/arch/x86/kvm/reverse_cpuid.h
> +++ b/arch/x86/kvm/reverse_cpuid.h
> @@ -56,7 +56,6 @@
>   #define X86_FEATURE_AMX_COMPLEX_ALIAS	KVM_X86_FEATURE(CPUID_1E_1_EAX, 2)
>   #define X86_FEATURE_AMX_FP16_ALIAS	KVM_X86_FEATURE(CPUID_1E_1_EAX, 3)
>   #define X86_FEATURE_AMX_FP8		KVM_X86_FEATURE(CPUID_1E_1_EAX, 4)
> -#define X86_FEATURE_AMX_TF32		KVM_X86_FEATURE(CPUID_1E_1_EAX, 6)
>   #define X86_FEATURE_AMX_AVX512		KVM_X86_FEATURE(CPUID_1E_1_EAX, 7)
>   #define X86_FEATURE_AMX_MOVRS		KVM_X86_FEATURE(CPUID_1E_1_EAX, 8)
>   

Re: [PATCH] KVM: x86: Remove AMX-TF32 enumeration

[Chang S. Bae]

On 7/8/2026 7:12 PM, Xiaoyao Li wrote:
> 
> BTW, I think the bit cannot be assigned for new other usage in the 
> future and becomes reserved forever, right?

Reserving the bit forever looks contrary to the purpose of this patch. 
Right now the bit is already taken. And shipping processors will report 
that CPUID bit as zero. So this removal intentionally makes the software 
into the "it was never defined before" state. Whether the bit will 
eventually be repurposed is what I don't know. But that being said, I 
think it should be also backported to @stable.

Thanks,
Chang

Re: [PATCH] KVM: x86: Remove AMX-TF32 enumeration

[Zhao Liu]

On Wed, Jul 08, 2026 at 09:01:18PM +0000, Chang S. Bae wrote:
> Date: Wed, 8 Jul 2026 21:01:18 +0000
> From: "Chang S. Bae" <chang.seok.bae@intel.com>
> Subject: [PATCH] KVM: x86: Remove AMX-TF32 enumeration
> X-Mailer: git-send-email 2.51.0
> 
> AMX-TF32 enumeration was added based on the Intel documentation [1]. The
> recent update removed the feature, indicating that the feature is no
> longer planned for hardware implementation.
> 
> [1] Intel Architecture Instruction Set Extensions and Future Features
> 
> Cc: Zhao Liu <zhao1.liu@intel.com>
> Cc: Binbin Wu <binbin.wu@linux.intel.com>
> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
> ---
> Note: The feature first appeared in the September 2025 revision of the
> document and was removed in the June 2026 revision.
> ---
>  arch/x86/kvm/cpuid.c         | 1 -
>  arch/x86/kvm/reverse_cpuid.h | 1 -
>  2 files changed, 2 deletions(-)

LGTM,

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>

Thanks,
Zhao

Re: [PATCH] KVM: x86: Remove AMX-TF32 enumeration

[Chang S. Bae]

On 7/9/2026 4:00 AM, Zhao Liu wrote:
> 
> Reviewed-by: Zhao Liu <zhao1.liu@intel.com>

Thanks!