[PATCH] x86/cpufeatures: Make AVX512_BMM depend on AVX512F

[PATCH] x86/cpufeatures: Make AVX512_BMM depend on AVX512F

[Jim Mattson]

Add an explicit dependency between X86_FEATURE_AVX512_BMM and
X86_FEATURE_AVX512F in the CPUID dependency table.

AVX512 Bit Matrix Multiply (BMM) instructions operate on vector registers
and require AVX512 Foundation support. Declaring this dependency ensures
that if AVX512F is disabled (e.g. via clearcpuid or host capabilities),
AVX512_BMM will be automatically cleared as well.

Fixes: de0bfdc7137d ("KVM: x86: Advertise AVX512 Bit Matrix Multiply (BMM) to userspace")
Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kernel/cpu/cpuid-deps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index 99801e844b30..e9fdf944633b 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -75,6 +75,7 @@ static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_SDCIAE,			X86_FEATURE_CAT_L3    },
 	{ X86_FEATURE_AVX512_BF16,		X86_FEATURE_AVX512VL  },
 	{ X86_FEATURE_AVX512_FP16,		X86_FEATURE_AVX512BW  },
+	{ X86_FEATURE_AVX512_BMM,		X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_ENQCMD,			X86_FEATURE_XSAVES    },
 	{ X86_FEATURE_PER_THREAD_MBA,		X86_FEATURE_MBA       },
 	{ X86_FEATURE_SGX_LC,			X86_FEATURE_SGX	      },
-- 
2.55.0.141.g00534a21ce-goog

Re: [PATCH] x86/cpufeatures: Make AVX512_BMM depend on AVX512F

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Build failure due to undeclared identifier X86_FEATURE_AVX512_BMM.
--

--- Patch [1]: [PATCH] x86/cpufeatures: Make AVX512_BMM depend on AVX512F ---
commit 5ec2859f67a824ceedb01518734f6afb9a711eef
Author: Jim Mattson <jmattson@google.com>

x86/cpufeatures: Make AVX512_BMM depend on AVX512F

This commit explicitly declares a CPUID dependency for AVX512_BMM on
AVX512F so that disabling AVX512F automatically clears AVX512_BMM.

> diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
> index 146f6f8b0650b..e2e3d0a3abcd5 100644
> --- a/arch/x86/kernel/cpu/cpuid-deps.c
> +++ b/arch/x86/kernel/cpu/cpuid-deps.c
> @@ -75,6 +75,7 @@ static const struct cpuid_dep cpuid_deps[] = {
>  	{ X86_FEATURE_SDCIAE,			X86_FEATURE_CAT_L3    },
>  	{ X86_FEATURE_AVX512_BF16,		X86_FEATURE_AVX512VL  },
>  	{ X86_FEATURE_AVX512_FP16,		X86_FEATURE_AVX512BW  },
> +	{ X86_FEATURE_AVX512_BMM,		X86_FEATURE_AVX512F   },

[Severity: Low]
Is X86_FEATURE_AVX512_BMM defined anywhere in the tree? It appears this
macro is undeclared, which will cause a build failure when compiling
arch/x86/kernel/cpu/cpuid-deps.c.

>  	{ X86_FEATURE_ENQCMD,			X86_FEATURE_XSAVES    },
>  	{ X86_FEATURE_PER_THREAD_MBA,		X86_FEATURE_MBA       },
>  	{ X86_FEATURE_SGX_LC,			X86_FEATURE_SGX	      },

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260715224030.3772948-1-jmattson@google.com?part=1

Re: [PATCH] x86/cpufeatures: Make AVX512_BMM depend on AVX512F

[Nikunj A. Dadhania]

On 7/16/2026 4:10 AM, Jim Mattson wrote:
> Add an explicit dependency between X86_FEATURE_AVX512_BMM and
> X86_FEATURE_AVX512F in the CPUID dependency table.
> 
> AVX512 Bit Matrix Multiply (BMM) instructions operate on vector registers
> and require AVX512 Foundation support. Declaring this dependency ensures
> that if AVX512F is disabled (e.g. via clearcpuid or host capabilities),
> AVX512_BMM will be automatically cleared as well.
> 
> Fixes: de0bfdc7137d ("KVM: x86: Advertise AVX512 Bit Matrix Multiply (BMM) to userspace")
> Signed-off-by: Jim Mattson <jmattson@google.com>

Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>