Re: [PATCH v4 08/11] x86/cpufeatures: Add feature bits for AMD heterogeneous processor

Borislav Petkov
2024-06-17T08:39:25Z

On Mon, Jun 17, 2024 at 02:59:10PM +0800, Perry Yuan wrote:
> CPUID leaf 0x80000026 advertises core types with different efficiency rankings
>
> Bit 30 indicates the heterogeneous core topology feature, if the bit
> set, it means not all instances at the current hierarchical level have
> the same core topology.
>
> For better utilization of feature words and help to identify core type,
> X86_FEATURE_HETERO_CORE_TOPOLOGY is added as a few scattered feature bits.
>
> Reference:
> See the page 119 of PPR for AMD Family 19h Model 61h B1, docID 56713
>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>
> ---
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/kernel/cpu/scattered.c | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index 6c128d463a14..eceaa0df0137 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -471,6 +471,7 @@
> #define X86_FEATURE_CLEAR_BHB_HW (21*32+ 3) /* "" BHI_DIS_S HW control enabled */
> #define X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT (21*32+ 4) /* "" Clear branch history at vmexit using SW loop */
> #define X86_FEATURE_FAST_CPPC (21*32 + 5) /* "" AMD Fast CPPC */
> +#define X86_FEATURE_HETERO_CORE_TOPOLOGY (21*32+ 6) /* "" Heterogeneous Core Topology */
>
> /*
> * BUG word(s)
> diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
> index c84c30188fdf..6b3477503dd0 100644
> --- a/arch/x86/kernel/cpu/scattered.c
> +++ b/arch/x86/kernel/cpu/scattered.c
> @@ -52,6 +52,7 @@ static const struct cpuid_bit cpuid_bits[] = {
> { X86_FEATURE_PERFMON_V2, CPUID_EAX, 0, 0x80000022, 0 },
> { X86_FEATURE_AMD_LBR_V2, CPUID_EAX, 1, 0x80000022, 0 },
> { X86_FEATURE_AMD_LBR_PMC_FREEZE, CPUID_EAX, 2, 0x80000022, 0 },
> + { X86_FEATURE_HETERO_CORE_TOPOLOGY, CPUID_EAX, 30, 0x80000026, 0 },
> { 0, 0, 0, 0, 0 }
> };
>
> --

Nacked-by: Borislav Petkov (AMD) <bp@alien8.de>

Until all review comments have been addressed:

https://lore.kernel.org/r/20240611105216.GAZmgsYC-J_yLfdupF@fat_crate.local

--
Regards/Gruss,
Boris.