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

Perry Yuan
2024-06-17T07:00:45Z

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 }
};

--
2.34.1