[v4,2/5] x86/cpufeatures: Add feature bits for AMD heterogeneous processor

Commit Message

Mario Limonciello Oct. 25, 2024, 5:14 p.m. UTC

From: Perry Yuan <[e-mail]>

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.

This is described in the AMD64 Architecture Programmers Manual Volume
2 and 3, doc ID #25493 and #25494.

Signed-off-by: Perry Yuan <[e-mail]>
Co-developed-by: Mario Limonciello <[e-mail]>
Signed-off-by: Mario Limonciello <[e-mail]>
---
v1->v2:
 * Drop tags
 * Squash original attempt and new changes with feedback together
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/scattered.c    | 1 +
 2 files changed, 2 insertions(+)

Patch

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index aa63437a677c0..51b38bc667960 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -474,6 +474,7 @@ 
 #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_AMD_FAST_CPPC	(21*32 + 5) /* Fast CPPC */
+#define X86_FEATURE_AMD_HETEROGENEOUS_CORES	(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 1db2bb81a3847..307a917415343 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_AMD_HETEROGENEOUS_CORES,	CPUID_EAX,  30, 0x80000026, 0 },
 	{ 0, 0, 0, 0, 0 }
 };