linux-kernel - [PATCH v4 03/13] x86/cpufeatures: add X86_FEATURE_WORKLOAD

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Message-ID: <20241021180252.3531-4-mario.limonciello@amd.com>
Date: Mon, 21 Oct 2024 13:02:42 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Borislav Petkov <bp@...en8.de>, Hans de Goede <hdegoede@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC: <x86@...nel.org>, "Gautham R . Shenoy" <gautham.shenoy@....com>, "Mario
 Limonciello" <mario.limonciello@....com>, Perry Yuan <perry.yuan@....com>,
	<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<linux-pm@...r.kernel.org>, <platform-driver-x86@...r.kernel.org>, "Shyam
 Sundar S K" <Shyam-sundar.S-k@....com>
Subject: [PATCH v4 03/13] x86/cpufeatures: add X86_FEATURE_WORKLOAD_CLASS feature bit

From: Perry Yuan <perry.yuan@....com>

Add new feature bit that indicates support for workload based
heuristic feedback to OS for scheduling decisions.
When the bit set, threads are classified during runtime into
enumerated classes. The classes represent thread performance/power
characteristics that may benefit from special scheduling behaviors.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>
Signed-off-by: Perry Yuan <perry.yuan@....com>
Signed-off-by: Mario Limonciello <mario.limonciello@....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 7f6c9fc465293..360bbfe8dd44f 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -474,6 +474,7 @@
 #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 */
+#define X86_FEATURE_AMD_WORKLOAD_CLASS	(21*32 + 7) /* Workload Classification */
 
 /*
  * BUG word(s)
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 307a917415343..1e54332594443 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -49,6 +49,7 @@ static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_MBA,		CPUID_EBX,  6, 0x80000008, 0 },
 	{ X86_FEATURE_SMBA,		CPUID_EBX,  2, 0x80000020, 0 },
 	{ X86_FEATURE_BMEC,		CPUID_EBX,  3, 0x80000020, 0 },
+	{ X86_FEATURE_AMD_WORKLOAD_CLASS,	CPUID_EAX,  22, 0x80000021, 0 },
 	{ 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 },
-- 
2.43.0