linux-kernel - [Patch v2 2/4] x86/cpu/intel: Define helper to get CPU core native ID

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Message-Id: <20240819145543.1833126-3-dapeng1.mi@linux.intel.com>
Date: Mon, 19 Aug 2024 14:55:41 +0000
From: Dapeng Mi <dapeng1.mi@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Kan Liang <kan.liang@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
	Andi Kleen <ak@...ux.intel.com>,
	Yongwei Ma <yongwei.ma@...el.com>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	Dapeng Mi <dapeng1.mi@...el.com>,
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: [Patch v2 2/4] x86/cpu/intel: Define helper to get CPU core native ID

Define helper get_this_hybrid_cpu_native_id() to return the CPU core
native ID. This core native ID combining with core type can be used to
figure out the CPU core uarch uniquely.

Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Tested-by: Yongwei Ma <yongwei.ma@...el.com>
---
 arch/x86/include/asm/cpu.h  |  6 ++++++
 arch/x86/kernel/cpu/intel.c | 15 +++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index aa30fd8cad7f..5af69b5be2fb 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -32,6 +32,7 @@ extern bool handle_user_split_lock(struct pt_regs *regs, long error_code);
 extern bool handle_guest_split_lock(unsigned long ip);
 extern void handle_bus_lock(struct pt_regs *regs);
 u8 get_this_hybrid_cpu_type(void);
+u32 get_this_hybrid_cpu_native_id(void);
 #else
 static inline void __init sld_setup(struct cpuinfo_x86 *c) {}
 static inline bool handle_user_split_lock(struct pt_regs *regs, long error_code)
@@ -50,6 +51,11 @@ static inline u8 get_this_hybrid_cpu_type(void)
 {
 	return 0;
 }
+
+static inline u32 get_this_hybrid_cpu_native_id(void)
+{
+	return 0;
+}
 #endif
 #ifdef CONFIG_IA32_FEAT_CTL
 void init_ia32_feat_ctl(struct cpuinfo_x86 *c);
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 08b95a35b5cb..dbc457626207 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -1297,3 +1297,18 @@ u8 get_this_hybrid_cpu_type(void)
 
 	return cpuid_eax(0x0000001a) >> X86_HYBRID_CPU_TYPE_ID_SHIFT;
 }
+
+/**
+ * get_this_hybrid_cpu_native_id() - Get the native id of this hybrid CPU
+ *
+ * Returns the uarch native ID [23:0] of a CPU in a hybrid processor.
+ * If the processor is not hybrid, returns 0.
+ */
+u32 get_this_hybrid_cpu_native_id(void)
+{
+	if (!cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
+		return 0;
+
+	return cpuid_eax(0x0000001a) &
+	       (BIT_ULL(X86_HYBRID_CPU_TYPE_ID_SHIFT) - 1);
+}
-- 
2.40.1