[PATCH v2 04/10] x86, amd: add accessor for number of cores per compute unit

[Huang Rui]

Add an accessor function amd_get_cores_per_cu() which returns the
number of cores per compute unit. In multiple CPUs, they always have
the same number of cores per compute unit.

In a subsequent patch, we will use this function in fam15h_power
driver.

Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/processor.h |  1 +
 arch/x86/kernel/cpu/amd.c        | 19 +++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 19577dd..831ad682 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -810,6 +810,7 @@ static inline int mpx_disable_management(void)
 
 extern u16 amd_get_nb_id(int cpu);
 extern u32 amd_get_nodes_per_socket(void);
+extern u32 amd_get_cores_per_cu(void);
 
 static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
 {
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 4a70fc6..a914b1b 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -27,6 +27,9 @@
  */
 static u32 nodes_per_socket = 1;
 
+/* cores_per_cu: stores the number of cores per compute unit */
+static u32 cores_per_cu = 1;
+
 static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
 {
 	u32 gprs[8] = { 0 };
@@ -299,7 +302,6 @@ static int nearby_node(int apicid)
 #ifdef CONFIG_SMP
 static void amd_get_topology(struct cpuinfo_x86 *c)
 {
-	u32 cores_per_cu = 1;
 	u8 node_id;
 	int cpu = smp_processor_id();
 
@@ -314,7 +316,6 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
 		/* get compute unit information */
 		smp_num_siblings = ((ebx >> 8) & 3) + 1;
 		c->compute_unit_id = ebx & 0xff;
-		cores_per_cu += ((ebx >> 8) & 3);
 	} else if (cpu_has(c, X86_FEATURE_NODEID_MSR)) {
 		u64 value;
 
@@ -380,6 +381,13 @@ u32 amd_get_nodes_per_socket(void)
 }
 EXPORT_SYMBOL_GPL(amd_get_nodes_per_socket);
 
+/* this function returns the number of cores per compute unit */
+u32 amd_get_cores_per_cu(void)
+{
+	return cores_per_cu;
+}
+EXPORT_SYMBOL_GPL(amd_get_cores_per_cu);
+
 static void srat_detect_node(struct cpuinfo_x86 *c)
 {
 #ifdef CONFIG_NUMA
@@ -510,6 +518,13 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 
 	if (cpu_has(c, X86_FEATURE_MWAITX))
 		use_mwaitx_delay();
+
+	if (cpu_has_topoext) {
+		u32 cpuid;
+
+		cpuid = cpuid_ebx(0x8000001e);
+		cores_per_cu += ((cpuid >> 8) & 3);
+	}
 }
 
 static void early_init_amd(struct cpuinfo_x86 *c)
-- 
1.9.1

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