linux-kernel - [PATCH v2 2/5] x86/amd: add accessor for number of cores per compute unit

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Date:	Thu, 14 Jan 2016 10:50:05 +0800
From:	Huang Rui <ray.huang@....com>
To:	Borislav Petkov <bp@...e.de>,
	Peter Zijlstra <peterz@...radead.org>,
	"Ingo Molnar" <mingo@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	Robert Richter <rric@...nel.org>,
	Jacob Shin <jacob.w.shin@...il.com>,
	John Stultz <john.stultz@...aro.org>,
	Frédéric Weisbecker <fweisbec@...il.com>
CC:	<linux-kernel@...r.kernel.org>, <spg_linux_kernel@....com>,
	<x86@...nel.org>, Guenter Roeck <linux@...ck-us.net>,
	Andreas Herrmann <herrmann.der.user@...glemail.com>,
	Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>,
	Borislav Petkov <bp@...en8.de>,
	"Fengguang Wu" <fengguang.wu@...el.com>,
	Aaron Lu <aaron.lu@...el.com>, Huang Rui <ray.huang@....com>
Subject: [PATCH v2 2/5] x86/amd: add accessor for number of cores per compute unit

Add an accessor function amd_get_cores_per_cu() which returns the
number of cores per compute unit.

In a subsequent patch, we will use this function in both x86 perf and
fam15h driver.

Signed-off-by: Huang Rui <ray.huang@....com>
Cc: Guenter Roeck <linux@...ck-us.net>
---
 arch/x86/include/asm/processor.h |  1 +
 arch/x86/kernel/cpu/amd.c        | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6752225..9bf48b2 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 97db1b6..d6e320f 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();
 
@@ -313,7 +315,6 @@ 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;
 
@@ -391,6 +392,13 @@ 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
@@ -523,10 +531,11 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 		use_mwaitx_delay();
 
 	if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
-		u32 ecx;
+		u32 eax, ebx, ecx, edx;
 
-		ecx = cpuid_ecx(0x8000001e);
+		cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
 		nodes_per_socket = ((ecx >> 8) & 7) + 1;
+		cores_per_cu = ((ebx >> 8) & 3) + 1;
 	} else if (boot_cpu_has(X86_FEATURE_NODEID_MSR)) {
 		u64 value;
 
-- 
1.9.1