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Subject[PATCH 2/4] x86/amd: add accessor for number of cores per compute unit
Date
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@amd.com>
---
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


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