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Subject[PATCH v2 2/2] x86/CPU/AMD: Derive CPU topology from CPUID Fn0xB when available
Date
Derive topology information from Extended Topology Enumeration
(CPUID Fn0x0000000B) when the information is available.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/kernel/cpu/amd.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 2c1a9f2..cdd67d1 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -327,6 +327,7 @@ static void amd_get_topology(struct cpuinfo_x86 *c)

/* get information required for multi-node processors */
if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
+ int err;
u32 eax, ebx, ecx, edx;

cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
@@ -344,6 +345,14 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
c->x86_max_cores /= smp_num_siblings;
}

+ /*
+ * In case leaf B is avaialble, use leaf B to derive
+ * topology information instead.
+ */
+ err = detect_extended_topology(c);
+ if (!err)
+ c->x86_coreid_bits = get_count_order(c->x86_max_cores);
+
cacheinfo_amd_init_llc_id(c, cpu, node_id);

} else if (cpu_has(c, X86_FEATURE_NODEID_MSR)) {
@@ -378,7 +387,6 @@ static void amd_detect_cmp(struct cpuinfo_x86 *c)
c->phys_proc_id = c->initial_apicid >> bits;
/* use socket ID also for last level cache */
per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
- amd_get_topology(c);
}

u16 amd_get_nb_id(int cpu)
@@ -823,6 +831,7 @@ static void init_amd(struct cpuinfo_x86 *c)
/* Multi core CPU? */
if (c->extended_cpuid_level >= 0x80000008) {
amd_detect_cmp(c);
+ amd_get_topology(c);
srat_detect_node(c);
}

--
2.7.4
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