x86, amd: Add support for CPUID topology extension of AMD CPUs

Node information (ID, number of internal nodes) is provided via
CPUID Fn8000_001e_ECX.

See AMD CPUID Specification (Publication # 25481, Revision 2.34,
September 2010).

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
LKML-Reference: <20100930123628.GD20545@loge.amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 26 insertions, 24 deletions

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 0f0ace5d7db5..7e6a37d24253 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -253,37 +253,41 @@ static int __cpuinit nearby_node(int apicid)
 #endif
 
 /*
- * Fixup core topology information for AMD multi-node processors.
- * Assumption: Number of cores in each internal node is the same.
+ * Fixup core topology information for
+ * (1) AMD multi-node processors
+ *     Assumption: Number of cores in each internal node is the same.
  */
 #ifdef CONFIG_X86_HT
-static void __cpuinit amd_fixup_dcm(struct cpuinfo_x86 *c)
+static void __cpuinit amd_get_topology(struct cpuinfo_x86 *c)
 {
-        unsigned long long value;
         u32 nodes, cores_per_node;
+        u8 node_id;
+        unsigned long long value;
         int cpu = smp_processor_id();
 
-        if (!cpu_has(c, X86_FEATURE_NODEID_MSR))
-                return;
-
-        /* fixup topology information only once for a core */
-        if (cpu_has(c, X86_FEATURE_AMD_DCM))
+        /* get information required for multi-node processors */
+        if (cpu_has(c, X86_FEATURE_TOPOEXT)) {
+                value = cpuid_ecx(0x8000001e);
+                nodes = ((value >> 8) & 7) + 1;
+                node_id = value & 7;
+        } else if (cpu_has(c, X86_FEATURE_NODEID_MSR)) {
+                rdmsrl(MSR_FAM10H_NODE_ID, value);
+                nodes = ((value >> 3) & 7) + 1;
+                node_id = value & 7;
+        } else
                 return;
 
-        rdmsrl(MSR_FAM10H_NODE_ID, value);
+        /* fixup multi-node processor information */
+        if (nodes > 1) {
+                set_cpu_cap(c, X86_FEATURE_AMD_DCM);
+                cores_per_node = c->x86_max_cores / nodes;
 
-        nodes = ((value >> 3) & 7) + 1;
-        if (nodes == 1)
-                return;
-
-        set_cpu_cap(c, X86_FEATURE_AMD_DCM);
-        cores_per_node = c->x86_max_cores / nodes;
+                /* store NodeID, use llc_shared_map to store sibling info */
+                per_cpu(cpu_llc_id, cpu) = node_id;
 
-        /* store NodeID, use llc_shared_map to store sibling info */
-        per_cpu(cpu_llc_id, cpu) = value & 7;
-
-        /* fixup core id to be in range from 0 to (cores_per_node - 1) */
-        c->cpu_core_id = c->cpu_core_id % cores_per_node;
+                /* core id to be in range from 0 to (cores_per_node - 1) */
+                c->cpu_core_id = c->cpu_core_id % cores_per_node;
+        }
 }
 #endif
 
@@ -304,9 +308,7 @@ static void __cpuinit 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;
-        /* fixup topology information on multi-node processors */
-        if ((c->x86 == 0x10) && (c->x86_model == 9))
-                amd_fixup_dcm(c);
+        amd_get_topology(c);
 #endif
 }