x86: use cpuid vector 0xb when available for detecting cpu topology
cpuid leaf 0xb provides extended topology enumeration. This interface provides
the 32-bit x2APIC id of the logical processor and it also provides a new
mechanism to detect SMT and core siblings (which provides increased
addressability).
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 77618c7..58a6f1a 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -176,9 +176,16 @@
if (p)
strcpy(c->x86_model_id, p);
- c->x86_max_cores = num_cpu_cores(c);
+ detect_extended_topology(c);
- detect_ht(c);
+ if (!cpu_has(c, X86_FEATURE_XTOPOLOGY)) {
+ /*
+ * let's use the legacy cpuid vector 0x1 and 0x4 for topology
+ * detection.
+ */
+ c->x86_max_cores = num_cpu_cores(c);
+ detect_ht(c);
+ }
/* Work around errata */
Intel_errata_workarounds(c);