x86/cpu/topology: Provide detect_extended_topology_early()
commit 95f3d39ccf7aaea79d1ffdac1c887c2e100ec1b6 upstream.
To support force disabling of SMT it's required to know the number of
thread siblings early. detect_extended_topology() cannot be called before
the APIC driver is selected, so split out the part which initializes
smp_num_siblings.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 898da0b..e59c0ea 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -55,6 +55,7 @@
extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
extern void detect_num_cpu_cores(struct cpuinfo_x86 *c);
+extern int detect_extended_topology_early(struct cpuinfo_x86 *c);
extern int detect_extended_topology(struct cpuinfo_x86 *c);
extern int detect_ht_early(struct cpuinfo_x86 *c);
extern void detect_ht(struct cpuinfo_x86 *c);
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 1072b5e..71ca064 100644
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -22,17 +22,10 @@
#define BITS_SHIFT_NEXT_LEVEL(eax) ((eax) & 0x1f)
#define LEVEL_MAX_SIBLINGS(ebx) ((ebx) & 0xffff)
-/*
- * Check for extended topology enumeration cpuid leaf 0xb and if it
- * exists, use it for populating initial_apicid and cpu topology
- * detection.
- */
-int detect_extended_topology(struct cpuinfo_x86 *c)
+int detect_extended_topology_early(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
- unsigned int eax, ebx, ecx, edx, sub_index;
- unsigned int ht_mask_width, core_plus_mask_width;
- unsigned int core_select_mask, core_level_siblings;
+ unsigned int eax, ebx, ecx, edx;
if (c->cpuid_level < 0xb)
return -1;
@@ -51,10 +44,30 @@
* initial apic id, which also represents 32-bit extended x2apic id.
*/
c->initial_apicid = edx;
+ smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
+#endif
+ return 0;
+}
+
+/*
+ * Check for extended topology enumeration cpuid leaf 0xb and if it
+ * exists, use it for populating initial_apicid and cpu topology
+ * detection.
+ */
+int detect_extended_topology(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+ unsigned int eax, ebx, ecx, edx, sub_index;
+ unsigned int ht_mask_width, core_plus_mask_width;
+ unsigned int core_select_mask, core_level_siblings;
+
+ if (detect_extended_topology_early(c) < 0)
+ return -1;
/*
* Populate HT related information from sub-leaf level 0.
*/
+ cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
