x86/cpu/topology: Provide detect_extended_topology_early()

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>

diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 898da0b974e217041467b00a93f72525d7841491..e59c0ea82a33ac5eda46b0f012cbc9b3dbd95def 100644 (file)
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -55,6 +55,7 @@ extern void init_intel_cacheinfo(struct cpuinfo_x86 *c);
 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 1072b5eda607764f57970cbfcae627372a1ab82d..71ca064e379488f072468f0d3bc57a37beec7855 100644 (file)
--- 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 @@ int detect_extended_topology(struct cpuinfo_x86 *c)
         * 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);