arch/x86/kernel/cpu/topology.c

   1 /*
   2  * Check for extended topology enumeration cpuid leaf 0xb and if it
   3  * exists, use it for populating initial_apicid and cpu topology
   4  * detection.
   5  */
   6
   7 #include <linux/cpu.h>
   8 #include <asm/apic.h>
   9 #include <asm/pat.h>
  10 #include <asm/processor.h>
  11
  12 /* leaf 0xb SMT level */
  13 #define SMT_LEVEL       0
  14
  15 /* leaf 0xb sub-leaf types */
  16 #define INVALID_TYPE    0
  17 #define SMT_TYPE        1
  18 #define CORE_TYPE       2
  19
  20 #define LEAFB_SUBTYPE(ecx)              (((ecx) >> 8) & 0xff)
  21 #define BITS_SHIFT_NEXT_LEVEL(eax)      ((eax) & 0x1f)
  22 #define LEVEL_MAX_SIBLINGS(ebx)         ((ebx) & 0xffff)
  23
  24 /*
  25  * Check for extended topology enumeration cpuid leaf 0xb and if it
  26  * exists, use it for populating initial_apicid and cpu topology
  27  * detection.
  28  */
  29 void __cpuinit detect_extended_topology(struct cpuinfo_x86 *c)
  30 {
  31 #ifdef CONFIG_SMP
  32         unsigned int eax, ebx, ecx, edx, sub_index;
  33         unsigned int ht_mask_width, core_plus_mask_width;
  34         unsigned int core_select_mask, core_level_siblings;
  35         static bool printed;
  36
  37         if (c->cpuid_level < 0xb)
  38                 return;
  39
  40         cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
  41
  42         /*
  43          * check if the cpuid leaf 0xb is actually implemented.
  44          */
  45         if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
  46                 return;
  47
  48         set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
  49
  50         /*
  51          * initial apic id, which also represents 32-bit extended x2apic id.
  52          */
  53         c->initial_apicid = edx;
  54
  55         /*
  56          * Populate HT related information from sub-leaf level 0.
  57          */
  58         core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
  59         core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
  60
  61         sub_index = 1;
  62         do {
  63                 cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);
  64
  65                 /*
  66                  * Check for the Core type in the implemented sub leaves.
  67                  */
  68                 if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
  69                         core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
  70                         core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
  71                         break;
  72                 }
  73
  74                 sub_index++;
  75         } while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);
  76
  77         core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;
  78
  79         c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, ht_mask_width)
  80                                                  & core_select_mask;
  81         c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, core_plus_mask_width);
  82         /*
  83          * Reinit the apicid, now that we have extended initial_apicid.
  84          */
  85         c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
  86
  87         c->x86_max_cores = (core_level_siblings / smp_num_siblings);
  88
  89         if (!printed) {
  90                 printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
  91                        c->phys_proc_id);
  92                 if (c->x86_max_cores > 1)
  93                         printk(KERN_INFO  "CPU: Processor Core ID: %d\n",
  94                                c->cpu_core_id);
  95                 printed = 1;
  96         }
  97         return;
  98 #endif
  99 }