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 int detect_extended_topology_early(struct cpuinfo_x86 *c)
  30 {
  31 #ifdef CONFIG_SMP
  32         unsigned int eax, ebx, ecx, edx;
  33
  34         if (c->cpuid_level < 0xb)
  35                 return -1;
  36
  37         cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
  38
  39         /*
  40          * check if the cpuid leaf 0xb is actually implemented.
  41          */
  42         if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
  43                 return -1;
  44
  45         set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
  46
  47         /*
  48          * initial apic id, which also represents 32-bit extended x2apic id.
  49          */
  50         c->initial_apicid = edx;
  51         smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
  52 #endif
  53         return 0;
  54 }
  55
  56 /*
  57  * Check for extended topology enumeration cpuid leaf 0xb and if it
  58  * exists, use it for populating initial_apicid and cpu topology
  59  * detection.
  60  */
  61 void detect_extended_topology(struct cpuinfo_x86 *c)
  62 {
  63 #ifdef CONFIG_SMP
  64         unsigned int eax, ebx, ecx, edx, sub_index;
  65         unsigned int ht_mask_width, core_plus_mask_width;
  66         unsigned int core_select_mask, core_level_siblings;
  67
  68         if (detect_extended_topology_early(c) < 0)
  69                 return;
  70
  71         /*
  72          * Populate HT related information from sub-leaf level 0.
  73          */
  74         cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
  75         core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
  76         core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
  77
  78         sub_index = 1;
  79         do {
  80                 cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);
  81
  82                 /*
  83                  * Check for the Core type in the implemented sub leaves.
  84                  */
  85                 if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
  86                         core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
  87                         core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
  88                         break;
  89                 }
  90
  91                 sub_index++;
  92         } while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);
  93
  94         core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;
  95
  96         c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, ht_mask_width)
  97                                                  & core_select_mask;
  98         c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, core_plus_mask_width);
  99         /*
 100          * Reinit the apicid, now that we have extended initial_apicid.
 101          */
 102         c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
 103
 104         c->x86_max_cores = (core_level_siblings / smp_num_siblings);
 105 #endif
 106 }