arch/x86/kernel/cpu/topology.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Check for extended topology enumeration cpuid leaf 0xb and if it
   4  * exists, use it for populating initial_apicid and cpu topology
   5  * detection.
   6  */
   7
   8 #include <linux/cpu.h>
   9 #include <asm/apic.h>
  10 #include <asm/pat.h>
  11 #include <asm/processor.h>
  12
  13 /* leaf 0xb SMT level */
  14 #define SMT_LEVEL       0
  15
  16 /* leaf 0xb sub-leaf types */
  17 #define INVALID_TYPE    0
  18 #define SMT_TYPE        1
  19 #define CORE_TYPE       2
  20
  21 #define LEAFB_SUBTYPE(ecx)              (((ecx) >> 8) & 0xff)
  22 #define BITS_SHIFT_NEXT_LEVEL(eax)      ((eax) & 0x1f)
  23 #define LEVEL_MAX_SIBLINGS(ebx)         ((ebx) & 0xffff)
  24
  25 /*
  26  * Check for extended topology enumeration cpuid leaf 0xb and if it
  27  * exists, use it for populating initial_apicid and cpu topology
  28  * detection.
  29  */
  30 int detect_extended_topology_early(struct cpuinfo_x86 *c)
  31 {
  32 #ifdef CONFIG_SMP
  33         unsigned int eax, ebx, ecx, edx;
  34
  35         if (c->cpuid_level < 0xb)
  36                 return -1;
  37
  38         cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
  39
  40         /*
  41          * check if the cpuid leaf 0xb is actually implemented.
  42          */
  43         if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
  44                 return -1;
  45
  46         set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
  47
  48         /*
  49          * initial apic id, which also represents 32-bit extended x2apic id.
  50          */
  51         c->initial_apicid = edx;
  52         smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
  53 #endif
  54         return 0;
  55 }
  56
  57 /*
  58  * Check for extended topology enumeration cpuid leaf 0xb and if it
  59  * exists, use it for populating initial_apicid and cpu topology
  60  * detection.
  61  */
  62 void detect_extended_topology(struct cpuinfo_x86 *c)
  63 {
  64 #ifdef CONFIG_SMP
  65         unsigned int eax, ebx, ecx, edx, sub_index;
  66         unsigned int ht_mask_width, core_plus_mask_width;
  67         unsigned int core_select_mask, core_level_siblings;
  68
  69         if (detect_extended_topology_early(c) < 0)
  70                 return;
  71
  72         /*
  73          * Populate HT related information from sub-leaf level 0.
  74          */
  75         cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
  76         core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
  77         core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
  78
  79         sub_index = 1;
  80         do {
  81                 cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);
  82
  83                 /*
  84                  * Check for the Core type in the implemented sub leaves.
  85                  */
  86                 if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
  87                         core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
  88                         core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
  89                         break;
  90                 }
  91
  92                 sub_index++;
  93         } while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);
  94
  95         core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;
  96
  97         c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, ht_mask_width)
  98                                                  & core_select_mask;
  99         c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, core_plus_mask_width);
 100         /*
 101          * Reinit the apicid, now that we have extended initial_apicid.
 102          */
 103         c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
 104
 105         c->x86_max_cores = (core_level_siblings / smp_num_siblings);
 106 #endif
 107 }