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