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