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/memtype.h>
  11 #include <asm/processor.h>
  12
  13 #include "cpu.h"
  14
  15 /* leaf 0xb SMT level */
  16 #define SMT_LEVEL       0
  17
  18 /* extended topology sub-leaf types */
  19 #define INVALID_TYPE    0
  20 #define SMT_TYPE        1
  21 #define CORE_TYPE       2
  22 #define DIE_TYPE        5
  23
  24 #define LEAFB_SUBTYPE(ecx)              (((ecx) >> 8) & 0xff)
  25 #define BITS_SHIFT_NEXT_LEVEL(eax)      ((eax) & 0x1f)
  26 #define LEVEL_MAX_SIBLINGS(ebx)         ((ebx) & 0xffff)
  27
  28 #ifdef CONFIG_SMP
  29 /*
  30  * Check if given CPUID extended topology "leaf" is implemented
  31  */
  32 static int check_extended_topology_leaf(int leaf)
  33 {
  34         unsigned int eax, ebx, ecx, edx;
  35
  36         cpuid_count(leaf, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
  37
  38         if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
  39                 return -1;
  40
  41         return 0;
  42 }
  43 /*
  44  * Return best CPUID Extended Topology Leaf supported
  45  */
  46 static int detect_extended_topology_leaf(struct cpuinfo_x86 *c)
  47 {
  48         if (c->cpuid_level >= 0x1f) {
  49                 if (check_extended_topology_leaf(0x1f) == 0)
  50                         return 0x1f;
  51         }
  52
  53         if (c->cpuid_level >= 0xb) {
  54                 if (check_extended_topology_leaf(0xb) == 0)
  55                         return 0xb;
  56         }
  57
  58         return -1;
  59 }
  60 #endif
  61
  62 int detect_extended_topology_early(struct cpuinfo_x86 *c)
  63 {
  64 #ifdef CONFIG_SMP
  65         unsigned int eax, ebx, ecx, edx;
  66         int leaf;
  67
  68         leaf = detect_extended_topology_leaf(c);
  69         if (leaf < 0)
  70                 return -1;
  71
  72         set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
  73
  74         cpuid_count(leaf, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
  75         /*
  76          * initial apic id, which also represents 32-bit extended x2apic id.
  77          */
  78         c->topo.initial_apicid = edx;
  79         smp_num_siblings = max_t(int, smp_num_siblings, LEVEL_MAX_SIBLINGS(ebx));
  80 #endif
  81         return 0;
  82 }
  83
  84 /*
  85  * Check for extended topology enumeration cpuid leaf, and if it
  86  * exists, use it for populating initial_apicid and cpu topology
  87  * detection.
  88  */
  89 int detect_extended_topology(struct cpuinfo_x86 *c)
  90 {
  91 #ifdef CONFIG_SMP
  92         unsigned int eax, ebx, ecx, edx, sub_index;
  93         unsigned int ht_mask_width, core_plus_mask_width, die_plus_mask_width;
  94         unsigned int core_select_mask, core_level_siblings;
  95         unsigned int die_select_mask, die_level_siblings;
  96         unsigned int pkg_mask_width;
  97         bool die_level_present = false;
  98         int leaf;
  99
 100         leaf = detect_extended_topology_leaf(c);
 101         if (leaf < 0)
 102                 return -1;
 103
 104         /*
 105          * Populate HT related information from sub-leaf level 0.
 106          */
 107         cpuid_count(leaf, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
 108         c->topo.initial_apicid = edx;
 109         core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
 110         smp_num_siblings = max_t(int, smp_num_siblings, LEVEL_MAX_SIBLINGS(ebx));
 111         core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 112         die_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
 113         pkg_mask_width = die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 114
 115         sub_index = 1;
 116         while (true) {
 117                 cpuid_count(leaf, sub_index, &eax, &ebx, &ecx, &edx);
 118
 119                 /*
 120                  * Check for the Core type in the implemented sub leaves.
 121                  */
 122                 if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
 123                         core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
 124                         core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 125                         die_level_siblings = core_level_siblings;
 126                         die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 127                 }
 128                 if (LEAFB_SUBTYPE(ecx) == DIE_TYPE) {
 129                         die_level_present = true;
 130                         die_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
 131                         die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 132                 }
 133
 134                 if (LEAFB_SUBTYPE(ecx) != INVALID_TYPE)
 135                         pkg_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 136                 else
 137                         break;
 138
 139                 sub_index++;
 140         }
 141
 142         core_select_mask = (~(-1 << pkg_mask_width)) >> ht_mask_width;
 143         die_select_mask = (~(-1 << die_plus_mask_width)) >>
 144                                 core_plus_mask_width;
 145
 146         c->topo.core_id = apic->phys_pkg_id(c->topo.initial_apicid,
 147                                 ht_mask_width) & core_select_mask;
 148
 149         if (die_level_present) {
 150                 c->topo.die_id = apic->phys_pkg_id(c->topo.initial_apicid,
 151                                         core_plus_mask_width) & die_select_mask;
 152         }
 153
 154         c->topo.pkg_id = apic->phys_pkg_id(c->topo.initial_apicid, pkg_mask_width);
 155         /*
 156          * Reinit the apicid, now that we have extended initial_apicid.
 157          */
 158         c->topo.apicid = apic->phys_pkg_id(c->topo.initial_apicid, 0);
 159
 160         c->x86_max_cores = (core_level_siblings / smp_num_siblings);
 161         __max_die_per_package = (die_level_siblings / core_level_siblings);
 162 #endif
 163         return 0;
 164 }