1// SPDX-License-Identifier: GPL-2.0
2#include <linux/cpu.h>
3
4#include <asm/apic.h>
5#include <asm/memtype.h>
6#include <asm/processor.h>
7
8#include "cpu.h"
9
10enum topo_types {
11 INVALID_TYPE = 0,
12 SMT_TYPE = 1,
13 CORE_TYPE = 2,
14 MAX_TYPE_0B = 3,
15 MODULE_TYPE = 3,
16 AMD_CCD_TYPE = 3,
17 TILE_TYPE = 4,
18 AMD_SOCKET_TYPE = 4,
19 MAX_TYPE_80000026 = 5,
20 DIE_TYPE = 5,
21 DIEGRP_TYPE = 6,
22 MAX_TYPE_1F = 7,
23};
24
25/*
26 * Use a lookup table for the case that there are future types > 6 which
27 * describe an intermediate domain level which does not exist today.
28 */
29static const unsigned int topo_domain_map_0b_1f[MAX_TYPE_1F] = {
30 [SMT_TYPE] = TOPO_SMT_DOMAIN,
31 [CORE_TYPE] = TOPO_CORE_DOMAIN,
32 [MODULE_TYPE] = TOPO_MODULE_DOMAIN,
33 [TILE_TYPE] = TOPO_TILE_DOMAIN,
34 [DIE_TYPE] = TOPO_DIE_DOMAIN,
35 [DIEGRP_TYPE] = TOPO_DIEGRP_DOMAIN,
36};
37
38static const unsigned int topo_domain_map_80000026[MAX_TYPE_80000026] = {
39 [SMT_TYPE] = TOPO_SMT_DOMAIN,
40 [CORE_TYPE] = TOPO_CORE_DOMAIN,
41 [AMD_CCD_TYPE] = TOPO_TILE_DOMAIN,
42 [AMD_SOCKET_TYPE] = TOPO_DIE_DOMAIN,
43};
44
45static inline bool topo_subleaf(struct topo_scan *tscan, u32 leaf, u32 subleaf,
46 unsigned int *last_dom)
47{
48 unsigned int dom, maxtype;
49 const unsigned int *map;
50 struct {
51 // eax
52 u32 x2apic_shift : 5, // Number of bits to shift APIC ID right
53 // for the topology ID at the next level
54 : 27; // Reserved
55 // ebx
56 u32 num_processors : 16, // Number of processors at current level
57 : 16; // Reserved
58 // ecx
59 u32 level : 8, // Current topology level. Same as sub leaf number
60 type : 8, // Level type. If 0, invalid
61 : 16; // Reserved
62 // edx
63 u32 x2apic_id : 32; // X2APIC ID of the current logical processor
64 } sl;
65
66 switch (leaf) {
67 case 0x0b: maxtype = MAX_TYPE_0B; map = topo_domain_map_0b_1f; break;
68 case 0x1f: maxtype = MAX_TYPE_1F; map = topo_domain_map_0b_1f; break;
69 case 0x80000026: maxtype = MAX_TYPE_80000026; map = topo_domain_map_80000026; break;
70 default: return false;
71 }
72
73 cpuid_subleaf(leaf, subleaf, &sl);
74
75 if (!sl.num_processors || sl.type == INVALID_TYPE)
76 return false;
77
78 if (sl.type >= maxtype) {
79 pr_err_once("Topology: leaf 0x%x:%d Unknown domain type %u\n",
80 leaf, subleaf, sl.type);
81 /*
82 * It really would have been too obvious to make the domain
83 * type space sparse and leave a few reserved types between
84 * the points which might change instead of following the
85 * usual "this can be fixed in software" principle.
86 */
87 dom = *last_dom + 1;
88 } else {
89 dom = map[sl.type];
90 *last_dom = dom;
91 }
92
93 if (!dom) {
94 tscan->c->topo.initial_apicid = sl.x2apic_id;
95 } else if (tscan->c->topo.initial_apicid != sl.x2apic_id) {
96 pr_warn_once(FW_BUG "CPUID leaf 0x%x subleaf %d APIC ID mismatch %x != %x\n",
97 leaf, subleaf, tscan->c->topo.initial_apicid, sl.x2apic_id);
98 }
99
100 topology_set_dom(tscan, dom, shift: sl.x2apic_shift, ncpus: sl.num_processors);
101 return true;
102}
103
104static bool parse_topology_leaf(struct topo_scan *tscan, u32 leaf)
105{
106 unsigned int last_dom;
107 u32 subleaf;
108
109 /* Read all available subleafs and populate the levels */
110 for (subleaf = 0, last_dom = 0; topo_subleaf(tscan, leaf, subleaf, last_dom: &last_dom); subleaf++);
111
112 /* If subleaf 0 failed to parse, give up */
113 if (!subleaf)
114 return false;
115
116 /*
117 * There are machines in the wild which have shift 0 in the subleaf
118 * 0, but advertise 2 logical processors at that level. They are
119 * truly SMT.
120 */
121 if (!tscan->dom_shifts[TOPO_SMT_DOMAIN] && tscan->dom_ncpus[TOPO_SMT_DOMAIN] > 1) {
122 unsigned int sft = get_count_order(count: tscan->dom_ncpus[TOPO_SMT_DOMAIN]);
123
124 pr_warn_once(FW_BUG "CPUID leaf 0x%x subleaf 0 has shift level 0 but %u CPUs. Fixing it up.\n",
125 leaf, tscan->dom_ncpus[TOPO_SMT_DOMAIN]);
126 topology_update_dom(tscan, dom: TOPO_SMT_DOMAIN, shift: sft, ncpus: tscan->dom_ncpus[TOPO_SMT_DOMAIN]);
127 }
128
129 set_cpu_cap(tscan->c, X86_FEATURE_XTOPOLOGY);
130 return true;
131}
132
133bool cpu_parse_topology_ext(struct topo_scan *tscan)
134{
135 /* Intel: Try leaf 0x1F first. */
136 if (tscan->c->cpuid_level >= 0x1f && parse_topology_leaf(tscan, leaf: 0x1f))
137 return true;
138
139 /* AMD: Try leaf 0x80000026 first. */
140 if (tscan->c->extended_cpuid_level >= 0x80000026 && parse_topology_leaf(tscan, leaf: 0x80000026))
141 return true;
142
143 /* Intel/AMD: Fall back to leaf 0xB if available */
144 return tscan->c->cpuid_level >= 0x0b && parse_topology_leaf(tscan, leaf: 0x0b);
145}
146

source code of linux/arch/x86/kernel/cpu/topology_ext.c