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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * CPUID parser; for populating the system's CPUID tables.
4 */
5
6#include <linux/kernel.h>
7
8#include <asm/cpuid/api.h>
9#include <asm/processor.h>
10
11#include "cpuid_parser.h"
12
13/* Clear a single CPUID table entry */
14static void cpuid_clear(const struct cpuid_parse_entry *e, const struct cpuid_output *out)
15{
16 struct cpuid_regs *regs = out->regs;
17
18 for (int i = 0; i < e->maxcnt; i++, regs++)
19 memset(regs, 0, sizeof(*regs));
20
21 memset(out->info, 0, sizeof(*out->info));
22}
23
24/*
25 * Leaf read functions:
26 */
27
28/*
29 * Default CPUID read function
30 * Satisfies the requirements stated at 'struct cpuid_parse_entry'->read().
31 */
32static void cpuid_read_generic(const struct cpuid_parse_entry *e, const struct cpuid_output *out)
33{
34 struct cpuid_regs *regs = out->regs;
35
36 for (int i = 0; i < e->maxcnt; i++, regs++, out->info->nr_entries++)
37 cpuid_read_subleaf(e->leaf, e->subleaf + i, regs);
38}
39
40/*
41 * CPUID parser table:
42 */
43
44static const struct cpuid_parse_entry cpuid_parse_entries[] = {
45 CPUID_PARSE_ENTRIES
46};
47
48/*
49 * Leaf-independent parser code:
50 */
51
52static unsigned int cpuid_range_max_leaf(const struct cpuid_table *t, unsigned int range)
53{
54 const struct leaf_0x0_0 *l0 = __cpuid_table_subleaf(t, 0x0, 0);
55
56 switch (range) {
57 case CPUID_BASE_START: return l0 ? l0->max_std_leaf : 0;
58 default: return 0;
59 }
60}
61
62static void __cpuid_reset_table(struct cpuid_table *t, const struct cpuid_parse_entry entries[],
63 unsigned int nr_entries, unsigned int start, unsigned int end, bool fill)
64{
65 const struct cpuid_parse_entry *entry = entries;
66 unsigned int range = CPUID_RANGE(start);
67
68 for (unsigned int i = 0; i < nr_entries; i++, entry++) {
69 struct cpuid_output out = {
70 .regs = cpuid_table_regs_p(t, entry->regs_offs),
71 .info = cpuid_table_info_p(t, entry->info_offs),
72 };
73
74 if (entry->leaf < start || entry->leaf > end)
75 continue;
76
77 cpuid_clear(entry, &out);
78
79 /*
80 * Read the range's anchor leaf unconditionally so that the cached
81 * maximum valid leaf value is available for the remaining entries.
82 */
83 if (fill && (entry->leaf == range || entry->leaf <= cpuid_range_max_leaf(t, range)))
84 entry->read(entry, &out);
85 }
86}
87
88/*
89 * Zero all cached CPUID entries within [@start-@end] range. This is needed when
90 * certain operations like MSR writes induce changes to the CPU's CPUID layout.
91 */
92static void __cpuid_zero_table(struct cpuid_table *t, const struct cpuid_parse_entry entries[],
93 unsigned int nr_entries, unsigned int start, unsigned int end)
94{
95 __cpuid_reset_table(t, entries, nr_entries, start, end, false);
96}
97
98static void __cpuid_fill_table(struct cpuid_table *t, const struct cpuid_parse_entry entries[],
99 unsigned int nr_entries, unsigned int start, unsigned int end)
100{
101 __cpuid_reset_table(t, entries, nr_entries, start, end, true);
102}
103
104static void cpuid_fill_table(struct cpuid_table *t, const struct cpuid_parse_entry entries[],
105 unsigned int nr_entries)
106{
107 static const struct {
108 unsigned int start;
109 unsigned int end;
110 } ranges[] = {
111 { CPUID_BASE_START, CPUID_BASE_END },
112 };
113
114 for (unsigned int i = 0; i < ARRAY_SIZE(ranges); i++)
115 __cpuid_fill_table(t, entries, nr_entries, ranges[i].start, ranges[i].end);
116}
117
118static void __cpuid_scan_cpu_full(struct cpuinfo_x86 *c)
119{
120 unsigned int nr_entries = ARRAY_SIZE(cpuid_parse_entries);
121 struct cpuid_table *table = &c->cpuid;
122
123 cpuid_fill_table(table, cpuid_parse_entries, nr_entries);
124}
125
126static void __cpuid_scan_cpu_partial(struct cpuinfo_x86 *c, unsigned int start_leaf,
127 unsigned int end_leaf)
128{
129 unsigned int nr_entries = ARRAY_SIZE(cpuid_parse_entries);
130 struct cpuid_table *table = &c->cpuid;
131
132 __cpuid_zero_table(table, cpuid_parse_entries, nr_entries, start_leaf, end_leaf);
133 __cpuid_fill_table(table, cpuid_parse_entries, nr_entries, start_leaf, end_leaf);
134}
135
136/*
137 * Call-site APIs:
138 */
139
140/**
141 * cpuid_scan_cpu() - Populate current CPU's CPUID table
142 * @c: CPU capability structure associated with the current CPU
143 *
144 * Populate the CPUID table embedded within @c with parsed CPUID data. All CPUID
145 * instructions are invoked locally, so this must be called on the CPU associated
146 * with @c.
147 */
148void cpuid_scan_cpu(struct cpuinfo_x86 *c)
149{
150 __cpuid_scan_cpu_full(c);
151}
152
153/**
154 * cpuid_refresh_range() - Rescan a CPUID table's leaf range
155 * @c: CPU capability structure associated with the current CPU
156 * @start: Start of leaf range to be re-scanned
157 * @end: End of leaf range
158 */
159void cpuid_refresh_range(struct cpuinfo_x86 *c, u32 start, u32 end)
160{
161 if (WARN_ON_ONCE(start > end))
162 return;
163
164 if (WARN_ON_ONCE(CPUID_RANGE(start) != CPUID_RANGE(end)))
165 return;
166
167 __cpuid_scan_cpu_partial(c, start, end);
168}
169
170/**
171 * cpuid_refresh_leaf() - Rescan a CPUID table's leaf
172 * @c: CPU capability structure associated with the current CPU
173 * @leaf: Leaf to be re-scanned
174 */
175void cpuid_refresh_leaf(struct cpuinfo_x86 *c, u32 leaf)
176{
177 cpuid_refresh_range(c, leaf, leaf);
178}