1// SPDX-License-Identifier: GPL-2.0
2/*
3 * x86 CPU caches detection and configuration
4 *
5 * Previous changes
6 * - Venkatesh Pallipadi: Cache identification through CPUID(0x4)
7 * - Ashok Raj <ashok.raj@intel.com>: Work with CPU hotplug infrastructure
8 * - Andi Kleen / Andreas Herrmann: CPUID(0x4) emulation on AMD
9 */
10
11#include <linux/cacheinfo.h>
12#include <linux/cpu.h>
13#include <linux/cpuhotplug.h>
14#include <linux/stop_machine.h>
15
16#include <asm/amd/nb.h>
17#include <asm/cacheinfo.h>
18#include <asm/cpufeature.h>
19#include <asm/cpuid/api.h>
20#include <asm/mtrr.h>
21#include <asm/smp.h>
22#include <asm/tlbflush.h>
23
24#include "cpu.h"
25
26/* Shared last level cache maps */
27DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
28
29/* Shared L2 cache maps */
30DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_l2c_shared_map);
31
32static cpumask_var_t cpu_cacheinfo_mask;
33
34/* Kernel controls MTRR and/or PAT MSRs. */
35unsigned int memory_caching_control __ro_after_init;
36
37enum _cache_type {
38 CTYPE_NULL = 0,
39 CTYPE_DATA = 1,
40 CTYPE_INST = 2,
41 CTYPE_UNIFIED = 3
42};
43
44union _cpuid4_leaf_eax {
45 struct {
46 enum _cache_type type :5;
47 unsigned int level :3;
48 unsigned int is_self_initializing :1;
49 unsigned int is_fully_associative :1;
50 unsigned int reserved :4;
51 unsigned int num_threads_sharing :12;
52 unsigned int num_cores_on_die :6;
53 } split;
54 u32 full;
55};
56
57union _cpuid4_leaf_ebx {
58 struct {
59 unsigned int coherency_line_size :12;
60 unsigned int physical_line_partition :10;
61 unsigned int ways_of_associativity :10;
62 } split;
63 u32 full;
64};
65
66union _cpuid4_leaf_ecx {
67 struct {
68 unsigned int number_of_sets :32;
69 } split;
70 u32 full;
71};
72
73struct _cpuid4_info {
74 union _cpuid4_leaf_eax eax;
75 union _cpuid4_leaf_ebx ebx;
76 union _cpuid4_leaf_ecx ecx;
77 unsigned int id;
78 unsigned long size;
79};
80
81/* Map CPUID(0x4) EAX.cache_type to <linux/cacheinfo.h> types */
82static const enum cache_type cache_type_map[] = {
83 [CTYPE_NULL] = CACHE_TYPE_NOCACHE,
84 [CTYPE_DATA] = CACHE_TYPE_DATA,
85 [CTYPE_INST] = CACHE_TYPE_INST,
86 [CTYPE_UNIFIED] = CACHE_TYPE_UNIFIED,
87};
88
89/*
90 * Fallback AMD CPUID(0x4) emulation
91 * AMD CPUs with TOPOEXT can just use CPUID(0x8000001d)
92 *
93 * @AMD_L2_L3_INVALID_ASSOC: cache info for the respective L2/L3 cache should
94 * be determined from CPUID(0x8000001d) instead of CPUID(0x80000006).
95 */
96
97#define AMD_CPUID4_FULLY_ASSOCIATIVE 0xffff
98#define AMD_L2_L3_INVALID_ASSOC 0x9
99
100union l1_cache {
101 struct {
102 unsigned line_size :8;
103 unsigned lines_per_tag :8;
104 unsigned assoc :8;
105 unsigned size_in_kb :8;
106 };
107 unsigned int val;
108};
109
110union l2_cache {
111 struct {
112 unsigned line_size :8;
113 unsigned lines_per_tag :4;
114 unsigned assoc :4;
115 unsigned size_in_kb :16;
116 };
117 unsigned int val;
118};
119
120union l3_cache {
121 struct {
122 unsigned line_size :8;
123 unsigned lines_per_tag :4;
124 unsigned assoc :4;
125 unsigned res :2;
126 unsigned size_encoded :14;
127 };
128 unsigned int val;
129};
130
131/* L2/L3 associativity mapping */
132static const unsigned short assocs[] = {
133 [1] = 1,
134 [2] = 2,
135 [3] = 3,
136 [4] = 4,
137 [5] = 6,
138 [6] = 8,
139 [8] = 16,
140 [0xa] = 32,
141 [0xb] = 48,
142 [0xc] = 64,
143 [0xd] = 96,
144 [0xe] = 128,
145 [0xf] = AMD_CPUID4_FULLY_ASSOCIATIVE
146};
147
148static const unsigned char levels[] = { 1, 1, 2, 3 };
149static const unsigned char types[] = { 1, 2, 3, 3 };
150
151static void legacy_amd_cpuid4(int index, union _cpuid4_leaf_eax *eax,
152 union _cpuid4_leaf_ebx *ebx, union _cpuid4_leaf_ecx *ecx)
153{
154 unsigned int dummy, line_size, lines_per_tag, assoc, size_in_kb;
155 union l1_cache l1i, l1d, *l1;
156 union l2_cache l2;
157 union l3_cache l3;
158
159 eax->full = 0;
160 ebx->full = 0;
161 ecx->full = 0;
162
163 cpuid(op: 0x80000005, eax: &dummy, ebx: &dummy, ecx: &l1d.val, edx: &l1i.val);
164 cpuid(op: 0x80000006, eax: &dummy, ebx: &dummy, ecx: &l2.val, edx: &l3.val);
165
166 l1 = &l1d;
167 switch (index) {
168 case 1:
169 l1 = &l1i;
170 fallthrough;
171 case 0:
172 if (!l1->val)
173 return;
174
175 assoc = (l1->assoc == 0xff) ? AMD_CPUID4_FULLY_ASSOCIATIVE : l1->assoc;
176 line_size = l1->line_size;
177 lines_per_tag = l1->lines_per_tag;
178 size_in_kb = l1->size_in_kb;
179 break;
180 case 2:
181 if (!l2.assoc || l2.assoc == AMD_L2_L3_INVALID_ASSOC)
182 return;
183
184 /* Use x86_cache_size as it might have K7 errata fixes */
185 assoc = assocs[l2.assoc];
186 line_size = l2.line_size;
187 lines_per_tag = l2.lines_per_tag;
188 size_in_kb = __this_cpu_read(cpu_info.x86_cache_size);
189 break;
190 case 3:
191 if (!l3.assoc || l3.assoc == AMD_L2_L3_INVALID_ASSOC)
192 return;
193
194 assoc = assocs[l3.assoc];
195 line_size = l3.line_size;
196 lines_per_tag = l3.lines_per_tag;
197 size_in_kb = l3.size_encoded * 512;
198 if (boot_cpu_has(X86_FEATURE_AMD_DCM)) {
199 size_in_kb = size_in_kb >> 1;
200 assoc = assoc >> 1;
201 }
202 break;
203 default:
204 return;
205 }
206
207 eax->split.is_self_initializing = 1;
208 eax->split.type = types[index];
209 eax->split.level = levels[index];
210 eax->split.num_threads_sharing = 0;
211 eax->split.num_cores_on_die = topology_num_cores_per_package();
212
213 if (assoc == AMD_CPUID4_FULLY_ASSOCIATIVE)
214 eax->split.is_fully_associative = 1;
215
216 ebx->split.coherency_line_size = line_size - 1;
217 ebx->split.ways_of_associativity = assoc - 1;
218 ebx->split.physical_line_partition = lines_per_tag - 1;
219 ecx->split.number_of_sets = (size_in_kb * 1024) / line_size /
220 (ebx->split.ways_of_associativity + 1) - 1;
221}
222
223static int cpuid4_info_fill_done(struct _cpuid4_info *id4, union _cpuid4_leaf_eax eax,
224 union _cpuid4_leaf_ebx ebx, union _cpuid4_leaf_ecx ecx)
225{
226 if (eax.split.type == CTYPE_NULL)
227 return -EIO;
228
229 id4->eax = eax;
230 id4->ebx = ebx;
231 id4->ecx = ecx;
232 id4->size = (ecx.split.number_of_sets + 1) *
233 (ebx.split.coherency_line_size + 1) *
234 (ebx.split.physical_line_partition + 1) *
235 (ebx.split.ways_of_associativity + 1);
236
237 return 0;
238}
239
240static int amd_fill_cpuid4_info(int index, struct _cpuid4_info *id4)
241{
242 union _cpuid4_leaf_eax eax;
243 union _cpuid4_leaf_ebx ebx;
244 union _cpuid4_leaf_ecx ecx;
245 u32 ignored;
246
247 if (boot_cpu_has(X86_FEATURE_TOPOEXT) || boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
248 cpuid_count(op: 0x8000001d, count: index, eax: &eax.full, ebx: &ebx.full, ecx: &ecx.full, edx: &ignored);
249 else
250 legacy_amd_cpuid4(index, eax: &eax, ebx: &ebx, ecx: &ecx);
251
252 return cpuid4_info_fill_done(id4, eax, ebx, ecx);
253}
254
255static int intel_fill_cpuid4_info(int index, struct _cpuid4_info *id4)
256{
257 union _cpuid4_leaf_eax eax;
258 union _cpuid4_leaf_ebx ebx;
259 union _cpuid4_leaf_ecx ecx;
260 u32 ignored;
261
262 cpuid_count(op: 4, count: index, eax: &eax.full, ebx: &ebx.full, ecx: &ecx.full, edx: &ignored);
263
264 return cpuid4_info_fill_done(id4, eax, ebx, ecx);
265}
266
267static int fill_cpuid4_info(int index, struct _cpuid4_info *id4)
268{
269 u8 cpu_vendor = boot_cpu_data.x86_vendor;
270
271 return (cpu_vendor == X86_VENDOR_AMD || cpu_vendor == X86_VENDOR_HYGON) ?
272 amd_fill_cpuid4_info(index, id4) :
273 intel_fill_cpuid4_info(index, id4);
274}
275
276static int find_num_cache_leaves(struct cpuinfo_x86 *c)
277{
278 unsigned int eax, ebx, ecx, edx, op;
279 union _cpuid4_leaf_eax cache_eax;
280 int i = -1;
281
282 /* Do a CPUID(op) loop to calculate num_cache_leaves */
283 op = (c->x86_vendor == X86_VENDOR_AMD || c->x86_vendor == X86_VENDOR_HYGON) ? 0x8000001d : 4;
284 do {
285 ++i;
286 cpuid_count(op, count: i, eax: &eax, ebx: &ebx, ecx: &ecx, edx: &edx);
287 cache_eax.full = eax;
288 } while (cache_eax.split.type != CTYPE_NULL);
289 return i;
290}
291
292/*
293 * The max shared threads number comes from CPUID(0x4) EAX[25-14] with input
294 * ECX as cache index. Then right shift apicid by the number's order to get
295 * cache id for this cache node.
296 */
297static unsigned int get_cache_id(u32 apicid, const struct _cpuid4_info *id4)
298{
299 unsigned long num_threads_sharing;
300 int index_msb;
301
302 num_threads_sharing = 1 + id4->eax.split.num_threads_sharing;
303 index_msb = get_count_order(count: num_threads_sharing);
304
305 return apicid >> index_msb;
306}
307
308/*
309 * AMD/Hygon CPUs may have multiple LLCs if L3 caches exist.
310 */
311
312void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, u16 die_id)
313{
314 if (!cpuid_amd_hygon_has_l3_cache())
315 return;
316
317 if (c->x86 < 0x17) {
318 /* Pre-Zen: LLC is at the node level */
319 c->topo.llc_id = die_id;
320 } else if (c->x86 == 0x17 && c->x86_model <= 0x1F) {
321 /*
322 * Family 17h up to 1F models: LLC is at the core
323 * complex level. Core complex ID is ApicId[3].
324 */
325 c->topo.llc_id = c->topo.apicid >> 3;
326 } else {
327 /*
328 * Newer families: LLC ID is calculated from the number
329 * of threads sharing the L3 cache.
330 */
331 u32 llc_index = find_num_cache_leaves(c) - 1;
332 struct _cpuid4_info id4 = {};
333
334 if (!amd_fill_cpuid4_info(index: llc_index, id4: &id4))
335 c->topo.llc_id = get_cache_id(apicid: c->topo.apicid, id4: &id4);
336 }
337}
338
339void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c)
340{
341 if (!cpuid_amd_hygon_has_l3_cache())
342 return;
343
344 /*
345 * Hygons are similar to AMD Family 17h up to 1F models: LLC is
346 * at the core complex level. Core complex ID is ApicId[3].
347 */
348 c->topo.llc_id = c->topo.apicid >> 3;
349}
350
351void init_amd_cacheinfo(struct cpuinfo_x86 *c)
352{
353 struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu: c->cpu_index);
354
355 if (boot_cpu_has(X86_FEATURE_TOPOEXT))
356 ci->num_leaves = find_num_cache_leaves(c);
357 else if (c->extended_cpuid_level >= 0x80000006)
358 ci->num_leaves = (cpuid_edx(op: 0x80000006) & 0xf000) ? 4 : 3;
359}
360
361void init_hygon_cacheinfo(struct cpuinfo_x86 *c)
362{
363 struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu: c->cpu_index);
364
365 ci->num_leaves = find_num_cache_leaves(c);
366}
367
368static void intel_cacheinfo_done(struct cpuinfo_x86 *c, unsigned int l3,
369 unsigned int l2, unsigned int l1i, unsigned int l1d)
370{
371 /*
372 * If llc_id is still unset, then cpuid_level < 4, which implies
373 * that the only possibility left is SMT. Since CPUID(0x2) doesn't
374 * specify any shared caches and SMT shares all caches, we can
375 * unconditionally set LLC ID to the package ID so that all
376 * threads share it.
377 */
378 if (c->topo.llc_id == BAD_APICID)
379 c->topo.llc_id = c->topo.pkg_id;
380
381 c->x86_cache_size = l3 ? l3 : (l2 ? l2 : l1i + l1d);
382
383 if (!l2)
384 cpu_detect_cache_sizes(c);
385}
386
387/*
388 * Legacy Intel CPUID(0x2) path if CPUID(0x4) is not available.
389 */
390static void intel_cacheinfo_0x2(struct cpuinfo_x86 *c)
391{
392 unsigned int l1i = 0, l1d = 0, l2 = 0, l3 = 0;
393 const struct leaf_0x2_table *desc;
394 union leaf_0x2_regs regs;
395 u8 *ptr;
396
397 if (c->cpuid_level < 2)
398 return;
399
400 cpuid_leaf_0x2(regs: &regs);
401 for_each_cpuid_0x2_desc(regs, ptr, desc) {
402 switch (desc->c_type) {
403 case CACHE_L1_INST: l1i += desc->c_size; break;
404 case CACHE_L1_DATA: l1d += desc->c_size; break;
405 case CACHE_L2: l2 += desc->c_size; break;
406 case CACHE_L3: l3 += desc->c_size; break;
407 }
408 }
409
410 intel_cacheinfo_done(c, l3, l2, l1i, l1d);
411}
412
413static unsigned int calc_cache_topo_id(struct cpuinfo_x86 *c, const struct _cpuid4_info *id4)
414{
415 unsigned int num_threads_sharing;
416 int index_msb;
417
418 num_threads_sharing = 1 + id4->eax.split.num_threads_sharing;
419 index_msb = get_count_order(count: num_threads_sharing);
420 return c->topo.apicid & ~((1 << index_msb) - 1);
421}
422
423static bool intel_cacheinfo_0x4(struct cpuinfo_x86 *c)
424{
425 struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu: c->cpu_index);
426 unsigned int l2_id = BAD_APICID, l3_id = BAD_APICID;
427 unsigned int l1d = 0, l1i = 0, l2 = 0, l3 = 0;
428
429 if (c->cpuid_level < 4)
430 return false;
431
432 /*
433 * There should be at least one leaf. A non-zero value means
434 * that the number of leaves has been previously initialized.
435 */
436 if (!ci->num_leaves)
437 ci->num_leaves = find_num_cache_leaves(c);
438
439 if (!ci->num_leaves)
440 return false;
441
442 for (int i = 0; i < ci->num_leaves; i++) {
443 struct _cpuid4_info id4 = {};
444 int ret;
445
446 ret = intel_fill_cpuid4_info(index: i, id4: &id4);
447 if (ret < 0)
448 continue;
449
450 switch (id4.eax.split.level) {
451 case 1:
452 if (id4.eax.split.type == CTYPE_DATA)
453 l1d = id4.size / 1024;
454 else if (id4.eax.split.type == CTYPE_INST)
455 l1i = id4.size / 1024;
456 break;
457 case 2:
458 l2 = id4.size / 1024;
459 l2_id = calc_cache_topo_id(c, id4: &id4);
460 break;
461 case 3:
462 l3 = id4.size / 1024;
463 l3_id = calc_cache_topo_id(c, id4: &id4);
464 break;
465 default:
466 break;
467 }
468 }
469
470 c->topo.l2c_id = l2_id;
471 c->topo.llc_id = (l3_id == BAD_APICID) ? l2_id : l3_id;
472 intel_cacheinfo_done(c, l3, l2, l1i, l1d);
473 return true;
474}
475
476void init_intel_cacheinfo(struct cpuinfo_x86 *c)
477{
478 /* Don't use CPUID(0x2) if CPUID(0x4) is supported. */
479 if (intel_cacheinfo_0x4(c))
480 return;
481
482 intel_cacheinfo_0x2(c);
483}
484
485/*
486 * <linux/cacheinfo.h> shared_cpu_map setup, AMD/Hygon
487 */
488static int __cache_amd_cpumap_setup(unsigned int cpu, int index,
489 const struct _cpuid4_info *id4)
490{
491 struct cpu_cacheinfo *this_cpu_ci;
492 struct cacheinfo *ci;
493 int i, sibling;
494
495 /*
496 * For L3, always use the pre-calculated cpu_llc_shared_mask
497 * to derive shared_cpu_map.
498 */
499 if (index == 3) {
500 for_each_cpu(i, cpu_llc_shared_mask(cpu)) {
501 this_cpu_ci = get_cpu_cacheinfo(cpu: i);
502 if (!this_cpu_ci->info_list)
503 continue;
504
505 ci = this_cpu_ci->info_list + index;
506 for_each_cpu(sibling, cpu_llc_shared_mask(cpu)) {
507 if (!cpu_online(cpu: sibling))
508 continue;
509 cpumask_set_cpu(cpu: sibling, dstp: &ci->shared_cpu_map);
510 }
511 }
512 } else if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
513 unsigned int apicid, nshared, first, last;
514
515 nshared = id4->eax.split.num_threads_sharing + 1;
516 apicid = cpu_data(cpu).topo.apicid;
517 first = apicid - (apicid % nshared);
518 last = first + nshared - 1;
519
520 for_each_online_cpu(i) {
521 this_cpu_ci = get_cpu_cacheinfo(cpu: i);
522 if (!this_cpu_ci->info_list)
523 continue;
524
525 apicid = cpu_data(i).topo.apicid;
526 if ((apicid < first) || (apicid > last))
527 continue;
528
529 ci = this_cpu_ci->info_list + index;
530
531 for_each_online_cpu(sibling) {
532 apicid = cpu_data(sibling).topo.apicid;
533 if ((apicid < first) || (apicid > last))
534 continue;
535 cpumask_set_cpu(cpu: sibling, dstp: &ci->shared_cpu_map);
536 }
537 }
538 } else
539 return 0;
540
541 return 1;
542}
543
544/*
545 * <linux/cacheinfo.h> shared_cpu_map setup, Intel + fallback AMD/Hygon
546 */
547static void __cache_cpumap_setup(unsigned int cpu, int index,
548 const struct _cpuid4_info *id4)
549{
550 struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
551 struct cpuinfo_x86 *c = &cpu_data(cpu);
552 struct cacheinfo *ci, *sibling_ci;
553 unsigned long num_threads_sharing;
554 int index_msb, i;
555
556 if (c->x86_vendor == X86_VENDOR_AMD || c->x86_vendor == X86_VENDOR_HYGON) {
557 if (__cache_amd_cpumap_setup(cpu, index, id4))
558 return;
559 }
560
561 ci = this_cpu_ci->info_list + index;
562 num_threads_sharing = 1 + id4->eax.split.num_threads_sharing;
563
564 cpumask_set_cpu(cpu, dstp: &ci->shared_cpu_map);
565 if (num_threads_sharing == 1)
566 return;
567
568 index_msb = get_count_order(count: num_threads_sharing);
569
570 for_each_online_cpu(i)
571 if (cpu_data(i).topo.apicid >> index_msb == c->topo.apicid >> index_msb) {
572 struct cpu_cacheinfo *sib_cpu_ci = get_cpu_cacheinfo(cpu: i);
573
574 /* Skip if itself or no cacheinfo */
575 if (i == cpu || !sib_cpu_ci->info_list)
576 continue;
577
578 sibling_ci = sib_cpu_ci->info_list + index;
579 cpumask_set_cpu(cpu: i, dstp: &ci->shared_cpu_map);
580 cpumask_set_cpu(cpu, dstp: &sibling_ci->shared_cpu_map);
581 }
582}
583
584static void ci_info_init(struct cacheinfo *ci, const struct _cpuid4_info *id4,
585 struct amd_northbridge *nb)
586{
587 ci->id = id4->id;
588 ci->attributes = CACHE_ID;
589 ci->level = id4->eax.split.level;
590 ci->type = cache_type_map[id4->eax.split.type];
591 ci->coherency_line_size = id4->ebx.split.coherency_line_size + 1;
592 ci->ways_of_associativity = id4->ebx.split.ways_of_associativity + 1;
593 ci->size = id4->size;
594 ci->number_of_sets = id4->ecx.split.number_of_sets + 1;
595 ci->physical_line_partition = id4->ebx.split.physical_line_partition + 1;
596 ci->priv = nb;
597}
598
599int init_cache_level(unsigned int cpu)
600{
601 struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
602
603 /* There should be at least one leaf. */
604 if (!ci->num_leaves)
605 return -ENOENT;
606
607 return 0;
608}
609
610int populate_cache_leaves(unsigned int cpu)
611{
612 struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
613 struct cacheinfo *ci = this_cpu_ci->info_list;
614 u8 cpu_vendor = boot_cpu_data.x86_vendor;
615 u32 apicid = cpu_data(cpu).topo.apicid;
616 struct amd_northbridge *nb = NULL;
617 struct _cpuid4_info id4 = {};
618 int idx, ret;
619
620 for (idx = 0; idx < this_cpu_ci->num_leaves; idx++) {
621 ret = fill_cpuid4_info(index: idx, id4: &id4);
622 if (ret)
623 return ret;
624
625 id4.id = get_cache_id(apicid, id4: &id4);
626
627 if (cpu_vendor == X86_VENDOR_AMD || cpu_vendor == X86_VENDOR_HYGON)
628 nb = amd_init_l3_cache(index: idx);
629
630 ci_info_init(ci: ci++, id4: &id4, nb);
631 __cache_cpumap_setup(cpu, index: idx, id4: &id4);
632 }
633
634 this_cpu_ci->cpu_map_populated = true;
635 return 0;
636}
637
638/*
639 * Disable and enable caches. Needed for changing MTRRs and the PAT MSR.
640 *
641 * Since we are disabling the cache don't allow any interrupts,
642 * they would run extremely slow and would only increase the pain.
643 *
644 * The caller must ensure that local interrupts are disabled and
645 * are reenabled after cache_enable() has been called.
646 */
647static unsigned long saved_cr4;
648static DEFINE_RAW_SPINLOCK(cache_disable_lock);
649
650/*
651 * Cache flushing is the most time-consuming step when programming the
652 * MTRRs. On many Intel CPUs without known erratas, it can be skipped
653 * if the CPU declares cache self-snooping support.
654 */
655static void maybe_flush_caches(void)
656{
657 if (!static_cpu_has(X86_FEATURE_SELFSNOOP))
658 wbinvd();
659}
660
661void cache_disable(void) __acquires(cache_disable_lock)
662{
663 unsigned long cr0;
664
665 /*
666 * This is not ideal since the cache is only flushed/disabled
667 * for this CPU while the MTRRs are changed, but changing this
668 * requires more invasive changes to the way the kernel boots.
669 */
670 raw_spin_lock(&cache_disable_lock);
671
672 /* Enter the no-fill (CD=1, NW=0) cache mode and flush caches. */
673 cr0 = read_cr0() | X86_CR0_CD;
674 write_cr0(x: cr0);
675
676 maybe_flush_caches();
677
678 /* Save value of CR4 and clear Page Global Enable (bit 7) */
679 if (cpu_feature_enabled(X86_FEATURE_PGE)) {
680 saved_cr4 = __read_cr4();
681 __write_cr4(x: saved_cr4 & ~X86_CR4_PGE);
682 }
683
684 /* Flush all TLBs via a mov %cr3, %reg; mov %reg, %cr3 */
685 count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
686 flush_tlb_local();
687
688 if (cpu_feature_enabled(X86_FEATURE_MTRR))
689 mtrr_disable();
690
691 maybe_flush_caches();
692}
693
694void cache_enable(void) __releases(cache_disable_lock)
695{
696 /* Flush TLBs (no need to flush caches - they are disabled) */
697 count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
698 flush_tlb_local();
699
700 if (cpu_feature_enabled(X86_FEATURE_MTRR))
701 mtrr_enable();
702
703 /* Enable caches */
704 write_cr0(x: read_cr0() & ~X86_CR0_CD);
705
706 /* Restore value of CR4 */
707 if (cpu_feature_enabled(X86_FEATURE_PGE))
708 __write_cr4(x: saved_cr4);
709
710 raw_spin_unlock(&cache_disable_lock);
711}
712
713static void cache_cpu_init(void)
714{
715 unsigned long flags;
716
717 local_irq_save(flags);
718
719 if (memory_caching_control & CACHE_MTRR) {
720 cache_disable();
721 mtrr_generic_set_state();
722 cache_enable();
723 }
724
725 if (memory_caching_control & CACHE_PAT)
726 pat_cpu_init();
727
728 local_irq_restore(flags);
729}
730
731static bool cache_aps_delayed_init = true;
732
733void set_cache_aps_delayed_init(bool val)
734{
735 cache_aps_delayed_init = val;
736}
737
738bool get_cache_aps_delayed_init(void)
739{
740 return cache_aps_delayed_init;
741}
742
743static int cache_rendezvous_handler(void *unused)
744{
745 if (get_cache_aps_delayed_init() || !cpu_online(smp_processor_id()))
746 cache_cpu_init();
747
748 return 0;
749}
750
751void __init cache_bp_init(void)
752{
753 mtrr_bp_init();
754 pat_bp_init();
755
756 if (memory_caching_control)
757 cache_cpu_init();
758}
759
760void cache_bp_restore(void)
761{
762 if (memory_caching_control)
763 cache_cpu_init();
764}
765
766static int cache_ap_online(unsigned int cpu)
767{
768 cpumask_set_cpu(cpu, dstp: cpu_cacheinfo_mask);
769
770 if (!memory_caching_control || get_cache_aps_delayed_init())
771 return 0;
772
773 /*
774 * Ideally we should hold mtrr_mutex here to avoid MTRR entries
775 * changed, but this routine will be called in CPU boot time,
776 * holding the lock breaks it.
777 *
778 * This routine is called in two cases:
779 *
780 * 1. very early time of software resume, when there absolutely
781 * isn't MTRR entry changes;
782 *
783 * 2. CPU hotadd time. We let mtrr_add/del_page hold cpuhotplug
784 * lock to prevent MTRR entry changes
785 */
786 stop_machine_from_inactive_cpu(fn: cache_rendezvous_handler, NULL,
787 cpus: cpu_cacheinfo_mask);
788
789 return 0;
790}
791
792static int cache_ap_offline(unsigned int cpu)
793{
794 cpumask_clear_cpu(cpu, dstp: cpu_cacheinfo_mask);
795 return 0;
796}
797
798/*
799 * Delayed cache initialization for all AP's
800 */
801void cache_aps_init(void)
802{
803 if (!memory_caching_control || !get_cache_aps_delayed_init())
804 return;
805
806 stop_machine(fn: cache_rendezvous_handler, NULL, cpu_online_mask);
807 set_cache_aps_delayed_init(false);
808}
809
810static int __init cache_ap_register(void)
811{
812 zalloc_cpumask_var(mask: &cpu_cacheinfo_mask, GFP_KERNEL);
813 cpumask_set_cpu(smp_processor_id(), dstp: cpu_cacheinfo_mask);
814
815 cpuhp_setup_state_nocalls(state: CPUHP_AP_CACHECTRL_STARTING,
816 name: "x86/cachectrl:starting",
817 startup: cache_ap_online, teardown: cache_ap_offline);
818 return 0;
819}
820early_initcall(cache_ap_register);
821

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