kernel/sched/topology.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Scheduler topology setup/handling methods
   4  */
   5 #include "sched.h"
   6
   7 DEFINE_MUTEX(sched_domains_mutex);
   8
   9 /* Protected by sched_domains_mutex: */
  10 static cpumask_var_t sched_domains_tmpmask;
  11 static cpumask_var_t sched_domains_tmpmask2;
  12
  13 #ifdef CONFIG_SCHED_DEBUG
  14
  15 static int __init sched_debug_setup(char *str)
  16 {
  17         sched_debug_verbose = true;
  18
  19         return 0;
  20 }
  21 early_param("sched_verbose", sched_debug_setup);
  22
  23 static inline bool sched_debug(void)
  24 {
  25         return sched_debug_verbose;
  26 }
  27
  28 #define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name },
  29 const struct sd_flag_debug sd_flag_debug[] = {
  30 #include <linux/sched/sd_flags.h>
  31 };
  32 #undef SD_FLAG
  33
  34 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
  35                                   struct cpumask *groupmask)
  36 {
  37         struct sched_group *group = sd->groups;
  38         unsigned long flags = sd->flags;
  39         unsigned int idx;
  40
  41         cpumask_clear(groupmask);
  42
  43         printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
  44         printk(KERN_CONT "span=%*pbl level=%s\n",
  45                cpumask_pr_args(sched_domain_span(sd)), sd->name);
  46
  47         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
  48                 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
  49         }
  50         if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
  51                 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
  52         }
  53
  54         for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {
  55                 unsigned int flag = BIT(idx);
  56                 unsigned int meta_flags = sd_flag_debug[idx].meta_flags;
  57
  58                 if ((meta_flags & SDF_SHARED_CHILD) && sd->child &&
  59                     !(sd->child->flags & flag))
  60                         printk(KERN_ERR "ERROR: flag %s set here but not in child\n",
  61                                sd_flag_debug[idx].name);
  62
  63                 if ((meta_flags & SDF_SHARED_PARENT) && sd->parent &&
  64                     !(sd->parent->flags & flag))
  65                         printk(KERN_ERR "ERROR: flag %s set here but not in parent\n",
  66                                sd_flag_debug[idx].name);
  67         }
  68
  69         printk(KERN_DEBUG "%*s groups:", level + 1, "");
  70         do {
  71                 if (!group) {
  72                         printk("\n");
  73                         printk(KERN_ERR "ERROR: group is NULL\n");
  74                         break;
  75                 }
  76
  77                 if (!cpumask_weight(sched_group_span(group))) {
  78                         printk(KERN_CONT "\n");
  79                         printk(KERN_ERR "ERROR: empty group\n");
  80                         break;
  81                 }
  82
  83                 if (!(sd->flags & SD_OVERLAP) &&
  84                     cpumask_intersects(groupmask, sched_group_span(group))) {
  85                         printk(KERN_CONT "\n");
  86                         printk(KERN_ERR "ERROR: repeated CPUs\n");
  87                         break;
  88                 }
  89
  90                 cpumask_or(groupmask, groupmask, sched_group_span(group));
  91
  92                 printk(KERN_CONT " %d:{ span=%*pbl",
  93                                 group->sgc->id,
  94                                 cpumask_pr_args(sched_group_span(group)));
  95
  96                 if ((sd->flags & SD_OVERLAP) &&
  97                     !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
  98                         printk(KERN_CONT " mask=%*pbl",
  99                                 cpumask_pr_args(group_balance_mask(group)));
 100                 }
 101
 102                 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
 103                         printk(KERN_CONT " cap=%lu", group->sgc->capacity);
 104
 105                 if (group == sd->groups && sd->child &&
 106                     !cpumask_equal(sched_domain_span(sd->child),
 107                                    sched_group_span(group))) {
 108                         printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
 109                 }
 110
 111                 printk(KERN_CONT " }");
 112
 113                 group = group->next;
 114
 115                 if (group != sd->groups)
 116                         printk(KERN_CONT ",");
 117
 118         } while (group != sd->groups);
 119         printk(KERN_CONT "\n");
 120
 121         if (!cpumask_equal(sched_domain_span(sd), groupmask))
 122                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
 123
 124         if (sd->parent &&
 125             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
 126                 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
 127         return 0;
 128 }
 129
 130 static void sched_domain_debug(struct sched_domain *sd, int cpu)
 131 {
 132         int level = 0;
 133
 134         if (!sched_debug_verbose)
 135                 return;
 136
 137         if (!sd) {
 138                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
 139                 return;
 140         }
 141
 142         printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
 143
 144         for (;;) {
 145                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
 146                         break;
 147                 level++;
 148                 sd = sd->parent;
 149                 if (!sd)
 150                         break;
 151         }
 152 }
 153 #else /* !CONFIG_SCHED_DEBUG */
 154
 155 # define sched_debug_verbose 0
 156 # define sched_domain_debug(sd, cpu) do { } while (0)
 157 static inline bool sched_debug(void)
 158 {
 159         return false;
 160 }
 161 #endif /* CONFIG_SCHED_DEBUG */
 162
 163 /* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
 164 #define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) |
 165 static const unsigned int SD_DEGENERATE_GROUPS_MASK =
 166 #include <linux/sched/sd_flags.h>
 167 0;
 168 #undef SD_FLAG
 169
 170 static int sd_degenerate(struct sched_domain *sd)
 171 {
 172         if (cpumask_weight(sched_domain_span(sd)) == 1)
 173                 return 1;
 174
 175         /* Following flags need at least 2 groups */
 176         if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) &&
 177             (sd->groups != sd->groups->next))
 178                 return 0;
 179
 180         /* Following flags don't use groups */
 181         if (sd->flags & (SD_WAKE_AFFINE))
 182                 return 0;
 183
 184         return 1;
 185 }
 186
 187 static int
 188 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 189 {
 190         unsigned long cflags = sd->flags, pflags = parent->flags;
 191
 192         if (sd_degenerate(parent))
 193                 return 1;
 194
 195         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
 196                 return 0;
 197
 198         /* Flags needing groups don't count if only 1 group in parent */
 199         if (parent->groups == parent->groups->next)
 200                 pflags &= ~SD_DEGENERATE_GROUPS_MASK;
 201
 202         if (~cflags & pflags)
 203                 return 0;
 204
 205         return 1;
 206 }
 207
 208 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 209 DEFINE_STATIC_KEY_FALSE(sched_energy_present);
 210 unsigned int sysctl_sched_energy_aware = 1;
 211 DEFINE_MUTEX(sched_energy_mutex);
 212 bool sched_energy_update;
 213
 214 void rebuild_sched_domains_energy(void)
 215 {
 216         mutex_lock(&sched_energy_mutex);
 217         sched_energy_update = true;
 218         rebuild_sched_domains();
 219         sched_energy_update = false;
 220         mutex_unlock(&sched_energy_mutex);
 221 }
 222
 223 #ifdef CONFIG_PROC_SYSCTL
 224 int sched_energy_aware_handler(struct ctl_table *table, int write,
 225                 void *buffer, size_t *lenp, loff_t *ppos)
 226 {
 227         int ret, state;
 228
 229         if (write && !capable(CAP_SYS_ADMIN))
 230                 return -EPERM;
 231
 232         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 233         if (!ret && write) {
 234                 state = static_branch_unlikely(&sched_energy_present);
 235                 if (state != sysctl_sched_energy_aware)
 236                         rebuild_sched_domains_energy();
 237         }
 238
 239         return ret;
 240 }
 241 #endif
 242
 243 static void free_pd(struct perf_domain *pd)
 244 {
 245         struct perf_domain *tmp;
 246
 247         while (pd) {
 248                 tmp = pd->next;
 249                 kfree(pd);
 250                 pd = tmp;
 251         }
 252 }
 253
 254 static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
 255 {
 256         while (pd) {
 257                 if (cpumask_test_cpu(cpu, perf_domain_span(pd)))
 258                         return pd;
 259                 pd = pd->next;
 260         }
 261
 262         return NULL;
 263 }
 264
 265 static struct perf_domain *pd_init(int cpu)
 266 {
 267         struct em_perf_domain *obj = em_cpu_get(cpu);
 268         struct perf_domain *pd;
 269
 270         if (!obj) {
 271                 if (sched_debug())
 272                         pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
 273                 return NULL;
 274         }
 275
 276         pd = kzalloc(sizeof(*pd), GFP_KERNEL);
 277         if (!pd)
 278                 return NULL;
 279         pd->em_pd = obj;
 280
 281         return pd;
 282 }
 283
 284 static void perf_domain_debug(const struct cpumask *cpu_map,
 285                                                 struct perf_domain *pd)
 286 {
 287         if (!sched_debug() || !pd)
 288                 return;
 289
 290         printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));
 291
 292         while (pd) {
 293                 printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }",
 294                                 cpumask_first(perf_domain_span(pd)),
 295                                 cpumask_pr_args(perf_domain_span(pd)),
 296                                 em_pd_nr_perf_states(pd->em_pd));
 297                 pd = pd->next;
 298         }
 299
 300         printk(KERN_CONT "\n");
 301 }
 302
 303 static void destroy_perf_domain_rcu(struct rcu_head *rp)
 304 {
 305         struct perf_domain *pd;
 306
 307         pd = container_of(rp, struct perf_domain, rcu);
 308         free_pd(pd);
 309 }
 310
 311 static void sched_energy_set(bool has_eas)
 312 {
 313         if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
 314                 if (sched_debug())
 315                         pr_info("%s: stopping EAS\n", __func__);
 316                 static_branch_disable_cpuslocked(&sched_energy_present);
 317         } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
 318                 if (sched_debug())
 319                         pr_info("%s: starting EAS\n", __func__);
 320                 static_branch_enable_cpuslocked(&sched_energy_present);
 321         }
 322 }
 323
 324 /*
 325  * EAS can be used on a root domain if it meets all the following conditions:
 326  *    1. an Energy Model (EM) is available;
 327  *    2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
 328  *    3. no SMT is detected.
 329  *    4. the EM complexity is low enough to keep scheduling overheads low;
 330  *    5. schedutil is driving the frequency of all CPUs of the rd;
 331  *    6. frequency invariance support is present;
 332  *
 333  * The complexity of the Energy Model is defined as:
 334  *
 335  *              C = nr_pd * (nr_cpus + nr_ps)
 336  *
 337  * with parameters defined as:
 338  *  - nr_pd:    the number of performance domains
 339  *  - nr_cpus:  the number of CPUs
 340  *  - nr_ps:    the sum of the number of performance states of all performance
 341  *              domains (for example, on a system with 2 performance domains,
 342  *              with 10 performance states each, nr_ps = 2 * 10 = 20).
 343  *
 344  * It is generally not a good idea to use such a model in the wake-up path on
 345  * very complex platforms because of the associated scheduling overheads. The
 346  * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs
 347  * with per-CPU DVFS and less than 8 performance states each, for example.
 348  */
 349 #define EM_MAX_COMPLEXITY 2048
 350
 351 extern struct cpufreq_governor schedutil_gov;
 352 static bool build_perf_domains(const struct cpumask *cpu_map)
 353 {
 354         int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map);
 355         struct perf_domain *pd = NULL, *tmp;
 356         int cpu = cpumask_first(cpu_map);
 357         struct root_domain *rd = cpu_rq(cpu)->rd;
 358         struct cpufreq_policy *policy;
 359         struct cpufreq_governor *gov;
 360
 361         if (!sysctl_sched_energy_aware)
 362                 goto free;
 363
 364         /* EAS is enabled for asymmetric CPU capacity topologies. */
 365         if (!per_cpu(sd_asym_cpucapacity, cpu)) {
 366                 if (sched_debug()) {
 367                         pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n",
 368                                         cpumask_pr_args(cpu_map));
 369                 }
 370                 goto free;
 371         }
 372
 373         /* EAS definitely does *not* handle SMT */
 374         if (sched_smt_active()) {
 375                 pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n",
 376                         cpumask_pr_args(cpu_map));
 377                 goto free;
 378         }
 379
 380         if (!arch_scale_freq_invariant()) {
 381                 if (sched_debug()) {
 382                         pr_warn("rd %*pbl: Disabling EAS: frequency-invariant load tracking not yet supported",
 383                                 cpumask_pr_args(cpu_map));
 384                 }
 385                 goto free;
 386         }
 387
 388         for_each_cpu(i, cpu_map) {
 389                 /* Skip already covered CPUs. */
 390                 if (find_pd(pd, i))
 391                         continue;
 392
 393                 /* Do not attempt EAS if schedutil is not being used. */
 394                 policy = cpufreq_cpu_get(i);
 395                 if (!policy)
 396                         goto free;
 397                 gov = policy->governor;
 398                 cpufreq_cpu_put(policy);
 399                 if (gov != &schedutil_gov) {
 400                         if (rd->pd)
 401                                 pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n",
 402                                                 cpumask_pr_args(cpu_map));
 403                         goto free;
 404                 }
 405
 406                 /* Create the new pd and add it to the local list. */
 407                 tmp = pd_init(i);
 408                 if (!tmp)
 409                         goto free;
 410                 tmp->next = pd;
 411                 pd = tmp;
 412
 413                 /*
 414                  * Count performance domains and performance states for the
 415                  * complexity check.
 416                  */
 417                 nr_pd++;
 418                 nr_ps += em_pd_nr_perf_states(pd->em_pd);
 419         }
 420
 421         /* Bail out if the Energy Model complexity is too high. */
 422         if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) {
 423                 WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n",
 424                                                 cpumask_pr_args(cpu_map));
 425                 goto free;
 426         }
 427
 428         perf_domain_debug(cpu_map, pd);
 429
 430         /* Attach the new list of performance domains to the root domain. */
 431         tmp = rd->pd;
 432         rcu_assign_pointer(rd->pd, pd);
 433         if (tmp)
 434                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 435
 436         return !!pd;
 437
 438 free:
 439         free_pd(pd);
 440         tmp = rd->pd;
 441         rcu_assign_pointer(rd->pd, NULL);
 442         if (tmp)
 443                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 444
 445         return false;
 446 }
 447 #else
 448 static void free_pd(struct perf_domain *pd) { }
 449 #endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/
 450
 451 static void free_rootdomain(struct rcu_head *rcu)
 452 {
 453         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
 454
 455         cpupri_cleanup(&rd->cpupri);
 456         cpudl_cleanup(&rd->cpudl);
 457         free_cpumask_var(rd->dlo_mask);
 458         free_cpumask_var(rd->rto_mask);
 459         free_cpumask_var(rd->online);
 460         free_cpumask_var(rd->span);
 461         free_pd(rd->pd);
 462         kfree(rd);
 463 }
 464
 465 void rq_attach_root(struct rq *rq, struct root_domain *rd)
 466 {
 467         struct root_domain *old_rd = NULL;
 468         unsigned long flags;
 469
 470         raw_spin_rq_lock_irqsave(rq, flags);
 471
 472         if (rq->rd) {
 473                 old_rd = rq->rd;
 474
 475                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
 476                         set_rq_offline(rq);
 477
 478                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 479
 480                 /*
 481                  * If we dont want to free the old_rd yet then
 482                  * set old_rd to NULL to skip the freeing later
 483                  * in this function:
 484                  */
 485                 if (!atomic_dec_and_test(&old_rd->refcount))
 486                         old_rd = NULL;
 487         }
 488
 489         atomic_inc(&rd->refcount);
 490         rq->rd = rd;
 491
 492         cpumask_set_cpu(rq->cpu, rd->span);
 493         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
 494                 set_rq_online(rq);
 495
 496         raw_spin_rq_unlock_irqrestore(rq, flags);
 497
 498         if (old_rd)
 499                 call_rcu(&old_rd->rcu, free_rootdomain);
 500 }
 501
 502 void sched_get_rd(struct root_domain *rd)
 503 {
 504         atomic_inc(&rd->refcount);
 505 }
 506
 507 void sched_put_rd(struct root_domain *rd)
 508 {
 509         if (!atomic_dec_and_test(&rd->refcount))
 510                 return;
 511
 512         call_rcu(&rd->rcu, free_rootdomain);
 513 }
 514
 515 static int init_rootdomain(struct root_domain *rd)
 516 {
 517         if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
 518                 goto out;
 519         if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
 520                 goto free_span;
 521         if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
 522                 goto free_online;
 523         if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
 524                 goto free_dlo_mask;
 525
 526 #ifdef HAVE_RT_PUSH_IPI
 527         rd->rto_cpu = -1;
 528         raw_spin_lock_init(&rd->rto_lock);
 529         rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
 530 #endif
 531
 532         rd->visit_gen = 0;
 533         init_dl_bw(&rd->dl_bw);
 534         if (cpudl_init(&rd->cpudl) != 0)
 535                 goto free_rto_mask;
 536
 537         if (cpupri_init(&rd->cpupri) != 0)
 538                 goto free_cpudl;
 539         return 0;
 540
 541 free_cpudl:
 542         cpudl_cleanup(&rd->cpudl);
 543 free_rto_mask:
 544         free_cpumask_var(rd->rto_mask);
 545 free_dlo_mask:
 546         free_cpumask_var(rd->dlo_mask);
 547 free_online:
 548         free_cpumask_var(rd->online);
 549 free_span:
 550         free_cpumask_var(rd->span);
 551 out:
 552         return -ENOMEM;
 553 }
 554
 555 /*
 556  * By default the system creates a single root-domain with all CPUs as
 557  * members (mimicking the global state we have today).
 558  */
 559 struct root_domain def_root_domain;
 560
 561 void init_defrootdomain(void)
 562 {
 563         init_rootdomain(&def_root_domain);
 564
 565         atomic_set(&def_root_domain.refcount, 1);
 566 }
 567
 568 static struct root_domain *alloc_rootdomain(void)
 569 {
 570         struct root_domain *rd;
 571
 572         rd = kzalloc(sizeof(*rd), GFP_KERNEL);
 573         if (!rd)
 574                 return NULL;
 575
 576         if (init_rootdomain(rd) != 0) {
 577                 kfree(rd);
 578                 return NULL;
 579         }
 580
 581         return rd;
 582 }
 583
 584 static void free_sched_groups(struct sched_group *sg, int free_sgc)
 585 {
 586         struct sched_group *tmp, *first;
 587
 588         if (!sg)
 589                 return;
 590
 591         first = sg;
 592         do {
 593                 tmp = sg->next;
 594
 595                 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
 596                         kfree(sg->sgc);
 597
 598                 if (atomic_dec_and_test(&sg->ref))
 599                         kfree(sg);
 600                 sg = tmp;
 601         } while (sg != first);
 602 }
 603
 604 static void destroy_sched_domain(struct sched_domain *sd)
 605 {
 606         /*
 607          * A normal sched domain may have multiple group references, an
 608          * overlapping domain, having private groups, only one.  Iterate,
 609          * dropping group/capacity references, freeing where none remain.
 610          */
 611         free_sched_groups(sd->groups, 1);
 612
 613         if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
 614                 kfree(sd->shared);
 615         kfree(sd);
 616 }
 617
 618 static void destroy_sched_domains_rcu(struct rcu_head *rcu)
 619 {
 620         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
 621
 622         while (sd) {
 623                 struct sched_domain *parent = sd->parent;
 624                 destroy_sched_domain(sd);
 625                 sd = parent;
 626         }
 627 }
 628
 629 static void destroy_sched_domains(struct sched_domain *sd)
 630 {
 631         if (sd)
 632                 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
 633 }
 634
 635 /*
 636  * Keep a special pointer to the highest sched_domain that has
 637  * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
 638  * allows us to avoid some pointer chasing select_idle_sibling().
 639  *
 640  * Also keep a unique ID per domain (we use the first CPU number in
 641  * the cpumask of the domain), this allows us to quickly tell if
 642  * two CPUs are in the same cache domain, see cpus_share_cache().
 643  */
 644 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
 645 DEFINE_PER_CPU(int, sd_llc_size);
 646 DEFINE_PER_CPU(int, sd_llc_id);
 647 DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
 648 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
 649 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 650 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
 651 DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
 652
 653 static void update_top_cache_domain(int cpu)
 654 {
 655         struct sched_domain_shared *sds = NULL;
 656         struct sched_domain *sd;
 657         int id = cpu;
 658         int size = 1;
 659
 660         sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
 661         if (sd) {
 662                 id = cpumask_first(sched_domain_span(sd));
 663                 size = cpumask_weight(sched_domain_span(sd));
 664                 sds = sd->shared;
 665         }
 666
 667         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
 668         per_cpu(sd_llc_size, cpu) = size;
 669         per_cpu(sd_llc_id, cpu) = id;
 670         rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
 671
 672         sd = lowest_flag_domain(cpu, SD_NUMA);
 673         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 674
 675         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
 676         rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
 677
 678         sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY_FULL);
 679         rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
 680 }
 681
 682 /*
 683  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
 684  * hold the hotplug lock.
 685  */
 686 static void
 687 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 688 {
 689         struct rq *rq = cpu_rq(cpu);
 690         struct sched_domain *tmp;
 691
 692         /* Remove the sched domains which do not contribute to scheduling. */
 693         for (tmp = sd; tmp; ) {
 694                 struct sched_domain *parent = tmp->parent;
 695                 if (!parent)
 696                         break;
 697
 698                 if (sd_parent_degenerate(tmp, parent)) {
 699                         tmp->parent = parent->parent;
 700                         if (parent->parent)
 701                                 parent->parent->child = tmp;
 702                         /*
 703                          * Transfer SD_PREFER_SIBLING down in case of a
 704                          * degenerate parent; the spans match for this
 705                          * so the property transfers.
 706                          */
 707                         if (parent->flags & SD_PREFER_SIBLING)
 708                                 tmp->flags |= SD_PREFER_SIBLING;
 709                         destroy_sched_domain(parent);
 710                 } else
 711                         tmp = tmp->parent;
 712         }
 713
 714         if (sd && sd_degenerate(sd)) {
 715                 tmp = sd;
 716                 sd = sd->parent;
 717                 destroy_sched_domain(tmp);
 718                 if (sd) {
 719                         struct sched_group *sg = sd->groups;
 720
 721                         /*
 722                          * sched groups hold the flags of the child sched
 723                          * domain for convenience. Clear such flags since
 724                          * the child is being destroyed.
 725                          */
 726                         do {
 727                                 sg->flags = 0;
 728                         } while (sg != sd->groups);
 729
 730                         sd->child = NULL;
 731                 }
 732         }
 733
 734         sched_domain_debug(sd, cpu);
 735
 736         rq_attach_root(rq, rd);
 737         tmp = rq->sd;
 738         rcu_assign_pointer(rq->sd, sd);
 739         dirty_sched_domain_sysctl(cpu);
 740         destroy_sched_domains(tmp);
 741
 742         update_top_cache_domain(cpu);
 743 }
 744
 745 struct s_data {
 746         struct sched_domain * __percpu *sd;
 747         struct root_domain      *rd;
 748 };
 749
 750 enum s_alloc {
 751         sa_rootdomain,
 752         sa_sd,
 753         sa_sd_storage,
 754         sa_none,
 755 };
 756
 757 /*
 758  * Return the canonical balance CPU for this group, this is the first CPU
 759  * of this group that's also in the balance mask.
 760  *
 761  * The balance mask are all those CPUs that could actually end up at this
 762  * group. See build_balance_mask().
 763  *
 764  * Also see should_we_balance().
 765  */
 766 int group_balance_cpu(struct sched_group *sg)
 767 {
 768         return cpumask_first(group_balance_mask(sg));
 769 }
 770
 771
 772 /*
 773  * NUMA topology (first read the regular topology blurb below)
 774  *
 775  * Given a node-distance table, for example:
 776  *
 777  *   node   0   1   2   3
 778  *     0:  10  20  30  20
 779  *     1:  20  10  20  30
 780  *     2:  30  20  10  20
 781  *     3:  20  30  20  10
 782  *
 783  * which represents a 4 node ring topology like:
 784  *
 785  *   0 ----- 1
 786  *   |       |
 787  *   |       |
 788  *   |       |
 789  *   3 ----- 2
 790  *
 791  * We want to construct domains and groups to represent this. The way we go
 792  * about doing this is to build the domains on 'hops'. For each NUMA level we
 793  * construct the mask of all nodes reachable in @level hops.
 794  *
 795  * For the above NUMA topology that gives 3 levels:
 796  *
 797  * NUMA-2       0-3             0-3             0-3             0-3
 798  *  groups:     {0-1,3},{1-3}   {0-2},{0,2-3}   {1-3},{0-1,3}   {0,2-3},{0-2}
 799  *
 800  * NUMA-1       0-1,3           0-2             1-3             0,2-3
 801  *  groups:     {0},{1},{3}     {0},{1},{2}     {1},{2},{3}     {0},{2},{3}
 802  *
 803  * NUMA-0       0               1               2               3
 804  *
 805  *
 806  * As can be seen; things don't nicely line up as with the regular topology.
 807  * When we iterate a domain in child domain chunks some nodes can be
 808  * represented multiple times -- hence the "overlap" naming for this part of
 809  * the topology.
 810  *
 811  * In order to minimize this overlap, we only build enough groups to cover the
 812  * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
 813  *
 814  * Because:
 815  *
 816  *  - the first group of each domain is its child domain; this
 817  *    gets us the first 0-1,3
 818  *  - the only uncovered node is 2, who's child domain is 1-3.
 819  *
 820  * However, because of the overlap, computing a unique CPU for each group is
 821  * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
 822  * groups include the CPUs of Node-0, while those CPUs would not in fact ever
 823  * end up at those groups (they would end up in group: 0-1,3).
 824  *
 825  * To correct this we have to introduce the group balance mask. This mask
 826  * will contain those CPUs in the group that can reach this group given the
 827  * (child) domain tree.
 828  *
 829  * With this we can once again compute balance_cpu and sched_group_capacity
 830  * relations.
 831  *
 832  * XXX include words on how balance_cpu is unique and therefore can be
 833  * used for sched_group_capacity links.
 834  *
 835  *
 836  * Another 'interesting' topology is:
 837  *
 838  *   node   0   1   2   3
 839  *     0:  10  20  20  30
 840  *     1:  20  10  20  20
 841  *     2:  20  20  10  20
 842  *     3:  30  20  20  10
 843  *
 844  * Which looks a little like:
 845  *
 846  *   0 ----- 1
 847  *   |     / |
 848  *   |   /   |
 849  *   | /     |
 850  *   2 ----- 3
 851  *
 852  * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
 853  * are not.
 854  *
 855  * This leads to a few particularly weird cases where the sched_domain's are
 856  * not of the same number for each CPU. Consider:
 857  *
 858  * NUMA-2       0-3                                             0-3
 859  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
 860  *
 861  * NUMA-1       0-2             0-3             0-3             1-3
 862  *
 863  * NUMA-0       0               1               2               3
 864  *
 865  */
 866
 867
 868 /*
 869  * Build the balance mask; it contains only those CPUs that can arrive at this
 870  * group and should be considered to continue balancing.
 871  *
 872  * We do this during the group creation pass, therefore the group information
 873  * isn't complete yet, however since each group represents a (child) domain we
 874  * can fully construct this using the sched_domain bits (which are already
 875  * complete).
 876  */
 877 static void
 878 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
 879 {
 880         const struct cpumask *sg_span = sched_group_span(sg);
 881         struct sd_data *sdd = sd->private;
 882         struct sched_domain *sibling;
 883         int i;
 884
 885         cpumask_clear(mask);
 886
 887         for_each_cpu(i, sg_span) {
 888                 sibling = *per_cpu_ptr(sdd->sd, i);
 889
 890                 /*
 891                  * Can happen in the asymmetric case, where these siblings are
 892                  * unused. The mask will not be empty because those CPUs that
 893                  * do have the top domain _should_ span the domain.
 894                  */
 895                 if (!sibling->child)
 896                         continue;
 897
 898                 /* If we would not end up here, we can't continue from here */
 899                 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
 900                         continue;
 901
 902                 cpumask_set_cpu(i, mask);
 903         }
 904
 905         /* We must not have empty masks here */
 906         WARN_ON_ONCE(cpumask_empty(mask));
 907 }
 908
 909 /*
 910  * XXX: This creates per-node group entries; since the load-balancer will
 911  * immediately access remote memory to construct this group's load-balance
 912  * statistics having the groups node local is of dubious benefit.
 913  */
 914 static struct sched_group *
 915 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
 916 {
 917         struct sched_group *sg;
 918         struct cpumask *sg_span;
 919
 920         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
 921                         GFP_KERNEL, cpu_to_node(cpu));
 922
 923         if (!sg)
 924                 return NULL;
 925
 926         sg_span = sched_group_span(sg);
 927         if (sd->child) {
 928                 cpumask_copy(sg_span, sched_domain_span(sd->child));
 929                 sg->flags = sd->child->flags;
 930         } else {
 931                 cpumask_copy(sg_span, sched_domain_span(sd));
 932         }
 933
 934         atomic_inc(&sg->ref);
 935         return sg;
 936 }
 937
 938 static void init_overlap_sched_group(struct sched_domain *sd,
 939                                      struct sched_group *sg)
 940 {
 941         struct cpumask *mask = sched_domains_tmpmask2;
 942         struct sd_data *sdd = sd->private;
 943         struct cpumask *sg_span;
 944         int cpu;
 945
 946         build_balance_mask(sd, sg, mask);
 947         cpu = cpumask_first(mask);
 948
 949         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
 950         if (atomic_inc_return(&sg->sgc->ref) == 1)
 951                 cpumask_copy(group_balance_mask(sg), mask);
 952         else
 953                 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
 954
 955         /*
 956          * Initialize sgc->capacity such that even if we mess up the
 957          * domains and no possible iteration will get us here, we won't
 958          * die on a /0 trap.
 959          */
 960         sg_span = sched_group_span(sg);
 961         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
 962         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
 963         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
 964 }
 965
 966 static struct sched_domain *
 967 find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling)
 968 {
 969         /*
 970          * The proper descendant would be the one whose child won't span out
 971          * of sd
 972          */
 973         while (sibling->child &&
 974                !cpumask_subset(sched_domain_span(sibling->child),
 975                                sched_domain_span(sd)))
 976                 sibling = sibling->child;
 977
 978         /*
 979          * As we are referencing sgc across different topology level, we need
 980          * to go down to skip those sched_domains which don't contribute to
 981          * scheduling because they will be degenerated in cpu_attach_domain
 982          */
 983         while (sibling->child &&
 984                cpumask_equal(sched_domain_span(sibling->child),
 985                              sched_domain_span(sibling)))
 986                 sibling = sibling->child;
 987
 988         return sibling;
 989 }
 990
 991 static int
 992 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 993 {
 994         struct sched_group *first = NULL, *last = NULL, *sg;
 995         const struct cpumask *span = sched_domain_span(sd);
 996         struct cpumask *covered = sched_domains_tmpmask;
 997         struct sd_data *sdd = sd->private;
 998         struct sched_domain *sibling;
 999         int i;
1000
1001         cpumask_clear(covered);
1002
1003         for_each_cpu_wrap(i, span, cpu) {
1004                 struct cpumask *sg_span;
1005
1006                 if (cpumask_test_cpu(i, covered))
1007                         continue;
1008
1009                 sibling = *per_cpu_ptr(sdd->sd, i);
1010
1011                 /*
1012                  * Asymmetric node setups can result in situations where the
1013                  * domain tree is of unequal depth, make sure to skip domains
1014                  * that already cover the entire range.
1015                  *
1016                  * In that case build_sched_domains() will have terminated the
1017                  * iteration early and our sibling sd spans will be empty.
1018                  * Domains should always include the CPU they're built on, so
1019                  * check that.
1020                  */
1021                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
1022                         continue;
1023
1024                 /*
1025                  * Usually we build sched_group by sibling's child sched_domain
1026                  * But for machines whose NUMA diameter are 3 or above, we move
1027                  * to build sched_group by sibling's proper descendant's child
1028                  * domain because sibling's child sched_domain will span out of
1029                  * the sched_domain being built as below.
1030                  *
1031                  * Smallest diameter=3 topology is:
1032                  *
1033                  *   node   0   1   2   3
1034                  *     0:  10  20  30  40
1035                  *     1:  20  10  20  30
1036                  *     2:  30  20  10  20
1037                  *     3:  40  30  20  10
1038                  *
1039                  *   0 --- 1 --- 2 --- 3
1040                  *
1041                  * NUMA-3       0-3             N/A             N/A             0-3
1042                  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
1043                  *
1044                  * NUMA-2       0-2             0-3             0-3             1-3
1045                  *  groups:     {0-1},{1-3}     {0-2},{2-3}     {1-3},{0-1}     {2-3},{0-2}
1046                  *
1047                  * NUMA-1       0-1             0-2             1-3             2-3
1048                  *  groups:     {0},{1}         {1},{2},{0}     {2},{3},{1}     {3},{2}
1049                  *
1050                  * NUMA-0       0               1               2               3
1051                  *
1052                  * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
1053                  * group span isn't a subset of the domain span.
1054                  */
1055                 if (sibling->child &&
1056                     !cpumask_subset(sched_domain_span(sibling->child), span))
1057                         sibling = find_descended_sibling(sd, sibling);
1058
1059                 sg = build_group_from_child_sched_domain(sibling, cpu);
1060                 if (!sg)
1061                         goto fail;
1062
1063                 sg_span = sched_group_span(sg);
1064                 cpumask_or(covered, covered, sg_span);
1065
1066                 init_overlap_sched_group(sibling, sg);
1067
1068                 if (!first)
1069                         first = sg;
1070                 if (last)
1071                         last->next = sg;
1072                 last = sg;
1073                 last->next = first;
1074         }
1075         sd->groups = first;
1076
1077         return 0;
1078
1079 fail:
1080         free_sched_groups(first, 0);
1081
1082         return -ENOMEM;
1083 }
1084
1085
1086 /*
1087  * Package topology (also see the load-balance blurb in fair.c)
1088  *
1089  * The scheduler builds a tree structure to represent a number of important
1090  * topology features. By default (default_topology[]) these include:
1091  *
1092  *  - Simultaneous multithreading (SMT)
1093  *  - Multi-Core Cache (MC)
1094  *  - Package (DIE)
1095  *
1096  * Where the last one more or less denotes everything up to a NUMA node.
1097  *
1098  * The tree consists of 3 primary data structures:
1099  *
1100  *      sched_domain -> sched_group -> sched_group_capacity
1101  *          ^ ^             ^ ^
1102  *          `-'             `-'
1103  *
1104  * The sched_domains are per-CPU and have a two way link (parent & child) and
1105  * denote the ever growing mask of CPUs belonging to that level of topology.
1106  *
1107  * Each sched_domain has a circular (double) linked list of sched_group's, each
1108  * denoting the domains of the level below (or individual CPUs in case of the
1109  * first domain level). The sched_group linked by a sched_domain includes the
1110  * CPU of that sched_domain [*].
1111  *
1112  * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
1113  *
1114  * CPU   0   1   2   3   4   5   6   7
1115  *
1116  * DIE  [                             ]
1117  * MC   [             ] [             ]
1118  * SMT  [     ] [     ] [     ] [     ]
1119  *
1120  *  - or -
1121  *
1122  * DIE  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
1123  * MC   0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
1124  * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
1125  *
1126  * CPU   0   1   2   3   4   5   6   7
1127  *
1128  * One way to think about it is: sched_domain moves you up and down among these
1129  * topology levels, while sched_group moves you sideways through it, at child
1130  * domain granularity.
1131  *
1132  * sched_group_capacity ensures each unique sched_group has shared storage.
1133  *
1134  * There are two related construction problems, both require a CPU that
1135  * uniquely identify each group (for a given domain):
1136  *
1137  *  - The first is the balance_cpu (see should_we_balance() and the
1138  *    load-balance blub in fair.c); for each group we only want 1 CPU to
1139  *    continue balancing at a higher domain.
1140  *
1141  *  - The second is the sched_group_capacity; we want all identical groups
1142  *    to share a single sched_group_capacity.
1143  *
1144  * Since these topologies are exclusive by construction. That is, its
1145  * impossible for an SMT thread to belong to multiple cores, and cores to
1146  * be part of multiple caches. There is a very clear and unique location
1147  * for each CPU in the hierarchy.
1148  *
1149  * Therefore computing a unique CPU for each group is trivial (the iteration
1150  * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
1151  * group), we can simply pick the first CPU in each group.
1152  *
1153  *
1154  * [*] in other words, the first group of each domain is its child domain.
1155  */
1156
1157 static struct sched_group *get_group(int cpu, struct sd_data *sdd)
1158 {
1159         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1160         struct sched_domain *child = sd->child;
1161         struct sched_group *sg;
1162         bool already_visited;
1163
1164         if (child)
1165                 cpu = cpumask_first(sched_domain_span(child));
1166
1167         sg = *per_cpu_ptr(sdd->sg, cpu);
1168         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
1169
1170         /* Increase refcounts for claim_allocations: */
1171         already_visited = atomic_inc_return(&sg->ref) > 1;
1172         /* sgc visits should follow a similar trend as sg */
1173         WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));
1174
1175         /* If we have already visited that group, it's already initialized. */
1176         if (already_visited)
1177                 return sg;
1178
1179         if (child) {
1180                 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
1181                 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
1182                 sg->flags = child->flags;
1183         } else {
1184                 cpumask_set_cpu(cpu, sched_group_span(sg));
1185                 cpumask_set_cpu(cpu, group_balance_mask(sg));
1186         }
1187
1188         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
1189         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1190         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1191
1192         return sg;
1193 }
1194
1195 /*
1196  * build_sched_groups will build a circular linked list of the groups
1197  * covered by the given span, will set each group's ->cpumask correctly,
1198  * and will initialize their ->sgc.
1199  *
1200  * Assumes the sched_domain tree is fully constructed
1201  */
1202 static int
1203 build_sched_groups(struct sched_domain *sd, int cpu)
1204 {
1205         struct sched_group *first = NULL, *last = NULL;
1206         struct sd_data *sdd = sd->private;
1207         const struct cpumask *span = sched_domain_span(sd);
1208         struct cpumask *covered;
1209         int i;
1210
1211         lockdep_assert_held(&sched_domains_mutex);
1212         covered = sched_domains_tmpmask;
1213
1214         cpumask_clear(covered);
1215
1216         for_each_cpu_wrap(i, span, cpu) {
1217                 struct sched_group *sg;
1218
1219                 if (cpumask_test_cpu(i, covered))
1220                         continue;
1221
1222                 sg = get_group(i, sdd);
1223
1224                 cpumask_or(covered, covered, sched_group_span(sg));
1225
1226                 if (!first)
1227                         first = sg;
1228                 if (last)
1229                         last->next = sg;
1230                 last = sg;
1231         }
1232         last->next = first;
1233         sd->groups = first;
1234
1235         return 0;
1236 }
1237
1238 /*
1239  * Initialize sched groups cpu_capacity.
1240  *
1241  * cpu_capacity indicates the capacity of sched group, which is used while
1242  * distributing the load between different sched groups in a sched domain.
1243  * Typically cpu_capacity for all the groups in a sched domain will be same
1244  * unless there are asymmetries in the topology. If there are asymmetries,
1245  * group having more cpu_capacity will pickup more load compared to the
1246  * group having less cpu_capacity.
1247  */
1248 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
1249 {
1250         struct sched_group *sg = sd->groups;
1251
1252         WARN_ON(!sg);
1253
1254         do {
1255                 int cpu, max_cpu = -1;
1256
1257                 sg->group_weight = cpumask_weight(sched_group_span(sg));
1258
1259                 if (!(sd->flags & SD_ASYM_PACKING))
1260                         goto next;
1261
1262                 for_each_cpu(cpu, sched_group_span(sg)) {
1263                         if (max_cpu < 0)
1264                                 max_cpu = cpu;
1265                         else if (sched_asym_prefer(cpu, max_cpu))
1266                                 max_cpu = cpu;
1267                 }
1268                 sg->asym_prefer_cpu = max_cpu;
1269
1270 next:
1271                 sg = sg->next;
1272         } while (sg != sd->groups);
1273
1274         if (cpu != group_balance_cpu(sg))
1275                 return;
1276
1277         update_group_capacity(sd, cpu);
1278 }
1279
1280 /*
1281  * Asymmetric CPU capacity bits
1282  */
1283 struct asym_cap_data {
1284         struct list_head link;
1285         unsigned long capacity;
1286         unsigned long cpus[];
1287 };
1288
1289 /*
1290  * Set of available CPUs grouped by their corresponding capacities
1291  * Each list entry contains a CPU mask reflecting CPUs that share the same
1292  * capacity.
1293  * The lifespan of data is unlimited.
1294  */
1295 static LIST_HEAD(asym_cap_list);
1296
1297 #define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus)
1298
1299 /*
1300  * Verify whether there is any CPU capacity asymmetry in a given sched domain.
1301  * Provides sd_flags reflecting the asymmetry scope.
1302  */
1303 static inline int
1304 asym_cpu_capacity_classify(const struct cpumask *sd_span,
1305                            const struct cpumask *cpu_map)
1306 {
1307         struct asym_cap_data *entry;
1308         int count = 0, miss = 0;
1309
1310         /*
1311          * Count how many unique CPU capacities this domain spans across
1312          * (compare sched_domain CPUs mask with ones representing  available
1313          * CPUs capacities). Take into account CPUs that might be offline:
1314          * skip those.
1315          */
1316         list_for_each_entry(entry, &asym_cap_list, link) {
1317                 if (cpumask_intersects(sd_span, cpu_capacity_span(entry)))
1318                         ++count;
1319                 else if (cpumask_intersects(cpu_map, cpu_capacity_span(entry)))
1320                         ++miss;
1321         }
1322
1323         WARN_ON_ONCE(!count && !list_empty(&asym_cap_list));
1324
1325         /* No asymmetry detected */
1326         if (count < 2)
1327                 return 0;
1328         /* Some of the available CPU capacity values have not been detected */
1329         if (miss)
1330                 return SD_ASYM_CPUCAPACITY;
1331
1332         /* Full asymmetry */
1333         return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL;
1334
1335 }
1336
1337 static inline void asym_cpu_capacity_update_data(int cpu)
1338 {
1339         unsigned long capacity = arch_scale_cpu_capacity(cpu);
1340         struct asym_cap_data *entry = NULL;
1341
1342         list_for_each_entry(entry, &asym_cap_list, link) {
1343                 if (capacity == entry->capacity)
1344                         goto done;
1345         }
1346
1347         entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
1348         if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n"))
1349                 return;
1350         entry->capacity = capacity;
1351         list_add(&entry->link, &asym_cap_list);
1352 done:
1353         __cpumask_set_cpu(cpu, cpu_capacity_span(entry));
1354 }
1355
1356 /*
1357  * Build-up/update list of CPUs grouped by their capacities
1358  * An update requires explicit request to rebuild sched domains
1359  * with state indicating CPU topology changes.
1360  */
1361 static void asym_cpu_capacity_scan(void)
1362 {
1363         struct asym_cap_data *entry, *next;
1364         int cpu;
1365
1366         list_for_each_entry(entry, &asym_cap_list, link)
1367                 cpumask_clear(cpu_capacity_span(entry));
1368
1369         for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_FLAG_DOMAIN))
1370                 asym_cpu_capacity_update_data(cpu);
1371
1372         list_for_each_entry_safe(entry, next, &asym_cap_list, link) {
1373                 if (cpumask_empty(cpu_capacity_span(entry))) {
1374                         list_del(&entry->link);
1375                         kfree(entry);
1376                 }
1377         }
1378
1379         /*
1380          * Only one capacity value has been detected i.e. this system is symmetric.
1381          * No need to keep this data around.
1382          */
1383         if (list_is_singular(&asym_cap_list)) {
1384                 entry = list_first_entry(&asym_cap_list, typeof(*entry), link);
1385                 list_del(&entry->link);
1386                 kfree(entry);
1387         }
1388 }
1389
1390 /*
1391  * Initializers for schedule domains
1392  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
1393  */
1394
1395 static int default_relax_domain_level = -1;
1396 int sched_domain_level_max;
1397
1398 static int __init setup_relax_domain_level(char *str)
1399 {
1400         if (kstrtoint(str, 0, &default_relax_domain_level))
1401                 pr_warn("Unable to set relax_domain_level\n");
1402
1403         return 1;
1404 }
1405 __setup("relax_domain_level=", setup_relax_domain_level);
1406
1407 static void set_domain_attribute(struct sched_domain *sd,
1408                                  struct sched_domain_attr *attr)
1409 {
1410         int request;
1411
1412         if (!attr || attr->relax_domain_level < 0) {
1413                 if (default_relax_domain_level < 0)
1414                         return;
1415                 request = default_relax_domain_level;
1416         } else
1417                 request = attr->relax_domain_level;
1418
1419         if (sd->level > request) {
1420                 /* Turn off idle balance on this domain: */
1421                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
1422         }
1423 }
1424
1425 static void __sdt_free(const struct cpumask *cpu_map);
1426 static int __sdt_alloc(const struct cpumask *cpu_map);
1427
1428 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
1429                                  const struct cpumask *cpu_map)
1430 {
1431         switch (what) {
1432         case sa_rootdomain:
1433                 if (!atomic_read(&d->rd->refcount))
1434                         free_rootdomain(&d->rd->rcu);
1435                 fallthrough;
1436         case sa_sd:
1437                 free_percpu(d->sd);
1438                 fallthrough;
1439         case sa_sd_storage:
1440                 __sdt_free(cpu_map);
1441                 fallthrough;
1442         case sa_none:
1443                 break;
1444         }
1445 }
1446
1447 static enum s_alloc
1448 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1449 {
1450         memset(d, 0, sizeof(*d));
1451
1452         if (__sdt_alloc(cpu_map))
1453                 return sa_sd_storage;
1454         d->sd = alloc_percpu(struct sched_domain *);
1455         if (!d->sd)
1456                 return sa_sd_storage;
1457         d->rd = alloc_rootdomain();
1458         if (!d->rd)
1459                 return sa_sd;
1460
1461         return sa_rootdomain;
1462 }
1463
1464 /*
1465  * NULL the sd_data elements we've used to build the sched_domain and
1466  * sched_group structure so that the subsequent __free_domain_allocs()
1467  * will not free the data we're using.
1468  */
1469 static void claim_allocations(int cpu, struct sched_domain *sd)
1470 {
1471         struct sd_data *sdd = sd->private;
1472
1473         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1474         *per_cpu_ptr(sdd->sd, cpu) = NULL;
1475
1476         if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1477                 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1478
1479         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1480                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1481
1482         if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1483                 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1484 }
1485
1486 #ifdef CONFIG_NUMA
1487 enum numa_topology_type sched_numa_topology_type;
1488
1489 static int                      sched_domains_numa_levels;
1490 static int                      sched_domains_curr_level;
1491
1492 int                             sched_max_numa_distance;
1493 static int                      *sched_domains_numa_distance;
1494 static struct cpumask           ***sched_domains_numa_masks;
1495
1496 static unsigned long __read_mostly *sched_numa_onlined_nodes;
1497 #endif
1498
1499 /*
1500  * SD_flags allowed in topology descriptions.
1501  *
1502  * These flags are purely descriptive of the topology and do not prescribe
1503  * behaviour. Behaviour is artificial and mapped in the below sd_init()
1504  * function:
1505  *
1506  *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
1507  *   SD_SHARE_PKG_RESOURCES - describes shared caches
1508  *   SD_NUMA                - describes NUMA topologies
1509  *
1510  * Odd one out, which beside describing the topology has a quirk also
1511  * prescribes the desired behaviour that goes along with it:
1512  *
1513  *   SD_ASYM_PACKING        - describes SMT quirks
1514  */
1515 #define TOPOLOGY_SD_FLAGS               \
1516         (SD_SHARE_CPUCAPACITY   |       \
1517          SD_SHARE_PKG_RESOURCES |       \
1518          SD_NUMA                |       \
1519          SD_ASYM_PACKING)
1520
1521 static struct sched_domain *
1522 sd_init(struct sched_domain_topology_level *tl,
1523         const struct cpumask *cpu_map,
1524         struct sched_domain *child, int cpu)
1525 {
1526         struct sd_data *sdd = &tl->data;
1527         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1528         int sd_id, sd_weight, sd_flags = 0;
1529         struct cpumask *sd_span;
1530
1531 #ifdef CONFIG_NUMA
1532         /*
1533          * Ugly hack to pass state to sd_numa_mask()...
1534          */
1535         sched_domains_curr_level = tl->numa_level;
1536 #endif
1537
1538         sd_weight = cpumask_weight(tl->mask(cpu));
1539
1540         if (tl->sd_flags)
1541                 sd_flags = (*tl->sd_flags)();
1542         if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1543                         "wrong sd_flags in topology description\n"))
1544                 sd_flags &= TOPOLOGY_SD_FLAGS;
1545
1546         *sd = (struct sched_domain){
1547                 .min_interval           = sd_weight,
1548                 .max_interval           = 2*sd_weight,
1549                 .busy_factor            = 16,
1550                 .imbalance_pct          = 117,
1551
1552                 .cache_nice_tries       = 0,
1553
1554                 .flags                  = 1*SD_BALANCE_NEWIDLE
1555                                         | 1*SD_BALANCE_EXEC
1556                                         | 1*SD_BALANCE_FORK
1557                                         | 0*SD_BALANCE_WAKE
1558                                         | 1*SD_WAKE_AFFINE
1559                                         | 0*SD_SHARE_CPUCAPACITY
1560                                         | 0*SD_SHARE_PKG_RESOURCES
1561                                         | 0*SD_SERIALIZE
1562                                         | 1*SD_PREFER_SIBLING
1563                                         | 0*SD_NUMA
1564                                         | sd_flags
1565                                         ,
1566
1567                 .last_balance           = jiffies,
1568                 .balance_interval       = sd_weight,
1569                 .max_newidle_lb_cost    = 0,
1570                 .last_decay_max_lb_cost = jiffies,
1571                 .child                  = child,
1572 #ifdef CONFIG_SCHED_DEBUG
1573                 .name                   = tl->name,
1574 #endif
1575         };
1576
1577         sd_span = sched_domain_span(sd);
1578         cpumask_and(sd_span, cpu_map, tl->mask(cpu));
1579         sd_id = cpumask_first(sd_span);
1580
1581         sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map);
1582
1583         WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) ==
1584                   (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY),
1585                   "CPU capacity asymmetry not supported on SMT\n");
1586
1587         /*
1588          * Convert topological properties into behaviour.
1589          */
1590         /* Don't attempt to spread across CPUs of different capacities. */
1591         if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child)
1592                 sd->child->flags &= ~SD_PREFER_SIBLING;
1593
1594         if (sd->flags & SD_SHARE_CPUCAPACITY) {
1595                 sd->imbalance_pct = 110;
1596
1597         } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1598                 sd->imbalance_pct = 117;
1599                 sd->cache_nice_tries = 1;
1600
1601 #ifdef CONFIG_NUMA
1602         } else if (sd->flags & SD_NUMA) {
1603                 sd->cache_nice_tries = 2;
1604
1605                 sd->flags &= ~SD_PREFER_SIBLING;
1606                 sd->flags |= SD_SERIALIZE;
1607                 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
1608                         sd->flags &= ~(SD_BALANCE_EXEC |
1609                                        SD_BALANCE_FORK |
1610                                        SD_WAKE_AFFINE);
1611                 }
1612
1613 #endif
1614         } else {
1615                 sd->cache_nice_tries = 1;
1616         }
1617
1618         /*
1619          * For all levels sharing cache; connect a sched_domain_shared
1620          * instance.
1621          */
1622         if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1623                 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1624                 atomic_inc(&sd->shared->ref);
1625                 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1626         }
1627
1628         sd->private = sdd;
1629
1630         return sd;
1631 }
1632
1633 /*
1634  * Topology list, bottom-up.
1635  */
1636 static struct sched_domain_topology_level default_topology[] = {
1637 #ifdef CONFIG_SCHED_SMT
1638         { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1639 #endif
1640
1641 #ifdef CONFIG_SCHED_CLUSTER
1642         { cpu_clustergroup_mask, cpu_cluster_flags, SD_INIT_NAME(CLS) },
1643 #endif
1644
1645 #ifdef CONFIG_SCHED_MC
1646         { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1647 #endif
1648         { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1649         { NULL, },
1650 };
1651
1652 static struct sched_domain_topology_level *sched_domain_topology =
1653         default_topology;
1654
1655 #define for_each_sd_topology(tl)                        \
1656         for (tl = sched_domain_topology; tl->mask; tl++)
1657
1658 void set_sched_topology(struct sched_domain_topology_level *tl)
1659 {
1660         if (WARN_ON_ONCE(sched_smp_initialized))
1661                 return;
1662
1663         sched_domain_topology = tl;
1664 }
1665
1666 #ifdef CONFIG_NUMA
1667
1668 static const struct cpumask *sd_numa_mask(int cpu)
1669 {
1670         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1671 }
1672
1673 static void sched_numa_warn(const char *str)
1674 {
1675         static int done = false;
1676         int i,j;
1677
1678         if (done)
1679                 return;
1680
1681         done = true;
1682
1683         printk(KERN_WARNING "ERROR: %s\n\n", str);
1684
1685         for (i = 0; i < nr_node_ids; i++) {
1686                 printk(KERN_WARNING "  ");
1687                 for (j = 0; j < nr_node_ids; j++)
1688                         printk(KERN_CONT "%02d ", node_distance(i,j));
1689                 printk(KERN_CONT "\n");
1690         }
1691         printk(KERN_WARNING "\n");
1692 }
1693
1694 bool find_numa_distance(int distance)
1695 {
1696         int i;
1697
1698         if (distance == node_distance(0, 0))
1699                 return true;
1700
1701         for (i = 0; i < sched_domains_numa_levels; i++) {
1702                 if (sched_domains_numa_distance[i] == distance)
1703                         return true;
1704         }
1705
1706         return false;
1707 }
1708
1709 /*
1710  * A system can have three types of NUMA topology:
1711  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1712  * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1713  * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1714  *
1715  * The difference between a glueless mesh topology and a backplane
1716  * topology lies in whether communication between not directly
1717  * connected nodes goes through intermediary nodes (where programs
1718  * could run), or through backplane controllers. This affects
1719  * placement of programs.
1720  *
1721  * The type of topology can be discerned with the following tests:
1722  * - If the maximum distance between any nodes is 1 hop, the system
1723  *   is directly connected.
1724  * - If for two nodes A and B, located N > 1 hops away from each other,
1725  *   there is an intermediary node C, which is < N hops away from both
1726  *   nodes A and B, the system is a glueless mesh.
1727  */
1728 static void init_numa_topology_type(void)
1729 {
1730         int a, b, c, n;
1731
1732         n = sched_max_numa_distance;
1733
1734         if (sched_domains_numa_levels <= 2) {
1735                 sched_numa_topology_type = NUMA_DIRECT;
1736                 return;
1737         }
1738
1739         for_each_online_node(a) {
1740                 for_each_online_node(b) {
1741                         /* Find two nodes furthest removed from each other. */
1742                         if (node_distance(a, b) < n)
1743                                 continue;
1744
1745                         /* Is there an intermediary node between a and b? */
1746                         for_each_online_node(c) {
1747                                 if (node_distance(a, c) < n &&
1748                                     node_distance(b, c) < n) {
1749                                         sched_numa_topology_type =
1750                                                         NUMA_GLUELESS_MESH;
1751                                         return;
1752                                 }
1753                         }
1754
1755                         sched_numa_topology_type = NUMA_BACKPLANE;
1756                         return;
1757                 }
1758         }
1759 }
1760
1761
1762 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
1763
1764 void sched_init_numa(void)
1765 {
1766         struct sched_domain_topology_level *tl;
1767         unsigned long *distance_map;
1768         int nr_levels = 0;
1769         int i, j;
1770
1771         /*
1772          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1773          * unique distances in the node_distance() table.
1774          */
1775         distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
1776         if (!distance_map)
1777                 return;
1778
1779         bitmap_zero(distance_map, NR_DISTANCE_VALUES);
1780         for (i = 0; i < nr_node_ids; i++) {
1781                 for (j = 0; j < nr_node_ids; j++) {
1782                         int distance = node_distance(i, j);
1783
1784                         if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
1785                                 sched_numa_warn("Invalid distance value range");
1786                                 return;
1787                         }
1788
1789                         bitmap_set(distance_map, distance, 1);
1790                 }
1791         }
1792         /*
1793          * We can now figure out how many unique distance values there are and
1794          * allocate memory accordingly.
1795          */
1796         nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);
1797
1798         sched_domains_numa_distance = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
1799         if (!sched_domains_numa_distance) {
1800                 bitmap_free(distance_map);
1801                 return;
1802         }
1803
1804         for (i = 0, j = 0; i < nr_levels; i++, j++) {
1805                 j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
1806                 sched_domains_numa_distance[i] = j;
1807         }
1808
1809         bitmap_free(distance_map);
1810
1811         /*
1812          * 'nr_levels' contains the number of unique distances
1813          *
1814          * The sched_domains_numa_distance[] array includes the actual distance
1815          * numbers.
1816          */
1817
1818         /*
1819          * Here, we should temporarily reset sched_domains_numa_levels to 0.
1820          * If it fails to allocate memory for array sched_domains_numa_masks[][],
1821          * the array will contain less then 'nr_levels' members. This could be
1822          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1823          * in other functions.
1824          *
1825          * We reset it to 'nr_levels' at the end of this function.
1826          */
1827         sched_domains_numa_levels = 0;
1828
1829         sched_domains_numa_masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
1830         if (!sched_domains_numa_masks)
1831                 return;
1832
1833         /*
1834          * Now for each level, construct a mask per node which contains all
1835          * CPUs of nodes that are that many hops away from us.
1836          */
1837         for (i = 0; i < nr_levels; i++) {
1838                 sched_domains_numa_masks[i] =
1839                         kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1840                 if (!sched_domains_numa_masks[i])
1841                         return;
1842
1843                 for (j = 0; j < nr_node_ids; j++) {
1844                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1845                         int k;
1846
1847                         if (!mask)
1848                                 return;
1849
1850                         sched_domains_numa_masks[i][j] = mask;
1851
1852                         for_each_node(k) {
1853                                 /*
1854                                  * Distance information can be unreliable for
1855                                  * offline nodes, defer building the node
1856                                  * masks to its bringup.
1857                                  * This relies on all unique distance values
1858                                  * still being visible at init time.
1859                                  */
1860                                 if (!node_online(j))
1861                                         continue;
1862
1863                                 if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
1864                                         sched_numa_warn("Node-distance not symmetric");
1865
1866                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
1867                                         continue;
1868
1869                                 cpumask_or(mask, mask, cpumask_of_node(k));
1870                         }
1871                 }
1872         }
1873
1874         /* Compute default topology size */
1875         for (i = 0; sched_domain_topology[i].mask; i++);
1876
1877         tl = kzalloc((i + nr_levels + 1) *
1878                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1879         if (!tl)
1880                 return;
1881
1882         /*
1883          * Copy the default topology bits..
1884          */
1885         for (i = 0; sched_domain_topology[i].mask; i++)
1886                 tl[i] = sched_domain_topology[i];
1887
1888         /*
1889          * Add the NUMA identity distance, aka single NODE.
1890          */
1891         tl[i++] = (struct sched_domain_topology_level){
1892                 .mask = sd_numa_mask,
1893                 .numa_level = 0,
1894                 SD_INIT_NAME(NODE)
1895         };
1896
1897         /*
1898          * .. and append 'j' levels of NUMA goodness.
1899          */
1900         for (j = 1; j < nr_levels; i++, j++) {
1901                 tl[i] = (struct sched_domain_topology_level){
1902                         .mask = sd_numa_mask,
1903                         .sd_flags = cpu_numa_flags,
1904                         .flags = SDTL_OVERLAP,
1905                         .numa_level = j,
1906                         SD_INIT_NAME(NUMA)
1907                 };
1908         }
1909
1910         sched_domain_topology = tl;
1911
1912         sched_domains_numa_levels = nr_levels;
1913         sched_max_numa_distance = sched_domains_numa_distance[nr_levels - 1];
1914
1915         init_numa_topology_type();
1916
1917         sched_numa_onlined_nodes = bitmap_alloc(nr_node_ids, GFP_KERNEL);
1918         if (!sched_numa_onlined_nodes)
1919                 return;
1920
1921         bitmap_zero(sched_numa_onlined_nodes, nr_node_ids);
1922         for_each_online_node(i)
1923                 bitmap_set(sched_numa_onlined_nodes, i, 1);
1924 }
1925
1926 static void __sched_domains_numa_masks_set(unsigned int node)
1927 {
1928         int i, j;
1929
1930         /*
1931          * NUMA masks are not built for offline nodes in sched_init_numa().
1932          * Thus, when a CPU of a never-onlined-before node gets plugged in,
1933          * adding that new CPU to the right NUMA masks is not sufficient: the
1934          * masks of that CPU's node must also be updated.
1935          */
1936         if (test_bit(node, sched_numa_onlined_nodes))
1937                 return;
1938
1939         bitmap_set(sched_numa_onlined_nodes, node, 1);
1940
1941         for (i = 0; i < sched_domains_numa_levels; i++) {
1942                 for (j = 0; j < nr_node_ids; j++) {
1943                         if (!node_online(j) || node == j)
1944                                 continue;
1945
1946                         if (node_distance(j, node) > sched_domains_numa_distance[i])
1947                                 continue;
1948
1949                         /* Add remote nodes in our masks */
1950                         cpumask_or(sched_domains_numa_masks[i][node],
1951                                    sched_domains_numa_masks[i][node],
1952                                    sched_domains_numa_masks[0][j]);
1953                 }
1954         }
1955
1956         /*
1957          * A new node has been brought up, potentially changing the topology
1958          * classification.
1959          *
1960          * Note that this is racy vs any use of sched_numa_topology_type :/
1961          */
1962         init_numa_topology_type();
1963 }
1964
1965 void sched_domains_numa_masks_set(unsigned int cpu)
1966 {
1967         int node = cpu_to_node(cpu);
1968         int i, j;
1969
1970         __sched_domains_numa_masks_set(node);
1971
1972         for (i = 0; i < sched_domains_numa_levels; i++) {
1973                 for (j = 0; j < nr_node_ids; j++) {
1974                         if (!node_online(j))
1975                                 continue;
1976
1977                         /* Set ourselves in the remote node's masks */
1978                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
1979                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
1980                 }
1981         }
1982 }
1983
1984 void sched_domains_numa_masks_clear(unsigned int cpu)
1985 {
1986         int i, j;
1987
1988         for (i = 0; i < sched_domains_numa_levels; i++) {
1989                 for (j = 0; j < nr_node_ids; j++)
1990                         cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
1991         }
1992 }
1993
1994 /*
1995  * sched_numa_find_closest() - given the NUMA topology, find the cpu
1996  *                             closest to @cpu from @cpumask.
1997  * cpumask: cpumask to find a cpu from
1998  * cpu: cpu to be close to
1999  *
2000  * returns: cpu, or nr_cpu_ids when nothing found.
2001  */
2002 int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
2003 {
2004         int i, j = cpu_to_node(cpu);
2005
2006         for (i = 0; i < sched_domains_numa_levels; i++) {
2007                 cpu = cpumask_any_and(cpus, sched_domains_numa_masks[i][j]);
2008                 if (cpu < nr_cpu_ids)
2009                         return cpu;
2010         }
2011         return nr_cpu_ids;
2012 }
2013
2014 #endif /* CONFIG_NUMA */
2015
2016 static int __sdt_alloc(const struct cpumask *cpu_map)
2017 {
2018         struct sched_domain_topology_level *tl;
2019         int j;
2020
2021         for_each_sd_topology(tl) {
2022                 struct sd_data *sdd = &tl->data;
2023
2024                 sdd->sd = alloc_percpu(struct sched_domain *);
2025                 if (!sdd->sd)
2026                         return -ENOMEM;
2027
2028                 sdd->sds = alloc_percpu(struct sched_domain_shared *);
2029                 if (!sdd->sds)
2030                         return -ENOMEM;
2031
2032                 sdd->sg = alloc_percpu(struct sched_group *);
2033                 if (!sdd->sg)
2034                         return -ENOMEM;
2035
2036                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
2037                 if (!sdd->sgc)
2038                         return -ENOMEM;
2039
2040                 for_each_cpu(j, cpu_map) {
2041                         struct sched_domain *sd;
2042                         struct sched_domain_shared *sds;
2043                         struct sched_group *sg;
2044                         struct sched_group_capacity *sgc;
2045
2046                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
2047                                         GFP_KERNEL, cpu_to_node(j));
2048                         if (!sd)
2049                                 return -ENOMEM;
2050
2051                         *per_cpu_ptr(sdd->sd, j) = sd;
2052
2053                         sds = kzalloc_node(sizeof(struct sched_domain_shared),
2054                                         GFP_KERNEL, cpu_to_node(j));
2055                         if (!sds)
2056                                 return -ENOMEM;
2057
2058                         *per_cpu_ptr(sdd->sds, j) = sds;
2059
2060                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
2061                                         GFP_KERNEL, cpu_to_node(j));
2062                         if (!sg)
2063                                 return -ENOMEM;
2064
2065                         sg->next = sg;
2066
2067                         *per_cpu_ptr(sdd->sg, j) = sg;
2068
2069                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
2070                                         GFP_KERNEL, cpu_to_node(j));
2071                         if (!sgc)
2072                                 return -ENOMEM;
2073
2074 #ifdef CONFIG_SCHED_DEBUG
2075                         sgc->id = j;
2076 #endif
2077
2078                         *per_cpu_ptr(sdd->sgc, j) = sgc;
2079                 }
2080         }
2081
2082         return 0;
2083 }
2084
2085 static void __sdt_free(const struct cpumask *cpu_map)
2086 {
2087         struct sched_domain_topology_level *tl;
2088         int j;
2089
2090         for_each_sd_topology(tl) {
2091                 struct sd_data *sdd = &tl->data;
2092
2093                 for_each_cpu(j, cpu_map) {
2094                         struct sched_domain *sd;
2095
2096                         if (sdd->sd) {
2097                                 sd = *per_cpu_ptr(sdd->sd, j);
2098                                 if (sd && (sd->flags & SD_OVERLAP))
2099                                         free_sched_groups(sd->groups, 0);
2100                                 kfree(*per_cpu_ptr(sdd->sd, j));
2101                         }
2102
2103                         if (sdd->sds)
2104                                 kfree(*per_cpu_ptr(sdd->sds, j));
2105                         if (sdd->sg)
2106                                 kfree(*per_cpu_ptr(sdd->sg, j));
2107                         if (sdd->sgc)
2108                                 kfree(*per_cpu_ptr(sdd->sgc, j));
2109                 }
2110                 free_percpu(sdd->sd);
2111                 sdd->sd = NULL;
2112                 free_percpu(sdd->sds);
2113                 sdd->sds = NULL;
2114                 free_percpu(sdd->sg);
2115                 sdd->sg = NULL;
2116                 free_percpu(sdd->sgc);
2117                 sdd->sgc = NULL;
2118         }
2119 }
2120
2121 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
2122                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
2123                 struct sched_domain *child, int cpu)
2124 {
2125         struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
2126
2127         if (child) {
2128                 sd->level = child->level + 1;
2129                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
2130                 child->parent = sd;
2131
2132                 if (!cpumask_subset(sched_domain_span(child),
2133                                     sched_domain_span(sd))) {
2134                         pr_err("BUG: arch topology borken\n");
2135 #ifdef CONFIG_SCHED_DEBUG
2136                         pr_err("     the %s domain not a subset of the %s domain\n",
2137                                         child->name, sd->name);
2138 #endif
2139                         /* Fixup, ensure @sd has at least @child CPUs. */
2140                         cpumask_or(sched_domain_span(sd),
2141                                    sched_domain_span(sd),
2142                                    sched_domain_span(child));
2143                 }
2144
2145         }
2146         set_domain_attribute(sd, attr);
2147
2148         return sd;
2149 }
2150
2151 /*
2152  * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
2153  * any two given CPUs at this (non-NUMA) topology level.
2154  */
2155 static bool topology_span_sane(struct sched_domain_topology_level *tl,
2156                               const struct cpumask *cpu_map, int cpu)
2157 {
2158         int i;
2159
2160         /* NUMA levels are allowed to overlap */
2161         if (tl->flags & SDTL_OVERLAP)
2162                 return true;
2163
2164         /*
2165          * Non-NUMA levels cannot partially overlap - they must be either
2166          * completely equal or completely disjoint. Otherwise we can end up
2167          * breaking the sched_group lists - i.e. a later get_group() pass
2168          * breaks the linking done for an earlier span.
2169          */
2170         for_each_cpu(i, cpu_map) {
2171                 if (i == cpu)
2172                         continue;
2173                 /*
2174                  * We should 'and' all those masks with 'cpu_map' to exactly
2175                  * match the topology we're about to build, but that can only
2176                  * remove CPUs, which only lessens our ability to detect
2177                  * overlaps
2178                  */
2179                 if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
2180                     cpumask_intersects(tl->mask(cpu), tl->mask(i)))
2181                         return false;
2182         }
2183
2184         return true;
2185 }
2186
2187 /*
2188  * Build sched domains for a given set of CPUs and attach the sched domains
2189  * to the individual CPUs
2190  */
2191 static int
2192 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
2193 {
2194         enum s_alloc alloc_state = sa_none;
2195         struct sched_domain *sd;
2196         struct s_data d;
2197         struct rq *rq = NULL;
2198         int i, ret = -ENOMEM;
2199         bool has_asym = false;
2200
2201         if (WARN_ON(cpumask_empty(cpu_map)))
2202                 goto error;
2203
2204         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
2205         if (alloc_state != sa_rootdomain)
2206                 goto error;
2207
2208         /* Set up domains for CPUs specified by the cpu_map: */
2209         for_each_cpu(i, cpu_map) {
2210                 struct sched_domain_topology_level *tl;
2211
2212                 sd = NULL;
2213                 for_each_sd_topology(tl) {
2214
2215                         if (WARN_ON(!topology_span_sane(tl, cpu_map, i)))
2216                                 goto error;
2217
2218                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
2219
2220                         has_asym |= sd->flags & SD_ASYM_CPUCAPACITY;
2221
2222                         if (tl == sched_domain_topology)
2223                                 *per_cpu_ptr(d.sd, i) = sd;
2224                         if (tl->flags & SDTL_OVERLAP)
2225                                 sd->flags |= SD_OVERLAP;
2226                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
2227                                 break;
2228                 }
2229         }
2230
2231         /* Build the groups for the domains */
2232         for_each_cpu(i, cpu_map) {
2233                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2234                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
2235                         if (sd->flags & SD_OVERLAP) {
2236                                 if (build_overlap_sched_groups(sd, i))
2237                                         goto error;
2238                         } else {
2239                                 if (build_sched_groups(sd, i))
2240                                         goto error;
2241                         }
2242                 }
2243         }
2244
2245         /* Calculate CPU capacity for physical packages and nodes */
2246         for (i = nr_cpumask_bits-1; i >= 0; i--) {
2247                 if (!cpumask_test_cpu(i, cpu_map))
2248                         continue;
2249
2250                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2251                         claim_allocations(i, sd);
2252                         init_sched_groups_capacity(i, sd);
2253                 }
2254         }
2255
2256         /* Attach the domains */
2257         rcu_read_lock();
2258         for_each_cpu(i, cpu_map) {
2259                 rq = cpu_rq(i);
2260                 sd = *per_cpu_ptr(d.sd, i);
2261
2262                 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
2263                 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
2264                         WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
2265
2266                 cpu_attach_domain(sd, d.rd, i);
2267         }
2268         rcu_read_unlock();
2269
2270         if (has_asym)
2271                 static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
2272
2273         if (rq && sched_debug_verbose) {
2274                 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
2275                         cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
2276         }
2277
2278         ret = 0;
2279 error:
2280         __free_domain_allocs(&d, alloc_state, cpu_map);
2281
2282         return ret;
2283 }
2284
2285 /* Current sched domains: */
2286 static cpumask_var_t                    *doms_cur;
2287
2288 /* Number of sched domains in 'doms_cur': */
2289 static int                              ndoms_cur;
2290
2291 /* Attributes of custom domains in 'doms_cur' */
2292 static struct sched_domain_attr         *dattr_cur;
2293
2294 /*
2295  * Special case: If a kmalloc() of a doms_cur partition (array of
2296  * cpumask) fails, then fallback to a single sched domain,
2297  * as determined by the single cpumask fallback_doms.
2298  */
2299 static cpumask_var_t                    fallback_doms;
2300
2301 /*
2302  * arch_update_cpu_topology lets virtualized architectures update the
2303  * CPU core maps. It is supposed to return 1 if the topology changed
2304  * or 0 if it stayed the same.
2305  */
2306 int __weak arch_update_cpu_topology(void)
2307 {
2308         return 0;
2309 }
2310
2311 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
2312 {
2313         int i;
2314         cpumask_var_t *doms;
2315
2316         doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
2317         if (!doms)
2318                 return NULL;
2319         for (i = 0; i < ndoms; i++) {
2320                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
2321                         free_sched_domains(doms, i);
2322                         return NULL;
2323                 }
2324         }
2325         return doms;
2326 }
2327
2328 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
2329 {
2330         unsigned int i;
2331         for (i = 0; i < ndoms; i++)
2332                 free_cpumask_var(doms[i]);
2333         kfree(doms);
2334 }
2335
2336 /*
2337  * Set up scheduler domains and groups.  For now this just excludes isolated
2338  * CPUs, but could be used to exclude other special cases in the future.
2339  */
2340 int sched_init_domains(const struct cpumask *cpu_map)
2341 {
2342         int err;
2343
2344         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
2345         zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
2346         zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
2347
2348         arch_update_cpu_topology();
2349         asym_cpu_capacity_scan();
2350         ndoms_cur = 1;
2351         doms_cur = alloc_sched_domains(ndoms_cur);
2352         if (!doms_cur)
2353                 doms_cur = &fallback_doms;
2354         cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
2355         err = build_sched_domains(doms_cur[0], NULL);
2356
2357         return err;
2358 }
2359
2360 /*
2361  * Detach sched domains from a group of CPUs specified in cpu_map
2362  * These CPUs will now be attached to the NULL domain
2363  */
2364 static void detach_destroy_domains(const struct cpumask *cpu_map)
2365 {
2366         unsigned int cpu = cpumask_any(cpu_map);
2367         int i;
2368
2369         if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
2370                 static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
2371
2372         rcu_read_lock();
2373         for_each_cpu(i, cpu_map)
2374                 cpu_attach_domain(NULL, &def_root_domain, i);
2375         rcu_read_unlock();
2376 }
2377
2378 /* handle null as "default" */
2379 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
2380                         struct sched_domain_attr *new, int idx_new)
2381 {
2382         struct sched_domain_attr tmp;
2383
2384         /* Fast path: */
2385         if (!new && !cur)
2386                 return 1;
2387
2388         tmp = SD_ATTR_INIT;
2389
2390         return !memcmp(cur ? (cur + idx_cur) : &tmp,
2391                         new ? (new + idx_new) : &tmp,
2392                         sizeof(struct sched_domain_attr));
2393 }
2394
2395 /*
2396  * Partition sched domains as specified by the 'ndoms_new'
2397  * cpumasks in the array doms_new[] of cpumasks. This compares
2398  * doms_new[] to the current sched domain partitioning, doms_cur[].
2399  * It destroys each deleted domain and builds each new domain.
2400  *
2401  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
2402  * The masks don't intersect (don't overlap.) We should setup one
2403  * sched domain for each mask. CPUs not in any of the cpumasks will
2404  * not be load balanced. If the same cpumask appears both in the
2405  * current 'doms_cur' domains and in the new 'doms_new', we can leave
2406  * it as it is.
2407  *
2408  * The passed in 'doms_new' should be allocated using
2409  * alloc_sched_domains.  This routine takes ownership of it and will
2410  * free_sched_domains it when done with it. If the caller failed the
2411  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
2412  * and partition_sched_domains() will fallback to the single partition
2413  * 'fallback_doms', it also forces the domains to be rebuilt.
2414  *
2415  * If doms_new == NULL it will be replaced with cpu_online_mask.
2416  * ndoms_new == 0 is a special case for destroying existing domains,
2417  * and it will not create the default domain.
2418  *
2419  * Call with hotplug lock and sched_domains_mutex held
2420  */
2421 void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
2422                                     struct sched_domain_attr *dattr_new)
2423 {
2424         bool __maybe_unused has_eas = false;
2425         int i, j, n;
2426         int new_topology;
2427
2428         lockdep_assert_held(&sched_domains_mutex);
2429
2430         /* Let the architecture update CPU core mappings: */
2431         new_topology = arch_update_cpu_topology();
2432         /* Trigger rebuilding CPU capacity asymmetry data */
2433         if (new_topology)
2434                 asym_cpu_capacity_scan();
2435
2436         if (!doms_new) {
2437                 WARN_ON_ONCE(dattr_new);
2438                 n = 0;
2439                 doms_new = alloc_sched_domains(1);
2440                 if (doms_new) {
2441                         n = 1;
2442                         cpumask_and(doms_new[0], cpu_active_mask,
2443                                     housekeeping_cpumask(HK_FLAG_DOMAIN));
2444                 }
2445         } else {
2446                 n = ndoms_new;
2447         }
2448
2449         /* Destroy deleted domains: */
2450         for (i = 0; i < ndoms_cur; i++) {
2451                 for (j = 0; j < n && !new_topology; j++) {
2452                         if (cpumask_equal(doms_cur[i], doms_new[j]) &&
2453                             dattrs_equal(dattr_cur, i, dattr_new, j)) {
2454                                 struct root_domain *rd;
2455
2456                                 /*
2457                                  * This domain won't be destroyed and as such
2458                                  * its dl_bw->total_bw needs to be cleared.  It
2459                                  * will be recomputed in function
2460                                  * update_tasks_root_domain().
2461                                  */
2462                                 rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
2463                                 dl_clear_root_domain(rd);
2464                                 goto match1;
2465                         }
2466                 }
2467                 /* No match - a current sched domain not in new doms_new[] */
2468                 detach_destroy_domains(doms_cur[i]);
2469 match1:
2470                 ;
2471         }
2472
2473         n = ndoms_cur;
2474         if (!doms_new) {
2475                 n = 0;
2476                 doms_new = &fallback_doms;
2477                 cpumask_and(doms_new[0], cpu_active_mask,
2478                             housekeeping_cpumask(HK_FLAG_DOMAIN));
2479         }
2480
2481         /* Build new domains: */
2482         for (i = 0; i < ndoms_new; i++) {
2483                 for (j = 0; j < n && !new_topology; j++) {
2484                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2485                             dattrs_equal(dattr_new, i, dattr_cur, j))
2486                                 goto match2;
2487                 }
2488                 /* No match - add a new doms_new */
2489                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
2490 match2:
2491                 ;
2492         }
2493
2494 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
2495         /* Build perf. domains: */
2496         for (i = 0; i < ndoms_new; i++) {
2497                 for (j = 0; j < n && !sched_energy_update; j++) {
2498                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2499                             cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
2500                                 has_eas = true;
2501                                 goto match3;
2502                         }
2503                 }
2504                 /* No match - add perf. domains for a new rd */
2505                 has_eas |= build_perf_domains(doms_new[i]);
2506 match3:
2507                 ;
2508         }
2509         sched_energy_set(has_eas);
2510 #endif
2511
2512         /* Remember the new sched domains: */
2513         if (doms_cur != &fallback_doms)
2514                 free_sched_domains(doms_cur, ndoms_cur);
2515
2516         kfree(dattr_cur);
2517         doms_cur = doms_new;
2518         dattr_cur = dattr_new;
2519         ndoms_cur = ndoms_new;
2520
2521         update_sched_domain_debugfs();
2522 }
2523
2524 /*
2525  * Call with hotplug lock held
2526  */
2527 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
2528                              struct sched_domain_attr *dattr_new)
2529 {
2530         mutex_lock(&sched_domains_mutex);
2531         partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
2532         mutex_unlock(&sched_domains_mutex);
2533 }