kernel/sched/topology.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Scheduler topology setup/handling methods
   4  */
   5
   6 DEFINE_MUTEX(sched_domains_mutex);
   7
   8 /* Protected by sched_domains_mutex: */
   9 static cpumask_var_t sched_domains_tmpmask;
  10 static cpumask_var_t sched_domains_tmpmask2;
  11
  12 #ifdef CONFIG_SCHED_DEBUG
  13
  14 static int __init sched_debug_setup(char *str)
  15 {
  16         sched_debug_verbose = true;
  17
  18         return 0;
  19 }
  20 early_param("sched_verbose", sched_debug_setup);
  21
  22 static inline bool sched_debug(void)
  23 {
  24         return sched_debug_verbose;
  25 }
  26
  27 #define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name },
  28 const struct sd_flag_debug sd_flag_debug[] = {
  29 #include <linux/sched/sd_flags.h>
  30 };
  31 #undef SD_FLAG
  32
  33 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
  34                                   struct cpumask *groupmask)
  35 {
  36         struct sched_group *group = sd->groups;
  37         unsigned long flags = sd->flags;
  38         unsigned int idx;
  39
  40         cpumask_clear(groupmask);
  41
  42         printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
  43         printk(KERN_CONT "span=%*pbl level=%s\n",
  44                cpumask_pr_args(sched_domain_span(sd)), sd->name);
  45
  46         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
  47                 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
  48         }
  49         if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
  50                 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
  51         }
  52
  53         for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {
  54                 unsigned int flag = BIT(idx);
  55                 unsigned int meta_flags = sd_flag_debug[idx].meta_flags;
  56
  57                 if ((meta_flags & SDF_SHARED_CHILD) && sd->child &&
  58                     !(sd->child->flags & flag))
  59                         printk(KERN_ERR "ERROR: flag %s set here but not in child\n",
  60                                sd_flag_debug[idx].name);
  61
  62                 if ((meta_flags & SDF_SHARED_PARENT) && sd->parent &&
  63                     !(sd->parent->flags & flag))
  64                         printk(KERN_ERR "ERROR: flag %s set here but not in parent\n",
  65                                sd_flag_debug[idx].name);
  66         }
  67
  68         printk(KERN_DEBUG "%*s groups:", level + 1, "");
  69         do {
  70                 if (!group) {
  71                         printk("\n");
  72                         printk(KERN_ERR "ERROR: group is NULL\n");
  73                         break;
  74                 }
  75
  76                 if (cpumask_empty(sched_group_span(group))) {
  77                         printk(KERN_CONT "\n");
  78                         printk(KERN_ERR "ERROR: empty group\n");
  79                         break;
  80                 }
  81
  82                 if (!(sd->flags & SD_OVERLAP) &&
  83                     cpumask_intersects(groupmask, sched_group_span(group))) {
  84                         printk(KERN_CONT "\n");
  85                         printk(KERN_ERR "ERROR: repeated CPUs\n");
  86                         break;
  87                 }
  88
  89                 cpumask_or(groupmask, groupmask, sched_group_span(group));
  90
  91                 printk(KERN_CONT " %d:{ span=%*pbl",
  92                                 group->sgc->id,
  93                                 cpumask_pr_args(sched_group_span(group)));
  94
  95                 if ((sd->flags & SD_OVERLAP) &&
  96                     !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
  97                         printk(KERN_CONT " mask=%*pbl",
  98                                 cpumask_pr_args(group_balance_mask(group)));
  99                 }
 100
 101                 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
 102                         printk(KERN_CONT " cap=%lu", group->sgc->capacity);
 103
 104                 if (group == sd->groups && sd->child &&
 105                     !cpumask_equal(sched_domain_span(sd->child),
 106                                    sched_group_span(group))) {
 107                         printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
 108                 }
 109
 110                 printk(KERN_CONT " }");
 111
 112                 group = group->next;
 113
 114                 if (group != sd->groups)
 115                         printk(KERN_CONT ",");
 116
 117         } while (group != sd->groups);
 118         printk(KERN_CONT "\n");
 119
 120         if (!cpumask_equal(sched_domain_span(sd), groupmask))
 121                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
 122
 123         if (sd->parent &&
 124             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
 125                 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
 126         return 0;
 127 }
 128
 129 static void sched_domain_debug(struct sched_domain *sd, int cpu)
 130 {
 131         int level = 0;
 132
 133         if (!sched_debug_verbose)
 134                 return;
 135
 136         if (!sd) {
 137                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
 138                 return;
 139         }
 140
 141         printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
 142
 143         for (;;) {
 144                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
 145                         break;
 146                 level++;
 147                 sd = sd->parent;
 148                 if (!sd)
 149                         break;
 150         }
 151 }
 152 #else /* !CONFIG_SCHED_DEBUG */
 153
 154 # define sched_debug_verbose 0
 155 # define sched_domain_debug(sd, cpu) do { } while (0)
 156 static inline bool sched_debug(void)
 157 {
 158         return false;
 159 }
 160 #endif /* CONFIG_SCHED_DEBUG */
 161
 162 /* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
 163 #define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) |
 164 static const unsigned int SD_DEGENERATE_GROUPS_MASK =
 165 #include <linux/sched/sd_flags.h>
 166 0;
 167 #undef SD_FLAG
 168
 169 static int sd_degenerate(struct sched_domain *sd)
 170 {
 171         if (cpumask_weight(sched_domain_span(sd)) == 1)
 172                 return 1;
 173
 174         /* Following flags need at least 2 groups */
 175         if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) &&
 176             (sd->groups != sd->groups->next))
 177                 return 0;
 178
 179         /* Following flags don't use groups */
 180         if (sd->flags & (SD_WAKE_AFFINE))
 181                 return 0;
 182
 183         return 1;
 184 }
 185
 186 static int
 187 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 188 {
 189         unsigned long cflags = sd->flags, pflags = parent->flags;
 190
 191         if (sd_degenerate(parent))
 192                 return 1;
 193
 194         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
 195                 return 0;
 196
 197         /* Flags needing groups don't count if only 1 group in parent */
 198         if (parent->groups == parent->groups->next)
 199                 pflags &= ~SD_DEGENERATE_GROUPS_MASK;
 200
 201         if (~cflags & pflags)
 202                 return 0;
 203
 204         return 1;
 205 }
 206
 207 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 208 DEFINE_STATIC_KEY_FALSE(sched_energy_present);
 209 unsigned int sysctl_sched_energy_aware = 1;
 210 DEFINE_MUTEX(sched_energy_mutex);
 211 bool sched_energy_update;
 212
 213 void rebuild_sched_domains_energy(void)
 214 {
 215         mutex_lock(&sched_energy_mutex);
 216         sched_energy_update = true;
 217         rebuild_sched_domains();
 218         sched_energy_update = false;
 219         mutex_unlock(&sched_energy_mutex);
 220 }
 221
 222 #ifdef CONFIG_PROC_SYSCTL
 223 int sched_energy_aware_handler(struct ctl_table *table, int write,
 224                 void *buffer, size_t *lenp, loff_t *ppos)
 225 {
 226         int ret, state;
 227
 228         if (write && !capable(CAP_SYS_ADMIN))
 229                 return -EPERM;
 230
 231         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 232         if (!ret && write) {
 233                 state = static_branch_unlikely(&sched_energy_present);
 234                 if (state != sysctl_sched_energy_aware)
 235                         rebuild_sched_domains_energy();
 236         }
 237
 238         return ret;
 239 }
 240 #endif
 241
 242 static void free_pd(struct perf_domain *pd)
 243 {
 244         struct perf_domain *tmp;
 245
 246         while (pd) {
 247                 tmp = pd->next;
 248                 kfree(pd);
 249                 pd = tmp;
 250         }
 251 }
 252
 253 static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
 254 {
 255         while (pd) {
 256                 if (cpumask_test_cpu(cpu, perf_domain_span(pd)))
 257                         return pd;
 258                 pd = pd->next;
 259         }
 260
 261         return NULL;
 262 }
 263
 264 static struct perf_domain *pd_init(int cpu)
 265 {
 266         struct em_perf_domain *obj = em_cpu_get(cpu);
 267         struct perf_domain *pd;
 268
 269         if (!obj) {
 270                 if (sched_debug())
 271                         pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
 272                 return NULL;
 273         }
 274
 275         pd = kzalloc(sizeof(*pd), GFP_KERNEL);
 276         if (!pd)
 277                 return NULL;
 278         pd->em_pd = obj;
 279
 280         return pd;
 281 }
 282
 283 static void perf_domain_debug(const struct cpumask *cpu_map,
 284                                                 struct perf_domain *pd)
 285 {
 286         if (!sched_debug() || !pd)
 287                 return;
 288
 289         printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));
 290
 291         while (pd) {
 292                 printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }",
 293                                 cpumask_first(perf_domain_span(pd)),
 294                                 cpumask_pr_args(perf_domain_span(pd)),
 295                                 em_pd_nr_perf_states(pd->em_pd));
 296                 pd = pd->next;
 297         }
 298
 299         printk(KERN_CONT "\n");
 300 }
 301
 302 static void destroy_perf_domain_rcu(struct rcu_head *rp)
 303 {
 304         struct perf_domain *pd;
 305
 306         pd = container_of(rp, struct perf_domain, rcu);
 307         free_pd(pd);
 308 }
 309
 310 static void sched_energy_set(bool has_eas)
 311 {
 312         if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
 313                 if (sched_debug())
 314                         pr_info("%s: stopping EAS\n", __func__);
 315                 static_branch_disable_cpuslocked(&sched_energy_present);
 316         } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
 317                 if (sched_debug())
 318                         pr_info("%s: starting EAS\n", __func__);
 319                 static_branch_enable_cpuslocked(&sched_energy_present);
 320         }
 321 }
 322
 323 /*
 324  * EAS can be used on a root domain if it meets all the following conditions:
 325  *    1. an Energy Model (EM) is available;
 326  *    2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
 327  *    3. no SMT is detected.
 328  *    4. the EM complexity is low enough to keep scheduling overheads low;
 329  *    5. schedutil is driving the frequency of all CPUs of the rd;
 330  *    6. frequency invariance support is present;
 331  *
 332  * The complexity of the Energy Model is defined as:
 333  *
 334  *              C = nr_pd * (nr_cpus + nr_ps)
 335  *
 336  * with parameters defined as:
 337  *  - nr_pd:    the number of performance domains
 338  *  - nr_cpus:  the number of CPUs
 339  *  - nr_ps:    the sum of the number of performance states of all performance
 340  *              domains (for example, on a system with 2 performance domains,
 341  *              with 10 performance states each, nr_ps = 2 * 10 = 20).
 342  *
 343  * It is generally not a good idea to use such a model in the wake-up path on
 344  * very complex platforms because of the associated scheduling overheads. The
 345  * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs
 346  * with per-CPU DVFS and less than 8 performance states each, for example.
 347  */
 348 #define EM_MAX_COMPLEXITY 2048
 349
 350 extern struct cpufreq_governor schedutil_gov;
 351 static bool build_perf_domains(const struct cpumask *cpu_map)
 352 {
 353         int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map);
 354         struct perf_domain *pd = NULL, *tmp;
 355         int cpu = cpumask_first(cpu_map);
 356         struct root_domain *rd = cpu_rq(cpu)->rd;
 357         struct cpufreq_policy *policy;
 358         struct cpufreq_governor *gov;
 359
 360         if (!sysctl_sched_energy_aware)
 361                 goto free;
 362
 363         /* EAS is enabled for asymmetric CPU capacity topologies. */
 364         if (!per_cpu(sd_asym_cpucapacity, cpu)) {
 365                 if (sched_debug()) {
 366                         pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n",
 367                                         cpumask_pr_args(cpu_map));
 368                 }
 369                 goto free;
 370         }
 371
 372         /* EAS definitely does *not* handle SMT */
 373         if (sched_smt_active()) {
 374                 pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n",
 375                         cpumask_pr_args(cpu_map));
 376                 goto free;
 377         }
 378
 379         if (!arch_scale_freq_invariant()) {
 380                 if (sched_debug()) {
 381                         pr_warn("rd %*pbl: Disabling EAS: frequency-invariant load tracking not yet supported",
 382                                 cpumask_pr_args(cpu_map));
 383                 }
 384                 goto free;
 385         }
 386
 387         for_each_cpu(i, cpu_map) {
 388                 /* Skip already covered CPUs. */
 389                 if (find_pd(pd, i))
 390                         continue;
 391
 392                 /* Do not attempt EAS if schedutil is not being used. */
 393                 policy = cpufreq_cpu_get(i);
 394                 if (!policy)
 395                         goto free;
 396                 gov = policy->governor;
 397                 cpufreq_cpu_put(policy);
 398                 if (gov != &schedutil_gov) {
 399                         if (rd->pd)
 400                                 pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n",
 401                                                 cpumask_pr_args(cpu_map));
 402                         goto free;
 403                 }
 404
 405                 /* Create the new pd and add it to the local list. */
 406                 tmp = pd_init(i);
 407                 if (!tmp)
 408                         goto free;
 409                 tmp->next = pd;
 410                 pd = tmp;
 411
 412                 /*
 413                  * Count performance domains and performance states for the
 414                  * complexity check.
 415                  */
 416                 nr_pd++;
 417                 nr_ps += em_pd_nr_perf_states(pd->em_pd);
 418         }
 419
 420         /* Bail out if the Energy Model complexity is too high. */
 421         if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) {
 422                 WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n",
 423                                                 cpumask_pr_args(cpu_map));
 424                 goto free;
 425         }
 426
 427         perf_domain_debug(cpu_map, pd);
 428
 429         /* Attach the new list of performance domains to the root domain. */
 430         tmp = rd->pd;
 431         rcu_assign_pointer(rd->pd, pd);
 432         if (tmp)
 433                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 434
 435         return !!pd;
 436
 437 free:
 438         free_pd(pd);
 439         tmp = rd->pd;
 440         rcu_assign_pointer(rd->pd, NULL);
 441         if (tmp)
 442                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 443
 444         return false;
 445 }
 446 #else
 447 static void free_pd(struct perf_domain *pd) { }
 448 #endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/
 449
 450 static void free_rootdomain(struct rcu_head *rcu)
 451 {
 452         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
 453
 454         cpupri_cleanup(&rd->cpupri);
 455         cpudl_cleanup(&rd->cpudl);
 456         free_cpumask_var(rd->dlo_mask);
 457         free_cpumask_var(rd->rto_mask);
 458         free_cpumask_var(rd->online);
 459         free_cpumask_var(rd->span);
 460         free_pd(rd->pd);
 461         kfree(rd);
 462 }
 463
 464 void rq_attach_root(struct rq *rq, struct root_domain *rd)
 465 {
 466         struct root_domain *old_rd = NULL;
 467         unsigned long flags;
 468
 469         raw_spin_rq_lock_irqsave(rq, flags);
 470
 471         if (rq->rd) {
 472                 old_rd = rq->rd;
 473
 474                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
 475                         set_rq_offline(rq);
 476
 477                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 478
 479                 /*
 480                  * If we dont want to free the old_rd yet then
 481                  * set old_rd to NULL to skip the freeing later
 482                  * in this function:
 483                  */
 484                 if (!atomic_dec_and_test(&old_rd->refcount))
 485                         old_rd = NULL;
 486         }
 487
 488         atomic_inc(&rd->refcount);
 489         rq->rd = rd;
 490
 491         cpumask_set_cpu(rq->cpu, rd->span);
 492         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
 493                 set_rq_online(rq);
 494
 495         raw_spin_rq_unlock_irqrestore(rq, flags);
 496
 497         if (old_rd)
 498                 call_rcu(&old_rd->rcu, free_rootdomain);
 499 }
 500
 501 void sched_get_rd(struct root_domain *rd)
 502 {
 503         atomic_inc(&rd->refcount);
 504 }
 505
 506 void sched_put_rd(struct root_domain *rd)
 507 {
 508         if (!atomic_dec_and_test(&rd->refcount))
 509                 return;
 510
 511         call_rcu(&rd->rcu, free_rootdomain);
 512 }
 513
 514 static int init_rootdomain(struct root_domain *rd)
 515 {
 516         if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
 517                 goto out;
 518         if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
 519                 goto free_span;
 520         if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
 521                 goto free_online;
 522         if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
 523                 goto free_dlo_mask;
 524
 525 #ifdef HAVE_RT_PUSH_IPI
 526         rd->rto_cpu = -1;
 527         raw_spin_lock_init(&rd->rto_lock);
 528         rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
 529 #endif
 530
 531         rd->visit_gen = 0;
 532         init_dl_bw(&rd->dl_bw);
 533         if (cpudl_init(&rd->cpudl) != 0)
 534                 goto free_rto_mask;
 535
 536         if (cpupri_init(&rd->cpupri) != 0)
 537                 goto free_cpudl;
 538         return 0;
 539
 540 free_cpudl:
 541         cpudl_cleanup(&rd->cpudl);
 542 free_rto_mask:
 543         free_cpumask_var(rd->rto_mask);
 544 free_dlo_mask:
 545         free_cpumask_var(rd->dlo_mask);
 546 free_online:
 547         free_cpumask_var(rd->online);
 548 free_span:
 549         free_cpumask_var(rd->span);
 550 out:
 551         return -ENOMEM;
 552 }
 553
 554 /*
 555  * By default the system creates a single root-domain with all CPUs as
 556  * members (mimicking the global state we have today).
 557  */
 558 struct root_domain def_root_domain;
 559
 560 void init_defrootdomain(void)
 561 {
 562         init_rootdomain(&def_root_domain);
 563
 564         atomic_set(&def_root_domain.refcount, 1);
 565 }
 566
 567 static struct root_domain *alloc_rootdomain(void)
 568 {
 569         struct root_domain *rd;
 570
 571         rd = kzalloc(sizeof(*rd), GFP_KERNEL);
 572         if (!rd)
 573                 return NULL;
 574
 575         if (init_rootdomain(rd) != 0) {
 576                 kfree(rd);
 577                 return NULL;
 578         }
 579
 580         return rd;
 581 }
 582
 583 static void free_sched_groups(struct sched_group *sg, int free_sgc)
 584 {
 585         struct sched_group *tmp, *first;
 586
 587         if (!sg)
 588                 return;
 589
 590         first = sg;
 591         do {
 592                 tmp = sg->next;
 593
 594                 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
 595                         kfree(sg->sgc);
 596
 597                 if (atomic_dec_and_test(&sg->ref))
 598                         kfree(sg);
 599                 sg = tmp;
 600         } while (sg != first);
 601 }
 602
 603 static void destroy_sched_domain(struct sched_domain *sd)
 604 {
 605         /*
 606          * A normal sched domain may have multiple group references, an
 607          * overlapping domain, having private groups, only one.  Iterate,
 608          * dropping group/capacity references, freeing where none remain.
 609          */
 610         free_sched_groups(sd->groups, 1);
 611
 612         if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
 613                 kfree(sd->shared);
 614         kfree(sd);
 615 }
 616
 617 static void destroy_sched_domains_rcu(struct rcu_head *rcu)
 618 {
 619         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
 620
 621         while (sd) {
 622                 struct sched_domain *parent = sd->parent;
 623                 destroy_sched_domain(sd);
 624                 sd = parent;
 625         }
 626 }
 627
 628 static void destroy_sched_domains(struct sched_domain *sd)
 629 {
 630         if (sd)
 631                 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
 632 }
 633
 634 /*
 635  * Keep a special pointer to the highest sched_domain that has
 636  * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
 637  * allows us to avoid some pointer chasing select_idle_sibling().
 638  *
 639  * Also keep a unique ID per domain (we use the first CPU number in
 640  * the cpumask of the domain), this allows us to quickly tell if
 641  * two CPUs are in the same cache domain, see cpus_share_cache().
 642  */
 643 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
 644 DEFINE_PER_CPU(int, sd_llc_size);
 645 DEFINE_PER_CPU(int, sd_llc_id);
 646 DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
 647 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
 648 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 649 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
 650 DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
 651
 652 static void update_top_cache_domain(int cpu)
 653 {
 654         struct sched_domain_shared *sds = NULL;
 655         struct sched_domain *sd;
 656         int id = cpu;
 657         int size = 1;
 658
 659         sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
 660         if (sd) {
 661                 id = cpumask_first(sched_domain_span(sd));
 662                 size = cpumask_weight(sched_domain_span(sd));
 663                 sds = sd->shared;
 664         }
 665
 666         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
 667         per_cpu(sd_llc_size, cpu) = size;
 668         per_cpu(sd_llc_id, cpu) = id;
 669         rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
 670
 671         sd = lowest_flag_domain(cpu, SD_NUMA);
 672         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 673
 674         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
 675         rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
 676
 677         sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY_FULL);
 678         rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
 679 }
 680
 681 /*
 682  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
 683  * hold the hotplug lock.
 684  */
 685 static void
 686 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 687 {
 688         struct rq *rq = cpu_rq(cpu);
 689         struct sched_domain *tmp;
 690
 691         /* Remove the sched domains which do not contribute to scheduling. */
 692         for (tmp = sd; tmp; ) {
 693                 struct sched_domain *parent = tmp->parent;
 694                 if (!parent)
 695                         break;
 696
 697                 if (sd_parent_degenerate(tmp, parent)) {
 698                         tmp->parent = parent->parent;
 699                         if (parent->parent)
 700                                 parent->parent->child = tmp;
 701                         /*
 702                          * Transfer SD_PREFER_SIBLING down in case of a
 703                          * degenerate parent; the spans match for this
 704                          * so the property transfers.
 705                          */
 706                         if (parent->flags & SD_PREFER_SIBLING)
 707                                 tmp->flags |= SD_PREFER_SIBLING;
 708                         destroy_sched_domain(parent);
 709                 } else
 710                         tmp = tmp->parent;
 711         }
 712
 713         if (sd && sd_degenerate(sd)) {
 714                 tmp = sd;
 715                 sd = sd->parent;
 716                 destroy_sched_domain(tmp);
 717                 if (sd) {
 718                         struct sched_group *sg = sd->groups;
 719
 720                         /*
 721                          * sched groups hold the flags of the child sched
 722                          * domain for convenience. Clear such flags since
 723                          * the child is being destroyed.
 724                          */
 725                         do {
 726                                 sg->flags = 0;
 727                         } while (sg != sd->groups);
 728
 729                         sd->child = NULL;
 730                 }
 731         }
 732
 733         sched_domain_debug(sd, cpu);
 734
 735         rq_attach_root(rq, rd);
 736         tmp = rq->sd;
 737         rcu_assign_pointer(rq->sd, sd);
 738         dirty_sched_domain_sysctl(cpu);
 739         destroy_sched_domains(tmp);
 740
 741         update_top_cache_domain(cpu);
 742 }
 743
 744 struct s_data {
 745         struct sched_domain * __percpu *sd;
 746         struct root_domain      *rd;
 747 };
 748
 749 enum s_alloc {
 750         sa_rootdomain,
 751         sa_sd,
 752         sa_sd_storage,
 753         sa_none,
 754 };
 755
 756 /*
 757  * Return the canonical balance CPU for this group, this is the first CPU
 758  * of this group that's also in the balance mask.
 759  *
 760  * The balance mask are all those CPUs that could actually end up at this
 761  * group. See build_balance_mask().
 762  *
 763  * Also see should_we_balance().
 764  */
 765 int group_balance_cpu(struct sched_group *sg)
 766 {
 767         return cpumask_first(group_balance_mask(sg));
 768 }
 769
 770
 771 /*
 772  * NUMA topology (first read the regular topology blurb below)
 773  *
 774  * Given a node-distance table, for example:
 775  *
 776  *   node   0   1   2   3
 777  *     0:  10  20  30  20
 778  *     1:  20  10  20  30
 779  *     2:  30  20  10  20
 780  *     3:  20  30  20  10
 781  *
 782  * which represents a 4 node ring topology like:
 783  *
 784  *   0 ----- 1
 785  *   |       |
 786  *   |       |
 787  *   |       |
 788  *   3 ----- 2
 789  *
 790  * We want to construct domains and groups to represent this. The way we go
 791  * about doing this is to build the domains on 'hops'. For each NUMA level we
 792  * construct the mask of all nodes reachable in @level hops.
 793  *
 794  * For the above NUMA topology that gives 3 levels:
 795  *
 796  * NUMA-2       0-3             0-3             0-3             0-3
 797  *  groups:     {0-1,3},{1-3}   {0-2},{0,2-3}   {1-3},{0-1,3}   {0,2-3},{0-2}
 798  *
 799  * NUMA-1       0-1,3           0-2             1-3             0,2-3
 800  *  groups:     {0},{1},{3}     {0},{1},{2}     {1},{2},{3}     {0},{2},{3}
 801  *
 802  * NUMA-0       0               1               2               3
 803  *
 804  *
 805  * As can be seen; things don't nicely line up as with the regular topology.
 806  * When we iterate a domain in child domain chunks some nodes can be
 807  * represented multiple times -- hence the "overlap" naming for this part of
 808  * the topology.
 809  *
 810  * In order to minimize this overlap, we only build enough groups to cover the
 811  * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
 812  *
 813  * Because:
 814  *
 815  *  - the first group of each domain is its child domain; this
 816  *    gets us the first 0-1,3
 817  *  - the only uncovered node is 2, who's child domain is 1-3.
 818  *
 819  * However, because of the overlap, computing a unique CPU for each group is
 820  * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
 821  * groups include the CPUs of Node-0, while those CPUs would not in fact ever
 822  * end up at those groups (they would end up in group: 0-1,3).
 823  *
 824  * To correct this we have to introduce the group balance mask. This mask
 825  * will contain those CPUs in the group that can reach this group given the
 826  * (child) domain tree.
 827  *
 828  * With this we can once again compute balance_cpu and sched_group_capacity
 829  * relations.
 830  *
 831  * XXX include words on how balance_cpu is unique and therefore can be
 832  * used for sched_group_capacity links.
 833  *
 834  *
 835  * Another 'interesting' topology is:
 836  *
 837  *   node   0   1   2   3
 838  *     0:  10  20  20  30
 839  *     1:  20  10  20  20
 840  *     2:  20  20  10  20
 841  *     3:  30  20  20  10
 842  *
 843  * Which looks a little like:
 844  *
 845  *   0 ----- 1
 846  *   |     / |
 847  *   |   /   |
 848  *   | /     |
 849  *   2 ----- 3
 850  *
 851  * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
 852  * are not.
 853  *
 854  * This leads to a few particularly weird cases where the sched_domain's are
 855  * not of the same number for each CPU. Consider:
 856  *
 857  * NUMA-2       0-3                                             0-3
 858  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
 859  *
 860  * NUMA-1       0-2             0-3             0-3             1-3
 861  *
 862  * NUMA-0       0               1               2               3
 863  *
 864  */
 865
 866
 867 /*
 868  * Build the balance mask; it contains only those CPUs that can arrive at this
 869  * group and should be considered to continue balancing.
 870  *
 871  * We do this during the group creation pass, therefore the group information
 872  * isn't complete yet, however since each group represents a (child) domain we
 873  * can fully construct this using the sched_domain bits (which are already
 874  * complete).
 875  */
 876 static void
 877 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
 878 {
 879         const struct cpumask *sg_span = sched_group_span(sg);
 880         struct sd_data *sdd = sd->private;
 881         struct sched_domain *sibling;
 882         int i;
 883
 884         cpumask_clear(mask);
 885
 886         for_each_cpu(i, sg_span) {
 887                 sibling = *per_cpu_ptr(sdd->sd, i);
 888
 889                 /*
 890                  * Can happen in the asymmetric case, where these siblings are
 891                  * unused. The mask will not be empty because those CPUs that
 892                  * do have the top domain _should_ span the domain.
 893                  */
 894                 if (!sibling->child)
 895                         continue;
 896
 897                 /* If we would not end up here, we can't continue from here */
 898                 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
 899                         continue;
 900
 901                 cpumask_set_cpu(i, mask);
 902         }
 903
 904         /* We must not have empty masks here */
 905         WARN_ON_ONCE(cpumask_empty(mask));
 906 }
 907
 908 /*
 909  * XXX: This creates per-node group entries; since the load-balancer will
 910  * immediately access remote memory to construct this group's load-balance
 911  * statistics having the groups node local is of dubious benefit.
 912  */
 913 static struct sched_group *
 914 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
 915 {
 916         struct sched_group *sg;
 917         struct cpumask *sg_span;
 918
 919         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
 920                         GFP_KERNEL, cpu_to_node(cpu));
 921
 922         if (!sg)
 923                 return NULL;
 924
 925         sg_span = sched_group_span(sg);
 926         if (sd->child) {
 927                 cpumask_copy(sg_span, sched_domain_span(sd->child));
 928                 sg->flags = sd->child->flags;
 929         } else {
 930                 cpumask_copy(sg_span, sched_domain_span(sd));
 931         }
 932
 933         atomic_inc(&sg->ref);
 934         return sg;
 935 }
 936
 937 static void init_overlap_sched_group(struct sched_domain *sd,
 938                                      struct sched_group *sg)
 939 {
 940         struct cpumask *mask = sched_domains_tmpmask2;
 941         struct sd_data *sdd = sd->private;
 942         struct cpumask *sg_span;
 943         int cpu;
 944
 945         build_balance_mask(sd, sg, mask);
 946         cpu = cpumask_first(mask);
 947
 948         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
 949         if (atomic_inc_return(&sg->sgc->ref) == 1)
 950                 cpumask_copy(group_balance_mask(sg), mask);
 951         else
 952                 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
 953
 954         /*
 955          * Initialize sgc->capacity such that even if we mess up the
 956          * domains and no possible iteration will get us here, we won't
 957          * die on a /0 trap.
 958          */
 959         sg_span = sched_group_span(sg);
 960         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
 961         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
 962         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
 963 }
 964
 965 static struct sched_domain *
 966 find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling)
 967 {
 968         /*
 969          * The proper descendant would be the one whose child won't span out
 970          * of sd
 971          */
 972         while (sibling->child &&
 973                !cpumask_subset(sched_domain_span(sibling->child),
 974                                sched_domain_span(sd)))
 975                 sibling = sibling->child;
 976
 977         /*
 978          * As we are referencing sgc across different topology level, we need
 979          * to go down to skip those sched_domains which don't contribute to
 980          * scheduling because they will be degenerated in cpu_attach_domain
 981          */
 982         while (sibling->child &&
 983                cpumask_equal(sched_domain_span(sibling->child),
 984                              sched_domain_span(sibling)))
 985                 sibling = sibling->child;
 986
 987         return sibling;
 988 }
 989
 990 static int
 991 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 992 {
 993         struct sched_group *first = NULL, *last = NULL, *sg;
 994         const struct cpumask *span = sched_domain_span(sd);
 995         struct cpumask *covered = sched_domains_tmpmask;
 996         struct sd_data *sdd = sd->private;
 997         struct sched_domain *sibling;
 998         int i;
 999
1000         cpumask_clear(covered);
1001
1002         for_each_cpu_wrap(i, span, cpu) {
1003                 struct cpumask *sg_span;
1004
1005                 if (cpumask_test_cpu(i, covered))
1006                         continue;
1007
1008                 sibling = *per_cpu_ptr(sdd->sd, i);
1009
1010                 /*
1011                  * Asymmetric node setups can result in situations where the
1012                  * domain tree is of unequal depth, make sure to skip domains
1013                  * that already cover the entire range.
1014                  *
1015                  * In that case build_sched_domains() will have terminated the
1016                  * iteration early and our sibling sd spans will be empty.
1017                  * Domains should always include the CPU they're built on, so
1018                  * check that.
1019                  */
1020                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
1021                         continue;
1022
1023                 /*
1024                  * Usually we build sched_group by sibling's child sched_domain
1025                  * But for machines whose NUMA diameter are 3 or above, we move
1026                  * to build sched_group by sibling's proper descendant's child
1027                  * domain because sibling's child sched_domain will span out of
1028                  * the sched_domain being built as below.
1029                  *
1030                  * Smallest diameter=3 topology is:
1031                  *
1032                  *   node   0   1   2   3
1033                  *     0:  10  20  30  40
1034                  *     1:  20  10  20  30
1035                  *     2:  30  20  10  20
1036                  *     3:  40  30  20  10
1037                  *
1038                  *   0 --- 1 --- 2 --- 3
1039                  *
1040                  * NUMA-3       0-3             N/A             N/A             0-3
1041                  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
1042                  *
1043                  * NUMA-2       0-2             0-3             0-3             1-3
1044                  *  groups:     {0-1},{1-3}     {0-2},{2-3}     {1-3},{0-1}     {2-3},{0-2}
1045                  *
1046                  * NUMA-1       0-1             0-2             1-3             2-3
1047                  *  groups:     {0},{1}         {1},{2},{0}     {2},{3},{1}     {3},{2}
1048                  *
1049                  * NUMA-0       0               1               2               3
1050                  *
1051                  * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
1052                  * group span isn't a subset of the domain span.
1053                  */
1054                 if (sibling->child &&
1055                     !cpumask_subset(sched_domain_span(sibling->child), span))
1056                         sibling = find_descended_sibling(sd, sibling);
1057
1058                 sg = build_group_from_child_sched_domain(sibling, cpu);
1059                 if (!sg)
1060                         goto fail;
1061
1062                 sg_span = sched_group_span(sg);
1063                 cpumask_or(covered, covered, sg_span);
1064
1065                 init_overlap_sched_group(sibling, sg);
1066
1067                 if (!first)
1068                         first = sg;
1069                 if (last)
1070                         last->next = sg;
1071                 last = sg;
1072                 last->next = first;
1073         }
1074         sd->groups = first;
1075
1076         return 0;
1077
1078 fail:
1079         free_sched_groups(first, 0);
1080
1081         return -ENOMEM;
1082 }
1083
1084
1085 /*
1086  * Package topology (also see the load-balance blurb in fair.c)
1087  *
1088  * The scheduler builds a tree structure to represent a number of important
1089  * topology features. By default (default_topology[]) these include:
1090  *
1091  *  - Simultaneous multithreading (SMT)
1092  *  - Multi-Core Cache (MC)
1093  *  - Package (DIE)
1094  *
1095  * Where the last one more or less denotes everything up to a NUMA node.
1096  *
1097  * The tree consists of 3 primary data structures:
1098  *
1099  *      sched_domain -> sched_group -> sched_group_capacity
1100  *          ^ ^             ^ ^
1101  *          `-'             `-'
1102  *
1103  * The sched_domains are per-CPU and have a two way link (parent & child) and
1104  * denote the ever growing mask of CPUs belonging to that level of topology.
1105  *
1106  * Each sched_domain has a circular (double) linked list of sched_group's, each
1107  * denoting the domains of the level below (or individual CPUs in case of the
1108  * first domain level). The sched_group linked by a sched_domain includes the
1109  * CPU of that sched_domain [*].
1110  *
1111  * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
1112  *
1113  * CPU   0   1   2   3   4   5   6   7
1114  *
1115  * DIE  [                             ]
1116  * MC   [             ] [             ]
1117  * SMT  [     ] [     ] [     ] [     ]
1118  *
1119  *  - or -
1120  *
1121  * DIE  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
1122  * MC   0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
1123  * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
1124  *
1125  * CPU   0   1   2   3   4   5   6   7
1126  *
1127  * One way to think about it is: sched_domain moves you up and down among these
1128  * topology levels, while sched_group moves you sideways through it, at child
1129  * domain granularity.
1130  *
1131  * sched_group_capacity ensures each unique sched_group has shared storage.
1132  *
1133  * There are two related construction problems, both require a CPU that
1134  * uniquely identify each group (for a given domain):
1135  *
1136  *  - The first is the balance_cpu (see should_we_balance() and the
1137  *    load-balance blub in fair.c); for each group we only want 1 CPU to
1138  *    continue balancing at a higher domain.
1139  *
1140  *  - The second is the sched_group_capacity; we want all identical groups
1141  *    to share a single sched_group_capacity.
1142  *
1143  * Since these topologies are exclusive by construction. That is, its
1144  * impossible for an SMT thread to belong to multiple cores, and cores to
1145  * be part of multiple caches. There is a very clear and unique location
1146  * for each CPU in the hierarchy.
1147  *
1148  * Therefore computing a unique CPU for each group is trivial (the iteration
1149  * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
1150  * group), we can simply pick the first CPU in each group.
1151  *
1152  *
1153  * [*] in other words, the first group of each domain is its child domain.
1154  */
1155
1156 static struct sched_group *get_group(int cpu, struct sd_data *sdd)
1157 {
1158         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1159         struct sched_domain *child = sd->child;
1160         struct sched_group *sg;
1161         bool already_visited;
1162
1163         if (child)
1164                 cpu = cpumask_first(sched_domain_span(child));
1165
1166         sg = *per_cpu_ptr(sdd->sg, cpu);
1167         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
1168
1169         /* Increase refcounts for claim_allocations: */
1170         already_visited = atomic_inc_return(&sg->ref) > 1;
1171         /* sgc visits should follow a similar trend as sg */
1172         WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));
1173
1174         /* If we have already visited that group, it's already initialized. */
1175         if (already_visited)
1176                 return sg;
1177
1178         if (child) {
1179                 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
1180                 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
1181                 sg->flags = child->flags;
1182         } else {
1183                 cpumask_set_cpu(cpu, sched_group_span(sg));
1184                 cpumask_set_cpu(cpu, group_balance_mask(sg));
1185         }
1186
1187         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
1188         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1189         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1190
1191         return sg;
1192 }
1193
1194 /*
1195  * build_sched_groups will build a circular linked list of the groups
1196  * covered by the given span, will set each group's ->cpumask correctly,
1197  * and will initialize their ->sgc.
1198  *
1199  * Assumes the sched_domain tree is fully constructed
1200  */
1201 static int
1202 build_sched_groups(struct sched_domain *sd, int cpu)
1203 {
1204         struct sched_group *first = NULL, *last = NULL;
1205         struct sd_data *sdd = sd->private;
1206         const struct cpumask *span = sched_domain_span(sd);
1207         struct cpumask *covered;
1208         int i;
1209
1210         lockdep_assert_held(&sched_domains_mutex);
1211         covered = sched_domains_tmpmask;
1212
1213         cpumask_clear(covered);
1214
1215         for_each_cpu_wrap(i, span, cpu) {
1216                 struct sched_group *sg;
1217
1218                 if (cpumask_test_cpu(i, covered))
1219                         continue;
1220
1221                 sg = get_group(i, sdd);
1222
1223                 cpumask_or(covered, covered, sched_group_span(sg));
1224
1225                 if (!first)
1226                         first = sg;
1227                 if (last)
1228                         last->next = sg;
1229                 last = sg;
1230         }
1231         last->next = first;
1232         sd->groups = first;
1233
1234         return 0;
1235 }
1236
1237 /*
1238  * Initialize sched groups cpu_capacity.
1239  *
1240  * cpu_capacity indicates the capacity of sched group, which is used while
1241  * distributing the load between different sched groups in a sched domain.
1242  * Typically cpu_capacity for all the groups in a sched domain will be same
1243  * unless there are asymmetries in the topology. If there are asymmetries,
1244  * group having more cpu_capacity will pickup more load compared to the
1245  * group having less cpu_capacity.
1246  */
1247 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
1248 {
1249         struct sched_group *sg = sd->groups;
1250
1251         WARN_ON(!sg);
1252
1253         do {
1254                 int cpu, max_cpu = -1;
1255
1256                 sg->group_weight = cpumask_weight(sched_group_span(sg));
1257
1258                 if (!(sd->flags & SD_ASYM_PACKING))
1259                         goto next;
1260
1261                 for_each_cpu(cpu, sched_group_span(sg)) {
1262                         if (max_cpu < 0)
1263                                 max_cpu = cpu;
1264                         else if (sched_asym_prefer(cpu, max_cpu))
1265                                 max_cpu = cpu;
1266                 }
1267                 sg->asym_prefer_cpu = max_cpu;
1268
1269 next:
1270                 sg = sg->next;
1271         } while (sg != sd->groups);
1272
1273         if (cpu != group_balance_cpu(sg))
1274                 return;
1275
1276         update_group_capacity(sd, cpu);
1277 }
1278
1279 /*
1280  * Asymmetric CPU capacity bits
1281  */
1282 struct asym_cap_data {
1283         struct list_head link;
1284         unsigned long capacity;
1285         unsigned long cpus[];
1286 };
1287
1288 /*
1289  * Set of available CPUs grouped by their corresponding capacities
1290  * Each list entry contains a CPU mask reflecting CPUs that share the same
1291  * capacity.
1292  * The lifespan of data is unlimited.
1293  */
1294 static LIST_HEAD(asym_cap_list);
1295
1296 #define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus)
1297
1298 /*
1299  * Verify whether there is any CPU capacity asymmetry in a given sched domain.
1300  * Provides sd_flags reflecting the asymmetry scope.
1301  */
1302 static inline int
1303 asym_cpu_capacity_classify(const struct cpumask *sd_span,
1304                            const struct cpumask *cpu_map)
1305 {
1306         struct asym_cap_data *entry;
1307         int count = 0, miss = 0;
1308
1309         /*
1310          * Count how many unique CPU capacities this domain spans across
1311          * (compare sched_domain CPUs mask with ones representing  available
1312          * CPUs capacities). Take into account CPUs that might be offline:
1313          * skip those.
1314          */
1315         list_for_each_entry(entry, &asym_cap_list, link) {
1316                 if (cpumask_intersects(sd_span, cpu_capacity_span(entry)))
1317                         ++count;
1318                 else if (cpumask_intersects(cpu_map, cpu_capacity_span(entry)))
1319                         ++miss;
1320         }
1321
1322         WARN_ON_ONCE(!count && !list_empty(&asym_cap_list));
1323
1324         /* No asymmetry detected */
1325         if (count < 2)
1326                 return 0;
1327         /* Some of the available CPU capacity values have not been detected */
1328         if (miss)
1329                 return SD_ASYM_CPUCAPACITY;
1330
1331         /* Full asymmetry */
1332         return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL;
1333
1334 }
1335
1336 static inline void asym_cpu_capacity_update_data(int cpu)
1337 {
1338         unsigned long capacity = arch_scale_cpu_capacity(cpu);
1339         struct asym_cap_data *entry = NULL;
1340
1341         list_for_each_entry(entry, &asym_cap_list, link) {
1342                 if (capacity == entry->capacity)
1343                         goto done;
1344         }
1345
1346         entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
1347         if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n"))
1348                 return;
1349         entry->capacity = capacity;
1350         list_add(&entry->link, &asym_cap_list);
1351 done:
1352         __cpumask_set_cpu(cpu, cpu_capacity_span(entry));
1353 }
1354
1355 /*
1356  * Build-up/update list of CPUs grouped by their capacities
1357  * An update requires explicit request to rebuild sched domains
1358  * with state indicating CPU topology changes.
1359  */
1360 static void asym_cpu_capacity_scan(void)
1361 {
1362         struct asym_cap_data *entry, *next;
1363         int cpu;
1364
1365         list_for_each_entry(entry, &asym_cap_list, link)
1366                 cpumask_clear(cpu_capacity_span(entry));
1367
1368         for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_TYPE_DOMAIN))
1369                 asym_cpu_capacity_update_data(cpu);
1370
1371         list_for_each_entry_safe(entry, next, &asym_cap_list, link) {
1372                 if (cpumask_empty(cpu_capacity_span(entry))) {
1373                         list_del(&entry->link);
1374                         kfree(entry);
1375                 }
1376         }
1377
1378         /*
1379          * Only one capacity value has been detected i.e. this system is symmetric.
1380          * No need to keep this data around.
1381          */
1382         if (list_is_singular(&asym_cap_list)) {
1383                 entry = list_first_entry(&asym_cap_list, typeof(*entry), link);
1384                 list_del(&entry->link);
1385                 kfree(entry);
1386         }
1387 }
1388
1389 /*
1390  * Initializers for schedule domains
1391  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
1392  */
1393
1394 static int default_relax_domain_level = -1;
1395 int sched_domain_level_max;
1396
1397 static int __init setup_relax_domain_level(char *str)
1398 {
1399         if (kstrtoint(str, 0, &default_relax_domain_level))
1400                 pr_warn("Unable to set relax_domain_level\n");
1401
1402         return 1;
1403 }
1404 __setup("relax_domain_level=", setup_relax_domain_level);
1405
1406 static void set_domain_attribute(struct sched_domain *sd,
1407                                  struct sched_domain_attr *attr)
1408 {
1409         int request;
1410
1411         if (!attr || attr->relax_domain_level < 0) {
1412                 if (default_relax_domain_level < 0)
1413                         return;
1414                 request = default_relax_domain_level;
1415         } else
1416                 request = attr->relax_domain_level;
1417
1418         if (sd->level > request) {
1419                 /* Turn off idle balance on this domain: */
1420                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
1421         }
1422 }
1423
1424 static void __sdt_free(const struct cpumask *cpu_map);
1425 static int __sdt_alloc(const struct cpumask *cpu_map);
1426
1427 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
1428                                  const struct cpumask *cpu_map)
1429 {
1430         switch (what) {
1431         case sa_rootdomain:
1432                 if (!atomic_read(&d->rd->refcount))
1433                         free_rootdomain(&d->rd->rcu);
1434                 fallthrough;
1435         case sa_sd:
1436                 free_percpu(d->sd);
1437                 fallthrough;
1438         case sa_sd_storage:
1439                 __sdt_free(cpu_map);
1440                 fallthrough;
1441         case sa_none:
1442                 break;
1443         }
1444 }
1445
1446 static enum s_alloc
1447 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1448 {
1449         memset(d, 0, sizeof(*d));
1450
1451         if (__sdt_alloc(cpu_map))
1452                 return sa_sd_storage;
1453         d->sd = alloc_percpu(struct sched_domain *);
1454         if (!d->sd)
1455                 return sa_sd_storage;
1456         d->rd = alloc_rootdomain();
1457         if (!d->rd)
1458                 return sa_sd;
1459
1460         return sa_rootdomain;
1461 }
1462
1463 /*
1464  * NULL the sd_data elements we've used to build the sched_domain and
1465  * sched_group structure so that the subsequent __free_domain_allocs()
1466  * will not free the data we're using.
1467  */
1468 static void claim_allocations(int cpu, struct sched_domain *sd)
1469 {
1470         struct sd_data *sdd = sd->private;
1471
1472         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1473         *per_cpu_ptr(sdd->sd, cpu) = NULL;
1474
1475         if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1476                 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1477
1478         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1479                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1480
1481         if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1482                 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1483 }
1484
1485 #ifdef CONFIG_NUMA
1486 enum numa_topology_type sched_numa_topology_type;
1487
1488 static int                      sched_domains_numa_levels;
1489 static int                      sched_domains_curr_level;
1490
1491 int                             sched_max_numa_distance;
1492 static int                      *sched_domains_numa_distance;
1493 static struct cpumask           ***sched_domains_numa_masks;
1494 #endif
1495
1496 /*
1497  * SD_flags allowed in topology descriptions.
1498  *
1499  * These flags are purely descriptive of the topology and do not prescribe
1500  * behaviour. Behaviour is artificial and mapped in the below sd_init()
1501  * function:
1502  *
1503  *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
1504  *   SD_SHARE_PKG_RESOURCES - describes shared caches
1505  *   SD_NUMA                - describes NUMA topologies
1506  *
1507  * Odd one out, which beside describing the topology has a quirk also
1508  * prescribes the desired behaviour that goes along with it:
1509  *
1510  *   SD_ASYM_PACKING        - describes SMT quirks
1511  */
1512 #define TOPOLOGY_SD_FLAGS               \
1513         (SD_SHARE_CPUCAPACITY   |       \
1514          SD_SHARE_PKG_RESOURCES |       \
1515          SD_NUMA                |       \
1516          SD_ASYM_PACKING)
1517
1518 static struct sched_domain *
1519 sd_init(struct sched_domain_topology_level *tl,
1520         const struct cpumask *cpu_map,
1521         struct sched_domain *child, int cpu)
1522 {
1523         struct sd_data *sdd = &tl->data;
1524         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1525         int sd_id, sd_weight, sd_flags = 0;
1526         struct cpumask *sd_span;
1527
1528 #ifdef CONFIG_NUMA
1529         /*
1530          * Ugly hack to pass state to sd_numa_mask()...
1531          */
1532         sched_domains_curr_level = tl->numa_level;
1533 #endif
1534
1535         sd_weight = cpumask_weight(tl->mask(cpu));
1536
1537         if (tl->sd_flags)
1538                 sd_flags = (*tl->sd_flags)();
1539         if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1540                         "wrong sd_flags in topology description\n"))
1541                 sd_flags &= TOPOLOGY_SD_FLAGS;
1542
1543         *sd = (struct sched_domain){
1544                 .min_interval           = sd_weight,
1545                 .max_interval           = 2*sd_weight,
1546                 .busy_factor            = 16,
1547                 .imbalance_pct          = 117,
1548
1549                 .cache_nice_tries       = 0,
1550
1551                 .flags                  = 1*SD_BALANCE_NEWIDLE
1552                                         | 1*SD_BALANCE_EXEC
1553                                         | 1*SD_BALANCE_FORK
1554                                         | 0*SD_BALANCE_WAKE
1555                                         | 1*SD_WAKE_AFFINE
1556                                         | 0*SD_SHARE_CPUCAPACITY
1557                                         | 0*SD_SHARE_PKG_RESOURCES
1558                                         | 0*SD_SERIALIZE
1559                                         | 1*SD_PREFER_SIBLING
1560                                         | 0*SD_NUMA
1561                                         | sd_flags
1562                                         ,
1563
1564                 .last_balance           = jiffies,
1565                 .balance_interval       = sd_weight,
1566                 .max_newidle_lb_cost    = 0,
1567                 .last_decay_max_lb_cost = jiffies,
1568                 .child                  = child,
1569 #ifdef CONFIG_SCHED_DEBUG
1570                 .name                   = tl->name,
1571 #endif
1572         };
1573
1574         sd_span = sched_domain_span(sd);
1575         cpumask_and(sd_span, cpu_map, tl->mask(cpu));
1576         sd_id = cpumask_first(sd_span);
1577
1578         sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map);
1579
1580         WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) ==
1581                   (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY),
1582                   "CPU capacity asymmetry not supported on SMT\n");
1583
1584         /*
1585          * Convert topological properties into behaviour.
1586          */
1587         /* Don't attempt to spread across CPUs of different capacities. */
1588         if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child)
1589                 sd->child->flags &= ~SD_PREFER_SIBLING;
1590
1591         if (sd->flags & SD_SHARE_CPUCAPACITY) {
1592                 sd->imbalance_pct = 110;
1593
1594         } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1595                 sd->imbalance_pct = 117;
1596                 sd->cache_nice_tries = 1;
1597
1598 #ifdef CONFIG_NUMA
1599         } else if (sd->flags & SD_NUMA) {
1600                 sd->cache_nice_tries = 2;
1601
1602                 sd->flags &= ~SD_PREFER_SIBLING;
1603                 sd->flags |= SD_SERIALIZE;
1604                 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
1605                         sd->flags &= ~(SD_BALANCE_EXEC |
1606                                        SD_BALANCE_FORK |
1607                                        SD_WAKE_AFFINE);
1608                 }
1609
1610 #endif
1611         } else {
1612                 sd->cache_nice_tries = 1;
1613         }
1614
1615         /*
1616          * For all levels sharing cache; connect a sched_domain_shared
1617          * instance.
1618          */
1619         if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1620                 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1621                 atomic_inc(&sd->shared->ref);
1622                 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1623         }
1624
1625         sd->private = sdd;
1626
1627         return sd;
1628 }
1629
1630 /*
1631  * Topology list, bottom-up.
1632  */
1633 static struct sched_domain_topology_level default_topology[] = {
1634 #ifdef CONFIG_SCHED_SMT
1635         { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1636 #endif
1637
1638 #ifdef CONFIG_SCHED_CLUSTER
1639         { cpu_clustergroup_mask, cpu_cluster_flags, SD_INIT_NAME(CLS) },
1640 #endif
1641
1642 #ifdef CONFIG_SCHED_MC
1643         { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1644 #endif
1645         { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1646         { NULL, },
1647 };
1648
1649 static struct sched_domain_topology_level *sched_domain_topology =
1650         default_topology;
1651 static struct sched_domain_topology_level *sched_domain_topology_saved;
1652
1653 #define for_each_sd_topology(tl)                        \
1654         for (tl = sched_domain_topology; tl->mask; tl++)
1655
1656 void set_sched_topology(struct sched_domain_topology_level *tl)
1657 {
1658         if (WARN_ON_ONCE(sched_smp_initialized))
1659                 return;
1660
1661         sched_domain_topology = tl;
1662         sched_domain_topology_saved = NULL;
1663 }
1664
1665 #ifdef CONFIG_NUMA
1666
1667 static const struct cpumask *sd_numa_mask(int cpu)
1668 {
1669         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1670 }
1671
1672 static void sched_numa_warn(const char *str)
1673 {
1674         static int done = false;
1675         int i,j;
1676
1677         if (done)
1678                 return;
1679
1680         done = true;
1681
1682         printk(KERN_WARNING "ERROR: %s\n\n", str);
1683
1684         for (i = 0; i < nr_node_ids; i++) {
1685                 printk(KERN_WARNING "  ");
1686                 for (j = 0; j < nr_node_ids; j++) {
1687                         if (!node_state(i, N_CPU) || !node_state(j, N_CPU))
1688                                 printk(KERN_CONT "(%02d) ", node_distance(i,j));
1689                         else
1690                                 printk(KERN_CONT " %02d  ", node_distance(i,j));
1691                 }
1692                 printk(KERN_CONT "\n");
1693         }
1694         printk(KERN_WARNING "\n");
1695 }
1696
1697 bool find_numa_distance(int distance)
1698 {
1699         bool found = false;
1700         int i, *distances;
1701
1702         if (distance == node_distance(0, 0))
1703                 return true;
1704
1705         rcu_read_lock();
1706         distances = rcu_dereference(sched_domains_numa_distance);
1707         if (!distances)
1708                 goto unlock;
1709         for (i = 0; i < sched_domains_numa_levels; i++) {
1710                 if (distances[i] == distance) {
1711                         found = true;
1712                         break;
1713                 }
1714         }
1715 unlock:
1716         rcu_read_unlock();
1717
1718         return found;
1719 }
1720
1721 #define for_each_cpu_node_but(n, nbut)          \
1722         for_each_node_state(n, N_CPU)           \
1723                 if (n == nbut)                  \
1724                         continue;               \
1725                 else
1726
1727 /*
1728  * A system can have three types of NUMA topology:
1729  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1730  * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1731  * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1732  *
1733  * The difference between a glueless mesh topology and a backplane
1734  * topology lies in whether communication between not directly
1735  * connected nodes goes through intermediary nodes (where programs
1736  * could run), or through backplane controllers. This affects
1737  * placement of programs.
1738  *
1739  * The type of topology can be discerned with the following tests:
1740  * - If the maximum distance between any nodes is 1 hop, the system
1741  *   is directly connected.
1742  * - If for two nodes A and B, located N > 1 hops away from each other,
1743  *   there is an intermediary node C, which is < N hops away from both
1744  *   nodes A and B, the system is a glueless mesh.
1745  */
1746 static void init_numa_topology_type(int offline_node)
1747 {
1748         int a, b, c, n;
1749
1750         n = sched_max_numa_distance;
1751
1752         if (sched_domains_numa_levels <= 2) {
1753                 sched_numa_topology_type = NUMA_DIRECT;
1754                 return;
1755         }
1756
1757         for_each_cpu_node_but(a, offline_node) {
1758                 for_each_cpu_node_but(b, offline_node) {
1759                         /* Find two nodes furthest removed from each other. */
1760                         if (node_distance(a, b) < n)
1761                                 continue;
1762
1763                         /* Is there an intermediary node between a and b? */
1764                         for_each_cpu_node_but(c, offline_node) {
1765                                 if (node_distance(a, c) < n &&
1766                                     node_distance(b, c) < n) {
1767                                         sched_numa_topology_type =
1768                                                         NUMA_GLUELESS_MESH;
1769                                         return;
1770                                 }
1771                         }
1772
1773                         sched_numa_topology_type = NUMA_BACKPLANE;
1774                         return;
1775                 }
1776         }
1777
1778         pr_err("Failed to find a NUMA topology type, defaulting to DIRECT\n");
1779         sched_numa_topology_type = NUMA_DIRECT;
1780 }
1781
1782
1783 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
1784
1785 void sched_init_numa(int offline_node)
1786 {
1787         struct sched_domain_topology_level *tl;
1788         unsigned long *distance_map;
1789         int nr_levels = 0;
1790         int i, j;
1791         int *distances;
1792         struct cpumask ***masks;
1793
1794         /*
1795          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1796          * unique distances in the node_distance() table.
1797          */
1798         distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
1799         if (!distance_map)
1800                 return;
1801
1802         bitmap_zero(distance_map, NR_DISTANCE_VALUES);
1803         for_each_cpu_node_but(i, offline_node) {
1804                 for_each_cpu_node_but(j, offline_node) {
1805                         int distance = node_distance(i, j);
1806
1807                         if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
1808                                 sched_numa_warn("Invalid distance value range");
1809                                 bitmap_free(distance_map);
1810                                 return;
1811                         }
1812
1813                         bitmap_set(distance_map, distance, 1);
1814                 }
1815         }
1816         /*
1817          * We can now figure out how many unique distance values there are and
1818          * allocate memory accordingly.
1819          */
1820         nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);
1821
1822         distances = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
1823         if (!distances) {
1824                 bitmap_free(distance_map);
1825                 return;
1826         }
1827
1828         for (i = 0, j = 0; i < nr_levels; i++, j++) {
1829                 j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
1830                 distances[i] = j;
1831         }
1832         rcu_assign_pointer(sched_domains_numa_distance, distances);
1833
1834         bitmap_free(distance_map);
1835
1836         /*
1837          * 'nr_levels' contains the number of unique distances
1838          *
1839          * The sched_domains_numa_distance[] array includes the actual distance
1840          * numbers.
1841          */
1842
1843         /*
1844          * Here, we should temporarily reset sched_domains_numa_levels to 0.
1845          * If it fails to allocate memory for array sched_domains_numa_masks[][],
1846          * the array will contain less then 'nr_levels' members. This could be
1847          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1848          * in other functions.
1849          *
1850          * We reset it to 'nr_levels' at the end of this function.
1851          */
1852         sched_domains_numa_levels = 0;
1853
1854         masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
1855         if (!masks)
1856                 return;
1857
1858         /*
1859          * Now for each level, construct a mask per node which contains all
1860          * CPUs of nodes that are that many hops away from us.
1861          */
1862         for (i = 0; i < nr_levels; i++) {
1863                 masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1864                 if (!masks[i])
1865                         return;
1866
1867                 for_each_cpu_node_but(j, offline_node) {
1868                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1869                         int k;
1870
1871                         if (!mask)
1872                                 return;
1873
1874                         masks[i][j] = mask;
1875
1876                         for_each_cpu_node_but(k, offline_node) {
1877                                 if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
1878                                         sched_numa_warn("Node-distance not symmetric");
1879
1880                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
1881                                         continue;
1882
1883                                 cpumask_or(mask, mask, cpumask_of_node(k));
1884                         }
1885                 }
1886         }
1887         rcu_assign_pointer(sched_domains_numa_masks, masks);
1888
1889         /* Compute default topology size */
1890         for (i = 0; sched_domain_topology[i].mask; i++);
1891
1892         tl = kzalloc((i + nr_levels + 1) *
1893                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1894         if (!tl)
1895                 return;
1896
1897         /*
1898          * Copy the default topology bits..
1899          */
1900         for (i = 0; sched_domain_topology[i].mask; i++)
1901                 tl[i] = sched_domain_topology[i];
1902
1903         /*
1904          * Add the NUMA identity distance, aka single NODE.
1905          */
1906         tl[i++] = (struct sched_domain_topology_level){
1907                 .mask = sd_numa_mask,
1908                 .numa_level = 0,
1909                 SD_INIT_NAME(NODE)
1910         };
1911
1912         /*
1913          * .. and append 'j' levels of NUMA goodness.
1914          */
1915         for (j = 1; j < nr_levels; i++, j++) {
1916                 tl[i] = (struct sched_domain_topology_level){
1917                         .mask = sd_numa_mask,
1918                         .sd_flags = cpu_numa_flags,
1919                         .flags = SDTL_OVERLAP,
1920                         .numa_level = j,
1921                         SD_INIT_NAME(NUMA)
1922                 };
1923         }
1924
1925         sched_domain_topology_saved = sched_domain_topology;
1926         sched_domain_topology = tl;
1927
1928         sched_domains_numa_levels = nr_levels;
1929         WRITE_ONCE(sched_max_numa_distance, sched_domains_numa_distance[nr_levels - 1]);
1930
1931         init_numa_topology_type(offline_node);
1932 }
1933
1934
1935 static void sched_reset_numa(void)
1936 {
1937         int nr_levels, *distances;
1938         struct cpumask ***masks;
1939
1940         nr_levels = sched_domains_numa_levels;
1941         sched_domains_numa_levels = 0;
1942         sched_max_numa_distance = 0;
1943         sched_numa_topology_type = NUMA_DIRECT;
1944         distances = sched_domains_numa_distance;
1945         rcu_assign_pointer(sched_domains_numa_distance, NULL);
1946         masks = sched_domains_numa_masks;
1947         rcu_assign_pointer(sched_domains_numa_masks, NULL);
1948         if (distances || masks) {
1949                 int i, j;
1950
1951                 synchronize_rcu();
1952                 kfree(distances);
1953                 for (i = 0; i < nr_levels && masks; i++) {
1954                         if (!masks[i])
1955                                 continue;
1956                         for_each_node(j)
1957                                 kfree(masks[i][j]);
1958                         kfree(masks[i]);
1959                 }
1960                 kfree(masks);
1961         }
1962         if (sched_domain_topology_saved) {
1963                 kfree(sched_domain_topology);
1964                 sched_domain_topology = sched_domain_topology_saved;
1965                 sched_domain_topology_saved = NULL;
1966         }
1967 }
1968
1969 /*
1970  * Call with hotplug lock held
1971  */
1972 void sched_update_numa(int cpu, bool online)
1973 {
1974         int node;
1975
1976         node = cpu_to_node(cpu);
1977         /*
1978          * Scheduler NUMA topology is updated when the first CPU of a
1979          * node is onlined or the last CPU of a node is offlined.
1980          */
1981         if (cpumask_weight(cpumask_of_node(node)) != 1)
1982                 return;
1983
1984         sched_reset_numa();
1985         sched_init_numa(online ? NUMA_NO_NODE : node);
1986 }
1987
1988 void sched_domains_numa_masks_set(unsigned int cpu)
1989 {
1990         int node = cpu_to_node(cpu);
1991         int i, j;
1992
1993         for (i = 0; i < sched_domains_numa_levels; i++) {
1994                 for (j = 0; j < nr_node_ids; j++) {
1995                         if (!node_state(j, N_CPU))
1996                                 continue;
1997
1998                         /* Set ourselves in the remote node's masks */
1999                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
2000                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
2001                 }
2002         }
2003 }
2004
2005 void sched_domains_numa_masks_clear(unsigned int cpu)
2006 {
2007         int i, j;
2008
2009         for (i = 0; i < sched_domains_numa_levels; i++) {
2010                 for (j = 0; j < nr_node_ids; j++) {
2011                         if (sched_domains_numa_masks[i][j])
2012                                 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
2013                 }
2014         }
2015 }
2016
2017 /*
2018  * sched_numa_find_closest() - given the NUMA topology, find the cpu
2019  *                             closest to @cpu from @cpumask.
2020  * cpumask: cpumask to find a cpu from
2021  * cpu: cpu to be close to
2022  *
2023  * returns: cpu, or nr_cpu_ids when nothing found.
2024  */
2025 int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
2026 {
2027         int i, j = cpu_to_node(cpu), found = nr_cpu_ids;
2028         struct cpumask ***masks;
2029
2030         rcu_read_lock();
2031         masks = rcu_dereference(sched_domains_numa_masks);
2032         if (!masks)
2033                 goto unlock;
2034         for (i = 0; i < sched_domains_numa_levels; i++) {
2035                 if (!masks[i][j])
2036                         break;
2037                 cpu = cpumask_any_and(cpus, masks[i][j]);
2038                 if (cpu < nr_cpu_ids) {
2039                         found = cpu;
2040                         break;
2041                 }
2042         }
2043 unlock:
2044         rcu_read_unlock();
2045
2046         return found;
2047 }
2048
2049 #endif /* CONFIG_NUMA */
2050
2051 static int __sdt_alloc(const struct cpumask *cpu_map)
2052 {
2053         struct sched_domain_topology_level *tl;
2054         int j;
2055
2056         for_each_sd_topology(tl) {
2057                 struct sd_data *sdd = &tl->data;
2058
2059                 sdd->sd = alloc_percpu(struct sched_domain *);
2060                 if (!sdd->sd)
2061                         return -ENOMEM;
2062
2063                 sdd->sds = alloc_percpu(struct sched_domain_shared *);
2064                 if (!sdd->sds)
2065                         return -ENOMEM;
2066
2067                 sdd->sg = alloc_percpu(struct sched_group *);
2068                 if (!sdd->sg)
2069                         return -ENOMEM;
2070
2071                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
2072                 if (!sdd->sgc)
2073                         return -ENOMEM;
2074
2075                 for_each_cpu(j, cpu_map) {
2076                         struct sched_domain *sd;
2077                         struct sched_domain_shared *sds;
2078                         struct sched_group *sg;
2079                         struct sched_group_capacity *sgc;
2080
2081                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
2082                                         GFP_KERNEL, cpu_to_node(j));
2083                         if (!sd)
2084                                 return -ENOMEM;
2085
2086                         *per_cpu_ptr(sdd->sd, j) = sd;
2087
2088                         sds = kzalloc_node(sizeof(struct sched_domain_shared),
2089                                         GFP_KERNEL, cpu_to_node(j));
2090                         if (!sds)
2091                                 return -ENOMEM;
2092
2093                         *per_cpu_ptr(sdd->sds, j) = sds;
2094
2095                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
2096                                         GFP_KERNEL, cpu_to_node(j));
2097                         if (!sg)
2098                                 return -ENOMEM;
2099
2100                         sg->next = sg;
2101
2102                         *per_cpu_ptr(sdd->sg, j) = sg;
2103
2104                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
2105                                         GFP_KERNEL, cpu_to_node(j));
2106                         if (!sgc)
2107                                 return -ENOMEM;
2108
2109 #ifdef CONFIG_SCHED_DEBUG
2110                         sgc->id = j;
2111 #endif
2112
2113                         *per_cpu_ptr(sdd->sgc, j) = sgc;
2114                 }
2115         }
2116
2117         return 0;
2118 }
2119
2120 static void __sdt_free(const struct cpumask *cpu_map)
2121 {
2122         struct sched_domain_topology_level *tl;
2123         int j;
2124
2125         for_each_sd_topology(tl) {
2126                 struct sd_data *sdd = &tl->data;
2127
2128                 for_each_cpu(j, cpu_map) {
2129                         struct sched_domain *sd;
2130
2131                         if (sdd->sd) {
2132                                 sd = *per_cpu_ptr(sdd->sd, j);
2133                                 if (sd && (sd->flags & SD_OVERLAP))
2134                                         free_sched_groups(sd->groups, 0);
2135                                 kfree(*per_cpu_ptr(sdd->sd, j));
2136                         }
2137
2138                         if (sdd->sds)
2139                                 kfree(*per_cpu_ptr(sdd->sds, j));
2140                         if (sdd->sg)
2141                                 kfree(*per_cpu_ptr(sdd->sg, j));
2142                         if (sdd->sgc)
2143                                 kfree(*per_cpu_ptr(sdd->sgc, j));
2144                 }
2145                 free_percpu(sdd->sd);
2146                 sdd->sd = NULL;
2147                 free_percpu(sdd->sds);
2148                 sdd->sds = NULL;
2149                 free_percpu(sdd->sg);
2150                 sdd->sg = NULL;
2151                 free_percpu(sdd->sgc);
2152                 sdd->sgc = NULL;
2153         }
2154 }
2155
2156 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
2157                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
2158                 struct sched_domain *child, int cpu)
2159 {
2160         struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
2161
2162         if (child) {
2163                 sd->level = child->level + 1;
2164                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
2165                 child->parent = sd;
2166
2167                 if (!cpumask_subset(sched_domain_span(child),
2168                                     sched_domain_span(sd))) {
2169                         pr_err("BUG: arch topology borken\n");
2170 #ifdef CONFIG_SCHED_DEBUG
2171                         pr_err("     the %s domain not a subset of the %s domain\n",
2172                                         child->name, sd->name);
2173 #endif
2174                         /* Fixup, ensure @sd has at least @child CPUs. */
2175                         cpumask_or(sched_domain_span(sd),
2176                                    sched_domain_span(sd),
2177                                    sched_domain_span(child));
2178                 }
2179
2180         }
2181         set_domain_attribute(sd, attr);
2182
2183         return sd;
2184 }
2185
2186 /*
2187  * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
2188  * any two given CPUs at this (non-NUMA) topology level.
2189  */
2190 static bool topology_span_sane(struct sched_domain_topology_level *tl,
2191                               const struct cpumask *cpu_map, int cpu)
2192 {
2193         int i;
2194
2195         /* NUMA levels are allowed to overlap */
2196         if (tl->flags & SDTL_OVERLAP)
2197                 return true;
2198
2199         /*
2200          * Non-NUMA levels cannot partially overlap - they must be either
2201          * completely equal or completely disjoint. Otherwise we can end up
2202          * breaking the sched_group lists - i.e. a later get_group() pass
2203          * breaks the linking done for an earlier span.
2204          */
2205         for_each_cpu(i, cpu_map) {
2206                 if (i == cpu)
2207                         continue;
2208                 /*
2209                  * We should 'and' all those masks with 'cpu_map' to exactly
2210                  * match the topology we're about to build, but that can only
2211                  * remove CPUs, which only lessens our ability to detect
2212                  * overlaps
2213                  */
2214                 if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
2215                     cpumask_intersects(tl->mask(cpu), tl->mask(i)))
2216                         return false;
2217         }
2218
2219         return true;
2220 }
2221
2222 /*
2223  * Build sched domains for a given set of CPUs and attach the sched domains
2224  * to the individual CPUs
2225  */
2226 static int
2227 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
2228 {
2229         enum s_alloc alloc_state = sa_none;
2230         struct sched_domain *sd;
2231         struct s_data d;
2232         struct rq *rq = NULL;
2233         int i, ret = -ENOMEM;
2234         bool has_asym = false;
2235
2236         if (WARN_ON(cpumask_empty(cpu_map)))
2237                 goto error;
2238
2239         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
2240         if (alloc_state != sa_rootdomain)
2241                 goto error;
2242
2243         /* Set up domains for CPUs specified by the cpu_map: */
2244         for_each_cpu(i, cpu_map) {
2245                 struct sched_domain_topology_level *tl;
2246
2247                 sd = NULL;
2248                 for_each_sd_topology(tl) {
2249
2250                         if (WARN_ON(!topology_span_sane(tl, cpu_map, i)))
2251                                 goto error;
2252
2253                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
2254
2255                         has_asym |= sd->flags & SD_ASYM_CPUCAPACITY;
2256
2257                         if (tl == sched_domain_topology)
2258                                 *per_cpu_ptr(d.sd, i) = sd;
2259                         if (tl->flags & SDTL_OVERLAP)
2260                                 sd->flags |= SD_OVERLAP;
2261                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
2262                                 break;
2263                 }
2264         }
2265
2266         /* Build the groups for the domains */
2267         for_each_cpu(i, cpu_map) {
2268                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2269                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
2270                         if (sd->flags & SD_OVERLAP) {
2271                                 if (build_overlap_sched_groups(sd, i))
2272                                         goto error;
2273                         } else {
2274                                 if (build_sched_groups(sd, i))
2275                                         goto error;
2276                         }
2277                 }
2278         }
2279
2280         /*
2281          * Calculate an allowed NUMA imbalance such that LLCs do not get
2282          * imbalanced.
2283          */
2284         for_each_cpu(i, cpu_map) {
2285                 unsigned int imb = 0;
2286                 unsigned int imb_span = 1;
2287
2288                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2289                         struct sched_domain *child = sd->child;
2290
2291                         if (!(sd->flags & SD_SHARE_PKG_RESOURCES) && child &&
2292                             (child->flags & SD_SHARE_PKG_RESOURCES)) {
2293                                 struct sched_domain __rcu *top_p;
2294                                 unsigned int nr_llcs;
2295
2296                                 /*
2297                                  * For a single LLC per node, allow an
2298                                  * imbalance up to 25% of the node. This is an
2299                                  * arbitrary cutoff based on SMT-2 to balance
2300                                  * between memory bandwidth and avoiding
2301                                  * premature sharing of HT resources and SMT-4
2302                                  * or SMT-8 *may* benefit from a different
2303                                  * cutoff.
2304                                  *
2305                                  * For multiple LLCs, allow an imbalance
2306                                  * until multiple tasks would share an LLC
2307                                  * on one node while LLCs on another node
2308                                  * remain idle.
2309                                  */
2310                                 nr_llcs = sd->span_weight / child->span_weight;
2311                                 if (nr_llcs == 1)
2312                                         imb = sd->span_weight >> 2;
2313                                 else
2314                                         imb = nr_llcs;
2315                                 sd->imb_numa_nr = imb;
2316
2317                                 /* Set span based on the first NUMA domain. */
2318                                 top_p = sd->parent;
2319                                 while (top_p && !(top_p->flags & SD_NUMA)) {
2320                                         top_p = top_p->parent;
2321                                 }
2322                                 imb_span = top_p ? top_p->span_weight : sd->span_weight;
2323                         } else {
2324                                 int factor = max(1U, (sd->span_weight / imb_span));
2325
2326                                 sd->imb_numa_nr = imb * factor;
2327                         }
2328                 }
2329         }
2330
2331         /* Calculate CPU capacity for physical packages and nodes */
2332         for (i = nr_cpumask_bits-1; i >= 0; i--) {
2333                 if (!cpumask_test_cpu(i, cpu_map))
2334                         continue;
2335
2336                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2337                         claim_allocations(i, sd);
2338                         init_sched_groups_capacity(i, sd);
2339                 }
2340         }
2341
2342         /* Attach the domains */
2343         rcu_read_lock();
2344         for_each_cpu(i, cpu_map) {
2345                 rq = cpu_rq(i);
2346                 sd = *per_cpu_ptr(d.sd, i);
2347
2348                 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
2349                 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
2350                         WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
2351
2352                 cpu_attach_domain(sd, d.rd, i);
2353         }
2354         rcu_read_unlock();
2355
2356         if (has_asym)
2357                 static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
2358
2359         if (rq && sched_debug_verbose) {
2360                 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
2361                         cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
2362         }
2363
2364         ret = 0;
2365 error:
2366         __free_domain_allocs(&d, alloc_state, cpu_map);
2367
2368         return ret;
2369 }
2370
2371 /* Current sched domains: */
2372 static cpumask_var_t                    *doms_cur;
2373
2374 /* Number of sched domains in 'doms_cur': */
2375 static int                              ndoms_cur;
2376
2377 /* Attributes of custom domains in 'doms_cur' */
2378 static struct sched_domain_attr         *dattr_cur;
2379
2380 /*
2381  * Special case: If a kmalloc() of a doms_cur partition (array of
2382  * cpumask) fails, then fallback to a single sched domain,
2383  * as determined by the single cpumask fallback_doms.
2384  */
2385 static cpumask_var_t                    fallback_doms;
2386
2387 /*
2388  * arch_update_cpu_topology lets virtualized architectures update the
2389  * CPU core maps. It is supposed to return 1 if the topology changed
2390  * or 0 if it stayed the same.
2391  */
2392 int __weak arch_update_cpu_topology(void)
2393 {
2394         return 0;
2395 }
2396
2397 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
2398 {
2399         int i;
2400         cpumask_var_t *doms;
2401
2402         doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
2403         if (!doms)
2404                 return NULL;
2405         for (i = 0; i < ndoms; i++) {
2406                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
2407                         free_sched_domains(doms, i);
2408                         return NULL;
2409                 }
2410         }
2411         return doms;
2412 }
2413
2414 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
2415 {
2416         unsigned int i;
2417         for (i = 0; i < ndoms; i++)
2418                 free_cpumask_var(doms[i]);
2419         kfree(doms);
2420 }
2421
2422 /*
2423  * Set up scheduler domains and groups.  For now this just excludes isolated
2424  * CPUs, but could be used to exclude other special cases in the future.
2425  */
2426 int sched_init_domains(const struct cpumask *cpu_map)
2427 {
2428         int err;
2429
2430         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
2431         zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
2432         zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
2433
2434         arch_update_cpu_topology();
2435         asym_cpu_capacity_scan();
2436         ndoms_cur = 1;
2437         doms_cur = alloc_sched_domains(ndoms_cur);
2438         if (!doms_cur)
2439                 doms_cur = &fallback_doms;
2440         cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_TYPE_DOMAIN));
2441         err = build_sched_domains(doms_cur[0], NULL);
2442
2443         return err;
2444 }
2445
2446 /*
2447  * Detach sched domains from a group of CPUs specified in cpu_map
2448  * These CPUs will now be attached to the NULL domain
2449  */
2450 static void detach_destroy_domains(const struct cpumask *cpu_map)
2451 {
2452         unsigned int cpu = cpumask_any(cpu_map);
2453         int i;
2454
2455         if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
2456                 static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
2457
2458         rcu_read_lock();
2459         for_each_cpu(i, cpu_map)
2460                 cpu_attach_domain(NULL, &def_root_domain, i);
2461         rcu_read_unlock();
2462 }
2463
2464 /* handle null as "default" */
2465 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
2466                         struct sched_domain_attr *new, int idx_new)
2467 {
2468         struct sched_domain_attr tmp;
2469
2470         /* Fast path: */
2471         if (!new && !cur)
2472                 return 1;
2473
2474         tmp = SD_ATTR_INIT;
2475
2476         return !memcmp(cur ? (cur + idx_cur) : &tmp,
2477                         new ? (new + idx_new) : &tmp,
2478                         sizeof(struct sched_domain_attr));
2479 }
2480
2481 /*
2482  * Partition sched domains as specified by the 'ndoms_new'
2483  * cpumasks in the array doms_new[] of cpumasks. This compares
2484  * doms_new[] to the current sched domain partitioning, doms_cur[].
2485  * It destroys each deleted domain and builds each new domain.
2486  *
2487  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
2488  * The masks don't intersect (don't overlap.) We should setup one
2489  * sched domain for each mask. CPUs not in any of the cpumasks will
2490  * not be load balanced. If the same cpumask appears both in the
2491  * current 'doms_cur' domains and in the new 'doms_new', we can leave
2492  * it as it is.
2493  *
2494  * The passed in 'doms_new' should be allocated using
2495  * alloc_sched_domains.  This routine takes ownership of it and will
2496  * free_sched_domains it when done with it. If the caller failed the
2497  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
2498  * and partition_sched_domains() will fallback to the single partition
2499  * 'fallback_doms', it also forces the domains to be rebuilt.
2500  *
2501  * If doms_new == NULL it will be replaced with cpu_online_mask.
2502  * ndoms_new == 0 is a special case for destroying existing domains,
2503  * and it will not create the default domain.
2504  *
2505  * Call with hotplug lock and sched_domains_mutex held
2506  */
2507 void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
2508                                     struct sched_domain_attr *dattr_new)
2509 {
2510         bool __maybe_unused has_eas = false;
2511         int i, j, n;
2512         int new_topology;
2513
2514         lockdep_assert_held(&sched_domains_mutex);
2515
2516         /* Let the architecture update CPU core mappings: */
2517         new_topology = arch_update_cpu_topology();
2518         /* Trigger rebuilding CPU capacity asymmetry data */
2519         if (new_topology)
2520                 asym_cpu_capacity_scan();
2521
2522         if (!doms_new) {
2523                 WARN_ON_ONCE(dattr_new);
2524                 n = 0;
2525                 doms_new = alloc_sched_domains(1);
2526                 if (doms_new) {
2527                         n = 1;
2528                         cpumask_and(doms_new[0], cpu_active_mask,
2529                                     housekeeping_cpumask(HK_TYPE_DOMAIN));
2530                 }
2531         } else {
2532                 n = ndoms_new;
2533         }
2534
2535         /* Destroy deleted domains: */
2536         for (i = 0; i < ndoms_cur; i++) {
2537                 for (j = 0; j < n && !new_topology; j++) {
2538                         if (cpumask_equal(doms_cur[i], doms_new[j]) &&
2539                             dattrs_equal(dattr_cur, i, dattr_new, j)) {
2540                                 struct root_domain *rd;
2541
2542                                 /*
2543                                  * This domain won't be destroyed and as such
2544                                  * its dl_bw->total_bw needs to be cleared.  It
2545                                  * will be recomputed in function
2546                                  * update_tasks_root_domain().
2547                                  */
2548                                 rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
2549                                 dl_clear_root_domain(rd);
2550                                 goto match1;
2551                         }
2552                 }
2553                 /* No match - a current sched domain not in new doms_new[] */
2554                 detach_destroy_domains(doms_cur[i]);
2555 match1:
2556                 ;
2557         }
2558
2559         n = ndoms_cur;
2560         if (!doms_new) {
2561                 n = 0;
2562                 doms_new = &fallback_doms;
2563                 cpumask_and(doms_new[0], cpu_active_mask,
2564                             housekeeping_cpumask(HK_TYPE_DOMAIN));
2565         }
2566
2567         /* Build new domains: */
2568         for (i = 0; i < ndoms_new; i++) {
2569                 for (j = 0; j < n && !new_topology; j++) {
2570                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2571                             dattrs_equal(dattr_new, i, dattr_cur, j))
2572                                 goto match2;
2573                 }
2574                 /* No match - add a new doms_new */
2575                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
2576 match2:
2577                 ;
2578         }
2579
2580 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
2581         /* Build perf. domains: */
2582         for (i = 0; i < ndoms_new; i++) {
2583                 for (j = 0; j < n && !sched_energy_update; j++) {
2584                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2585                             cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
2586                                 has_eas = true;
2587                                 goto match3;
2588                         }
2589                 }
2590                 /* No match - add perf. domains for a new rd */
2591                 has_eas |= build_perf_domains(doms_new[i]);
2592 match3:
2593                 ;
2594         }
2595         sched_energy_set(has_eas);
2596 #endif
2597
2598         /* Remember the new sched domains: */
2599         if (doms_cur != &fallback_doms)
2600                 free_sched_domains(doms_cur, ndoms_cur);
2601
2602         kfree(dattr_cur);
2603         doms_cur = doms_new;
2604         dattr_cur = dattr_new;
2605         ndoms_cur = ndoms_new;
2606
2607         update_sched_domain_debugfs();
2608 }
2609
2610 /*
2611  * Call with hotplug lock held
2612  */
2613 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
2614                              struct sched_domain_attr *dattr_new)
2615 {
2616         mutex_lock(&sched_domains_mutex);
2617         partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
2618         mutex_unlock(&sched_domains_mutex);
2619 }