| 1 | /* CPU control. |
| 2 | * (C) 2001, 2002, 2003, 2004 Rusty Russell |
| 3 | * |
| 4 | * This code is licenced under the GPL. |
| 5 | */ |
| 6 | #include <linux/proc_fs.h> |
| 7 | #include <linux/smp.h> |
| 8 | #include <linux/init.h> |
| 9 | #include <linux/notifier.h> |
| 10 | #include <linux/sched/signal.h> |
| 11 | #include <linux/sched/hotplug.h> |
| 12 | #include <linux/sched/isolation.h> |
| 13 | #include <linux/sched/task.h> |
| 14 | #include <linux/sched/smt.h> |
| 15 | #include <linux/unistd.h> |
| 16 | #include <linux/cpu.h> |
| 17 | #include <linux/oom.h> |
| 18 | #include <linux/rcupdate.h> |
| 19 | #include <linux/export.h> |
| 20 | #include <linux/bug.h> |
| 21 | #include <linux/kthread.h> |
| 22 | #include <linux/stop_machine.h> |
| 23 | #include <linux/mutex.h> |
| 24 | #include <linux/gfp.h> |
| 25 | #include <linux/suspend.h> |
| 26 | #include <linux/lockdep.h> |
| 27 | #include <linux/tick.h> |
| 28 | #include <linux/irq.h> |
| 29 | #include <linux/nmi.h> |
| 30 | #include <linux/smpboot.h> |
| 31 | #include <linux/relay.h> |
| 32 | #include <linux/slab.h> |
| 33 | #include <linux/percpu-rwsem.h> |
| 34 | |
| 35 | #include <trace/events/power.h> |
| 36 | #define CREATE_TRACE_POINTS |
| 37 | #include <trace/events/cpuhp.h> |
| 38 | |
| 39 | #include "smpboot.h" |
| 40 | |
| 41 | /** |
| 42 | * cpuhp_cpu_state - Per cpu hotplug state storage |
| 43 | * @state: The current cpu state |
| 44 | * @target: The target state |
| 45 | * @thread: Pointer to the hotplug thread |
| 46 | * @should_run: Thread should execute |
| 47 | * @rollback: Perform a rollback |
| 48 | * @single: Single callback invocation |
| 49 | * @bringup: Single callback bringup or teardown selector |
| 50 | * @cb_state: The state for a single callback (install/uninstall) |
| 51 | * @result: Result of the operation |
| 52 | * @done_up: Signal completion to the issuer of the task for cpu-up |
| 53 | * @done_down: Signal completion to the issuer of the task for cpu-down |
| 54 | */ |
| 55 | struct cpuhp_cpu_state { |
| 56 | enum cpuhp_state state; |
| 57 | enum cpuhp_state target; |
| 58 | enum cpuhp_state fail; |
| 59 | #ifdef CONFIG_SMP |
| 60 | struct task_struct *thread; |
| 61 | bool should_run; |
| 62 | bool rollback; |
| 63 | bool single; |
| 64 | bool bringup; |
| 65 | bool booted_once; |
| 66 | struct hlist_node *node; |
| 67 | struct hlist_node *last; |
| 68 | enum cpuhp_state cb_state; |
| 69 | int result; |
| 70 | struct completion done_up; |
| 71 | struct completion done_down; |
| 72 | #endif |
| 73 | }; |
| 74 | |
| 75 | static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = { |
| 76 | .fail = CPUHP_INVALID, |
| 77 | }; |
| 78 | |
| 79 | #if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP) |
| 80 | static struct lockdep_map cpuhp_state_up_map = |
| 81 | STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map); |
| 82 | static struct lockdep_map cpuhp_state_down_map = |
| 83 | STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map); |
| 84 | |
| 85 | |
| 86 | static inline void cpuhp_lock_acquire(bool bringup) |
| 87 | { |
| 88 | lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); |
| 89 | } |
| 90 | |
| 91 | static inline void cpuhp_lock_release(bool bringup) |
| 92 | { |
| 93 | lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); |
| 94 | } |
| 95 | #else |
| 96 | |
| 97 | static inline void cpuhp_lock_acquire(bool bringup) { } |
| 98 | static inline void cpuhp_lock_release(bool bringup) { } |
| 99 | |
| 100 | #endif |
| 101 | |
| 102 | /** |
| 103 | * cpuhp_step - Hotplug state machine step |
| 104 | * @name: Name of the step |
| 105 | * @startup: Startup function of the step |
| 106 | * @teardown: Teardown function of the step |
| 107 | * @cant_stop: Bringup/teardown can't be stopped at this step |
| 108 | */ |
| 109 | struct cpuhp_step { |
| 110 | const char *name; |
| 111 | union { |
| 112 | int (*single)(unsigned int cpu); |
| 113 | int (*multi)(unsigned int cpu, |
| 114 | struct hlist_node *node); |
| 115 | } startup; |
| 116 | union { |
| 117 | int (*single)(unsigned int cpu); |
| 118 | int (*multi)(unsigned int cpu, |
| 119 | struct hlist_node *node); |
| 120 | } teardown; |
| 121 | struct hlist_head list; |
| 122 | bool cant_stop; |
| 123 | bool multi_instance; |
| 124 | }; |
| 125 | |
| 126 | static DEFINE_MUTEX(cpuhp_state_mutex); |
| 127 | static struct cpuhp_step cpuhp_hp_states[]; |
| 128 | |
| 129 | static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) |
| 130 | { |
| 131 | return cpuhp_hp_states + state; |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * cpuhp_invoke_callback _ Invoke the callbacks for a given state |
| 136 | * @cpu: The cpu for which the callback should be invoked |
| 137 | * @state: The state to do callbacks for |
| 138 | * @bringup: True if the bringup callback should be invoked |
| 139 | * @node: For multi-instance, do a single entry callback for install/remove |
| 140 | * @lastp: For multi-instance rollback, remember how far we got |
| 141 | * |
| 142 | * Called from cpu hotplug and from the state register machinery. |
| 143 | */ |
| 144 | static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, |
| 145 | bool bringup, struct hlist_node *node, |
| 146 | struct hlist_node **lastp) |
| 147 | { |
| 148 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 149 | struct cpuhp_step *step = cpuhp_get_step(state); |
| 150 | int (*cbm)(unsigned int cpu, struct hlist_node *node); |
| 151 | int (*cb)(unsigned int cpu); |
| 152 | int ret, cnt; |
| 153 | |
| 154 | if (st->fail == state) { |
| 155 | st->fail = CPUHP_INVALID; |
| 156 | |
| 157 | if (!(bringup ? step->startup.single : step->teardown.single)) |
| 158 | return 0; |
| 159 | |
| 160 | return -EAGAIN; |
| 161 | } |
| 162 | |
| 163 | if (!step->multi_instance) { |
| 164 | WARN_ON_ONCE(lastp && *lastp); |
| 165 | cb = bringup ? step->startup.single : step->teardown.single; |
| 166 | if (!cb) |
| 167 | return 0; |
| 168 | trace_cpuhp_enter(cpu, st->target, state, cb); |
| 169 | ret = cb(cpu); |
| 170 | trace_cpuhp_exit(cpu, st->state, state, ret); |
| 171 | return ret; |
| 172 | } |
| 173 | cbm = bringup ? step->startup.multi : step->teardown.multi; |
| 174 | if (!cbm) |
| 175 | return 0; |
| 176 | |
| 177 | /* Single invocation for instance add/remove */ |
| 178 | if (node) { |
| 179 | WARN_ON_ONCE(lastp && *lastp); |
| 180 | trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); |
| 181 | ret = cbm(cpu, node); |
| 182 | trace_cpuhp_exit(cpu, st->state, state, ret); |
| 183 | return ret; |
| 184 | } |
| 185 | |
| 186 | /* State transition. Invoke on all instances */ |
| 187 | cnt = 0; |
| 188 | hlist_for_each(node, &step->list) { |
| 189 | if (lastp && node == *lastp) |
| 190 | break; |
| 191 | |
| 192 | trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); |
| 193 | ret = cbm(cpu, node); |
| 194 | trace_cpuhp_exit(cpu, st->state, state, ret); |
| 195 | if (ret) { |
| 196 | if (!lastp) |
| 197 | goto err; |
| 198 | |
| 199 | *lastp = node; |
| 200 | return ret; |
| 201 | } |
| 202 | cnt++; |
| 203 | } |
| 204 | if (lastp) |
| 205 | *lastp = NULL; |
| 206 | return 0; |
| 207 | err: |
| 208 | /* Rollback the instances if one failed */ |
| 209 | cbm = !bringup ? step->startup.multi : step->teardown.multi; |
| 210 | if (!cbm) |
| 211 | return ret; |
| 212 | |
| 213 | hlist_for_each(node, &step->list) { |
| 214 | if (!cnt--) |
| 215 | break; |
| 216 | |
| 217 | trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); |
| 218 | ret = cbm(cpu, node); |
| 219 | trace_cpuhp_exit(cpu, st->state, state, ret); |
| 220 | /* |
| 221 | * Rollback must not fail, |
| 222 | */ |
| 223 | WARN_ON_ONCE(ret); |
| 224 | } |
| 225 | return ret; |
| 226 | } |
| 227 | |
| 228 | #ifdef CONFIG_SMP |
| 229 | static bool cpuhp_is_ap_state(enum cpuhp_state state) |
| 230 | { |
| 231 | /* |
| 232 | * The extra check for CPUHP_TEARDOWN_CPU is only for documentation |
| 233 | * purposes as that state is handled explicitly in cpu_down. |
| 234 | */ |
| 235 | return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU; |
| 236 | } |
| 237 | |
| 238 | static inline void wait_for_ap_thread(struct cpuhp_cpu_state *st, bool bringup) |
| 239 | { |
| 240 | struct completion *done = bringup ? &st->done_up : &st->done_down; |
| 241 | wait_for_completion(done); |
| 242 | } |
| 243 | |
| 244 | static inline void complete_ap_thread(struct cpuhp_cpu_state *st, bool bringup) |
| 245 | { |
| 246 | struct completion *done = bringup ? &st->done_up : &st->done_down; |
| 247 | complete(done); |
| 248 | } |
| 249 | |
| 250 | /* |
| 251 | * The former STARTING/DYING states, ran with IRQs disabled and must not fail. |
| 252 | */ |
| 253 | static bool cpuhp_is_atomic_state(enum cpuhp_state state) |
| 254 | { |
| 255 | return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE; |
| 256 | } |
| 257 | |
| 258 | /* Serializes the updates to cpu_online_mask, cpu_present_mask */ |
| 259 | static DEFINE_MUTEX(cpu_add_remove_lock); |
| 260 | bool cpuhp_tasks_frozen; |
| 261 | EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen); |
| 262 | |
| 263 | /* |
| 264 | * The following two APIs (cpu_maps_update_begin/done) must be used when |
| 265 | * attempting to serialize the updates to cpu_online_mask & cpu_present_mask. |
| 266 | */ |
| 267 | void cpu_maps_update_begin(void) |
| 268 | { |
| 269 | mutex_lock(&cpu_add_remove_lock); |
| 270 | } |
| 271 | |
| 272 | void cpu_maps_update_done(void) |
| 273 | { |
| 274 | mutex_unlock(&cpu_add_remove_lock); |
| 275 | } |
| 276 | |
| 277 | /* |
| 278 | * If set, cpu_up and cpu_down will return -EBUSY and do nothing. |
| 279 | * Should always be manipulated under cpu_add_remove_lock |
| 280 | */ |
| 281 | static int cpu_hotplug_disabled; |
| 282 | |
| 283 | #ifdef CONFIG_HOTPLUG_CPU |
| 284 | |
| 285 | DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock); |
| 286 | |
| 287 | void cpus_read_lock(void) |
| 288 | { |
| 289 | percpu_down_read(&cpu_hotplug_lock); |
| 290 | } |
| 291 | EXPORT_SYMBOL_GPL(cpus_read_lock); |
| 292 | |
| 293 | int cpus_read_trylock(void) |
| 294 | { |
| 295 | return percpu_down_read_trylock(&cpu_hotplug_lock); |
| 296 | } |
| 297 | EXPORT_SYMBOL_GPL(cpus_read_trylock); |
| 298 | |
| 299 | void cpus_read_unlock(void) |
| 300 | { |
| 301 | percpu_up_read(&cpu_hotplug_lock); |
| 302 | } |
| 303 | EXPORT_SYMBOL_GPL(cpus_read_unlock); |
| 304 | |
| 305 | void cpus_write_lock(void) |
| 306 | { |
| 307 | percpu_down_write(&cpu_hotplug_lock); |
| 308 | } |
| 309 | |
| 310 | void cpus_write_unlock(void) |
| 311 | { |
| 312 | percpu_up_write(&cpu_hotplug_lock); |
| 313 | } |
| 314 | |
| 315 | void lockdep_assert_cpus_held(void) |
| 316 | { |
| 317 | /* |
| 318 | * We can't have hotplug operations before userspace starts running, |
| 319 | * and some init codepaths will knowingly not take the hotplug lock. |
| 320 | * This is all valid, so mute lockdep until it makes sense to report |
| 321 | * unheld locks. |
| 322 | */ |
| 323 | if (system_state < SYSTEM_RUNNING) |
| 324 | return; |
| 325 | |
| 326 | percpu_rwsem_assert_held(&cpu_hotplug_lock); |
| 327 | } |
| 328 | |
| 329 | static void lockdep_acquire_cpus_lock(void) |
| 330 | { |
| 331 | rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_); |
| 332 | } |
| 333 | |
| 334 | static void lockdep_release_cpus_lock(void) |
| 335 | { |
| 336 | rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, 1, _THIS_IP_); |
| 337 | } |
| 338 | |
| 339 | /* |
| 340 | * Wait for currently running CPU hotplug operations to complete (if any) and |
| 341 | * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects |
| 342 | * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the |
| 343 | * hotplug path before performing hotplug operations. So acquiring that lock |
| 344 | * guarantees mutual exclusion from any currently running hotplug operations. |
| 345 | */ |
| 346 | void cpu_hotplug_disable(void) |
| 347 | { |
| 348 | cpu_maps_update_begin(); |
| 349 | cpu_hotplug_disabled++; |
| 350 | cpu_maps_update_done(); |
| 351 | } |
| 352 | EXPORT_SYMBOL_GPL(cpu_hotplug_disable); |
| 353 | |
| 354 | static void __cpu_hotplug_enable(void) |
| 355 | { |
| 356 | if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n")) |
| 357 | return; |
| 358 | cpu_hotplug_disabled--; |
| 359 | } |
| 360 | |
| 361 | void cpu_hotplug_enable(void) |
| 362 | { |
| 363 | cpu_maps_update_begin(); |
| 364 | __cpu_hotplug_enable(); |
| 365 | cpu_maps_update_done(); |
| 366 | } |
| 367 | EXPORT_SYMBOL_GPL(cpu_hotplug_enable); |
| 368 | |
| 369 | #else |
| 370 | |
| 371 | static void lockdep_acquire_cpus_lock(void) |
| 372 | { |
| 373 | } |
| 374 | |
| 375 | static void lockdep_release_cpus_lock(void) |
| 376 | { |
| 377 | } |
| 378 | |
| 379 | #endif /* CONFIG_HOTPLUG_CPU */ |
| 380 | |
| 381 | /* |
| 382 | * Architectures that need SMT-specific errata handling during SMT hotplug |
| 383 | * should override this. |
| 384 | */ |
| 385 | void __weak arch_smt_update(void) { } |
| 386 | |
| 387 | #ifdef CONFIG_HOTPLUG_SMT |
| 388 | enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; |
| 389 | |
| 390 | void __init cpu_smt_disable(bool force) |
| 391 | { |
| 392 | if (cpu_smt_control == CPU_SMT_FORCE_DISABLED || |
| 393 | cpu_smt_control == CPU_SMT_NOT_SUPPORTED) |
| 394 | return; |
| 395 | |
| 396 | if (force) { |
| 397 | pr_info("SMT: Force disabled\n"); |
| 398 | cpu_smt_control = CPU_SMT_FORCE_DISABLED; |
| 399 | } else { |
| 400 | pr_info("SMT: disabled\n"); |
| 401 | cpu_smt_control = CPU_SMT_DISABLED; |
| 402 | } |
| 403 | } |
| 404 | |
| 405 | /* |
| 406 | * The decision whether SMT is supported can only be done after the full |
| 407 | * CPU identification. Called from architecture code. |
| 408 | */ |
| 409 | void __init cpu_smt_check_topology(void) |
| 410 | { |
| 411 | if (!topology_smt_supported()) |
| 412 | cpu_smt_control = CPU_SMT_NOT_SUPPORTED; |
| 413 | } |
| 414 | |
| 415 | static int __init smt_cmdline_disable(char *str) |
| 416 | { |
| 417 | cpu_smt_disable(str && !strcmp(str, "force")); |
| 418 | return 0; |
| 419 | } |
| 420 | early_param("nosmt", smt_cmdline_disable); |
| 421 | |
| 422 | static inline bool cpu_smt_allowed(unsigned int cpu) |
| 423 | { |
| 424 | if (cpu_smt_control == CPU_SMT_ENABLED) |
| 425 | return true; |
| 426 | |
| 427 | if (topology_is_primary_thread(cpu)) |
| 428 | return true; |
| 429 | |
| 430 | /* |
| 431 | * On x86 it's required to boot all logical CPUs at least once so |
| 432 | * that the init code can get a chance to set CR4.MCE on each |
| 433 | * CPU. Otherwise, a broadacasted MCE observing CR4.MCE=0b on any |
| 434 | * core will shutdown the machine. |
| 435 | */ |
| 436 | return !per_cpu(cpuhp_state, cpu).booted_once; |
| 437 | } |
| 438 | #else |
| 439 | static inline bool cpu_smt_allowed(unsigned int cpu) { return true; } |
| 440 | #endif |
| 441 | |
| 442 | static inline enum cpuhp_state |
| 443 | cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target) |
| 444 | { |
| 445 | enum cpuhp_state prev_state = st->state; |
| 446 | |
| 447 | st->rollback = false; |
| 448 | st->last = NULL; |
| 449 | |
| 450 | st->target = target; |
| 451 | st->single = false; |
| 452 | st->bringup = st->state < target; |
| 453 | |
| 454 | return prev_state; |
| 455 | } |
| 456 | |
| 457 | static inline void |
| 458 | cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state) |
| 459 | { |
| 460 | st->rollback = true; |
| 461 | |
| 462 | /* |
| 463 | * If we have st->last we need to undo partial multi_instance of this |
| 464 | * state first. Otherwise start undo at the previous state. |
| 465 | */ |
| 466 | if (!st->last) { |
| 467 | if (st->bringup) |
| 468 | st->state--; |
| 469 | else |
| 470 | st->state++; |
| 471 | } |
| 472 | |
| 473 | st->target = prev_state; |
| 474 | st->bringup = !st->bringup; |
| 475 | } |
| 476 | |
| 477 | /* Regular hotplug invocation of the AP hotplug thread */ |
| 478 | static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st) |
| 479 | { |
| 480 | if (!st->single && st->state == st->target) |
| 481 | return; |
| 482 | |
| 483 | st->result = 0; |
| 484 | /* |
| 485 | * Make sure the above stores are visible before should_run becomes |
| 486 | * true. Paired with the mb() above in cpuhp_thread_fun() |
| 487 | */ |
| 488 | smp_mb(); |
| 489 | st->should_run = true; |
| 490 | wake_up_process(st->thread); |
| 491 | wait_for_ap_thread(st, st->bringup); |
| 492 | } |
| 493 | |
| 494 | static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target) |
| 495 | { |
| 496 | enum cpuhp_state prev_state; |
| 497 | int ret; |
| 498 | |
| 499 | prev_state = cpuhp_set_state(st, target); |
| 500 | __cpuhp_kick_ap(st); |
| 501 | if ((ret = st->result)) { |
| 502 | cpuhp_reset_state(st, prev_state); |
| 503 | __cpuhp_kick_ap(st); |
| 504 | } |
| 505 | |
| 506 | return ret; |
| 507 | } |
| 508 | |
| 509 | static int bringup_wait_for_ap(unsigned int cpu) |
| 510 | { |
| 511 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 512 | |
| 513 | /* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */ |
| 514 | wait_for_ap_thread(st, true); |
| 515 | if (WARN_ON_ONCE((!cpu_online(cpu)))) |
| 516 | return -ECANCELED; |
| 517 | |
| 518 | /* Unpark the stopper thread and the hotplug thread of the target cpu */ |
| 519 | stop_machine_unpark(cpu); |
| 520 | kthread_unpark(st->thread); |
| 521 | |
| 522 | /* |
| 523 | * SMT soft disabling on X86 requires to bring the CPU out of the |
| 524 | * BIOS 'wait for SIPI' state in order to set the CR4.MCE bit. The |
| 525 | * CPU marked itself as booted_once in notify_cpu_starting() so the |
| 526 | * cpu_smt_allowed() check will now return false if this is not the |
| 527 | * primary sibling. |
| 528 | */ |
| 529 | if (!cpu_smt_allowed(cpu)) |
| 530 | return -ECANCELED; |
| 531 | |
| 532 | if (st->target <= CPUHP_AP_ONLINE_IDLE) |
| 533 | return 0; |
| 534 | |
| 535 | return cpuhp_kick_ap(st, st->target); |
| 536 | } |
| 537 | |
| 538 | static int bringup_cpu(unsigned int cpu) |
| 539 | { |
| 540 | struct task_struct *idle = idle_thread_get(cpu); |
| 541 | int ret; |
| 542 | |
| 543 | /* |
| 544 | * Some architectures have to walk the irq descriptors to |
| 545 | * setup the vector space for the cpu which comes online. |
| 546 | * Prevent irq alloc/free across the bringup. |
| 547 | */ |
| 548 | irq_lock_sparse(); |
| 549 | |
| 550 | /* Arch-specific enabling code. */ |
| 551 | ret = __cpu_up(cpu, idle); |
| 552 | irq_unlock_sparse(); |
| 553 | if (ret) |
| 554 | return ret; |
| 555 | return bringup_wait_for_ap(cpu); |
| 556 | } |
| 557 | |
| 558 | /* |
| 559 | * Hotplug state machine related functions |
| 560 | */ |
| 561 | |
| 562 | static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st) |
| 563 | { |
| 564 | for (st->state--; st->state > st->target; st->state--) |
| 565 | cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); |
| 566 | } |
| 567 | |
| 568 | static inline bool can_rollback_cpu(struct cpuhp_cpu_state *st) |
| 569 | { |
| 570 | if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) |
| 571 | return true; |
| 572 | /* |
| 573 | * When CPU hotplug is disabled, then taking the CPU down is not |
| 574 | * possible because takedown_cpu() and the architecture and |
| 575 | * subsystem specific mechanisms are not available. So the CPU |
| 576 | * which would be completely unplugged again needs to stay around |
| 577 | * in the current state. |
| 578 | */ |
| 579 | return st->state <= CPUHP_BRINGUP_CPU; |
| 580 | } |
| 581 | |
| 582 | static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, |
| 583 | enum cpuhp_state target) |
| 584 | { |
| 585 | enum cpuhp_state prev_state = st->state; |
| 586 | int ret = 0; |
| 587 | |
| 588 | while (st->state < target) { |
| 589 | st->state++; |
| 590 | ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); |
| 591 | if (ret) { |
| 592 | if (can_rollback_cpu(st)) { |
| 593 | st->target = prev_state; |
| 594 | undo_cpu_up(cpu, st); |
| 595 | } |
| 596 | break; |
| 597 | } |
| 598 | } |
| 599 | return ret; |
| 600 | } |
| 601 | |
| 602 | /* |
| 603 | * The cpu hotplug threads manage the bringup and teardown of the cpus |
| 604 | */ |
| 605 | static void cpuhp_create(unsigned int cpu) |
| 606 | { |
| 607 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 608 | |
| 609 | init_completion(&st->done_up); |
| 610 | init_completion(&st->done_down); |
| 611 | } |
| 612 | |
| 613 | static int cpuhp_should_run(unsigned int cpu) |
| 614 | { |
| 615 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
| 616 | |
| 617 | return st->should_run; |
| 618 | } |
| 619 | |
| 620 | /* |
| 621 | * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke |
| 622 | * callbacks when a state gets [un]installed at runtime. |
| 623 | * |
| 624 | * Each invocation of this function by the smpboot thread does a single AP |
| 625 | * state callback. |
| 626 | * |
| 627 | * It has 3 modes of operation: |
| 628 | * - single: runs st->cb_state |
| 629 | * - up: runs ++st->state, while st->state < st->target |
| 630 | * - down: runs st->state--, while st->state > st->target |
| 631 | * |
| 632 | * When complete or on error, should_run is cleared and the completion is fired. |
| 633 | */ |
| 634 | static void cpuhp_thread_fun(unsigned int cpu) |
| 635 | { |
| 636 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
| 637 | bool bringup = st->bringup; |
| 638 | enum cpuhp_state state; |
| 639 | |
| 640 | if (WARN_ON_ONCE(!st->should_run)) |
| 641 | return; |
| 642 | |
| 643 | /* |
| 644 | * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures |
| 645 | * that if we see ->should_run we also see the rest of the state. |
| 646 | */ |
| 647 | smp_mb(); |
| 648 | |
| 649 | /* |
| 650 | * The BP holds the hotplug lock, but we're now running on the AP, |
| 651 | * ensure that anybody asserting the lock is held, will actually find |
| 652 | * it so. |
| 653 | */ |
| 654 | lockdep_acquire_cpus_lock(); |
| 655 | cpuhp_lock_acquire(bringup); |
| 656 | |
| 657 | if (st->single) { |
| 658 | state = st->cb_state; |
| 659 | st->should_run = false; |
| 660 | } else { |
| 661 | if (bringup) { |
| 662 | st->state++; |
| 663 | state = st->state; |
| 664 | st->should_run = (st->state < st->target); |
| 665 | WARN_ON_ONCE(st->state > st->target); |
| 666 | } else { |
| 667 | state = st->state; |
| 668 | st->state--; |
| 669 | st->should_run = (st->state > st->target); |
| 670 | WARN_ON_ONCE(st->state < st->target); |
| 671 | } |
| 672 | } |
| 673 | |
| 674 | WARN_ON_ONCE(!cpuhp_is_ap_state(state)); |
| 675 | |
| 676 | if (cpuhp_is_atomic_state(state)) { |
| 677 | local_irq_disable(); |
| 678 | st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last); |
| 679 | local_irq_enable(); |
| 680 | |
| 681 | /* |
| 682 | * STARTING/DYING must not fail! |
| 683 | */ |
| 684 | WARN_ON_ONCE(st->result); |
| 685 | } else { |
| 686 | st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last); |
| 687 | } |
| 688 | |
| 689 | if (st->result) { |
| 690 | /* |
| 691 | * If we fail on a rollback, we're up a creek without no |
| 692 | * paddle, no way forward, no way back. We loose, thanks for |
| 693 | * playing. |
| 694 | */ |
| 695 | WARN_ON_ONCE(st->rollback); |
| 696 | st->should_run = false; |
| 697 | } |
| 698 | |
| 699 | cpuhp_lock_release(bringup); |
| 700 | lockdep_release_cpus_lock(); |
| 701 | |
| 702 | if (!st->should_run) |
| 703 | complete_ap_thread(st, bringup); |
| 704 | } |
| 705 | |
| 706 | /* Invoke a single callback on a remote cpu */ |
| 707 | static int |
| 708 | cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup, |
| 709 | struct hlist_node *node) |
| 710 | { |
| 711 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 712 | int ret; |
| 713 | |
| 714 | if (!cpu_online(cpu)) |
| 715 | return 0; |
| 716 | |
| 717 | cpuhp_lock_acquire(false); |
| 718 | cpuhp_lock_release(false); |
| 719 | |
| 720 | cpuhp_lock_acquire(true); |
| 721 | cpuhp_lock_release(true); |
| 722 | |
| 723 | /* |
| 724 | * If we are up and running, use the hotplug thread. For early calls |
| 725 | * we invoke the thread function directly. |
| 726 | */ |
| 727 | if (!st->thread) |
| 728 | return cpuhp_invoke_callback(cpu, state, bringup, node, NULL); |
| 729 | |
| 730 | st->rollback = false; |
| 731 | st->last = NULL; |
| 732 | |
| 733 | st->node = node; |
| 734 | st->bringup = bringup; |
| 735 | st->cb_state = state; |
| 736 | st->single = true; |
| 737 | |
| 738 | __cpuhp_kick_ap(st); |
| 739 | |
| 740 | /* |
| 741 | * If we failed and did a partial, do a rollback. |
| 742 | */ |
| 743 | if ((ret = st->result) && st->last) { |
| 744 | st->rollback = true; |
| 745 | st->bringup = !bringup; |
| 746 | |
| 747 | __cpuhp_kick_ap(st); |
| 748 | } |
| 749 | |
| 750 | /* |
| 751 | * Clean up the leftovers so the next hotplug operation wont use stale |
| 752 | * data. |
| 753 | */ |
| 754 | st->node = st->last = NULL; |
| 755 | return ret; |
| 756 | } |
| 757 | |
| 758 | static int cpuhp_kick_ap_work(unsigned int cpu) |
| 759 | { |
| 760 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 761 | enum cpuhp_state prev_state = st->state; |
| 762 | int ret; |
| 763 | |
| 764 | cpuhp_lock_acquire(false); |
| 765 | cpuhp_lock_release(false); |
| 766 | |
| 767 | cpuhp_lock_acquire(true); |
| 768 | cpuhp_lock_release(true); |
| 769 | |
| 770 | trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work); |
| 771 | ret = cpuhp_kick_ap(st, st->target); |
| 772 | trace_cpuhp_exit(cpu, st->state, prev_state, ret); |
| 773 | |
| 774 | return ret; |
| 775 | } |
| 776 | |
| 777 | static struct smp_hotplug_thread cpuhp_threads = { |
| 778 | .store = &cpuhp_state.thread, |
| 779 | .create = &cpuhp_create, |
| 780 | .thread_should_run = cpuhp_should_run, |
| 781 | .thread_fn = cpuhp_thread_fun, |
| 782 | .thread_comm = "cpuhp/%u", |
| 783 | .selfparking = true, |
| 784 | }; |
| 785 | |
| 786 | void __init cpuhp_threads_init(void) |
| 787 | { |
| 788 | BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads)); |
| 789 | kthread_unpark(this_cpu_read(cpuhp_state.thread)); |
| 790 | } |
| 791 | |
| 792 | #ifdef CONFIG_HOTPLUG_CPU |
| 793 | /** |
| 794 | * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU |
| 795 | * @cpu: a CPU id |
| 796 | * |
| 797 | * This function walks all processes, finds a valid mm struct for each one and |
| 798 | * then clears a corresponding bit in mm's cpumask. While this all sounds |
| 799 | * trivial, there are various non-obvious corner cases, which this function |
| 800 | * tries to solve in a safe manner. |
| 801 | * |
| 802 | * Also note that the function uses a somewhat relaxed locking scheme, so it may |
| 803 | * be called only for an already offlined CPU. |
| 804 | */ |
| 805 | void clear_tasks_mm_cpumask(int cpu) |
| 806 | { |
| 807 | struct task_struct *p; |
| 808 | |
| 809 | /* |
| 810 | * This function is called after the cpu is taken down and marked |
| 811 | * offline, so its not like new tasks will ever get this cpu set in |
| 812 | * their mm mask. -- Peter Zijlstra |
| 813 | * Thus, we may use rcu_read_lock() here, instead of grabbing |
| 814 | * full-fledged tasklist_lock. |
| 815 | */ |
| 816 | WARN_ON(cpu_online(cpu)); |
| 817 | rcu_read_lock(); |
| 818 | for_each_process(p) { |
| 819 | struct task_struct *t; |
| 820 | |
| 821 | /* |
| 822 | * Main thread might exit, but other threads may still have |
| 823 | * a valid mm. Find one. |
| 824 | */ |
| 825 | t = find_lock_task_mm(p); |
| 826 | if (!t) |
| 827 | continue; |
| 828 | cpumask_clear_cpu(cpu, mm_cpumask(t->mm)); |
| 829 | task_unlock(t); |
| 830 | } |
| 831 | rcu_read_unlock(); |
| 832 | } |
| 833 | |
| 834 | /* Take this CPU down. */ |
| 835 | static int take_cpu_down(void *_param) |
| 836 | { |
| 837 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
| 838 | enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE); |
| 839 | int err, cpu = smp_processor_id(); |
| 840 | int ret; |
| 841 | |
| 842 | /* Ensure this CPU doesn't handle any more interrupts. */ |
| 843 | err = __cpu_disable(); |
| 844 | if (err < 0) |
| 845 | return err; |
| 846 | |
| 847 | /* |
| 848 | * We get here while we are in CPUHP_TEARDOWN_CPU state and we must not |
| 849 | * do this step again. |
| 850 | */ |
| 851 | WARN_ON(st->state != CPUHP_TEARDOWN_CPU); |
| 852 | st->state--; |
| 853 | /* Invoke the former CPU_DYING callbacks */ |
| 854 | for (; st->state > target; st->state--) { |
| 855 | ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); |
| 856 | /* |
| 857 | * DYING must not fail! |
| 858 | */ |
| 859 | WARN_ON_ONCE(ret); |
| 860 | } |
| 861 | |
| 862 | /* Give up timekeeping duties */ |
| 863 | tick_handover_do_timer(); |
| 864 | /* Remove CPU from timer broadcasting */ |
| 865 | tick_offline_cpu(cpu); |
| 866 | /* Park the stopper thread */ |
| 867 | stop_machine_park(cpu); |
| 868 | return 0; |
| 869 | } |
| 870 | |
| 871 | static int takedown_cpu(unsigned int cpu) |
| 872 | { |
| 873 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 874 | int err; |
| 875 | |
| 876 | /* Park the smpboot threads */ |
| 877 | kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread); |
| 878 | |
| 879 | /* |
| 880 | * Prevent irq alloc/free while the dying cpu reorganizes the |
| 881 | * interrupt affinities. |
| 882 | */ |
| 883 | irq_lock_sparse(); |
| 884 | |
| 885 | /* |
| 886 | * So now all preempt/rcu users must observe !cpu_active(). |
| 887 | */ |
| 888 | err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu)); |
| 889 | if (err) { |
| 890 | /* CPU refused to die */ |
| 891 | irq_unlock_sparse(); |
| 892 | /* Unpark the hotplug thread so we can rollback there */ |
| 893 | kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread); |
| 894 | return err; |
| 895 | } |
| 896 | BUG_ON(cpu_online(cpu)); |
| 897 | |
| 898 | /* |
| 899 | * The teardown callback for CPUHP_AP_SCHED_STARTING will have removed |
| 900 | * all runnable tasks from the CPU, there's only the idle task left now |
| 901 | * that the migration thread is done doing the stop_machine thing. |
| 902 | * |
| 903 | * Wait for the stop thread to go away. |
| 904 | */ |
| 905 | wait_for_ap_thread(st, false); |
| 906 | BUG_ON(st->state != CPUHP_AP_IDLE_DEAD); |
| 907 | |
| 908 | /* Interrupts are moved away from the dying cpu, reenable alloc/free */ |
| 909 | irq_unlock_sparse(); |
| 910 | |
| 911 | hotplug_cpu__broadcast_tick_pull(cpu); |
| 912 | /* This actually kills the CPU. */ |
| 913 | __cpu_die(cpu); |
| 914 | |
| 915 | tick_cleanup_dead_cpu(cpu); |
| 916 | rcutree_migrate_callbacks(cpu); |
| 917 | return 0; |
| 918 | } |
| 919 | |
| 920 | static void cpuhp_complete_idle_dead(void *arg) |
| 921 | { |
| 922 | struct cpuhp_cpu_state *st = arg; |
| 923 | |
| 924 | complete_ap_thread(st, false); |
| 925 | } |
| 926 | |
| 927 | void cpuhp_report_idle_dead(void) |
| 928 | { |
| 929 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
| 930 | |
| 931 | BUG_ON(st->state != CPUHP_AP_OFFLINE); |
| 932 | rcu_report_dead(smp_processor_id()); |
| 933 | st->state = CPUHP_AP_IDLE_DEAD; |
| 934 | /* |
| 935 | * We cannot call complete after rcu_report_dead() so we delegate it |
| 936 | * to an online cpu. |
| 937 | */ |
| 938 | smp_call_function_single(cpumask_first(cpu_online_mask), |
| 939 | cpuhp_complete_idle_dead, st, 0); |
| 940 | } |
| 941 | |
| 942 | static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st) |
| 943 | { |
| 944 | for (st->state++; st->state < st->target; st->state++) |
| 945 | cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); |
| 946 | } |
| 947 | |
| 948 | static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, |
| 949 | enum cpuhp_state target) |
| 950 | { |
| 951 | enum cpuhp_state prev_state = st->state; |
| 952 | int ret = 0; |
| 953 | |
| 954 | for (; st->state > target; st->state--) { |
| 955 | ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); |
| 956 | if (ret) { |
| 957 | st->target = prev_state; |
| 958 | if (st->state < prev_state) |
| 959 | undo_cpu_down(cpu, st); |
| 960 | break; |
| 961 | } |
| 962 | } |
| 963 | return ret; |
| 964 | } |
| 965 | |
| 966 | /* Requires cpu_add_remove_lock to be held */ |
| 967 | static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, |
| 968 | enum cpuhp_state target) |
| 969 | { |
| 970 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 971 | int prev_state, ret = 0; |
| 972 | |
| 973 | if (num_online_cpus() == 1) |
| 974 | return -EBUSY; |
| 975 | |
| 976 | if (!cpu_present(cpu)) |
| 977 | return -EINVAL; |
| 978 | |
| 979 | cpus_write_lock(); |
| 980 | |
| 981 | cpuhp_tasks_frozen = tasks_frozen; |
| 982 | |
| 983 | prev_state = cpuhp_set_state(st, target); |
| 984 | /* |
| 985 | * If the current CPU state is in the range of the AP hotplug thread, |
| 986 | * then we need to kick the thread. |
| 987 | */ |
| 988 | if (st->state > CPUHP_TEARDOWN_CPU) { |
| 989 | st->target = max((int)target, CPUHP_TEARDOWN_CPU); |
| 990 | ret = cpuhp_kick_ap_work(cpu); |
| 991 | /* |
| 992 | * The AP side has done the error rollback already. Just |
| 993 | * return the error code.. |
| 994 | */ |
| 995 | if (ret) |
| 996 | goto out; |
| 997 | |
| 998 | /* |
| 999 | * We might have stopped still in the range of the AP hotplug |
| 1000 | * thread. Nothing to do anymore. |
| 1001 | */ |
| 1002 | if (st->state > CPUHP_TEARDOWN_CPU) |
| 1003 | goto out; |
| 1004 | |
| 1005 | st->target = target; |
| 1006 | } |
| 1007 | /* |
| 1008 | * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need |
| 1009 | * to do the further cleanups. |
| 1010 | */ |
| 1011 | ret = cpuhp_down_callbacks(cpu, st, target); |
| 1012 | if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) { |
| 1013 | cpuhp_reset_state(st, prev_state); |
| 1014 | __cpuhp_kick_ap(st); |
| 1015 | } |
| 1016 | |
| 1017 | out: |
| 1018 | cpus_write_unlock(); |
| 1019 | /* |
| 1020 | * Do post unplug cleanup. This is still protected against |
| 1021 | * concurrent CPU hotplug via cpu_add_remove_lock. |
| 1022 | */ |
| 1023 | lockup_detector_cleanup(); |
| 1024 | arch_smt_update(); |
| 1025 | return ret; |
| 1026 | } |
| 1027 | |
| 1028 | static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target) |
| 1029 | { |
| 1030 | if (cpu_hotplug_disabled) |
| 1031 | return -EBUSY; |
| 1032 | return _cpu_down(cpu, 0, target); |
| 1033 | } |
| 1034 | |
| 1035 | static int do_cpu_down(unsigned int cpu, enum cpuhp_state target) |
| 1036 | { |
| 1037 | int err; |
| 1038 | |
| 1039 | cpu_maps_update_begin(); |
| 1040 | err = cpu_down_maps_locked(cpu, target); |
| 1041 | cpu_maps_update_done(); |
| 1042 | return err; |
| 1043 | } |
| 1044 | |
| 1045 | int cpu_down(unsigned int cpu) |
| 1046 | { |
| 1047 | return do_cpu_down(cpu, CPUHP_OFFLINE); |
| 1048 | } |
| 1049 | EXPORT_SYMBOL(cpu_down); |
| 1050 | |
| 1051 | #else |
| 1052 | #define takedown_cpu NULL |
| 1053 | #endif /*CONFIG_HOTPLUG_CPU*/ |
| 1054 | |
| 1055 | /** |
| 1056 | * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU |
| 1057 | * @cpu: cpu that just started |
| 1058 | * |
| 1059 | * It must be called by the arch code on the new cpu, before the new cpu |
| 1060 | * enables interrupts and before the "boot" cpu returns from __cpu_up(). |
| 1061 | */ |
| 1062 | void notify_cpu_starting(unsigned int cpu) |
| 1063 | { |
| 1064 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 1065 | enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE); |
| 1066 | int ret; |
| 1067 | |
| 1068 | rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ |
| 1069 | st->booted_once = true; |
| 1070 | while (st->state < target) { |
| 1071 | st->state++; |
| 1072 | ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); |
| 1073 | /* |
| 1074 | * STARTING must not fail! |
| 1075 | */ |
| 1076 | WARN_ON_ONCE(ret); |
| 1077 | } |
| 1078 | } |
| 1079 | |
| 1080 | /* |
| 1081 | * Called from the idle task. Wake up the controlling task which brings the |
| 1082 | * stopper and the hotplug thread of the upcoming CPU up and then delegates |
| 1083 | * the rest of the online bringup to the hotplug thread. |
| 1084 | */ |
| 1085 | void cpuhp_online_idle(enum cpuhp_state state) |
| 1086 | { |
| 1087 | struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
| 1088 | |
| 1089 | /* Happens for the boot cpu */ |
| 1090 | if (state != CPUHP_AP_ONLINE_IDLE) |
| 1091 | return; |
| 1092 | |
| 1093 | st->state = CPUHP_AP_ONLINE_IDLE; |
| 1094 | complete_ap_thread(st, true); |
| 1095 | } |
| 1096 | |
| 1097 | /* Requires cpu_add_remove_lock to be held */ |
| 1098 | static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) |
| 1099 | { |
| 1100 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 1101 | struct task_struct *idle; |
| 1102 | int ret = 0; |
| 1103 | |
| 1104 | cpus_write_lock(); |
| 1105 | |
| 1106 | if (!cpu_present(cpu)) { |
| 1107 | ret = -EINVAL; |
| 1108 | goto out; |
| 1109 | } |
| 1110 | |
| 1111 | /* |
| 1112 | * The caller of do_cpu_up might have raced with another |
| 1113 | * caller. Ignore it for now. |
| 1114 | */ |
| 1115 | if (st->state >= target) |
| 1116 | goto out; |
| 1117 | |
| 1118 | if (st->state == CPUHP_OFFLINE) { |
| 1119 | /* Let it fail before we try to bring the cpu up */ |
| 1120 | idle = idle_thread_get(cpu); |
| 1121 | if (IS_ERR(idle)) { |
| 1122 | ret = PTR_ERR(idle); |
| 1123 | goto out; |
| 1124 | } |
| 1125 | } |
| 1126 | |
| 1127 | cpuhp_tasks_frozen = tasks_frozen; |
| 1128 | |
| 1129 | cpuhp_set_state(st, target); |
| 1130 | /* |
| 1131 | * If the current CPU state is in the range of the AP hotplug thread, |
| 1132 | * then we need to kick the thread once more. |
| 1133 | */ |
| 1134 | if (st->state > CPUHP_BRINGUP_CPU) { |
| 1135 | ret = cpuhp_kick_ap_work(cpu); |
| 1136 | /* |
| 1137 | * The AP side has done the error rollback already. Just |
| 1138 | * return the error code.. |
| 1139 | */ |
| 1140 | if (ret) |
| 1141 | goto out; |
| 1142 | } |
| 1143 | |
| 1144 | /* |
| 1145 | * Try to reach the target state. We max out on the BP at |
| 1146 | * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is |
| 1147 | * responsible for bringing it up to the target state. |
| 1148 | */ |
| 1149 | target = min((int)target, CPUHP_BRINGUP_CPU); |
| 1150 | ret = cpuhp_up_callbacks(cpu, st, target); |
| 1151 | out: |
| 1152 | cpus_write_unlock(); |
| 1153 | arch_smt_update(); |
| 1154 | return ret; |
| 1155 | } |
| 1156 | |
| 1157 | static int do_cpu_up(unsigned int cpu, enum cpuhp_state target) |
| 1158 | { |
| 1159 | int err = 0; |
| 1160 | |
| 1161 | if (!cpu_possible(cpu)) { |
| 1162 | pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n", |
| 1163 | cpu); |
| 1164 | #if defined(CONFIG_IA64) |
| 1165 | pr_err("please check additional_cpus= boot parameter\n"); |
| 1166 | #endif |
| 1167 | return -EINVAL; |
| 1168 | } |
| 1169 | |
| 1170 | err = try_online_node(cpu_to_node(cpu)); |
| 1171 | if (err) |
| 1172 | return err; |
| 1173 | |
| 1174 | cpu_maps_update_begin(); |
| 1175 | |
| 1176 | if (cpu_hotplug_disabled) { |
| 1177 | err = -EBUSY; |
| 1178 | goto out; |
| 1179 | } |
| 1180 | if (!cpu_smt_allowed(cpu)) { |
| 1181 | err = -EPERM; |
| 1182 | goto out; |
| 1183 | } |
| 1184 | |
| 1185 | err = _cpu_up(cpu, 0, target); |
| 1186 | out: |
| 1187 | cpu_maps_update_done(); |
| 1188 | return err; |
| 1189 | } |
| 1190 | |
| 1191 | int cpu_up(unsigned int cpu) |
| 1192 | { |
| 1193 | return do_cpu_up(cpu, CPUHP_ONLINE); |
| 1194 | } |
| 1195 | EXPORT_SYMBOL_GPL(cpu_up); |
| 1196 | |
| 1197 | #ifdef CONFIG_PM_SLEEP_SMP |
| 1198 | static cpumask_var_t frozen_cpus; |
| 1199 | |
| 1200 | int freeze_secondary_cpus(int primary) |
| 1201 | { |
| 1202 | int cpu, error = 0; |
| 1203 | |
| 1204 | cpu_maps_update_begin(); |
| 1205 | if (primary == -1) { |
| 1206 | primary = cpumask_first(cpu_online_mask); |
| 1207 | if (!housekeeping_cpu(primary, HK_FLAG_TIMER)) |
| 1208 | primary = housekeeping_any_cpu(HK_FLAG_TIMER); |
| 1209 | } else { |
| 1210 | if (!cpu_online(primary)) |
| 1211 | primary = cpumask_first(cpu_online_mask); |
| 1212 | } |
| 1213 | |
| 1214 | /* |
| 1215 | * We take down all of the non-boot CPUs in one shot to avoid races |
| 1216 | * with the userspace trying to use the CPU hotplug at the same time |
| 1217 | */ |
| 1218 | cpumask_clear(frozen_cpus); |
| 1219 | |
| 1220 | pr_info("Disabling non-boot CPUs ...\n"); |
| 1221 | for_each_online_cpu(cpu) { |
| 1222 | if (cpu == primary) |
| 1223 | continue; |
| 1224 | |
| 1225 | if (pm_wakeup_pending()) { |
| 1226 | pr_info("Wakeup pending. Abort CPU freeze\n"); |
| 1227 | error = -EBUSY; |
| 1228 | break; |
| 1229 | } |
| 1230 | |
| 1231 | trace_suspend_resume(TPS("CPU_OFF"), cpu, true); |
| 1232 | error = _cpu_down(cpu, 1, CPUHP_OFFLINE); |
| 1233 | trace_suspend_resume(TPS("CPU_OFF"), cpu, false); |
| 1234 | if (!error) |
| 1235 | cpumask_set_cpu(cpu, frozen_cpus); |
| 1236 | else { |
| 1237 | pr_err("Error taking CPU%d down: %d\n", cpu, error); |
| 1238 | break; |
| 1239 | } |
| 1240 | } |
| 1241 | |
| 1242 | if (!error) |
| 1243 | BUG_ON(num_online_cpus() > 1); |
| 1244 | else |
| 1245 | pr_err("Non-boot CPUs are not disabled\n"); |
| 1246 | |
| 1247 | /* |
| 1248 | * Make sure the CPUs won't be enabled by someone else. We need to do |
| 1249 | * this even in case of failure as all disable_nonboot_cpus() users are |
| 1250 | * supposed to do enable_nonboot_cpus() on the failure path. |
| 1251 | */ |
| 1252 | cpu_hotplug_disabled++; |
| 1253 | |
| 1254 | cpu_maps_update_done(); |
| 1255 | return error; |
| 1256 | } |
| 1257 | |
| 1258 | void __weak arch_enable_nonboot_cpus_begin(void) |
| 1259 | { |
| 1260 | } |
| 1261 | |
| 1262 | void __weak arch_enable_nonboot_cpus_end(void) |
| 1263 | { |
| 1264 | } |
| 1265 | |
| 1266 | void enable_nonboot_cpus(void) |
| 1267 | { |
| 1268 | int cpu, error; |
| 1269 | |
| 1270 | /* Allow everyone to use the CPU hotplug again */ |
| 1271 | cpu_maps_update_begin(); |
| 1272 | __cpu_hotplug_enable(); |
| 1273 | if (cpumask_empty(frozen_cpus)) |
| 1274 | goto out; |
| 1275 | |
| 1276 | pr_info("Enabling non-boot CPUs ...\n"); |
| 1277 | |
| 1278 | arch_enable_nonboot_cpus_begin(); |
| 1279 | |
| 1280 | for_each_cpu(cpu, frozen_cpus) { |
| 1281 | trace_suspend_resume(TPS("CPU_ON"), cpu, true); |
| 1282 | error = _cpu_up(cpu, 1, CPUHP_ONLINE); |
| 1283 | trace_suspend_resume(TPS("CPU_ON"), cpu, false); |
| 1284 | if (!error) { |
| 1285 | pr_info("CPU%d is up\n", cpu); |
| 1286 | continue; |
| 1287 | } |
| 1288 | pr_warn("Error taking CPU%d up: %d\n", cpu, error); |
| 1289 | } |
| 1290 | |
| 1291 | arch_enable_nonboot_cpus_end(); |
| 1292 | |
| 1293 | cpumask_clear(frozen_cpus); |
| 1294 | out: |
| 1295 | cpu_maps_update_done(); |
| 1296 | } |
| 1297 | |
| 1298 | static int __init alloc_frozen_cpus(void) |
| 1299 | { |
| 1300 | if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO)) |
| 1301 | return -ENOMEM; |
| 1302 | return 0; |
| 1303 | } |
| 1304 | core_initcall(alloc_frozen_cpus); |
| 1305 | |
| 1306 | /* |
| 1307 | * When callbacks for CPU hotplug notifications are being executed, we must |
| 1308 | * ensure that the state of the system with respect to the tasks being frozen |
| 1309 | * or not, as reported by the notification, remains unchanged *throughout the |
| 1310 | * duration* of the execution of the callbacks. |
| 1311 | * Hence we need to prevent the freezer from racing with regular CPU hotplug. |
| 1312 | * |
| 1313 | * This synchronization is implemented by mutually excluding regular CPU |
| 1314 | * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/ |
| 1315 | * Hibernate notifications. |
| 1316 | */ |
| 1317 | static int |
| 1318 | cpu_hotplug_pm_callback(struct notifier_block *nb, |
| 1319 | unsigned long action, void *ptr) |
| 1320 | { |
| 1321 | switch (action) { |
| 1322 | |
| 1323 | case PM_SUSPEND_PREPARE: |
| 1324 | case PM_HIBERNATION_PREPARE: |
| 1325 | cpu_hotplug_disable(); |
| 1326 | break; |
| 1327 | |
| 1328 | case PM_POST_SUSPEND: |
| 1329 | case PM_POST_HIBERNATION: |
| 1330 | cpu_hotplug_enable(); |
| 1331 | break; |
| 1332 | |
| 1333 | default: |
| 1334 | return NOTIFY_DONE; |
| 1335 | } |
| 1336 | |
| 1337 | return NOTIFY_OK; |
| 1338 | } |
| 1339 | |
| 1340 | |
| 1341 | static int __init cpu_hotplug_pm_sync_init(void) |
| 1342 | { |
| 1343 | /* |
| 1344 | * cpu_hotplug_pm_callback has higher priority than x86 |
| 1345 | * bsp_pm_callback which depends on cpu_hotplug_pm_callback |
| 1346 | * to disable cpu hotplug to avoid cpu hotplug race. |
| 1347 | */ |
| 1348 | pm_notifier(cpu_hotplug_pm_callback, 0); |
| 1349 | return 0; |
| 1350 | } |
| 1351 | core_initcall(cpu_hotplug_pm_sync_init); |
| 1352 | |
| 1353 | #endif /* CONFIG_PM_SLEEP_SMP */ |
| 1354 | |
| 1355 | int __boot_cpu_id; |
| 1356 | |
| 1357 | #endif /* CONFIG_SMP */ |
| 1358 | |
| 1359 | /* Boot processor state steps */ |
| 1360 | static struct cpuhp_step cpuhp_hp_states[] = { |
| 1361 | [CPUHP_OFFLINE] = { |
| 1362 | .name = "offline", |
| 1363 | .startup.single = NULL, |
| 1364 | .teardown.single = NULL, |
| 1365 | }, |
| 1366 | #ifdef CONFIG_SMP |
| 1367 | [CPUHP_CREATE_THREADS]= { |
| 1368 | .name = "threads:prepare", |
| 1369 | .startup.single = smpboot_create_threads, |
| 1370 | .teardown.single = NULL, |
| 1371 | .cant_stop = true, |
| 1372 | }, |
| 1373 | [CPUHP_PERF_PREPARE] = { |
| 1374 | .name = "perf:prepare", |
| 1375 | .startup.single = perf_event_init_cpu, |
| 1376 | .teardown.single = perf_event_exit_cpu, |
| 1377 | }, |
| 1378 | [CPUHP_WORKQUEUE_PREP] = { |
| 1379 | .name = "workqueue:prepare", |
| 1380 | .startup.single = workqueue_prepare_cpu, |
| 1381 | .teardown.single = NULL, |
| 1382 | }, |
| 1383 | [CPUHP_HRTIMERS_PREPARE] = { |
| 1384 | .name = "hrtimers:prepare", |
| 1385 | .startup.single = hrtimers_prepare_cpu, |
| 1386 | .teardown.single = hrtimers_dead_cpu, |
| 1387 | }, |
| 1388 | [CPUHP_SMPCFD_PREPARE] = { |
| 1389 | .name = "smpcfd:prepare", |
| 1390 | .startup.single = smpcfd_prepare_cpu, |
| 1391 | .teardown.single = smpcfd_dead_cpu, |
| 1392 | }, |
| 1393 | [CPUHP_RELAY_PREPARE] = { |
| 1394 | .name = "relay:prepare", |
| 1395 | .startup.single = relay_prepare_cpu, |
| 1396 | .teardown.single = NULL, |
| 1397 | }, |
| 1398 | [CPUHP_SLAB_PREPARE] = { |
| 1399 | .name = "slab:prepare", |
| 1400 | .startup.single = slab_prepare_cpu, |
| 1401 | .teardown.single = slab_dead_cpu, |
| 1402 | }, |
| 1403 | [CPUHP_RCUTREE_PREP] = { |
| 1404 | .name = "RCU/tree:prepare", |
| 1405 | .startup.single = rcutree_prepare_cpu, |
| 1406 | .teardown.single = rcutree_dead_cpu, |
| 1407 | }, |
| 1408 | /* |
| 1409 | * On the tear-down path, timers_dead_cpu() must be invoked |
| 1410 | * before blk_mq_queue_reinit_notify() from notify_dead(), |
| 1411 | * otherwise a RCU stall occurs. |
| 1412 | */ |
| 1413 | [CPUHP_TIMERS_PREPARE] = { |
| 1414 | .name = "timers:prepare", |
| 1415 | .startup.single = timers_prepare_cpu, |
| 1416 | .teardown.single = timers_dead_cpu, |
| 1417 | }, |
| 1418 | /* Kicks the plugged cpu into life */ |
| 1419 | [CPUHP_BRINGUP_CPU] = { |
| 1420 | .name = "cpu:bringup", |
| 1421 | .startup.single = bringup_cpu, |
| 1422 | .teardown.single = NULL, |
| 1423 | .cant_stop = true, |
| 1424 | }, |
| 1425 | /* Final state before CPU kills itself */ |
| 1426 | [CPUHP_AP_IDLE_DEAD] = { |
| 1427 | .name = "idle:dead", |
| 1428 | }, |
| 1429 | /* |
| 1430 | * Last state before CPU enters the idle loop to die. Transient state |
| 1431 | * for synchronization. |
| 1432 | */ |
| 1433 | [CPUHP_AP_OFFLINE] = { |
| 1434 | .name = "ap:offline", |
| 1435 | .cant_stop = true, |
| 1436 | }, |
| 1437 | /* First state is scheduler control. Interrupts are disabled */ |
| 1438 | [CPUHP_AP_SCHED_STARTING] = { |
| 1439 | .name = "sched:starting", |
| 1440 | .startup.single = sched_cpu_starting, |
| 1441 | .teardown.single = sched_cpu_dying, |
| 1442 | }, |
| 1443 | [CPUHP_AP_RCUTREE_DYING] = { |
| 1444 | .name = "RCU/tree:dying", |
| 1445 | .startup.single = NULL, |
| 1446 | .teardown.single = rcutree_dying_cpu, |
| 1447 | }, |
| 1448 | [CPUHP_AP_SMPCFD_DYING] = { |
| 1449 | .name = "smpcfd:dying", |
| 1450 | .startup.single = NULL, |
| 1451 | .teardown.single = smpcfd_dying_cpu, |
| 1452 | }, |
| 1453 | /* Entry state on starting. Interrupts enabled from here on. Transient |
| 1454 | * state for synchronsization */ |
| 1455 | [CPUHP_AP_ONLINE] = { |
| 1456 | .name = "ap:online", |
| 1457 | }, |
| 1458 | /* |
| 1459 | * Handled on controll processor until the plugged processor manages |
| 1460 | * this itself. |
| 1461 | */ |
| 1462 | [CPUHP_TEARDOWN_CPU] = { |
| 1463 | .name = "cpu:teardown", |
| 1464 | .startup.single = NULL, |
| 1465 | .teardown.single = takedown_cpu, |
| 1466 | .cant_stop = true, |
| 1467 | }, |
| 1468 | /* Handle smpboot threads park/unpark */ |
| 1469 | [CPUHP_AP_SMPBOOT_THREADS] = { |
| 1470 | .name = "smpboot/threads:online", |
| 1471 | .startup.single = smpboot_unpark_threads, |
| 1472 | .teardown.single = smpboot_park_threads, |
| 1473 | }, |
| 1474 | [CPUHP_AP_IRQ_AFFINITY_ONLINE] = { |
| 1475 | .name = "irq/affinity:online", |
| 1476 | .startup.single = irq_affinity_online_cpu, |
| 1477 | .teardown.single = NULL, |
| 1478 | }, |
| 1479 | [CPUHP_AP_PERF_ONLINE] = { |
| 1480 | .name = "perf:online", |
| 1481 | .startup.single = perf_event_init_cpu, |
| 1482 | .teardown.single = perf_event_exit_cpu, |
| 1483 | }, |
| 1484 | [CPUHP_AP_WATCHDOG_ONLINE] = { |
| 1485 | .name = "lockup_detector:online", |
| 1486 | .startup.single = lockup_detector_online_cpu, |
| 1487 | .teardown.single = lockup_detector_offline_cpu, |
| 1488 | }, |
| 1489 | [CPUHP_AP_WORKQUEUE_ONLINE] = { |
| 1490 | .name = "workqueue:online", |
| 1491 | .startup.single = workqueue_online_cpu, |
| 1492 | .teardown.single = workqueue_offline_cpu, |
| 1493 | }, |
| 1494 | [CPUHP_AP_RCUTREE_ONLINE] = { |
| 1495 | .name = "RCU/tree:online", |
| 1496 | .startup.single = rcutree_online_cpu, |
| 1497 | .teardown.single = rcutree_offline_cpu, |
| 1498 | }, |
| 1499 | #endif |
| 1500 | /* |
| 1501 | * The dynamically registered state space is here |
| 1502 | */ |
| 1503 | |
| 1504 | #ifdef CONFIG_SMP |
| 1505 | /* Last state is scheduler control setting the cpu active */ |
| 1506 | [CPUHP_AP_ACTIVE] = { |
| 1507 | .name = "sched:active", |
| 1508 | .startup.single = sched_cpu_activate, |
| 1509 | .teardown.single = sched_cpu_deactivate, |
| 1510 | }, |
| 1511 | #endif |
| 1512 | |
| 1513 | /* CPU is fully up and running. */ |
| 1514 | [CPUHP_ONLINE] = { |
| 1515 | .name = "online", |
| 1516 | .startup.single = NULL, |
| 1517 | .teardown.single = NULL, |
| 1518 | }, |
| 1519 | }; |
| 1520 | |
| 1521 | /* Sanity check for callbacks */ |
| 1522 | static int cpuhp_cb_check(enum cpuhp_state state) |
| 1523 | { |
| 1524 | if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE) |
| 1525 | return -EINVAL; |
| 1526 | return 0; |
| 1527 | } |
| 1528 | |
| 1529 | /* |
| 1530 | * Returns a free for dynamic slot assignment of the Online state. The states |
| 1531 | * are protected by the cpuhp_slot_states mutex and an empty slot is identified |
| 1532 | * by having no name assigned. |
| 1533 | */ |
| 1534 | static int cpuhp_reserve_state(enum cpuhp_state state) |
| 1535 | { |
| 1536 | enum cpuhp_state i, end; |
| 1537 | struct cpuhp_step *step; |
| 1538 | |
| 1539 | switch (state) { |
| 1540 | case CPUHP_AP_ONLINE_DYN: |
| 1541 | step = cpuhp_hp_states + CPUHP_AP_ONLINE_DYN; |
| 1542 | end = CPUHP_AP_ONLINE_DYN_END; |
| 1543 | break; |
| 1544 | case CPUHP_BP_PREPARE_DYN: |
| 1545 | step = cpuhp_hp_states + CPUHP_BP_PREPARE_DYN; |
| 1546 | end = CPUHP_BP_PREPARE_DYN_END; |
| 1547 | break; |
| 1548 | default: |
| 1549 | return -EINVAL; |
| 1550 | } |
| 1551 | |
| 1552 | for (i = state; i <= end; i++, step++) { |
| 1553 | if (!step->name) |
| 1554 | return i; |
| 1555 | } |
| 1556 | WARN(1, "No more dynamic states available for CPU hotplug\n"); |
| 1557 | return -ENOSPC; |
| 1558 | } |
| 1559 | |
| 1560 | static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name, |
| 1561 | int (*startup)(unsigned int cpu), |
| 1562 | int (*teardown)(unsigned int cpu), |
| 1563 | bool multi_instance) |
| 1564 | { |
| 1565 | /* (Un)Install the callbacks for further cpu hotplug operations */ |
| 1566 | struct cpuhp_step *sp; |
| 1567 | int ret = 0; |
| 1568 | |
| 1569 | /* |
| 1570 | * If name is NULL, then the state gets removed. |
| 1571 | * |
| 1572 | * CPUHP_AP_ONLINE_DYN and CPUHP_BP_PREPARE_DYN are handed out on |
| 1573 | * the first allocation from these dynamic ranges, so the removal |
| 1574 | * would trigger a new allocation and clear the wrong (already |
| 1575 | * empty) state, leaving the callbacks of the to be cleared state |
| 1576 | * dangling, which causes wreckage on the next hotplug operation. |
| 1577 | */ |
| 1578 | if (name && (state == CPUHP_AP_ONLINE_DYN || |
| 1579 | state == CPUHP_BP_PREPARE_DYN)) { |
| 1580 | ret = cpuhp_reserve_state(state); |
| 1581 | if (ret < 0) |
| 1582 | return ret; |
| 1583 | state = ret; |
| 1584 | } |
| 1585 | sp = cpuhp_get_step(state); |
| 1586 | if (name && sp->name) |
| 1587 | return -EBUSY; |
| 1588 | |
| 1589 | sp->startup.single = startup; |
| 1590 | sp->teardown.single = teardown; |
| 1591 | sp->name = name; |
| 1592 | sp->multi_instance = multi_instance; |
| 1593 | INIT_HLIST_HEAD(&sp->list); |
| 1594 | return ret; |
| 1595 | } |
| 1596 | |
| 1597 | static void *cpuhp_get_teardown_cb(enum cpuhp_state state) |
| 1598 | { |
| 1599 | return cpuhp_get_step(state)->teardown.single; |
| 1600 | } |
| 1601 | |
| 1602 | /* |
| 1603 | * Call the startup/teardown function for a step either on the AP or |
| 1604 | * on the current CPU. |
| 1605 | */ |
| 1606 | static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup, |
| 1607 | struct hlist_node *node) |
| 1608 | { |
| 1609 | struct cpuhp_step *sp = cpuhp_get_step(state); |
| 1610 | int ret; |
| 1611 | |
| 1612 | /* |
| 1613 | * If there's nothing to do, we done. |
| 1614 | * Relies on the union for multi_instance. |
| 1615 | */ |
| 1616 | if ((bringup && !sp->startup.single) || |
| 1617 | (!bringup && !sp->teardown.single)) |
| 1618 | return 0; |
| 1619 | /* |
| 1620 | * The non AP bound callbacks can fail on bringup. On teardown |
| 1621 | * e.g. module removal we crash for now. |
| 1622 | */ |
| 1623 | #ifdef CONFIG_SMP |
| 1624 | if (cpuhp_is_ap_state(state)) |
| 1625 | ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node); |
| 1626 | else |
| 1627 | ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL); |
| 1628 | #else |
| 1629 | ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL); |
| 1630 | #endif |
| 1631 | BUG_ON(ret && !bringup); |
| 1632 | return ret; |
| 1633 | } |
| 1634 | |
| 1635 | /* |
| 1636 | * Called from __cpuhp_setup_state on a recoverable failure. |
| 1637 | * |
| 1638 | * Note: The teardown callbacks for rollback are not allowed to fail! |
| 1639 | */ |
| 1640 | static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state, |
| 1641 | struct hlist_node *node) |
| 1642 | { |
| 1643 | int cpu; |
| 1644 | |
| 1645 | /* Roll back the already executed steps on the other cpus */ |
| 1646 | for_each_present_cpu(cpu) { |
| 1647 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 1648 | int cpustate = st->state; |
| 1649 | |
| 1650 | if (cpu >= failedcpu) |
| 1651 | break; |
| 1652 | |
| 1653 | /* Did we invoke the startup call on that cpu ? */ |
| 1654 | if (cpustate >= state) |
| 1655 | cpuhp_issue_call(cpu, state, false, node); |
| 1656 | } |
| 1657 | } |
| 1658 | |
| 1659 | int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state, |
| 1660 | struct hlist_node *node, |
| 1661 | bool invoke) |
| 1662 | { |
| 1663 | struct cpuhp_step *sp; |
| 1664 | int cpu; |
| 1665 | int ret; |
| 1666 | |
| 1667 | lockdep_assert_cpus_held(); |
| 1668 | |
| 1669 | sp = cpuhp_get_step(state); |
| 1670 | if (sp->multi_instance == false) |
| 1671 | return -EINVAL; |
| 1672 | |
| 1673 | mutex_lock(&cpuhp_state_mutex); |
| 1674 | |
| 1675 | if (!invoke || !sp->startup.multi) |
| 1676 | goto add_node; |
| 1677 | |
| 1678 | /* |
| 1679 | * Try to call the startup callback for each present cpu |
| 1680 | * depending on the hotplug state of the cpu. |
| 1681 | */ |
| 1682 | for_each_present_cpu(cpu) { |
| 1683 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 1684 | int cpustate = st->state; |
| 1685 | |
| 1686 | if (cpustate < state) |
| 1687 | continue; |
| 1688 | |
| 1689 | ret = cpuhp_issue_call(cpu, state, true, node); |
| 1690 | if (ret) { |
| 1691 | if (sp->teardown.multi) |
| 1692 | cpuhp_rollback_install(cpu, state, node); |
| 1693 | goto unlock; |
| 1694 | } |
| 1695 | } |
| 1696 | add_node: |
| 1697 | ret = 0; |
| 1698 | hlist_add_head(node, &sp->list); |
| 1699 | unlock: |
| 1700 | mutex_unlock(&cpuhp_state_mutex); |
| 1701 | return ret; |
| 1702 | } |
| 1703 | |
| 1704 | int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, |
| 1705 | bool invoke) |
| 1706 | { |
| 1707 | int ret; |
| 1708 | |
| 1709 | cpus_read_lock(); |
| 1710 | ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke); |
| 1711 | cpus_read_unlock(); |
| 1712 | return ret; |
| 1713 | } |
| 1714 | EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); |
| 1715 | |
| 1716 | /** |
| 1717 | * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state |
| 1718 | * @state: The state to setup |
| 1719 | * @invoke: If true, the startup function is invoked for cpus where |
| 1720 | * cpu state >= @state |
| 1721 | * @startup: startup callback function |
| 1722 | * @teardown: teardown callback function |
| 1723 | * @multi_instance: State is set up for multiple instances which get |
| 1724 | * added afterwards. |
| 1725 | * |
| 1726 | * The caller needs to hold cpus read locked while calling this function. |
| 1727 | * Returns: |
| 1728 | * On success: |
| 1729 | * Positive state number if @state is CPUHP_AP_ONLINE_DYN |
| 1730 | * 0 for all other states |
| 1731 | * On failure: proper (negative) error code |
| 1732 | */ |
| 1733 | int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state, |
| 1734 | const char *name, bool invoke, |
| 1735 | int (*startup)(unsigned int cpu), |
| 1736 | int (*teardown)(unsigned int cpu), |
| 1737 | bool multi_instance) |
| 1738 | { |
| 1739 | int cpu, ret = 0; |
| 1740 | bool dynstate; |
| 1741 | |
| 1742 | lockdep_assert_cpus_held(); |
| 1743 | |
| 1744 | if (cpuhp_cb_check(state) || !name) |
| 1745 | return -EINVAL; |
| 1746 | |
| 1747 | mutex_lock(&cpuhp_state_mutex); |
| 1748 | |
| 1749 | ret = cpuhp_store_callbacks(state, name, startup, teardown, |
| 1750 | multi_instance); |
| 1751 | |
| 1752 | dynstate = state == CPUHP_AP_ONLINE_DYN; |
| 1753 | if (ret > 0 && dynstate) { |
| 1754 | state = ret; |
| 1755 | ret = 0; |
| 1756 | } |
| 1757 | |
| 1758 | if (ret || !invoke || !startup) |
| 1759 | goto out; |
| 1760 | |
| 1761 | /* |
| 1762 | * Try to call the startup callback for each present cpu |
| 1763 | * depending on the hotplug state of the cpu. |
| 1764 | */ |
| 1765 | for_each_present_cpu(cpu) { |
| 1766 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 1767 | int cpustate = st->state; |
| 1768 | |
| 1769 | if (cpustate < state) |
| 1770 | continue; |
| 1771 | |
| 1772 | ret = cpuhp_issue_call(cpu, state, true, NULL); |
| 1773 | if (ret) { |
| 1774 | if (teardown) |
| 1775 | cpuhp_rollback_install(cpu, state, NULL); |
| 1776 | cpuhp_store_callbacks(state, NULL, NULL, NULL, false); |
| 1777 | goto out; |
| 1778 | } |
| 1779 | } |
| 1780 | out: |
| 1781 | mutex_unlock(&cpuhp_state_mutex); |
| 1782 | /* |
| 1783 | * If the requested state is CPUHP_AP_ONLINE_DYN, return the |
| 1784 | * dynamically allocated state in case of success. |
| 1785 | */ |
| 1786 | if (!ret && dynstate) |
| 1787 | return state; |
| 1788 | return ret; |
| 1789 | } |
| 1790 | EXPORT_SYMBOL(__cpuhp_setup_state_cpuslocked); |
| 1791 | |
| 1792 | int __cpuhp_setup_state(enum cpuhp_state state, |
| 1793 | const char *name, bool invoke, |
| 1794 | int (*startup)(unsigned int cpu), |
| 1795 | int (*teardown)(unsigned int cpu), |
| 1796 | bool multi_instance) |
| 1797 | { |
| 1798 | int ret; |
| 1799 | |
| 1800 | cpus_read_lock(); |
| 1801 | ret = __cpuhp_setup_state_cpuslocked(state, name, invoke, startup, |
| 1802 | teardown, multi_instance); |
| 1803 | cpus_read_unlock(); |
| 1804 | return ret; |
| 1805 | } |
| 1806 | EXPORT_SYMBOL(__cpuhp_setup_state); |
| 1807 | |
| 1808 | int __cpuhp_state_remove_instance(enum cpuhp_state state, |
| 1809 | struct hlist_node *node, bool invoke) |
| 1810 | { |
| 1811 | struct cpuhp_step *sp = cpuhp_get_step(state); |
| 1812 | int cpu; |
| 1813 | |
| 1814 | BUG_ON(cpuhp_cb_check(state)); |
| 1815 | |
| 1816 | if (!sp->multi_instance) |
| 1817 | return -EINVAL; |
| 1818 | |
| 1819 | cpus_read_lock(); |
| 1820 | mutex_lock(&cpuhp_state_mutex); |
| 1821 | |
| 1822 | if (!invoke || !cpuhp_get_teardown_cb(state)) |
| 1823 | goto remove; |
| 1824 | /* |
| 1825 | * Call the teardown callback for each present cpu depending |
| 1826 | * on the hotplug state of the cpu. This function is not |
| 1827 | * allowed to fail currently! |
| 1828 | */ |
| 1829 | for_each_present_cpu(cpu) { |
| 1830 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 1831 | int cpustate = st->state; |
| 1832 | |
| 1833 | if (cpustate >= state) |
| 1834 | cpuhp_issue_call(cpu, state, false, node); |
| 1835 | } |
| 1836 | |
| 1837 | remove: |
| 1838 | hlist_del(node); |
| 1839 | mutex_unlock(&cpuhp_state_mutex); |
| 1840 | cpus_read_unlock(); |
| 1841 | |
| 1842 | return 0; |
| 1843 | } |
| 1844 | EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance); |
| 1845 | |
| 1846 | /** |
| 1847 | * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state |
| 1848 | * @state: The state to remove |
| 1849 | * @invoke: If true, the teardown function is invoked for cpus where |
| 1850 | * cpu state >= @state |
| 1851 | * |
| 1852 | * The caller needs to hold cpus read locked while calling this function. |
| 1853 | * The teardown callback is currently not allowed to fail. Think |
| 1854 | * about module removal! |
| 1855 | */ |
| 1856 | void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke) |
| 1857 | { |
| 1858 | struct cpuhp_step *sp = cpuhp_get_step(state); |
| 1859 | int cpu; |
| 1860 | |
| 1861 | BUG_ON(cpuhp_cb_check(state)); |
| 1862 | |
| 1863 | lockdep_assert_cpus_held(); |
| 1864 | |
| 1865 | mutex_lock(&cpuhp_state_mutex); |
| 1866 | if (sp->multi_instance) { |
| 1867 | WARN(!hlist_empty(&sp->list), |
| 1868 | "Error: Removing state %d which has instances left.\n", |
| 1869 | state); |
| 1870 | goto remove; |
| 1871 | } |
| 1872 | |
| 1873 | if (!invoke || !cpuhp_get_teardown_cb(state)) |
| 1874 | goto remove; |
| 1875 | |
| 1876 | /* |
| 1877 | * Call the teardown callback for each present cpu depending |
| 1878 | * on the hotplug state of the cpu. This function is not |
| 1879 | * allowed to fail currently! |
| 1880 | */ |
| 1881 | for_each_present_cpu(cpu) { |
| 1882 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
| 1883 | int cpustate = st->state; |
| 1884 | |
| 1885 | if (cpustate >= state) |
| 1886 | cpuhp_issue_call(cpu, state, false, NULL); |
| 1887 | } |
| 1888 | remove: |
| 1889 | cpuhp_store_callbacks(state, NULL, NULL, NULL, false); |
| 1890 | mutex_unlock(&cpuhp_state_mutex); |
| 1891 | } |
| 1892 | EXPORT_SYMBOL(__cpuhp_remove_state_cpuslocked); |
| 1893 | |
| 1894 | void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) |
| 1895 | { |
| 1896 | cpus_read_lock(); |
| 1897 | __cpuhp_remove_state_cpuslocked(state, invoke); |
| 1898 | cpus_read_unlock(); |
| 1899 | } |
| 1900 | EXPORT_SYMBOL(__cpuhp_remove_state); |
| 1901 | |
| 1902 | #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU) |
| 1903 | static ssize_t show_cpuhp_state(struct device *dev, |
| 1904 | struct device_attribute *attr, char *buf) |
| 1905 | { |
| 1906 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); |
| 1907 | |
| 1908 | return sprintf(buf, "%d\n", st->state); |
| 1909 | } |
| 1910 | static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL); |
| 1911 | |
| 1912 | static ssize_t write_cpuhp_target(struct device *dev, |
| 1913 | struct device_attribute *attr, |
| 1914 | const char *buf, size_t count) |
| 1915 | { |
| 1916 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); |
| 1917 | struct cpuhp_step *sp; |
| 1918 | int target, ret; |
| 1919 | |
| 1920 | ret = kstrtoint(buf, 10, &target); |
| 1921 | if (ret) |
| 1922 | return ret; |
| 1923 | |
| 1924 | #ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL |
| 1925 | if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE) |
| 1926 | return -EINVAL; |
| 1927 | #else |
| 1928 | if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE) |
| 1929 | return -EINVAL; |
| 1930 | #endif |
| 1931 | |
| 1932 | ret = lock_device_hotplug_sysfs(); |
| 1933 | if (ret) |
| 1934 | return ret; |
| 1935 | |
| 1936 | mutex_lock(&cpuhp_state_mutex); |
| 1937 | sp = cpuhp_get_step(target); |
| 1938 | ret = !sp->name || sp->cant_stop ? -EINVAL : 0; |
| 1939 | mutex_unlock(&cpuhp_state_mutex); |
| 1940 | if (ret) |
| 1941 | goto out; |
| 1942 | |
| 1943 | if (st->state < target) |
| 1944 | ret = do_cpu_up(dev->id, target); |
| 1945 | else |
| 1946 | ret = do_cpu_down(dev->id, target); |
| 1947 | out: |
| 1948 | unlock_device_hotplug(); |
| 1949 | return ret ? ret : count; |
| 1950 | } |
| 1951 | |
| 1952 | static ssize_t show_cpuhp_target(struct device *dev, |
| 1953 | struct device_attribute *attr, char *buf) |
| 1954 | { |
| 1955 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); |
| 1956 | |
| 1957 | return sprintf(buf, "%d\n", st->target); |
| 1958 | } |
| 1959 | static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target); |
| 1960 | |
| 1961 | |
| 1962 | static ssize_t write_cpuhp_fail(struct device *dev, |
| 1963 | struct device_attribute *attr, |
| 1964 | const char *buf, size_t count) |
| 1965 | { |
| 1966 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); |
| 1967 | struct cpuhp_step *sp; |
| 1968 | int fail, ret; |
| 1969 | |
| 1970 | ret = kstrtoint(buf, 10, &fail); |
| 1971 | if (ret) |
| 1972 | return ret; |
| 1973 | |
| 1974 | if (fail < CPUHP_OFFLINE || fail > CPUHP_ONLINE) |
| 1975 | return -EINVAL; |
| 1976 | |
| 1977 | /* |
| 1978 | * Cannot fail STARTING/DYING callbacks. |
| 1979 | */ |
| 1980 | if (cpuhp_is_atomic_state(fail)) |
| 1981 | return -EINVAL; |
| 1982 | |
| 1983 | /* |
| 1984 | * Cannot fail anything that doesn't have callbacks. |
| 1985 | */ |
| 1986 | mutex_lock(&cpuhp_state_mutex); |
| 1987 | sp = cpuhp_get_step(fail); |
| 1988 | if (!sp->startup.single && !sp->teardown.single) |
| 1989 | ret = -EINVAL; |
| 1990 | mutex_unlock(&cpuhp_state_mutex); |
| 1991 | if (ret) |
| 1992 | return ret; |
| 1993 | |
| 1994 | st->fail = fail; |
| 1995 | |
| 1996 | return count; |
| 1997 | } |
| 1998 | |
| 1999 | static ssize_t show_cpuhp_fail(struct device *dev, |
| 2000 | struct device_attribute *attr, char *buf) |
| 2001 | { |
| 2002 | struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); |
| 2003 | |
| 2004 | return sprintf(buf, "%d\n", st->fail); |
| 2005 | } |
| 2006 | |
| 2007 | static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail); |
| 2008 | |
| 2009 | static struct attribute *cpuhp_cpu_attrs[] = { |
| 2010 | &dev_attr_state.attr, |
| 2011 | &dev_attr_target.attr, |
| 2012 | &dev_attr_fail.attr, |
| 2013 | NULL |
| 2014 | }; |
| 2015 | |
| 2016 | static const struct attribute_group cpuhp_cpu_attr_group = { |
| 2017 | .attrs = cpuhp_cpu_attrs, |
| 2018 | .name = "hotplug", |
| 2019 | NULL |
| 2020 | }; |
| 2021 | |
| 2022 | static ssize_t show_cpuhp_states(struct device *dev, |
| 2023 | struct device_attribute *attr, char *buf) |
| 2024 | { |
| 2025 | ssize_t cur, res = 0; |
| 2026 | int i; |
| 2027 | |
| 2028 | mutex_lock(&cpuhp_state_mutex); |
| 2029 | for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) { |
| 2030 | struct cpuhp_step *sp = cpuhp_get_step(i); |
| 2031 | |
| 2032 | if (sp->name) { |
| 2033 | cur = sprintf(buf, "%3d: %s\n", i, sp->name); |
| 2034 | buf += cur; |
| 2035 | res += cur; |
| 2036 | } |
| 2037 | } |
| 2038 | mutex_unlock(&cpuhp_state_mutex); |
| 2039 | return res; |
| 2040 | } |
| 2041 | static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL); |
| 2042 | |
| 2043 | static struct attribute *cpuhp_cpu_root_attrs[] = { |
| 2044 | &dev_attr_states.attr, |
| 2045 | NULL |
| 2046 | }; |
| 2047 | |
| 2048 | static const struct attribute_group cpuhp_cpu_root_attr_group = { |
| 2049 | .attrs = cpuhp_cpu_root_attrs, |
| 2050 | .name = "hotplug", |
| 2051 | NULL |
| 2052 | }; |
| 2053 | |
| 2054 | #ifdef CONFIG_HOTPLUG_SMT |
| 2055 | |
| 2056 | static void cpuhp_offline_cpu_device(unsigned int cpu) |
| 2057 | { |
| 2058 | struct device *dev = get_cpu_device(cpu); |
| 2059 | |
| 2060 | dev->offline = true; |
| 2061 | /* Tell user space about the state change */ |
| 2062 | kobject_uevent(&dev->kobj, KOBJ_OFFLINE); |
| 2063 | } |
| 2064 | |
| 2065 | static void cpuhp_online_cpu_device(unsigned int cpu) |
| 2066 | { |
| 2067 | struct device *dev = get_cpu_device(cpu); |
| 2068 | |
| 2069 | dev->offline = false; |
| 2070 | /* Tell user space about the state change */ |
| 2071 | kobject_uevent(&dev->kobj, KOBJ_ONLINE); |
| 2072 | } |
| 2073 | |
| 2074 | int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) |
| 2075 | { |
| 2076 | int cpu, ret = 0; |
| 2077 | |
| 2078 | cpu_maps_update_begin(); |
| 2079 | for_each_online_cpu(cpu) { |
| 2080 | if (topology_is_primary_thread(cpu)) |
| 2081 | continue; |
| 2082 | ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE); |
| 2083 | if (ret) |
| 2084 | break; |
| 2085 | /* |
| 2086 | * As this needs to hold the cpu maps lock it's impossible |
| 2087 | * to call device_offline() because that ends up calling |
| 2088 | * cpu_down() which takes cpu maps lock. cpu maps lock |
| 2089 | * needs to be held as this might race against in kernel |
| 2090 | * abusers of the hotplug machinery (thermal management). |
| 2091 | * |
| 2092 | * So nothing would update device:offline state. That would |
| 2093 | * leave the sysfs entry stale and prevent onlining after |
| 2094 | * smt control has been changed to 'off' again. This is |
| 2095 | * called under the sysfs hotplug lock, so it is properly |
| 2096 | * serialized against the regular offline usage. |
| 2097 | */ |
| 2098 | cpuhp_offline_cpu_device(cpu); |
| 2099 | } |
| 2100 | if (!ret) |
| 2101 | cpu_smt_control = ctrlval; |
| 2102 | cpu_maps_update_done(); |
| 2103 | return ret; |
| 2104 | } |
| 2105 | |
| 2106 | int cpuhp_smt_enable(void) |
| 2107 | { |
| 2108 | int cpu, ret = 0; |
| 2109 | |
| 2110 | cpu_maps_update_begin(); |
| 2111 | cpu_smt_control = CPU_SMT_ENABLED; |
| 2112 | for_each_present_cpu(cpu) { |
| 2113 | /* Skip online CPUs and CPUs on offline nodes */ |
| 2114 | if (cpu_online(cpu) || !node_online(cpu_to_node(cpu))) |
| 2115 | continue; |
| 2116 | ret = _cpu_up(cpu, 0, CPUHP_ONLINE); |
| 2117 | if (ret) |
| 2118 | break; |
| 2119 | /* See comment in cpuhp_smt_disable() */ |
| 2120 | cpuhp_online_cpu_device(cpu); |
| 2121 | } |
| 2122 | cpu_maps_update_done(); |
| 2123 | return ret; |
| 2124 | } |
| 2125 | |
| 2126 | |
| 2127 | static ssize_t |
| 2128 | __store_smt_control(struct device *dev, struct device_attribute *attr, |
| 2129 | const char *buf, size_t count) |
| 2130 | { |
| 2131 | int ctrlval, ret; |
| 2132 | |
| 2133 | if (sysfs_streq(buf, "on")) |
| 2134 | ctrlval = CPU_SMT_ENABLED; |
| 2135 | else if (sysfs_streq(buf, "off")) |
| 2136 | ctrlval = CPU_SMT_DISABLED; |
| 2137 | else if (sysfs_streq(buf, "forceoff")) |
| 2138 | ctrlval = CPU_SMT_FORCE_DISABLED; |
| 2139 | else |
| 2140 | return -EINVAL; |
| 2141 | |
| 2142 | if (cpu_smt_control == CPU_SMT_FORCE_DISABLED) |
| 2143 | return -EPERM; |
| 2144 | |
| 2145 | if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED) |
| 2146 | return -ENODEV; |
| 2147 | |
| 2148 | ret = lock_device_hotplug_sysfs(); |
| 2149 | if (ret) |
| 2150 | return ret; |
| 2151 | |
| 2152 | if (ctrlval != cpu_smt_control) { |
| 2153 | switch (ctrlval) { |
| 2154 | case CPU_SMT_ENABLED: |
| 2155 | ret = cpuhp_smt_enable(); |
| 2156 | break; |
| 2157 | case CPU_SMT_DISABLED: |
| 2158 | case CPU_SMT_FORCE_DISABLED: |
| 2159 | ret = cpuhp_smt_disable(ctrlval); |
| 2160 | break; |
| 2161 | } |
| 2162 | } |
| 2163 | |
| 2164 | unlock_device_hotplug(); |
| 2165 | return ret ? ret : count; |
| 2166 | } |
| 2167 | |
| 2168 | #else /* !CONFIG_HOTPLUG_SMT */ |
| 2169 | static ssize_t |
| 2170 | __store_smt_control(struct device *dev, struct device_attribute *attr, |
| 2171 | const char *buf, size_t count) |
| 2172 | { |
| 2173 | return -ENODEV; |
| 2174 | } |
| 2175 | #endif /* CONFIG_HOTPLUG_SMT */ |
| 2176 | |
| 2177 | static const char *smt_states[] = { |
| 2178 | [CPU_SMT_ENABLED] = "on", |
| 2179 | [CPU_SMT_DISABLED] = "off", |
| 2180 | [CPU_SMT_FORCE_DISABLED] = "forceoff", |
| 2181 | [CPU_SMT_NOT_SUPPORTED] = "notsupported", |
| 2182 | [CPU_SMT_NOT_IMPLEMENTED] = "notimplemented", |
| 2183 | }; |
| 2184 | |
| 2185 | static ssize_t |
| 2186 | show_smt_control(struct device *dev, struct device_attribute *attr, char *buf) |
| 2187 | { |
| 2188 | const char *state = smt_states[cpu_smt_control]; |
| 2189 | |
| 2190 | return snprintf(buf, PAGE_SIZE - 2, "%s\n", state); |
| 2191 | } |
| 2192 | |
| 2193 | static ssize_t |
| 2194 | store_smt_control(struct device *dev, struct device_attribute *attr, |
| 2195 | const char *buf, size_t count) |
| 2196 | { |
| 2197 | return __store_smt_control(dev, attr, buf, count); |
| 2198 | } |
| 2199 | static DEVICE_ATTR(control, 0644, show_smt_control, store_smt_control); |
| 2200 | |
| 2201 | static ssize_t |
| 2202 | show_smt_active(struct device *dev, struct device_attribute *attr, char *buf) |
| 2203 | { |
| 2204 | return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active()); |
| 2205 | } |
| 2206 | static DEVICE_ATTR(active, 0444, show_smt_active, NULL); |
| 2207 | |
| 2208 | static struct attribute *cpuhp_smt_attrs[] = { |
| 2209 | &dev_attr_control.attr, |
| 2210 | &dev_attr_active.attr, |
| 2211 | NULL |
| 2212 | }; |
| 2213 | |
| 2214 | static const struct attribute_group cpuhp_smt_attr_group = { |
| 2215 | .attrs = cpuhp_smt_attrs, |
| 2216 | .name = "smt", |
| 2217 | NULL |
| 2218 | }; |
| 2219 | |
| 2220 | static int __init cpu_smt_sysfs_init(void) |
| 2221 | { |
| 2222 | return sysfs_create_group(&cpu_subsys.dev_root->kobj, |
| 2223 | &cpuhp_smt_attr_group); |
| 2224 | } |
| 2225 | |
| 2226 | static int __init cpuhp_sysfs_init(void) |
| 2227 | { |
| 2228 | int cpu, ret; |
| 2229 | |
| 2230 | ret = cpu_smt_sysfs_init(); |
| 2231 | if (ret) |
| 2232 | return ret; |
| 2233 | |
| 2234 | ret = sysfs_create_group(&cpu_subsys.dev_root->kobj, |
| 2235 | &cpuhp_cpu_root_attr_group); |
| 2236 | if (ret) |
| 2237 | return ret; |
| 2238 | |
| 2239 | for_each_possible_cpu(cpu) { |
| 2240 | struct device *dev = get_cpu_device(cpu); |
| 2241 | |
| 2242 | if (!dev) |
| 2243 | continue; |
| 2244 | ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group); |
| 2245 | if (ret) |
| 2246 | return ret; |
| 2247 | } |
| 2248 | return 0; |
| 2249 | } |
| 2250 | device_initcall(cpuhp_sysfs_init); |
| 2251 | #endif /* CONFIG_SYSFS && CONFIG_HOTPLUG_CPU */ |
| 2252 | |
| 2253 | /* |
| 2254 | * cpu_bit_bitmap[] is a special, "compressed" data structure that |
| 2255 | * represents all NR_CPUS bits binary values of 1<<nr. |
| 2256 | * |
| 2257 | * It is used by cpumask_of() to get a constant address to a CPU |
| 2258 | * mask value that has a single bit set only. |
| 2259 | */ |
| 2260 | |
| 2261 | /* cpu_bit_bitmap[0] is empty - so we can back into it */ |
| 2262 | #define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x)) |
| 2263 | #define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1) |
| 2264 | #define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2) |
| 2265 | #define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4) |
| 2266 | |
| 2267 | const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = { |
| 2268 | |
| 2269 | MASK_DECLARE_8(0), MASK_DECLARE_8(8), |
| 2270 | MASK_DECLARE_8(16), MASK_DECLARE_8(24), |
| 2271 | #if BITS_PER_LONG > 32 |
| 2272 | MASK_DECLARE_8(32), MASK_DECLARE_8(40), |
| 2273 | MASK_DECLARE_8(48), MASK_DECLARE_8(56), |
| 2274 | #endif |
| 2275 | }; |
| 2276 | EXPORT_SYMBOL_GPL(cpu_bit_bitmap); |
| 2277 | |
| 2278 | const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL; |
| 2279 | EXPORT_SYMBOL(cpu_all_bits); |
| 2280 | |
| 2281 | #ifdef CONFIG_INIT_ALL_POSSIBLE |
| 2282 | struct cpumask __cpu_possible_mask __read_mostly |
| 2283 | = {CPU_BITS_ALL}; |
| 2284 | #else |
| 2285 | struct cpumask __cpu_possible_mask __read_mostly; |
| 2286 | #endif |
| 2287 | EXPORT_SYMBOL(__cpu_possible_mask); |
| 2288 | |
| 2289 | struct cpumask __cpu_online_mask __read_mostly; |
| 2290 | EXPORT_SYMBOL(__cpu_online_mask); |
| 2291 | |
| 2292 | struct cpumask __cpu_present_mask __read_mostly; |
| 2293 | EXPORT_SYMBOL(__cpu_present_mask); |
| 2294 | |
| 2295 | struct cpumask __cpu_active_mask __read_mostly; |
| 2296 | EXPORT_SYMBOL(__cpu_active_mask); |
| 2297 | |
| 2298 | void init_cpu_present(const struct cpumask *src) |
| 2299 | { |
| 2300 | cpumask_copy(&__cpu_present_mask, src); |
| 2301 | } |
| 2302 | |
| 2303 | void init_cpu_possible(const struct cpumask *src) |
| 2304 | { |
| 2305 | cpumask_copy(&__cpu_possible_mask, src); |
| 2306 | } |
| 2307 | |
| 2308 | void init_cpu_online(const struct cpumask *src) |
| 2309 | { |
| 2310 | cpumask_copy(&__cpu_online_mask, src); |
| 2311 | } |
| 2312 | |
| 2313 | /* |
| 2314 | * Activate the first processor. |
| 2315 | */ |
| 2316 | void __init boot_cpu_init(void) |
| 2317 | { |
| 2318 | int cpu = smp_processor_id(); |
| 2319 | |
| 2320 | /* Mark the boot cpu "present", "online" etc for SMP and UP case */ |
| 2321 | set_cpu_online(cpu, true); |
| 2322 | set_cpu_active(cpu, true); |
| 2323 | set_cpu_present(cpu, true); |
| 2324 | set_cpu_possible(cpu, true); |
| 2325 | |
| 2326 | #ifdef CONFIG_SMP |
| 2327 | __boot_cpu_id = cpu; |
| 2328 | #endif |
| 2329 | } |
| 2330 | |
| 2331 | /* |
| 2332 | * Must be called _AFTER_ setting up the per_cpu areas |
| 2333 | */ |
| 2334 | void __init boot_cpu_hotplug_init(void) |
| 2335 | { |
| 2336 | #ifdef CONFIG_SMP |
| 2337 | this_cpu_write(cpuhp_state.booted_once, true); |
| 2338 | #endif |
| 2339 | this_cpu_write(cpuhp_state.state, CPUHP_ONLINE); |
| 2340 | } |
| 2341 | |
| 2342 | enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO; |
| 2343 | |
| 2344 | static int __init mitigations_parse_cmdline(char *arg) |
| 2345 | { |
| 2346 | if (!strcmp(arg, "off")) |
| 2347 | cpu_mitigations = CPU_MITIGATIONS_OFF; |
| 2348 | else if (!strcmp(arg, "auto")) |
| 2349 | cpu_mitigations = CPU_MITIGATIONS_AUTO; |
| 2350 | else if (!strcmp(arg, "auto,nosmt")) |
| 2351 | cpu_mitigations = CPU_MITIGATIONS_AUTO_NOSMT; |
| 2352 | else |
| 2353 | pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n", |
| 2354 | arg); |
| 2355 | |
| 2356 | return 0; |
| 2357 | } |
| 2358 | early_param("mitigations", mitigations_parse_cmdline); |