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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Generic helpers for smp ipi calls
4 *
5 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/irq_work.h>
11#include <linux/rcupdate.h>
12#include <linux/rculist.h>
13#include <linux/kernel.h>
14#include <linux/export.h>
15#include <linux/percpu.h>
16#include <linux/init.h>
17#include <linux/gfp.h>
18#include <linux/smp.h>
19#include <linux/cpu.h>
20#include <linux/sched.h>
21#include <linux/sched/idle.h>
22#include <linux/hypervisor.h>
23
24#include "smpboot.h"
25
26enum {
27 CSD_FLAG_LOCK = 0x01,
28 CSD_FLAG_SYNCHRONOUS = 0x02,
29};
30
31struct call_function_data {
32 call_single_data_t __percpu *csd;
33 cpumask_var_t cpumask;
34 cpumask_var_t cpumask_ipi;
35};
36
37static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
38
39static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
40
41static void flush_smp_call_function_queue(bool warn_cpu_offline);
42
43int smpcfd_prepare_cpu(unsigned int cpu)
44{
45 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
46
47 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
48 cpu_to_node(cpu)))
49 return -ENOMEM;
50 if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
51 cpu_to_node(cpu))) {
52 free_cpumask_var(cfd->cpumask);
53 return -ENOMEM;
54 }
55 cfd->csd = alloc_percpu(call_single_data_t);
56 if (!cfd->csd) {
57 free_cpumask_var(cfd->cpumask);
58 free_cpumask_var(cfd->cpumask_ipi);
59 return -ENOMEM;
60 }
61
62 return 0;
63}
64
65int smpcfd_dead_cpu(unsigned int cpu)
66{
67 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
68
69 free_cpumask_var(cfd->cpumask);
70 free_cpumask_var(cfd->cpumask_ipi);
71 free_percpu(cfd->csd);
72 return 0;
73}
74
75int smpcfd_dying_cpu(unsigned int cpu)
76{
77 /*
78 * The IPIs for the smp-call-function callbacks queued by other
79 * CPUs might arrive late, either due to hardware latencies or
80 * because this CPU disabled interrupts (inside stop-machine)
81 * before the IPIs were sent. So flush out any pending callbacks
82 * explicitly (without waiting for the IPIs to arrive), to
83 * ensure that the outgoing CPU doesn't go offline with work
84 * still pending.
85 */
86 flush_smp_call_function_queue(false);
87 return 0;
88}
89
90void __init call_function_init(void)
91{
92 int i;
93
94 for_each_possible_cpu(i)
95 init_llist_head(&per_cpu(call_single_queue, i));
96
97 smpcfd_prepare_cpu(smp_processor_id());
98}
99
100/*
101 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
102 *
103 * For non-synchronous ipi calls the csd can still be in use by the
104 * previous function call. For multi-cpu calls its even more interesting
105 * as we'll have to ensure no other cpu is observing our csd.
106 */
107static __always_inline void csd_lock_wait(call_single_data_t *csd)
108{
109 smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
110}
111
112static __always_inline void csd_lock(call_single_data_t *csd)
113{
114 csd_lock_wait(csd);
115 csd->flags |= CSD_FLAG_LOCK;
116
117 /*
118 * prevent CPU from reordering the above assignment
119 * to ->flags with any subsequent assignments to other
120 * fields of the specified call_single_data_t structure:
121 */
122 smp_wmb();
123}
124
125static __always_inline void csd_unlock(call_single_data_t *csd)
126{
127 WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
128
129 /*
130 * ensure we're all done before releasing data:
131 */
132 smp_store_release(&csd->flags, 0);
133}
134
135static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
136
137/*
138 * Insert a previously allocated call_single_data_t element
139 * for execution on the given CPU. data must already have
140 * ->func, ->info, and ->flags set.
141 */
142static int generic_exec_single(int cpu, call_single_data_t *csd,
143 smp_call_func_t func, void *info)
144{
145 if (cpu == smp_processor_id()) {
146 unsigned long flags;
147
148 /*
149 * We can unlock early even for the synchronous on-stack case,
150 * since we're doing this from the same CPU..
151 */
152 csd_unlock(csd);
153 local_irq_save(flags);
154 func(info);
155 local_irq_restore(flags);
156 return 0;
157 }
158
159
160 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
161 csd_unlock(csd);
162 return -ENXIO;
163 }
164
165 csd->func = func;
166 csd->info = info;
167
168 /*
169 * The list addition should be visible before sending the IPI
170 * handler locks the list to pull the entry off it because of
171 * normal cache coherency rules implied by spinlocks.
172 *
173 * If IPIs can go out of order to the cache coherency protocol
174 * in an architecture, sufficient synchronisation should be added
175 * to arch code to make it appear to obey cache coherency WRT
176 * locking and barrier primitives. Generic code isn't really
177 * equipped to do the right thing...
178 */
179 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
180 arch_send_call_function_single_ipi(cpu);
181
182 return 0;
183}
184
185/**
186 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
187 *
188 * Invoked by arch to handle an IPI for call function single.
189 * Must be called with interrupts disabled.
190 */
191void generic_smp_call_function_single_interrupt(void)
192{
193 flush_smp_call_function_queue(true);
194}
195
196/**
197 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
198 *
199 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
200 * offline CPU. Skip this check if set to 'false'.
201 *
202 * Flush any pending smp-call-function callbacks queued on this CPU. This is
203 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
204 * to ensure that all pending IPI callbacks are run before it goes completely
205 * offline.
206 *
207 * Loop through the call_single_queue and run all the queued callbacks.
208 * Must be called with interrupts disabled.
209 */
210static void flush_smp_call_function_queue(bool warn_cpu_offline)
211{
212 struct llist_head *head;
213 struct llist_node *entry;
214 call_single_data_t *csd, *csd_next;
215 static bool warned;
216
217 lockdep_assert_irqs_disabled();
218
219 head = this_cpu_ptr(&call_single_queue);
220 entry = llist_del_all(head);
221 entry = llist_reverse_order(entry);
222
223 /* There shouldn't be any pending callbacks on an offline CPU. */
224 if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
225 !warned && !llist_empty(head))) {
226 warned = true;
227 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
228
229 /*
230 * We don't have to use the _safe() variant here
231 * because we are not invoking the IPI handlers yet.
232 */
233 llist_for_each_entry(csd, entry, llist)
234 pr_warn("IPI callback %pS sent to offline CPU\n",
235 csd->func);
236 }
237
238 llist_for_each_entry_safe(csd, csd_next, entry, llist) {
239 smp_call_func_t func = csd->func;
240 void *info = csd->info;
241
242 /* Do we wait until *after* callback? */
243 if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
244 func(info);
245 csd_unlock(csd);
246 } else {
247 csd_unlock(csd);
248 func(info);
249 }
250 }
251
252 /*
253 * Handle irq works queued remotely by irq_work_queue_on().
254 * Smp functions above are typically synchronous so they
255 * better run first since some other CPUs may be busy waiting
256 * for them.
257 */
258 irq_work_run();
259}
260
261/*
262 * smp_call_function_single - Run a function on a specific CPU
263 * @func: The function to run. This must be fast and non-blocking.
264 * @info: An arbitrary pointer to pass to the function.
265 * @wait: If true, wait until function has completed on other CPUs.
266 *
267 * Returns 0 on success, else a negative status code.
268 */
269int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
270 int wait)
271{
272 call_single_data_t *csd;
273 call_single_data_t csd_stack = {
274 .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS,
275 };
276 int this_cpu;
277 int err;
278
279 /*
280 * prevent preemption and reschedule on another processor,
281 * as well as CPU removal
282 */
283 this_cpu = get_cpu();
284
285 /*
286 * Can deadlock when called with interrupts disabled.
287 * We allow cpu's that are not yet online though, as no one else can
288 * send smp call function interrupt to this cpu and as such deadlocks
289 * can't happen.
290 */
291 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
292 && !oops_in_progress);
293
294 /*
295 * When @wait we can deadlock when we interrupt between llist_add() and
296 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
297 * csd_lock() on because the interrupt context uses the same csd
298 * storage.
299 */
300 WARN_ON_ONCE(!in_task());
301
302 csd = &csd_stack;
303 if (!wait) {
304 csd = this_cpu_ptr(&csd_data);
305 csd_lock(csd);
306 }
307
308 err = generic_exec_single(cpu, csd, func, info);
309
310 if (wait)
311 csd_lock_wait(csd);
312
313 put_cpu();
314
315 return err;
316}
317EXPORT_SYMBOL(smp_call_function_single);
318
319/**
320 * smp_call_function_single_async(): Run an asynchronous function on a
321 * specific CPU.
322 * @cpu: The CPU to run on.
323 * @csd: Pre-allocated and setup data structure
324 *
325 * Like smp_call_function_single(), but the call is asynchonous and
326 * can thus be done from contexts with disabled interrupts.
327 *
328 * The caller passes his own pre-allocated data structure
329 * (ie: embedded in an object) and is responsible for synchronizing it
330 * such that the IPIs performed on the @csd are strictly serialized.
331 *
332 * NOTE: Be careful, there is unfortunately no current debugging facility to
333 * validate the correctness of this serialization.
334 */
335int smp_call_function_single_async(int cpu, call_single_data_t *csd)
336{
337 int err = 0;
338
339 preempt_disable();
340
341 /* We could deadlock if we have to wait here with interrupts disabled! */
342 if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
343 csd_lock_wait(csd);
344
345 csd->flags = CSD_FLAG_LOCK;
346 smp_wmb();
347
348 err = generic_exec_single(cpu, csd, csd->func, csd->info);
349 preempt_enable();
350
351 return err;
352}
353EXPORT_SYMBOL_GPL(smp_call_function_single_async);
354
355/*
356 * smp_call_function_any - Run a function on any of the given cpus
357 * @mask: The mask of cpus it can run on.
358 * @func: The function to run. This must be fast and non-blocking.
359 * @info: An arbitrary pointer to pass to the function.
360 * @wait: If true, wait until function has completed.
361 *
362 * Returns 0 on success, else a negative status code (if no cpus were online).
363 *
364 * Selection preference:
365 * 1) current cpu if in @mask
366 * 2) any cpu of current node if in @mask
367 * 3) any other online cpu in @mask
368 */
369int smp_call_function_any(const struct cpumask *mask,
370 smp_call_func_t func, void *info, int wait)
371{
372 unsigned int cpu;
373 const struct cpumask *nodemask;
374 int ret;
375
376 /* Try for same CPU (cheapest) */
377 cpu = get_cpu();
378 if (cpumask_test_cpu(cpu, mask))
379 goto call;
380
381 /* Try for same node. */
382 nodemask = cpumask_of_node(cpu_to_node(cpu));
383 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
384 cpu = cpumask_next_and(cpu, nodemask, mask)) {
385 if (cpu_online(cpu))
386 goto call;
387 }
388
389 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
390 cpu = cpumask_any_and(mask, cpu_online_mask);
391call:
392 ret = smp_call_function_single(cpu, func, info, wait);
393 put_cpu();
394 return ret;
395}
396EXPORT_SYMBOL_GPL(smp_call_function_any);
397
398/**
399 * smp_call_function_many(): Run a function on a set of other CPUs.
400 * @mask: The set of cpus to run on (only runs on online subset).
401 * @func: The function to run. This must be fast and non-blocking.
402 * @info: An arbitrary pointer to pass to the function.
403 * @wait: If true, wait (atomically) until function has completed
404 * on other CPUs.
405 *
406 * If @wait is true, then returns once @func has returned.
407 *
408 * You must not call this function with disabled interrupts or from a
409 * hardware interrupt handler or from a bottom half handler. Preemption
410 * must be disabled when calling this function.
411 */
412void smp_call_function_many(const struct cpumask *mask,
413 smp_call_func_t func, void *info, bool wait)
414{
415 struct call_function_data *cfd;
416 int cpu, next_cpu, this_cpu = smp_processor_id();
417
418 /*
419 * Can deadlock when called with interrupts disabled.
420 * We allow cpu's that are not yet online though, as no one else can
421 * send smp call function interrupt to this cpu and as such deadlocks
422 * can't happen.
423 */
424 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
425 && !oops_in_progress && !early_boot_irqs_disabled);
426
427 /*
428 * When @wait we can deadlock when we interrupt between llist_add() and
429 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
430 * csd_lock() on because the interrupt context uses the same csd
431 * storage.
432 */
433 WARN_ON_ONCE(!in_task());
434
435 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
436 cpu = cpumask_first_and(mask, cpu_online_mask);
437 if (cpu == this_cpu)
438 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
439
440 /* No online cpus? We're done. */
441 if (cpu >= nr_cpu_ids)
442 return;
443
444 /* Do we have another CPU which isn't us? */
445 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
446 if (next_cpu == this_cpu)
447 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
448
449 /* Fastpath: do that cpu by itself. */
450 if (next_cpu >= nr_cpu_ids) {
451 smp_call_function_single(cpu, func, info, wait);
452 return;
453 }
454
455 cfd = this_cpu_ptr(&cfd_data);
456
457 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
458 __cpumask_clear_cpu(this_cpu, cfd->cpumask);
459
460 /* Some callers race with other cpus changing the passed mask */
461 if (unlikely(!cpumask_weight(cfd->cpumask)))
462 return;
463
464 cpumask_clear(cfd->cpumask_ipi);
465 for_each_cpu(cpu, cfd->cpumask) {
466 call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
467
468 csd_lock(csd);
469 if (wait)
470 csd->flags |= CSD_FLAG_SYNCHRONOUS;
471 csd->func = func;
472 csd->info = info;
473 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
474 __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
475 }
476
477 /* Send a message to all CPUs in the map */
478 arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
479
480 if (wait) {
481 for_each_cpu(cpu, cfd->cpumask) {
482 call_single_data_t *csd;
483
484 csd = per_cpu_ptr(cfd->csd, cpu);
485 csd_lock_wait(csd);
486 }
487 }
488}
489EXPORT_SYMBOL(smp_call_function_many);
490
491/**
492 * smp_call_function(): Run a function on all other CPUs.
493 * @func: The function to run. This must be fast and non-blocking.
494 * @info: An arbitrary pointer to pass to the function.
495 * @wait: If true, wait (atomically) until function has completed
496 * on other CPUs.
497 *
498 * Returns 0.
499 *
500 * If @wait is true, then returns once @func has returned; otherwise
501 * it returns just before the target cpu calls @func.
502 *
503 * You must not call this function with disabled interrupts or from a
504 * hardware interrupt handler or from a bottom half handler.
505 */
506void smp_call_function(smp_call_func_t func, void *info, int wait)
507{
508 preempt_disable();
509 smp_call_function_many(cpu_online_mask, func, info, wait);
510 preempt_enable();
511}
512EXPORT_SYMBOL(smp_call_function);
513
514/* Setup configured maximum number of CPUs to activate */
515unsigned int setup_max_cpus = NR_CPUS;
516EXPORT_SYMBOL(setup_max_cpus);
517
518
519/*
520 * Setup routine for controlling SMP activation
521 *
522 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
523 * activation entirely (the MPS table probe still happens, though).
524 *
525 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
526 * greater than 0, limits the maximum number of CPUs activated in
527 * SMP mode to <NUM>.
528 */
529
530void __weak arch_disable_smp_support(void) { }
531
532static int __init nosmp(char *str)
533{
534 setup_max_cpus = 0;
535 arch_disable_smp_support();
536
537 return 0;
538}
539
540early_param("nosmp", nosmp);
541
542/* this is hard limit */
543static int __init nrcpus(char *str)
544{
545 int nr_cpus;
546
547 get_option(&str, &nr_cpus);
548 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
549 nr_cpu_ids = nr_cpus;
550
551 return 0;
552}
553
554early_param("nr_cpus", nrcpus);
555
556static int __init maxcpus(char *str)
557{
558 get_option(&str, &setup_max_cpus);
559 if (setup_max_cpus == 0)
560 arch_disable_smp_support();
561
562 return 0;
563}
564
565early_param("maxcpus", maxcpus);
566
567/* Setup number of possible processor ids */
568unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
569EXPORT_SYMBOL(nr_cpu_ids);
570
571/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
572void __init setup_nr_cpu_ids(void)
573{
574 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
575}
576
577/* Called by boot processor to activate the rest. */
578void __init smp_init(void)
579{
580 int num_nodes, num_cpus;
581 unsigned int cpu;
582
583 idle_threads_init();
584 cpuhp_threads_init();
585
586 pr_info("Bringing up secondary CPUs ...\n");
587
588 /* FIXME: This should be done in userspace --RR */
589 for_each_present_cpu(cpu) {
590 if (num_online_cpus() >= setup_max_cpus)
591 break;
592 if (!cpu_online(cpu))
593 cpu_up(cpu);
594 }
595
596 num_nodes = num_online_nodes();
597 num_cpus = num_online_cpus();
598 pr_info("Brought up %d node%s, %d CPU%s\n",
599 num_nodes, (num_nodes > 1 ? "s" : ""),
600 num_cpus, (num_cpus > 1 ? "s" : ""));
601
602 /* Any cleanup work */
603 smp_cpus_done(setup_max_cpus);
604}
605
606/*
607 * Call a function on all processors. May be used during early boot while
608 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
609 * of local_irq_disable/enable().
610 */
611void on_each_cpu(void (*func) (void *info), void *info, int wait)
612{
613 unsigned long flags;
614
615 preempt_disable();
616 smp_call_function(func, info, wait);
617 local_irq_save(flags);
618 func(info);
619 local_irq_restore(flags);
620 preempt_enable();
621}
622EXPORT_SYMBOL(on_each_cpu);
623
624/**
625 * on_each_cpu_mask(): Run a function on processors specified by
626 * cpumask, which may include the local processor.
627 * @mask: The set of cpus to run on (only runs on online subset).
628 * @func: The function to run. This must be fast and non-blocking.
629 * @info: An arbitrary pointer to pass to the function.
630 * @wait: If true, wait (atomically) until function has completed
631 * on other CPUs.
632 *
633 * If @wait is true, then returns once @func has returned.
634 *
635 * You must not call this function with disabled interrupts or from a
636 * hardware interrupt handler or from a bottom half handler. The
637 * exception is that it may be used during early boot while
638 * early_boot_irqs_disabled is set.
639 */
640void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
641 void *info, bool wait)
642{
643 int cpu = get_cpu();
644
645 smp_call_function_many(mask, func, info, wait);
646 if (cpumask_test_cpu(cpu, mask)) {
647 unsigned long flags;
648 local_irq_save(flags);
649 func(info);
650 local_irq_restore(flags);
651 }
652 put_cpu();
653}
654EXPORT_SYMBOL(on_each_cpu_mask);
655
656/*
657 * on_each_cpu_cond(): Call a function on each processor for which
658 * the supplied function cond_func returns true, optionally waiting
659 * for all the required CPUs to finish. This may include the local
660 * processor.
661 * @cond_func: A callback function that is passed a cpu id and
662 * the the info parameter. The function is called
663 * with preemption disabled. The function should
664 * return a blooean value indicating whether to IPI
665 * the specified CPU.
666 * @func: The function to run on all applicable CPUs.
667 * This must be fast and non-blocking.
668 * @info: An arbitrary pointer to pass to both functions.
669 * @wait: If true, wait (atomically) until function has
670 * completed on other CPUs.
671 * @gfp_flags: GFP flags to use when allocating the cpumask
672 * used internally by the function.
673 *
674 * The function might sleep if the GFP flags indicates a non
675 * atomic allocation is allowed.
676 *
677 * Preemption is disabled to protect against CPUs going offline but not online.
678 * CPUs going online during the call will not be seen or sent an IPI.
679 *
680 * You must not call this function with disabled interrupts or
681 * from a hardware interrupt handler or from a bottom half handler.
682 */
683void on_each_cpu_cond_mask(bool (*cond_func)(int cpu, void *info),
684 smp_call_func_t func, void *info, bool wait,
685 gfp_t gfp_flags, const struct cpumask *mask)
686{
687 cpumask_var_t cpus;
688 int cpu, ret;
689
690 might_sleep_if(gfpflags_allow_blocking(gfp_flags));
691
692 if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
693 preempt_disable();
694 for_each_cpu(cpu, mask)
695 if (cond_func(cpu, info))
696 __cpumask_set_cpu(cpu, cpus);
697 on_each_cpu_mask(cpus, func, info, wait);
698 preempt_enable();
699 free_cpumask_var(cpus);
700 } else {
701 /*
702 * No free cpumask, bother. No matter, we'll
703 * just have to IPI them one by one.
704 */
705 preempt_disable();
706 for_each_cpu(cpu, mask)
707 if (cond_func(cpu, info)) {
708 ret = smp_call_function_single(cpu, func,
709 info, wait);
710 WARN_ON_ONCE(ret);
711 }
712 preempt_enable();
713 }
714}
715EXPORT_SYMBOL(on_each_cpu_cond_mask);
716
717void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
718 smp_call_func_t func, void *info, bool wait,
719 gfp_t gfp_flags)
720{
721 on_each_cpu_cond_mask(cond_func, func, info, wait, gfp_flags,
722 cpu_online_mask);
723}
724EXPORT_SYMBOL(on_each_cpu_cond);
725
726static void do_nothing(void *unused)
727{
728}
729
730/**
731 * kick_all_cpus_sync - Force all cpus out of idle
732 *
733 * Used to synchronize the update of pm_idle function pointer. It's
734 * called after the pointer is updated and returns after the dummy
735 * callback function has been executed on all cpus. The execution of
736 * the function can only happen on the remote cpus after they have
737 * left the idle function which had been called via pm_idle function
738 * pointer. So it's guaranteed that nothing uses the previous pointer
739 * anymore.
740 */
741void kick_all_cpus_sync(void)
742{
743 /* Make sure the change is visible before we kick the cpus */
744 smp_mb();
745 smp_call_function(do_nothing, NULL, 1);
746}
747EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
748
749/**
750 * wake_up_all_idle_cpus - break all cpus out of idle
751 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
752 * including idle polling cpus, for non-idle cpus, we will do nothing
753 * for them.
754 */
755void wake_up_all_idle_cpus(void)
756{
757 int cpu;
758
759 preempt_disable();
760 for_each_online_cpu(cpu) {
761 if (cpu == smp_processor_id())
762 continue;
763
764 wake_up_if_idle(cpu);
765 }
766 preempt_enable();
767}
768EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
769
770/**
771 * smp_call_on_cpu - Call a function on a specific cpu
772 *
773 * Used to call a function on a specific cpu and wait for it to return.
774 * Optionally make sure the call is done on a specified physical cpu via vcpu
775 * pinning in order to support virtualized environments.
776 */
777struct smp_call_on_cpu_struct {
778 struct work_struct work;
779 struct completion done;
780 int (*func)(void *);
781 void *data;
782 int ret;
783 int cpu;
784};
785
786static void smp_call_on_cpu_callback(struct work_struct *work)
787{
788 struct smp_call_on_cpu_struct *sscs;
789
790 sscs = container_of(work, struct smp_call_on_cpu_struct, work);
791 if (sscs->cpu >= 0)
792 hypervisor_pin_vcpu(sscs->cpu);
793 sscs->ret = sscs->func(sscs->data);
794 if (sscs->cpu >= 0)
795 hypervisor_pin_vcpu(-1);
796
797 complete(&sscs->done);
798}
799
800int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
801{
802 struct smp_call_on_cpu_struct sscs = {
803 .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
804 .func = func,
805 .data = par,
806 .cpu = phys ? cpu : -1,
807 };
808
809 INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
810
811 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
812 return -ENXIO;
813
814 queue_work_on(cpu, system_wq, &sscs.work);
815 wait_for_completion(&sscs.done);
816
817 return sscs.ret;
818}
819EXPORT_SYMBOL_GPL(smp_call_on_cpu);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Generic helpers for smp ipi calls
4 *
5 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/irq_work.h>
11#include <linux/rcupdate.h>
12#include <linux/rculist.h>
13#include <linux/kernel.h>
14#include <linux/export.h>
15#include <linux/percpu.h>
16#include <linux/init.h>
17#include <linux/gfp.h>
18#include <linux/smp.h>
19#include <linux/cpu.h>
20#include <linux/sched.h>
21#include <linux/sched/idle.h>
22#include <linux/hypervisor.h>
23
24#include "smpboot.h"
25#include "sched/smp.h"
26
27#define CSD_TYPE(_csd) ((_csd)->flags & CSD_FLAG_TYPE_MASK)
28
29struct call_function_data {
30 call_single_data_t __percpu *csd;
31 cpumask_var_t cpumask;
32 cpumask_var_t cpumask_ipi;
33};
34
35static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
36
37static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
38
39static void flush_smp_call_function_queue(bool warn_cpu_offline);
40
41int smpcfd_prepare_cpu(unsigned int cpu)
42{
43 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
44
45 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
46 cpu_to_node(cpu)))
47 return -ENOMEM;
48 if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
49 cpu_to_node(cpu))) {
50 free_cpumask_var(cfd->cpumask);
51 return -ENOMEM;
52 }
53 cfd->csd = alloc_percpu(call_single_data_t);
54 if (!cfd->csd) {
55 free_cpumask_var(cfd->cpumask);
56 free_cpumask_var(cfd->cpumask_ipi);
57 return -ENOMEM;
58 }
59
60 return 0;
61}
62
63int smpcfd_dead_cpu(unsigned int cpu)
64{
65 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
66
67 free_cpumask_var(cfd->cpumask);
68 free_cpumask_var(cfd->cpumask_ipi);
69 free_percpu(cfd->csd);
70 return 0;
71}
72
73int smpcfd_dying_cpu(unsigned int cpu)
74{
75 /*
76 * The IPIs for the smp-call-function callbacks queued by other
77 * CPUs might arrive late, either due to hardware latencies or
78 * because this CPU disabled interrupts (inside stop-machine)
79 * before the IPIs were sent. So flush out any pending callbacks
80 * explicitly (without waiting for the IPIs to arrive), to
81 * ensure that the outgoing CPU doesn't go offline with work
82 * still pending.
83 */
84 flush_smp_call_function_queue(false);
85 irq_work_run();
86 return 0;
87}
88
89void __init call_function_init(void)
90{
91 int i;
92
93 for_each_possible_cpu(i)
94 init_llist_head(&per_cpu(call_single_queue, i));
95
96 smpcfd_prepare_cpu(smp_processor_id());
97}
98
99/*
100 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
101 *
102 * For non-synchronous ipi calls the csd can still be in use by the
103 * previous function call. For multi-cpu calls its even more interesting
104 * as we'll have to ensure no other cpu is observing our csd.
105 */
106static __always_inline void csd_lock_wait(call_single_data_t *csd)
107{
108 smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
109}
110
111static __always_inline void csd_lock(call_single_data_t *csd)
112{
113 csd_lock_wait(csd);
114 csd->flags |= CSD_FLAG_LOCK;
115
116 /*
117 * prevent CPU from reordering the above assignment
118 * to ->flags with any subsequent assignments to other
119 * fields of the specified call_single_data_t structure:
120 */
121 smp_wmb();
122}
123
124static __always_inline void csd_unlock(call_single_data_t *csd)
125{
126 WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
127
128 /*
129 * ensure we're all done before releasing data:
130 */
131 smp_store_release(&csd->flags, 0);
132}
133
134static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
135
136void __smp_call_single_queue(int cpu, struct llist_node *node)
137{
138 /*
139 * The list addition should be visible before sending the IPI
140 * handler locks the list to pull the entry off it because of
141 * normal cache coherency rules implied by spinlocks.
142 *
143 * If IPIs can go out of order to the cache coherency protocol
144 * in an architecture, sufficient synchronisation should be added
145 * to arch code to make it appear to obey cache coherency WRT
146 * locking and barrier primitives. Generic code isn't really
147 * equipped to do the right thing...
148 */
149 if (llist_add(node, &per_cpu(call_single_queue, cpu)))
150 send_call_function_single_ipi(cpu);
151}
152
153/*
154 * Insert a previously allocated call_single_data_t element
155 * for execution on the given CPU. data must already have
156 * ->func, ->info, and ->flags set.
157 */
158static int generic_exec_single(int cpu, call_single_data_t *csd)
159{
160 if (cpu == smp_processor_id()) {
161 smp_call_func_t func = csd->func;
162 void *info = csd->info;
163 unsigned long flags;
164
165 /*
166 * We can unlock early even for the synchronous on-stack case,
167 * since we're doing this from the same CPU..
168 */
169 csd_unlock(csd);
170 local_irq_save(flags);
171 func(info);
172 local_irq_restore(flags);
173 return 0;
174 }
175
176 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
177 csd_unlock(csd);
178 return -ENXIO;
179 }
180
181 __smp_call_single_queue(cpu, &csd->llist);
182
183 return 0;
184}
185
186/**
187 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
188 *
189 * Invoked by arch to handle an IPI for call function single.
190 * Must be called with interrupts disabled.
191 */
192void generic_smp_call_function_single_interrupt(void)
193{
194 flush_smp_call_function_queue(true);
195}
196
197/**
198 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
199 *
200 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
201 * offline CPU. Skip this check if set to 'false'.
202 *
203 * Flush any pending smp-call-function callbacks queued on this CPU. This is
204 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
205 * to ensure that all pending IPI callbacks are run before it goes completely
206 * offline.
207 *
208 * Loop through the call_single_queue and run all the queued callbacks.
209 * Must be called with interrupts disabled.
210 */
211static void flush_smp_call_function_queue(bool warn_cpu_offline)
212{
213 call_single_data_t *csd, *csd_next;
214 struct llist_node *entry, *prev;
215 struct llist_head *head;
216 static bool warned;
217
218 lockdep_assert_irqs_disabled();
219
220 head = this_cpu_ptr(&call_single_queue);
221 entry = llist_del_all(head);
222 entry = llist_reverse_order(entry);
223
224 /* There shouldn't be any pending callbacks on an offline CPU. */
225 if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
226 !warned && !llist_empty(head))) {
227 warned = true;
228 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
229
230 /*
231 * We don't have to use the _safe() variant here
232 * because we are not invoking the IPI handlers yet.
233 */
234 llist_for_each_entry(csd, entry, llist) {
235 switch (CSD_TYPE(csd)) {
236 case CSD_TYPE_ASYNC:
237 case CSD_TYPE_SYNC:
238 case CSD_TYPE_IRQ_WORK:
239 pr_warn("IPI callback %pS sent to offline CPU\n",
240 csd->func);
241 break;
242
243 case CSD_TYPE_TTWU:
244 pr_warn("IPI task-wakeup sent to offline CPU\n");
245 break;
246
247 default:
248 pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
249 CSD_TYPE(csd));
250 break;
251 }
252 }
253 }
254
255 /*
256 * First; run all SYNC callbacks, people are waiting for us.
257 */
258 prev = NULL;
259 llist_for_each_entry_safe(csd, csd_next, entry, llist) {
260 /* Do we wait until *after* callback? */
261 if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
262 smp_call_func_t func = csd->func;
263 void *info = csd->info;
264
265 if (prev) {
266 prev->next = &csd_next->llist;
267 } else {
268 entry = &csd_next->llist;
269 }
270
271 func(info);
272 csd_unlock(csd);
273 } else {
274 prev = &csd->llist;
275 }
276 }
277
278 if (!entry)
279 return;
280
281 /*
282 * Second; run all !SYNC callbacks.
283 */
284 prev = NULL;
285 llist_for_each_entry_safe(csd, csd_next, entry, llist) {
286 int type = CSD_TYPE(csd);
287
288 if (type != CSD_TYPE_TTWU) {
289 if (prev) {
290 prev->next = &csd_next->llist;
291 } else {
292 entry = &csd_next->llist;
293 }
294
295 if (type == CSD_TYPE_ASYNC) {
296 smp_call_func_t func = csd->func;
297 void *info = csd->info;
298
299 csd_unlock(csd);
300 func(info);
301 } else if (type == CSD_TYPE_IRQ_WORK) {
302 irq_work_single(csd);
303 }
304
305 } else {
306 prev = &csd->llist;
307 }
308 }
309
310 /*
311 * Third; only CSD_TYPE_TTWU is left, issue those.
312 */
313 if (entry)
314 sched_ttwu_pending(entry);
315}
316
317void flush_smp_call_function_from_idle(void)
318{
319 unsigned long flags;
320
321 if (llist_empty(this_cpu_ptr(&call_single_queue)))
322 return;
323
324 local_irq_save(flags);
325 flush_smp_call_function_queue(true);
326 local_irq_restore(flags);
327}
328
329/*
330 * smp_call_function_single - Run a function on a specific CPU
331 * @func: The function to run. This must be fast and non-blocking.
332 * @info: An arbitrary pointer to pass to the function.
333 * @wait: If true, wait until function has completed on other CPUs.
334 *
335 * Returns 0 on success, else a negative status code.
336 */
337int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
338 int wait)
339{
340 call_single_data_t *csd;
341 call_single_data_t csd_stack = {
342 .flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC,
343 };
344 int this_cpu;
345 int err;
346
347 /*
348 * prevent preemption and reschedule on another processor,
349 * as well as CPU removal
350 */
351 this_cpu = get_cpu();
352
353 /*
354 * Can deadlock when called with interrupts disabled.
355 * We allow cpu's that are not yet online though, as no one else can
356 * send smp call function interrupt to this cpu and as such deadlocks
357 * can't happen.
358 */
359 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
360 && !oops_in_progress);
361
362 /*
363 * When @wait we can deadlock when we interrupt between llist_add() and
364 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
365 * csd_lock() on because the interrupt context uses the same csd
366 * storage.
367 */
368 WARN_ON_ONCE(!in_task());
369
370 csd = &csd_stack;
371 if (!wait) {
372 csd = this_cpu_ptr(&csd_data);
373 csd_lock(csd);
374 }
375
376 csd->func = func;
377 csd->info = info;
378
379 err = generic_exec_single(cpu, csd);
380
381 if (wait)
382 csd_lock_wait(csd);
383
384 put_cpu();
385
386 return err;
387}
388EXPORT_SYMBOL(smp_call_function_single);
389
390/**
391 * smp_call_function_single_async(): Run an asynchronous function on a
392 * specific CPU.
393 * @cpu: The CPU to run on.
394 * @csd: Pre-allocated and setup data structure
395 *
396 * Like smp_call_function_single(), but the call is asynchonous and
397 * can thus be done from contexts with disabled interrupts.
398 *
399 * The caller passes his own pre-allocated data structure
400 * (ie: embedded in an object) and is responsible for synchronizing it
401 * such that the IPIs performed on the @csd are strictly serialized.
402 *
403 * If the function is called with one csd which has not yet been
404 * processed by previous call to smp_call_function_single_async(), the
405 * function will return immediately with -EBUSY showing that the csd
406 * object is still in progress.
407 *
408 * NOTE: Be careful, there is unfortunately no current debugging facility to
409 * validate the correctness of this serialization.
410 */
411int smp_call_function_single_async(int cpu, call_single_data_t *csd)
412{
413 int err = 0;
414
415 preempt_disable();
416
417 if (csd->flags & CSD_FLAG_LOCK) {
418 err = -EBUSY;
419 goto out;
420 }
421
422 csd->flags = CSD_FLAG_LOCK;
423 smp_wmb();
424
425 err = generic_exec_single(cpu, csd);
426
427out:
428 preempt_enable();
429
430 return err;
431}
432EXPORT_SYMBOL_GPL(smp_call_function_single_async);
433
434/*
435 * smp_call_function_any - Run a function on any of the given cpus
436 * @mask: The mask of cpus it can run on.
437 * @func: The function to run. This must be fast and non-blocking.
438 * @info: An arbitrary pointer to pass to the function.
439 * @wait: If true, wait until function has completed.
440 *
441 * Returns 0 on success, else a negative status code (if no cpus were online).
442 *
443 * Selection preference:
444 * 1) current cpu if in @mask
445 * 2) any cpu of current node if in @mask
446 * 3) any other online cpu in @mask
447 */
448int smp_call_function_any(const struct cpumask *mask,
449 smp_call_func_t func, void *info, int wait)
450{
451 unsigned int cpu;
452 const struct cpumask *nodemask;
453 int ret;
454
455 /* Try for same CPU (cheapest) */
456 cpu = get_cpu();
457 if (cpumask_test_cpu(cpu, mask))
458 goto call;
459
460 /* Try for same node. */
461 nodemask = cpumask_of_node(cpu_to_node(cpu));
462 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
463 cpu = cpumask_next_and(cpu, nodemask, mask)) {
464 if (cpu_online(cpu))
465 goto call;
466 }
467
468 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
469 cpu = cpumask_any_and(mask, cpu_online_mask);
470call:
471 ret = smp_call_function_single(cpu, func, info, wait);
472 put_cpu();
473 return ret;
474}
475EXPORT_SYMBOL_GPL(smp_call_function_any);
476
477static void smp_call_function_many_cond(const struct cpumask *mask,
478 smp_call_func_t func, void *info,
479 bool wait, smp_cond_func_t cond_func)
480{
481 struct call_function_data *cfd;
482 int cpu, next_cpu, this_cpu = smp_processor_id();
483
484 /*
485 * Can deadlock when called with interrupts disabled.
486 * We allow cpu's that are not yet online though, as no one else can
487 * send smp call function interrupt to this cpu and as such deadlocks
488 * can't happen.
489 */
490 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
491 && !oops_in_progress && !early_boot_irqs_disabled);
492
493 /*
494 * When @wait we can deadlock when we interrupt between llist_add() and
495 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
496 * csd_lock() on because the interrupt context uses the same csd
497 * storage.
498 */
499 WARN_ON_ONCE(!in_task());
500
501 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
502 cpu = cpumask_first_and(mask, cpu_online_mask);
503 if (cpu == this_cpu)
504 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
505
506 /* No online cpus? We're done. */
507 if (cpu >= nr_cpu_ids)
508 return;
509
510 /* Do we have another CPU which isn't us? */
511 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
512 if (next_cpu == this_cpu)
513 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
514
515 /* Fastpath: do that cpu by itself. */
516 if (next_cpu >= nr_cpu_ids) {
517 if (!cond_func || cond_func(cpu, info))
518 smp_call_function_single(cpu, func, info, wait);
519 return;
520 }
521
522 cfd = this_cpu_ptr(&cfd_data);
523
524 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
525 __cpumask_clear_cpu(this_cpu, cfd->cpumask);
526
527 /* Some callers race with other cpus changing the passed mask */
528 if (unlikely(!cpumask_weight(cfd->cpumask)))
529 return;
530
531 cpumask_clear(cfd->cpumask_ipi);
532 for_each_cpu(cpu, cfd->cpumask) {
533 call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
534
535 if (cond_func && !cond_func(cpu, info))
536 continue;
537
538 csd_lock(csd);
539 if (wait)
540 csd->flags |= CSD_TYPE_SYNC;
541 csd->func = func;
542 csd->info = info;
543 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
544 __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
545 }
546
547 /* Send a message to all CPUs in the map */
548 arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
549
550 if (wait) {
551 for_each_cpu(cpu, cfd->cpumask) {
552 call_single_data_t *csd;
553
554 csd = per_cpu_ptr(cfd->csd, cpu);
555 csd_lock_wait(csd);
556 }
557 }
558}
559
560/**
561 * smp_call_function_many(): Run a function on a set of other CPUs.
562 * @mask: The set of cpus to run on (only runs on online subset).
563 * @func: The function to run. This must be fast and non-blocking.
564 * @info: An arbitrary pointer to pass to the function.
565 * @wait: If true, wait (atomically) until function has completed
566 * on other CPUs.
567 *
568 * If @wait is true, then returns once @func has returned.
569 *
570 * You must not call this function with disabled interrupts or from a
571 * hardware interrupt handler or from a bottom half handler. Preemption
572 * must be disabled when calling this function.
573 */
574void smp_call_function_many(const struct cpumask *mask,
575 smp_call_func_t func, void *info, bool wait)
576{
577 smp_call_function_many_cond(mask, func, info, wait, NULL);
578}
579EXPORT_SYMBOL(smp_call_function_many);
580
581/**
582 * smp_call_function(): Run a function on all other CPUs.
583 * @func: The function to run. This must be fast and non-blocking.
584 * @info: An arbitrary pointer to pass to the function.
585 * @wait: If true, wait (atomically) until function has completed
586 * on other CPUs.
587 *
588 * Returns 0.
589 *
590 * If @wait is true, then returns once @func has returned; otherwise
591 * it returns just before the target cpu calls @func.
592 *
593 * You must not call this function with disabled interrupts or from a
594 * hardware interrupt handler or from a bottom half handler.
595 */
596void smp_call_function(smp_call_func_t func, void *info, int wait)
597{
598 preempt_disable();
599 smp_call_function_many(cpu_online_mask, func, info, wait);
600 preempt_enable();
601}
602EXPORT_SYMBOL(smp_call_function);
603
604/* Setup configured maximum number of CPUs to activate */
605unsigned int setup_max_cpus = NR_CPUS;
606EXPORT_SYMBOL(setup_max_cpus);
607
608
609/*
610 * Setup routine for controlling SMP activation
611 *
612 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
613 * activation entirely (the MPS table probe still happens, though).
614 *
615 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
616 * greater than 0, limits the maximum number of CPUs activated in
617 * SMP mode to <NUM>.
618 */
619
620void __weak arch_disable_smp_support(void) { }
621
622static int __init nosmp(char *str)
623{
624 setup_max_cpus = 0;
625 arch_disable_smp_support();
626
627 return 0;
628}
629
630early_param("nosmp", nosmp);
631
632/* this is hard limit */
633static int __init nrcpus(char *str)
634{
635 int nr_cpus;
636
637 if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
638 nr_cpu_ids = nr_cpus;
639
640 return 0;
641}
642
643early_param("nr_cpus", nrcpus);
644
645static int __init maxcpus(char *str)
646{
647 get_option(&str, &setup_max_cpus);
648 if (setup_max_cpus == 0)
649 arch_disable_smp_support();
650
651 return 0;
652}
653
654early_param("maxcpus", maxcpus);
655
656/* Setup number of possible processor ids */
657unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
658EXPORT_SYMBOL(nr_cpu_ids);
659
660/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
661void __init setup_nr_cpu_ids(void)
662{
663 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
664}
665
666/* Called by boot processor to activate the rest. */
667void __init smp_init(void)
668{
669 int num_nodes, num_cpus;
670
671 idle_threads_init();
672 cpuhp_threads_init();
673
674 pr_info("Bringing up secondary CPUs ...\n");
675
676 bringup_nonboot_cpus(setup_max_cpus);
677
678 num_nodes = num_online_nodes();
679 num_cpus = num_online_cpus();
680 pr_info("Brought up %d node%s, %d CPU%s\n",
681 num_nodes, (num_nodes > 1 ? "s" : ""),
682 num_cpus, (num_cpus > 1 ? "s" : ""));
683
684 /* Any cleanup work */
685 smp_cpus_done(setup_max_cpus);
686}
687
688/*
689 * Call a function on all processors. May be used during early boot while
690 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
691 * of local_irq_disable/enable().
692 */
693void on_each_cpu(smp_call_func_t func, void *info, int wait)
694{
695 unsigned long flags;
696
697 preempt_disable();
698 smp_call_function(func, info, wait);
699 local_irq_save(flags);
700 func(info);
701 local_irq_restore(flags);
702 preempt_enable();
703}
704EXPORT_SYMBOL(on_each_cpu);
705
706/**
707 * on_each_cpu_mask(): Run a function on processors specified by
708 * cpumask, which may include the local processor.
709 * @mask: The set of cpus to run on (only runs on online subset).
710 * @func: The function to run. This must be fast and non-blocking.
711 * @info: An arbitrary pointer to pass to the function.
712 * @wait: If true, wait (atomically) until function has completed
713 * on other CPUs.
714 *
715 * If @wait is true, then returns once @func has returned.
716 *
717 * You must not call this function with disabled interrupts or from a
718 * hardware interrupt handler or from a bottom half handler. The
719 * exception is that it may be used during early boot while
720 * early_boot_irqs_disabled is set.
721 */
722void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
723 void *info, bool wait)
724{
725 int cpu = get_cpu();
726
727 smp_call_function_many(mask, func, info, wait);
728 if (cpumask_test_cpu(cpu, mask)) {
729 unsigned long flags;
730 local_irq_save(flags);
731 func(info);
732 local_irq_restore(flags);
733 }
734 put_cpu();
735}
736EXPORT_SYMBOL(on_each_cpu_mask);
737
738/*
739 * on_each_cpu_cond(): Call a function on each processor for which
740 * the supplied function cond_func returns true, optionally waiting
741 * for all the required CPUs to finish. This may include the local
742 * processor.
743 * @cond_func: A callback function that is passed a cpu id and
744 * the the info parameter. The function is called
745 * with preemption disabled. The function should
746 * return a blooean value indicating whether to IPI
747 * the specified CPU.
748 * @func: The function to run on all applicable CPUs.
749 * This must be fast and non-blocking.
750 * @info: An arbitrary pointer to pass to both functions.
751 * @wait: If true, wait (atomically) until function has
752 * completed on other CPUs.
753 *
754 * Preemption is disabled to protect against CPUs going offline but not online.
755 * CPUs going online during the call will not be seen or sent an IPI.
756 *
757 * You must not call this function with disabled interrupts or
758 * from a hardware interrupt handler or from a bottom half handler.
759 */
760void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
761 void *info, bool wait, const struct cpumask *mask)
762{
763 int cpu = get_cpu();
764
765 smp_call_function_many_cond(mask, func, info, wait, cond_func);
766 if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) {
767 unsigned long flags;
768
769 local_irq_save(flags);
770 func(info);
771 local_irq_restore(flags);
772 }
773 put_cpu();
774}
775EXPORT_SYMBOL(on_each_cpu_cond_mask);
776
777void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
778 void *info, bool wait)
779{
780 on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
781}
782EXPORT_SYMBOL(on_each_cpu_cond);
783
784static void do_nothing(void *unused)
785{
786}
787
788/**
789 * kick_all_cpus_sync - Force all cpus out of idle
790 *
791 * Used to synchronize the update of pm_idle function pointer. It's
792 * called after the pointer is updated and returns after the dummy
793 * callback function has been executed on all cpus. The execution of
794 * the function can only happen on the remote cpus after they have
795 * left the idle function which had been called via pm_idle function
796 * pointer. So it's guaranteed that nothing uses the previous pointer
797 * anymore.
798 */
799void kick_all_cpus_sync(void)
800{
801 /* Make sure the change is visible before we kick the cpus */
802 smp_mb();
803 smp_call_function(do_nothing, NULL, 1);
804}
805EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
806
807/**
808 * wake_up_all_idle_cpus - break all cpus out of idle
809 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
810 * including idle polling cpus, for non-idle cpus, we will do nothing
811 * for them.
812 */
813void wake_up_all_idle_cpus(void)
814{
815 int cpu;
816
817 preempt_disable();
818 for_each_online_cpu(cpu) {
819 if (cpu == smp_processor_id())
820 continue;
821
822 wake_up_if_idle(cpu);
823 }
824 preempt_enable();
825}
826EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
827
828/**
829 * smp_call_on_cpu - Call a function on a specific cpu
830 *
831 * Used to call a function on a specific cpu and wait for it to return.
832 * Optionally make sure the call is done on a specified physical cpu via vcpu
833 * pinning in order to support virtualized environments.
834 */
835struct smp_call_on_cpu_struct {
836 struct work_struct work;
837 struct completion done;
838 int (*func)(void *);
839 void *data;
840 int ret;
841 int cpu;
842};
843
844static void smp_call_on_cpu_callback(struct work_struct *work)
845{
846 struct smp_call_on_cpu_struct *sscs;
847
848 sscs = container_of(work, struct smp_call_on_cpu_struct, work);
849 if (sscs->cpu >= 0)
850 hypervisor_pin_vcpu(sscs->cpu);
851 sscs->ret = sscs->func(sscs->data);
852 if (sscs->cpu >= 0)
853 hypervisor_pin_vcpu(-1);
854
855 complete(&sscs->done);
856}
857
858int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
859{
860 struct smp_call_on_cpu_struct sscs = {
861 .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
862 .func = func,
863 .data = par,
864 .cpu = phys ? cpu : -1,
865 };
866
867 INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
868
869 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
870 return -ENXIO;
871
872 queue_work_on(cpu, system_wq, &sscs.work);
873 wait_for_completion(&sscs.done);
874
875 return sscs.ret;
876}
877EXPORT_SYMBOL_GPL(smp_call_on_cpu);