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