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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 cpumask_var_t cpumask_ipi;
34 };
35
36 static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
37
38 static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
39
40 static void flush_smp_call_function_queue(bool warn_cpu_offline);
41
42 int smpcfd_prepare_cpu(unsigned int cpu)
43 {
44 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
45
46 if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
47 cpu_to_node(cpu)))
48 return -ENOMEM;
49 if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
50 cpu_to_node(cpu))) {
51 free_cpumask_var(cfd->cpumask);
52 return -ENOMEM;
53 }
54 cfd->csd = alloc_percpu(struct call_single_data);
55 if (!cfd->csd) {
56 free_cpumask_var(cfd->cpumask);
57 free_cpumask_var(cfd->cpumask_ipi);
58 return -ENOMEM;
59 }
60
61 return 0;
62 }
63
64 int smpcfd_dead_cpu(unsigned int cpu)
65 {
66 struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
67
68 free_cpumask_var(cfd->cpumask);
69 free_cpumask_var(cfd->cpumask_ipi);
70 free_percpu(cfd->csd);
71 return 0;
72 }
73
74 int smpcfd_dying_cpu(unsigned int cpu)
75 {
76 /*
77 * The IPIs for the smp-call-function callbacks queued by other
78 * CPUs might arrive late, either due to hardware latencies or
79 * because this CPU disabled interrupts (inside stop-machine)
80 * before the IPIs were sent. So flush out any pending callbacks
81 * explicitly (without waiting for the IPIs to arrive), to
82 * ensure that the outgoing CPU doesn't go offline with work
83 * still pending.
84 */
85 flush_smp_call_function_queue(false);
86 return 0;
87 }
88
89 void __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 */
106 static __always_inline void csd_lock_wait(struct call_single_data *csd)
107 {
108 smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
109 }
110
111 static __always_inline void csd_lock(struct call_single_data *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 structure:
120 */
121 smp_wmb();
122 }
123
124 static __always_inline void csd_unlock(struct call_single_data *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
134 static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
135
136 /*
137 * Insert a previously allocated call_single_data element
138 * for execution on the given CPU. data must already have
139 * ->func, ->info, and ->flags set.
140 */
141 static int generic_exec_single(int cpu, struct call_single_data *csd,
142 smp_call_func_t func, void *info)
143 {
144 if (cpu == smp_processor_id()) {
145 unsigned long flags;
146
147 /*
148 * We can unlock early even for the synchronous on-stack case,
149 * since we're doing this from the same CPU..
150 */
151 csd_unlock(csd);
152 local_irq_save(flags);
153 func(info);
154 local_irq_restore(flags);
155 return 0;
156 }
157
158
159 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
160 csd_unlock(csd);
161 return -ENXIO;
162 }
163
164 csd->func = func;
165 csd->info = info;
166
167 /*
168 * The list addition should be visible before sending the IPI
169 * handler locks the list to pull the entry off it because of
170 * normal cache coherency rules implied by spinlocks.
171 *
172 * If IPIs can go out of order to the cache coherency protocol
173 * in an architecture, sufficient synchronisation should be added
174 * to arch code to make it appear to obey cache coherency WRT
175 * locking and barrier primitives. Generic code isn't really
176 * equipped to do the right thing...
177 */
178 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
179 arch_send_call_function_single_ipi(cpu);
180
181 return 0;
182 }
183
184 /**
185 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
186 *
187 * Invoked by arch to handle an IPI for call function single.
188 * Must be called with interrupts disabled.
189 */
190 void generic_smp_call_function_single_interrupt(void)
191 {
192 flush_smp_call_function_queue(true);
193 }
194
195 /**
196 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
197 *
198 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
199 * offline CPU. Skip this check if set to 'false'.
200 *
201 * Flush any pending smp-call-function callbacks queued on this CPU. This is
202 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
203 * to ensure that all pending IPI callbacks are run before it goes completely
204 * offline.
205 *
206 * Loop through the call_single_queue and run all the queued callbacks.
207 * Must be called with interrupts disabled.
208 */
209 static void flush_smp_call_function_queue(bool warn_cpu_offline)
210 {
211 struct llist_head *head;
212 struct llist_node *entry;
213 struct call_single_data *csd, *csd_next;
214 static bool warned;
215
216 WARN_ON(!irqs_disabled());
217
218 head = this_cpu_ptr(&call_single_queue);
219 entry = llist_del_all(head);
220 entry = llist_reverse_order(entry);
221
222 /* There shouldn't be any pending callbacks on an offline CPU. */
223 if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
224 !warned && !llist_empty(head))) {
225 warned = true;
226 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
227
228 /*
229 * We don't have to use the _safe() variant here
230 * because we are not invoking the IPI handlers yet.
231 */
232 llist_for_each_entry(csd, entry, llist)
233 pr_warn("IPI callback %pS sent to offline CPU\n",
234 csd->func);
235 }
236
237 llist_for_each_entry_safe(csd, csd_next, entry, llist) {
238 smp_call_func_t func = csd->func;
239 void *info = csd->info;
240
241 /* Do we wait until *after* callback? */
242 if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
243 func(info);
244 csd_unlock(csd);
245 } else {
246 csd_unlock(csd);
247 func(info);
248 }
249 }
250
251 /*
252 * Handle irq works queued remotely by irq_work_queue_on().
253 * Smp functions above are typically synchronous so they
254 * better run first since some other CPUs may be busy waiting
255 * for them.
256 */
257 irq_work_run();
258 }
259
260 /*
261 * smp_call_function_single - Run a function on a specific CPU
262 * @func: The function to run. This must be fast and non-blocking.
263 * @info: An arbitrary pointer to pass to the function.
264 * @wait: If true, wait until function has completed on other CPUs.
265 *
266 * Returns 0 on success, else a negative status code.
267 */
268 int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
269 int wait)
270 {
271 struct call_single_data *csd;
272 struct call_single_data csd_stack = { .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS };
273 int this_cpu;
274 int err;
275
276 /*
277 * prevent preemption and reschedule on another processor,
278 * as well as CPU removal
279 */
280 this_cpu = get_cpu();
281
282 /*
283 * Can deadlock when called with interrupts disabled.
284 * We allow cpu's that are not yet online though, as no one else can
285 * send smp call function interrupt to this cpu and as such deadlocks
286 * can't happen.
287 */
288 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
289 && !oops_in_progress);
290
291 csd = &csd_stack;
292 if (!wait) {
293 csd = this_cpu_ptr(&csd_data);
294 csd_lock(csd);
295 }
296
297 err = generic_exec_single(cpu, csd, func, info);
298
299 if (wait)
300 csd_lock_wait(csd);
301
302 put_cpu();
303
304 return err;
305 }
306 EXPORT_SYMBOL(smp_call_function_single);
307
308 /**
309 * smp_call_function_single_async(): Run an asynchronous function on a
310 * specific CPU.
311 * @cpu: The CPU to run on.
312 * @csd: Pre-allocated and setup data structure
313 *
314 * Like smp_call_function_single(), but the call is asynchonous and
315 * can thus be done from contexts with disabled interrupts.
316 *
317 * The caller passes his own pre-allocated data structure
318 * (ie: embedded in an object) and is responsible for synchronizing it
319 * such that the IPIs performed on the @csd are strictly serialized.
320 *
321 * NOTE: Be careful, there is unfortunately no current debugging facility to
322 * validate the correctness of this serialization.
323 */
324 int smp_call_function_single_async(int cpu, struct call_single_data *csd)
325 {
326 int err = 0;
327
328 preempt_disable();
329
330 /* We could deadlock if we have to wait here with interrupts disabled! */
331 if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
332 csd_lock_wait(csd);
333
334 csd->flags = CSD_FLAG_LOCK;
335 smp_wmb();
336
337 err = generic_exec_single(cpu, csd, csd->func, csd->info);
338 preempt_enable();
339
340 return err;
341 }
342 EXPORT_SYMBOL_GPL(smp_call_function_single_async);
343
344 /*
345 * smp_call_function_any - Run a function on any of the given cpus
346 * @mask: The mask of cpus it can run on.
347 * @func: The function to run. This must be fast and non-blocking.
348 * @info: An arbitrary pointer to pass to the function.
349 * @wait: If true, wait until function has completed.
350 *
351 * Returns 0 on success, else a negative status code (if no cpus were online).
352 *
353 * Selection preference:
354 * 1) current cpu if in @mask
355 * 2) any cpu of current node if in @mask
356 * 3) any other online cpu in @mask
357 */
358 int smp_call_function_any(const struct cpumask *mask,
359 smp_call_func_t func, void *info, int wait)
360 {
361 unsigned int cpu;
362 const struct cpumask *nodemask;
363 int ret;
364
365 /* Try for same CPU (cheapest) */
366 cpu = get_cpu();
367 if (cpumask_test_cpu(cpu, mask))
368 goto call;
369
370 /* Try for same node. */
371 nodemask = cpumask_of_node(cpu_to_node(cpu));
372 for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
373 cpu = cpumask_next_and(cpu, nodemask, mask)) {
374 if (cpu_online(cpu))
375 goto call;
376 }
377
378 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
379 cpu = cpumask_any_and(mask, cpu_online_mask);
380 call:
381 ret = smp_call_function_single(cpu, func, info, wait);
382 put_cpu();
383 return ret;
384 }
385 EXPORT_SYMBOL_GPL(smp_call_function_any);
386
387 /**
388 * smp_call_function_many(): Run a function on a set of other CPUs.
389 * @mask: The set of cpus to run on (only runs on online subset).
390 * @func: The function to run. This must be fast and non-blocking.
391 * @info: An arbitrary pointer to pass to the function.
392 * @wait: If true, wait (atomically) until function has completed
393 * on other CPUs.
394 *
395 * If @wait is true, then returns once @func has returned.
396 *
397 * You must not call this function with disabled interrupts or from a
398 * hardware interrupt handler or from a bottom half handler. Preemption
399 * must be disabled when calling this function.
400 */
401 void smp_call_function_many(const struct cpumask *mask,
402 smp_call_func_t func, void *info, bool wait)
403 {
404 struct call_function_data *cfd;
405 int cpu, next_cpu, this_cpu = smp_processor_id();
406
407 /*
408 * Can deadlock when called with interrupts disabled.
409 * We allow cpu's that are not yet online though, as no one else can
410 * send smp call function interrupt to this cpu and as such deadlocks
411 * can't happen.
412 */
413 WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
414 && !oops_in_progress && !early_boot_irqs_disabled);
415
416 /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
417 cpu = cpumask_first_and(mask, cpu_online_mask);
418 if (cpu == this_cpu)
419 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
420
421 /* No online cpus? We're done. */
422 if (cpu >= nr_cpu_ids)
423 return;
424
425 /* Do we have another CPU which isn't us? */
426 next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
427 if (next_cpu == this_cpu)
428 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
429
430 /* Fastpath: do that cpu by itself. */
431 if (next_cpu >= nr_cpu_ids) {
432 smp_call_function_single(cpu, func, info, wait);
433 return;
434 }
435
436 cfd = this_cpu_ptr(&cfd_data);
437
438 cpumask_and(cfd->cpumask, mask, cpu_online_mask);
439 __cpumask_clear_cpu(this_cpu, cfd->cpumask);
440
441 /* Some callers race with other cpus changing the passed mask */
442 if (unlikely(!cpumask_weight(cfd->cpumask)))
443 return;
444
445 cpumask_clear(cfd->cpumask_ipi);
446 for_each_cpu(cpu, cfd->cpumask) {
447 struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu);
448
449 csd_lock(csd);
450 if (wait)
451 csd->flags |= CSD_FLAG_SYNCHRONOUS;
452 csd->func = func;
453 csd->info = info;
454 if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
455 __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
456 }
457
458 /* Send a message to all CPUs in the map */
459 arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
460
461 if (wait) {
462 for_each_cpu(cpu, cfd->cpumask) {
463 struct call_single_data *csd;
464
465 csd = per_cpu_ptr(cfd->csd, cpu);
466 csd_lock_wait(csd);
467 }
468 }
469 }
470 EXPORT_SYMBOL(smp_call_function_many);
471
472 /**
473 * smp_call_function(): Run a function on all other CPUs.
474 * @func: The function to run. This must be fast and non-blocking.
475 * @info: An arbitrary pointer to pass to the function.
476 * @wait: If true, wait (atomically) until function has completed
477 * on other CPUs.
478 *
479 * Returns 0.
480 *
481 * If @wait is true, then returns once @func has returned; otherwise
482 * it returns just before the target cpu calls @func.
483 *
484 * You must not call this function with disabled interrupts or from a
485 * hardware interrupt handler or from a bottom half handler.
486 */
487 int smp_call_function(smp_call_func_t func, void *info, int wait)
488 {
489 preempt_disable();
490 smp_call_function_many(cpu_online_mask, func, info, wait);
491 preempt_enable();
492
493 return 0;
494 }
495 EXPORT_SYMBOL(smp_call_function);
496
497 /* Setup configured maximum number of CPUs to activate */
498 unsigned int setup_max_cpus = NR_CPUS;
499 EXPORT_SYMBOL(setup_max_cpus);
500
501 #ifdef CONFIG_X86
502 /*
503 * use IBRS
504 * bit 0 = indicate if ibrs is currently in use
505 * bit 1 = indicate if system supports ibrs
506 * bit 2 = indicate if admin disables ibrs
507 */
508
509 int use_ibrs;
510 EXPORT_SYMBOL(use_ibrs);
511
512 /*
513 * use IBRS
514 * bit 0 = indicate if ibpb is currently in use
515 * bit 1 = indicate if system supports ibpb
516 * bit 2 = indicate if admin disables ibpb
517 */
518 int use_ibpb;
519 EXPORT_SYMBOL(use_ibpb);
520 #endif
521
522 /* mutex to serialize IBRS & IBPB control changes */
523 DEFINE_MUTEX(spec_ctrl_mutex);
524 EXPORT_SYMBOL(spec_ctrl_mutex);
525
526 /*
527 * Setup routine for controlling SMP activation
528 *
529 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
530 * activation entirely (the MPS table probe still happens, though).
531 *
532 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
533 * greater than 0, limits the maximum number of CPUs activated in
534 * SMP mode to <NUM>.
535 */
536
537 void __weak arch_disable_smp_support(void) { }
538
539 static int __init nosmp(char *str)
540 {
541 setup_max_cpus = 0;
542 arch_disable_smp_support();
543
544 return 0;
545 }
546
547 early_param("nosmp", nosmp);
548
549 #ifdef CONFIG_X86
550 static int __init noibrs(char *str)
551 {
552 set_ibrs_disabled();
553
554 return 0;
555 }
556
557 early_param("noibrs", noibrs);
558
559 static int __init noibpb(char *str)
560 {
561 set_ibpb_disabled();
562
563 return 0;
564 }
565
566 early_param("noibpb", noibpb);
567 #endif
568
569
570 /* this is hard limit */
571 static int __init nrcpus(char *str)
572 {
573 int nr_cpus;
574
575 get_option(&str, &nr_cpus);
576 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
577 nr_cpu_ids = nr_cpus;
578
579 return 0;
580 }
581
582 early_param("nr_cpus", nrcpus);
583
584 static int __init maxcpus(char *str)
585 {
586 get_option(&str, &setup_max_cpus);
587 if (setup_max_cpus == 0)
588 arch_disable_smp_support();
589
590 return 0;
591 }
592
593 early_param("maxcpus", maxcpus);
594
595 /* Setup number of possible processor ids */
596 int nr_cpu_ids __read_mostly = NR_CPUS;
597 EXPORT_SYMBOL(nr_cpu_ids);
598
599 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
600 void __init setup_nr_cpu_ids(void)
601 {
602 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
603 }
604
605 /* Called by boot processor to activate the rest. */
606 void __init smp_init(void)
607 {
608 int num_nodes, num_cpus;
609 unsigned int cpu;
610
611 idle_threads_init();
612 cpuhp_threads_init();
613
614 pr_info("Bringing up secondary CPUs ...\n");
615
616 /* FIXME: This should be done in userspace --RR */
617 for_each_present_cpu(cpu) {
618 if (num_online_cpus() >= setup_max_cpus)
619 break;
620 if (!cpu_online(cpu))
621 cpu_up(cpu);
622 }
623
624 num_nodes = num_online_nodes();
625 num_cpus = num_online_cpus();
626 pr_info("Brought up %d node%s, %d CPU%s\n",
627 num_nodes, (num_nodes > 1 ? "s" : ""),
628 num_cpus, (num_cpus > 1 ? "s" : ""));
629
630 /* Any cleanup work */
631 smp_cpus_done(setup_max_cpus);
632 }
633
634 /*
635 * Call a function on all processors. May be used during early boot while
636 * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
637 * of local_irq_disable/enable().
638 */
639 int on_each_cpu(void (*func) (void *info), void *info, int wait)
640 {
641 unsigned long flags;
642 int ret = 0;
643
644 preempt_disable();
645 ret = smp_call_function(func, info, wait);
646 local_irq_save(flags);
647 func(info);
648 local_irq_restore(flags);
649 preempt_enable();
650 return ret;
651 }
652 EXPORT_SYMBOL(on_each_cpu);
653
654 /**
655 * on_each_cpu_mask(): Run a function on processors specified by
656 * cpumask, which may include the local processor.
657 * @mask: The set of cpus to run on (only runs on online subset).
658 * @func: The function to run. This must be fast and non-blocking.
659 * @info: An arbitrary pointer to pass to the function.
660 * @wait: If true, wait (atomically) until function has completed
661 * on other CPUs.
662 *
663 * If @wait is true, then returns once @func has returned.
664 *
665 * You must not call this function with disabled interrupts or from a
666 * hardware interrupt handler or from a bottom half handler. The
667 * exception is that it may be used during early boot while
668 * early_boot_irqs_disabled is set.
669 */
670 void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
671 void *info, bool wait)
672 {
673 int cpu = get_cpu();
674
675 smp_call_function_many(mask, func, info, wait);
676 if (cpumask_test_cpu(cpu, mask)) {
677 unsigned long flags;
678 local_irq_save(flags);
679 func(info);
680 local_irq_restore(flags);
681 }
682 put_cpu();
683 }
684 EXPORT_SYMBOL(on_each_cpu_mask);
685
686 /*
687 * on_each_cpu_cond(): Call a function on each processor for which
688 * the supplied function cond_func returns true, optionally waiting
689 * for all the required CPUs to finish. This may include the local
690 * processor.
691 * @cond_func: A callback function that is passed a cpu id and
692 * the the info parameter. The function is called
693 * with preemption disabled. The function should
694 * return a blooean value indicating whether to IPI
695 * the specified CPU.
696 * @func: The function to run on all applicable CPUs.
697 * This must be fast and non-blocking.
698 * @info: An arbitrary pointer to pass to both functions.
699 * @wait: If true, wait (atomically) until function has
700 * completed on other CPUs.
701 * @gfp_flags: GFP flags to use when allocating the cpumask
702 * used internally by the function.
703 *
704 * The function might sleep if the GFP flags indicates a non
705 * atomic allocation is allowed.
706 *
707 * Preemption is disabled to protect against CPUs going offline but not online.
708 * CPUs going online during the call will not be seen or sent an IPI.
709 *
710 * You must not call this function with disabled interrupts or
711 * from a hardware interrupt handler or from a bottom half handler.
712 */
713 void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
714 smp_call_func_t func, void *info, bool wait,
715 gfp_t gfp_flags)
716 {
717 cpumask_var_t cpus;
718 int cpu, ret;
719
720 might_sleep_if(gfpflags_allow_blocking(gfp_flags));
721
722 if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
723 preempt_disable();
724 for_each_online_cpu(cpu)
725 if (cond_func(cpu, info))
726 cpumask_set_cpu(cpu, cpus);
727 on_each_cpu_mask(cpus, func, info, wait);
728 preempt_enable();
729 free_cpumask_var(cpus);
730 } else {
731 /*
732 * No free cpumask, bother. No matter, we'll
733 * just have to IPI them one by one.
734 */
735 preempt_disable();
736 for_each_online_cpu(cpu)
737 if (cond_func(cpu, info)) {
738 ret = smp_call_function_single(cpu, func,
739 info, wait);
740 WARN_ON_ONCE(ret);
741 }
742 preempt_enable();
743 }
744 }
745 EXPORT_SYMBOL(on_each_cpu_cond);
746
747 static void do_nothing(void *unused)
748 {
749 }
750
751 /**
752 * kick_all_cpus_sync - Force all cpus out of idle
753 *
754 * Used to synchronize the update of pm_idle function pointer. It's
755 * called after the pointer is updated and returns after the dummy
756 * callback function has been executed on all cpus. The execution of
757 * the function can only happen on the remote cpus after they have
758 * left the idle function which had been called via pm_idle function
759 * pointer. So it's guaranteed that nothing uses the previous pointer
760 * anymore.
761 */
762 void kick_all_cpus_sync(void)
763 {
764 /* Make sure the change is visible before we kick the cpus */
765 smp_mb();
766 smp_call_function(do_nothing, NULL, 1);
767 }
768 EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
769
770 /**
771 * wake_up_all_idle_cpus - break all cpus out of idle
772 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
773 * including idle polling cpus, for non-idle cpus, we will do nothing
774 * for them.
775 */
776 void wake_up_all_idle_cpus(void)
777 {
778 int cpu;
779
780 preempt_disable();
781 for_each_online_cpu(cpu) {
782 if (cpu == smp_processor_id())
783 continue;
784
785 wake_up_if_idle(cpu);
786 }
787 preempt_enable();
788 }
789 EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
790
791 /**
792 * smp_call_on_cpu - Call a function on a specific cpu
793 *
794 * Used to call a function on a specific cpu and wait for it to return.
795 * Optionally make sure the call is done on a specified physical cpu via vcpu
796 * pinning in order to support virtualized environments.
797 */
798 struct smp_call_on_cpu_struct {
799 struct work_struct work;
800 struct completion done;
801 int (*func)(void *);
802 void *data;
803 int ret;
804 int cpu;
805 };
806
807 static void smp_call_on_cpu_callback(struct work_struct *work)
808 {
809 struct smp_call_on_cpu_struct *sscs;
810
811 sscs = container_of(work, struct smp_call_on_cpu_struct, work);
812 if (sscs->cpu >= 0)
813 hypervisor_pin_vcpu(sscs->cpu);
814 sscs->ret = sscs->func(sscs->data);
815 if (sscs->cpu >= 0)
816 hypervisor_pin_vcpu(-1);
817
818 complete(&sscs->done);
819 }
820
821 int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
822 {
823 struct smp_call_on_cpu_struct sscs = {
824 .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
825 .func = func,
826 .data = par,
827 .cpu = phys ? cpu : -1,
828 };
829
830 INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
831
832 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
833 return -ENXIO;
834
835 queue_work_on(cpu, system_wq, &sscs.work);
836 wait_for_completion(&sscs.done);
837
838 return sscs.ret;
839 }
840 EXPORT_SYMBOL_GPL(smp_call_on_cpu);