Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
3d442233 JA |
2 | /* |
3 | * Generic helpers for smp ipi calls | |
4 | * | |
5 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 | |
3d442233 | 6 | */ |
ca7dfdbb ME |
7 | |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
9 | ||
47885016 | 10 | #include <linux/irq_work.h> |
3d442233 | 11 | #include <linux/rcupdate.h> |
59190f42 | 12 | #include <linux/rculist.h> |
641cd4cf | 13 | #include <linux/kernel.h> |
9984de1a | 14 | #include <linux/export.h> |
0b13fda1 IM |
15 | #include <linux/percpu.h> |
16 | #include <linux/init.h> | |
5a0e3ad6 | 17 | #include <linux/gfp.h> |
3d442233 | 18 | #include <linux/smp.h> |
8969a5ed | 19 | #include <linux/cpu.h> |
c6f4459f | 20 | #include <linux/sched.h> |
4c822698 | 21 | #include <linux/sched/idle.h> |
47ae4b05 | 22 | #include <linux/hypervisor.h> |
3d442233 | 23 | |
3bb5d2ee SS |
24 | #include "smpboot.h" |
25 | ||
3d442233 | 26 | enum { |
6e275637 | 27 | CSD_FLAG_LOCK = 0x01, |
8053871d | 28 | CSD_FLAG_SYNCHRONOUS = 0x02, |
3d442233 JA |
29 | }; |
30 | ||
31 | struct call_function_data { | |
966a9671 | 32 | call_single_data_t __percpu *csd; |
0b13fda1 | 33 | cpumask_var_t cpumask; |
3fc5b3b6 | 34 | cpumask_var_t cpumask_ipi; |
3d442233 JA |
35 | }; |
36 | ||
a22793c7 | 37 | static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data); |
e03bcb68 | 38 | |
6897fc22 | 39 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); |
8969a5ed | 40 | |
8d056c48 SB |
41 | static void flush_smp_call_function_queue(bool warn_cpu_offline); |
42 | ||
31487f83 | 43 | int smpcfd_prepare_cpu(unsigned int cpu) |
8969a5ed | 44 | { |
8969a5ed PZ |
45 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
46 | ||
31487f83 RW |
47 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, |
48 | cpu_to_node(cpu))) | |
49 | return -ENOMEM; | |
3fc5b3b6 AL |
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 | } | |
966a9671 | 55 | cfd->csd = alloc_percpu(call_single_data_t); |
31487f83 | 56 | if (!cfd->csd) { |
8969a5ed | 57 | free_cpumask_var(cfd->cpumask); |
3fc5b3b6 | 58 | free_cpumask_var(cfd->cpumask_ipi); |
31487f83 RW |
59 | return -ENOMEM; |
60 | } | |
61 | ||
62 | return 0; | |
8969a5ed PZ |
63 | } |
64 | ||
31487f83 RW |
65 | int 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); | |
3fc5b3b6 | 70 | free_cpumask_var(cfd->cpumask_ipi); |
31487f83 RW |
71 | free_percpu(cfd->csd); |
72 | return 0; | |
73 | } | |
74 | ||
75 | int 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 | } | |
8969a5ed | 89 | |
d8ad7d11 | 90 | void __init call_function_init(void) |
3d442233 JA |
91 | { |
92 | int i; | |
93 | ||
6897fc22 CH |
94 | for_each_possible_cpu(i) |
95 | init_llist_head(&per_cpu(call_single_queue, i)); | |
8969a5ed | 96 | |
31487f83 | 97 | smpcfd_prepare_cpu(smp_processor_id()); |
3d442233 JA |
98 | } |
99 | ||
8969a5ed PZ |
100 | /* |
101 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources | |
102 | * | |
0b13fda1 IM |
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. | |
8969a5ed | 106 | */ |
966a9671 | 107 | static __always_inline void csd_lock_wait(call_single_data_t *csd) |
8969a5ed | 108 | { |
1f03e8d2 | 109 | smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK)); |
6e275637 PZ |
110 | } |
111 | ||
966a9671 | 112 | static __always_inline void csd_lock(call_single_data_t *csd) |
6e275637 | 113 | { |
e1d12f32 AM |
114 | csd_lock_wait(csd); |
115 | csd->flags |= CSD_FLAG_LOCK; | |
8969a5ed PZ |
116 | |
117 | /* | |
0b13fda1 IM |
118 | * prevent CPU from reordering the above assignment |
119 | * to ->flags with any subsequent assignments to other | |
966a9671 | 120 | * fields of the specified call_single_data_t structure: |
8969a5ed | 121 | */ |
8053871d | 122 | smp_wmb(); |
8969a5ed PZ |
123 | } |
124 | ||
966a9671 | 125 | static __always_inline void csd_unlock(call_single_data_t *csd) |
8969a5ed | 126 | { |
8053871d | 127 | WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); |
0b13fda1 | 128 | |
8969a5ed | 129 | /* |
0b13fda1 | 130 | * ensure we're all done before releasing data: |
8969a5ed | 131 | */ |
8053871d | 132 | smp_store_release(&csd->flags, 0); |
3d442233 JA |
133 | } |
134 | ||
966a9671 | 135 | static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data); |
8b28499a | 136 | |
3d442233 | 137 | /* |
966a9671 | 138 | * Insert a previously allocated call_single_data_t element |
0b13fda1 IM |
139 | * for execution on the given CPU. data must already have |
140 | * ->func, ->info, and ->flags set. | |
3d442233 | 141 | */ |
966a9671 | 142 | static int generic_exec_single(int cpu, call_single_data_t *csd, |
8053871d | 143 | smp_call_func_t func, void *info) |
3d442233 | 144 | { |
8b28499a | 145 | if (cpu == smp_processor_id()) { |
8053871d LT |
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); | |
8b28499a FW |
153 | local_irq_save(flags); |
154 | func(info); | |
155 | local_irq_restore(flags); | |
156 | return 0; | |
157 | } | |
158 | ||
159 | ||
5224b961 LT |
160 | if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { |
161 | csd_unlock(csd); | |
8b28499a | 162 | return -ENXIO; |
5224b961 | 163 | } |
8b28499a | 164 | |
8b28499a FW |
165 | csd->func = func; |
166 | csd->info = info; | |
167 | ||
561920a0 | 168 | /* |
15d0d3b3 NP |
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 | |
0b13fda1 IM |
176 | * locking and barrier primitives. Generic code isn't really |
177 | * equipped to do the right thing... | |
561920a0 | 178 | */ |
6897fc22 | 179 | if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) |
3d442233 JA |
180 | arch_send_call_function_single_ipi(cpu); |
181 | ||
8b28499a | 182 | return 0; |
3d442233 JA |
183 | } |
184 | ||
8d056c48 SB |
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. | |
3d442233 JA |
190 | */ |
191 | void generic_smp_call_function_single_interrupt(void) | |
192 | { | |
8d056c48 SB |
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 | */ | |
210 | static void flush_smp_call_function_queue(bool warn_cpu_offline) | |
211 | { | |
212 | struct llist_head *head; | |
5fd77595 | 213 | struct llist_node *entry; |
966a9671 | 214 | call_single_data_t *csd, *csd_next; |
a219ccf4 SB |
215 | static bool warned; |
216 | ||
83efcbd0 | 217 | lockdep_assert_irqs_disabled(); |
8d056c48 | 218 | |
bb964a92 | 219 | head = this_cpu_ptr(&call_single_queue); |
8d056c48 | 220 | entry = llist_del_all(head); |
a219ccf4 | 221 | entry = llist_reverse_order(entry); |
3d442233 | 222 | |
8d056c48 SB |
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))) { | |
a219ccf4 SB |
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 | } | |
3d442233 | 237 | |
5fd77595 | 238 | llist_for_each_entry_safe(csd, csd_next, entry, llist) { |
8053871d LT |
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 | } | |
3d442233 | 250 | } |
47885016 FW |
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(); | |
3d442233 JA |
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. | |
3d442233 JA |
265 | * @wait: If true, wait until function has completed on other CPUs. |
266 | * | |
72f279b2 | 267 | * Returns 0 on success, else a negative status code. |
3d442233 | 268 | */ |
3a5f65df | 269 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
8691e5a8 | 270 | int wait) |
3d442233 | 271 | { |
966a9671 YH |
272 | call_single_data_t *csd; |
273 | call_single_data_t csd_stack = { | |
274 | .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS, | |
275 | }; | |
0b13fda1 | 276 | int this_cpu; |
8b28499a | 277 | int err; |
3d442233 | 278 | |
0b13fda1 IM |
279 | /* |
280 | * prevent preemption and reschedule on another processor, | |
281 | * as well as CPU removal | |
282 | */ | |
283 | this_cpu = get_cpu(); | |
284 | ||
269c861b SS |
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); | |
3d442233 | 293 | |
8053871d LT |
294 | csd = &csd_stack; |
295 | if (!wait) { | |
296 | csd = this_cpu_ptr(&csd_data); | |
297 | csd_lock(csd); | |
298 | } | |
299 | ||
300 | err = generic_exec_single(cpu, csd, func, info); | |
301 | ||
302 | if (wait) | |
303 | csd_lock_wait(csd); | |
3d442233 JA |
304 | |
305 | put_cpu(); | |
0b13fda1 | 306 | |
f73be6de | 307 | return err; |
3d442233 JA |
308 | } |
309 | EXPORT_SYMBOL(smp_call_function_single); | |
310 | ||
d7877c03 | 311 | /** |
c46fff2a FW |
312 | * smp_call_function_single_async(): Run an asynchronous function on a |
313 | * specific CPU. | |
d7877c03 FW |
314 | * @cpu: The CPU to run on. |
315 | * @csd: Pre-allocated and setup data structure | |
d7877c03 | 316 | * |
c46fff2a FW |
317 | * Like smp_call_function_single(), but the call is asynchonous and |
318 | * can thus be done from contexts with disabled interrupts. | |
319 | * | |
320 | * The caller passes his own pre-allocated data structure | |
321 | * (ie: embedded in an object) and is responsible for synchronizing it | |
322 | * such that the IPIs performed on the @csd are strictly serialized. | |
323 | * | |
324 | * NOTE: Be careful, there is unfortunately no current debugging facility to | |
325 | * validate the correctness of this serialization. | |
d7877c03 | 326 | */ |
966a9671 | 327 | int smp_call_function_single_async(int cpu, call_single_data_t *csd) |
d7877c03 FW |
328 | { |
329 | int err = 0; | |
d7877c03 | 330 | |
fce8ad15 | 331 | preempt_disable(); |
8053871d LT |
332 | |
333 | /* We could deadlock if we have to wait here with interrupts disabled! */ | |
334 | if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK)) | |
335 | csd_lock_wait(csd); | |
336 | ||
337 | csd->flags = CSD_FLAG_LOCK; | |
338 | smp_wmb(); | |
339 | ||
340 | err = generic_exec_single(cpu, csd, csd->func, csd->info); | |
fce8ad15 | 341 | preempt_enable(); |
d7877c03 FW |
342 | |
343 | return err; | |
344 | } | |
c46fff2a | 345 | EXPORT_SYMBOL_GPL(smp_call_function_single_async); |
d7877c03 | 346 | |
2ea6dec4 RR |
347 | /* |
348 | * smp_call_function_any - Run a function on any of the given cpus | |
349 | * @mask: The mask of cpus it can run on. | |
350 | * @func: The function to run. This must be fast and non-blocking. | |
351 | * @info: An arbitrary pointer to pass to the function. | |
352 | * @wait: If true, wait until function has completed. | |
353 | * | |
354 | * Returns 0 on success, else a negative status code (if no cpus were online). | |
2ea6dec4 RR |
355 | * |
356 | * Selection preference: | |
357 | * 1) current cpu if in @mask | |
358 | * 2) any cpu of current node if in @mask | |
359 | * 3) any other online cpu in @mask | |
360 | */ | |
361 | int smp_call_function_any(const struct cpumask *mask, | |
3a5f65df | 362 | smp_call_func_t func, void *info, int wait) |
2ea6dec4 RR |
363 | { |
364 | unsigned int cpu; | |
365 | const struct cpumask *nodemask; | |
366 | int ret; | |
367 | ||
368 | /* Try for same CPU (cheapest) */ | |
369 | cpu = get_cpu(); | |
370 | if (cpumask_test_cpu(cpu, mask)) | |
371 | goto call; | |
372 | ||
373 | /* Try for same node. */ | |
af2422c4 | 374 | nodemask = cpumask_of_node(cpu_to_node(cpu)); |
2ea6dec4 RR |
375 | for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; |
376 | cpu = cpumask_next_and(cpu, nodemask, mask)) { | |
377 | if (cpu_online(cpu)) | |
378 | goto call; | |
379 | } | |
380 | ||
381 | /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ | |
382 | cpu = cpumask_any_and(mask, cpu_online_mask); | |
383 | call: | |
384 | ret = smp_call_function_single(cpu, func, info, wait); | |
385 | put_cpu(); | |
386 | return ret; | |
387 | } | |
388 | EXPORT_SYMBOL_GPL(smp_call_function_any); | |
389 | ||
3d442233 | 390 | /** |
54b11e6d RR |
391 | * smp_call_function_many(): Run a function on a set of other CPUs. |
392 | * @mask: The set of cpus to run on (only runs on online subset). | |
3d442233 JA |
393 | * @func: The function to run. This must be fast and non-blocking. |
394 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
395 | * @wait: If true, wait (atomically) until function has completed |
396 | * on other CPUs. | |
3d442233 | 397 | * |
72f279b2 | 398 | * If @wait is true, then returns once @func has returned. |
3d442233 JA |
399 | * |
400 | * You must not call this function with disabled interrupts or from a | |
401 | * hardware interrupt handler or from a bottom half handler. Preemption | |
402 | * must be disabled when calling this function. | |
403 | */ | |
54b11e6d | 404 | void smp_call_function_many(const struct cpumask *mask, |
3a5f65df | 405 | smp_call_func_t func, void *info, bool wait) |
3d442233 | 406 | { |
e1d12f32 | 407 | struct call_function_data *cfd; |
9a46ad6d | 408 | int cpu, next_cpu, this_cpu = smp_processor_id(); |
3d442233 | 409 | |
269c861b SS |
410 | /* |
411 | * Can deadlock when called with interrupts disabled. | |
412 | * We allow cpu's that are not yet online though, as no one else can | |
413 | * send smp call function interrupt to this cpu and as such deadlocks | |
414 | * can't happen. | |
415 | */ | |
416 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
bd924e8c | 417 | && !oops_in_progress && !early_boot_irqs_disabled); |
3d442233 | 418 | |
723aae25 | 419 | /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ |
54b11e6d | 420 | cpu = cpumask_first_and(mask, cpu_online_mask); |
0b13fda1 | 421 | if (cpu == this_cpu) |
54b11e6d | 422 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); |
0b13fda1 | 423 | |
54b11e6d RR |
424 | /* No online cpus? We're done. */ |
425 | if (cpu >= nr_cpu_ids) | |
426 | return; | |
427 | ||
428 | /* Do we have another CPU which isn't us? */ | |
429 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
0b13fda1 | 430 | if (next_cpu == this_cpu) |
54b11e6d RR |
431 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); |
432 | ||
433 | /* Fastpath: do that cpu by itself. */ | |
434 | if (next_cpu >= nr_cpu_ids) { | |
435 | smp_call_function_single(cpu, func, info, wait); | |
436 | return; | |
3d442233 JA |
437 | } |
438 | ||
bb964a92 | 439 | cfd = this_cpu_ptr(&cfd_data); |
45a57919 | 440 | |
e1d12f32 | 441 | cpumask_and(cfd->cpumask, mask, cpu_online_mask); |
6c8557bd | 442 | __cpumask_clear_cpu(this_cpu, cfd->cpumask); |
723aae25 MM |
443 | |
444 | /* Some callers race with other cpus changing the passed mask */ | |
e1d12f32 | 445 | if (unlikely(!cpumask_weight(cfd->cpumask))) |
723aae25 | 446 | return; |
3d442233 | 447 | |
3fc5b3b6 | 448 | cpumask_clear(cfd->cpumask_ipi); |
e1d12f32 | 449 | for_each_cpu(cpu, cfd->cpumask) { |
966a9671 | 450 | call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu); |
9a46ad6d SL |
451 | |
452 | csd_lock(csd); | |
8053871d LT |
453 | if (wait) |
454 | csd->flags |= CSD_FLAG_SYNCHRONOUS; | |
9a46ad6d SL |
455 | csd->func = func; |
456 | csd->info = info; | |
3fc5b3b6 | 457 | if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) |
6c8557bd | 458 | __cpumask_set_cpu(cpu, cfd->cpumask_ipi); |
9a46ad6d | 459 | } |
561920a0 | 460 | |
3d442233 | 461 | /* Send a message to all CPUs in the map */ |
3fc5b3b6 | 462 | arch_send_call_function_ipi_mask(cfd->cpumask_ipi); |
3d442233 | 463 | |
9a46ad6d | 464 | if (wait) { |
e1d12f32 | 465 | for_each_cpu(cpu, cfd->cpumask) { |
966a9671 | 466 | call_single_data_t *csd; |
e1d12f32 AM |
467 | |
468 | csd = per_cpu_ptr(cfd->csd, cpu); | |
9a46ad6d SL |
469 | csd_lock_wait(csd); |
470 | } | |
471 | } | |
3d442233 | 472 | } |
54b11e6d | 473 | EXPORT_SYMBOL(smp_call_function_many); |
3d442233 JA |
474 | |
475 | /** | |
476 | * smp_call_function(): Run a function on all other CPUs. | |
477 | * @func: The function to run. This must be fast and non-blocking. | |
478 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
479 | * @wait: If true, wait (atomically) until function has completed |
480 | * on other CPUs. | |
3d442233 | 481 | * |
54b11e6d | 482 | * Returns 0. |
3d442233 JA |
483 | * |
484 | * If @wait is true, then returns once @func has returned; otherwise | |
72f279b2 | 485 | * it returns just before the target cpu calls @func. |
3d442233 JA |
486 | * |
487 | * You must not call this function with disabled interrupts or from a | |
488 | * hardware interrupt handler or from a bottom half handler. | |
489 | */ | |
caa75932 | 490 | void smp_call_function(smp_call_func_t func, void *info, int wait) |
3d442233 | 491 | { |
3d442233 | 492 | preempt_disable(); |
54b11e6d | 493 | smp_call_function_many(cpu_online_mask, func, info, wait); |
3d442233 | 494 | preempt_enable(); |
3d442233 JA |
495 | } |
496 | EXPORT_SYMBOL(smp_call_function); | |
351f8f8e | 497 | |
34db18a0 AW |
498 | /* Setup configured maximum number of CPUs to activate */ |
499 | unsigned int setup_max_cpus = NR_CPUS; | |
500 | EXPORT_SYMBOL(setup_max_cpus); | |
501 | ||
502 | ||
503 | /* | |
504 | * Setup routine for controlling SMP activation | |
505 | * | |
506 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP | |
507 | * activation entirely (the MPS table probe still happens, though). | |
508 | * | |
509 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer | |
510 | * greater than 0, limits the maximum number of CPUs activated in | |
511 | * SMP mode to <NUM>. | |
512 | */ | |
513 | ||
514 | void __weak arch_disable_smp_support(void) { } | |
515 | ||
516 | static int __init nosmp(char *str) | |
517 | { | |
518 | setup_max_cpus = 0; | |
519 | arch_disable_smp_support(); | |
520 | ||
521 | return 0; | |
522 | } | |
523 | ||
524 | early_param("nosmp", nosmp); | |
525 | ||
526 | /* this is hard limit */ | |
527 | static int __init nrcpus(char *str) | |
528 | { | |
529 | int nr_cpus; | |
530 | ||
531 | get_option(&str, &nr_cpus); | |
532 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) | |
533 | nr_cpu_ids = nr_cpus; | |
534 | ||
535 | return 0; | |
536 | } | |
537 | ||
538 | early_param("nr_cpus", nrcpus); | |
539 | ||
540 | static int __init maxcpus(char *str) | |
541 | { | |
542 | get_option(&str, &setup_max_cpus); | |
543 | if (setup_max_cpus == 0) | |
544 | arch_disable_smp_support(); | |
545 | ||
546 | return 0; | |
547 | } | |
548 | ||
549 | early_param("maxcpus", maxcpus); | |
550 | ||
551 | /* Setup number of possible processor ids */ | |
9b130ad5 | 552 | unsigned int nr_cpu_ids __read_mostly = NR_CPUS; |
34db18a0 AW |
553 | EXPORT_SYMBOL(nr_cpu_ids); |
554 | ||
555 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ | |
556 | void __init setup_nr_cpu_ids(void) | |
557 | { | |
558 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; | |
559 | } | |
560 | ||
561 | /* Called by boot processor to activate the rest. */ | |
562 | void __init smp_init(void) | |
563 | { | |
92b23278 | 564 | int num_nodes, num_cpus; |
34db18a0 AW |
565 | unsigned int cpu; |
566 | ||
3bb5d2ee | 567 | idle_threads_init(); |
4cb28ced | 568 | cpuhp_threads_init(); |
3bb5d2ee | 569 | |
51111dce ME |
570 | pr_info("Bringing up secondary CPUs ...\n"); |
571 | ||
34db18a0 AW |
572 | /* FIXME: This should be done in userspace --RR */ |
573 | for_each_present_cpu(cpu) { | |
574 | if (num_online_cpus() >= setup_max_cpus) | |
575 | break; | |
576 | if (!cpu_online(cpu)) | |
577 | cpu_up(cpu); | |
578 | } | |
579 | ||
92b23278 ME |
580 | num_nodes = num_online_nodes(); |
581 | num_cpus = num_online_cpus(); | |
582 | pr_info("Brought up %d node%s, %d CPU%s\n", | |
583 | num_nodes, (num_nodes > 1 ? "s" : ""), | |
584 | num_cpus, (num_cpus > 1 ? "s" : "")); | |
585 | ||
34db18a0 | 586 | /* Any cleanup work */ |
34db18a0 AW |
587 | smp_cpus_done(setup_max_cpus); |
588 | } | |
589 | ||
351f8f8e | 590 | /* |
bd924e8c TH |
591 | * Call a function on all processors. May be used during early boot while |
592 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead | |
593 | * of local_irq_disable/enable(). | |
351f8f8e | 594 | */ |
caa75932 | 595 | void on_each_cpu(void (*func) (void *info), void *info, int wait) |
351f8f8e | 596 | { |
bd924e8c | 597 | unsigned long flags; |
351f8f8e AW |
598 | |
599 | preempt_disable(); | |
caa75932 | 600 | smp_call_function(func, info, wait); |
bd924e8c | 601 | local_irq_save(flags); |
351f8f8e | 602 | func(info); |
bd924e8c | 603 | local_irq_restore(flags); |
351f8f8e | 604 | preempt_enable(); |
351f8f8e AW |
605 | } |
606 | EXPORT_SYMBOL(on_each_cpu); | |
3fc498f1 GBY |
607 | |
608 | /** | |
609 | * on_each_cpu_mask(): Run a function on processors specified by | |
610 | * cpumask, which may include the local processor. | |
611 | * @mask: The set of cpus to run on (only runs on online subset). | |
612 | * @func: The function to run. This must be fast and non-blocking. | |
613 | * @info: An arbitrary pointer to pass to the function. | |
614 | * @wait: If true, wait (atomically) until function has completed | |
615 | * on other CPUs. | |
616 | * | |
617 | * If @wait is true, then returns once @func has returned. | |
618 | * | |
202da400 DD |
619 | * You must not call this function with disabled interrupts or from a |
620 | * hardware interrupt handler or from a bottom half handler. The | |
621 | * exception is that it may be used during early boot while | |
622 | * early_boot_irqs_disabled is set. | |
3fc498f1 GBY |
623 | */ |
624 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, | |
625 | void *info, bool wait) | |
626 | { | |
627 | int cpu = get_cpu(); | |
628 | ||
629 | smp_call_function_many(mask, func, info, wait); | |
630 | if (cpumask_test_cpu(cpu, mask)) { | |
202da400 DD |
631 | unsigned long flags; |
632 | local_irq_save(flags); | |
3fc498f1 | 633 | func(info); |
202da400 | 634 | local_irq_restore(flags); |
3fc498f1 GBY |
635 | } |
636 | put_cpu(); | |
637 | } | |
638 | EXPORT_SYMBOL(on_each_cpu_mask); | |
b3a7e98e GBY |
639 | |
640 | /* | |
641 | * on_each_cpu_cond(): Call a function on each processor for which | |
642 | * the supplied function cond_func returns true, optionally waiting | |
643 | * for all the required CPUs to finish. This may include the local | |
644 | * processor. | |
645 | * @cond_func: A callback function that is passed a cpu id and | |
646 | * the the info parameter. The function is called | |
647 | * with preemption disabled. The function should | |
648 | * return a blooean value indicating whether to IPI | |
649 | * the specified CPU. | |
650 | * @func: The function to run on all applicable CPUs. | |
651 | * This must be fast and non-blocking. | |
652 | * @info: An arbitrary pointer to pass to both functions. | |
653 | * @wait: If true, wait (atomically) until function has | |
654 | * completed on other CPUs. | |
655 | * @gfp_flags: GFP flags to use when allocating the cpumask | |
656 | * used internally by the function. | |
657 | * | |
658 | * The function might sleep if the GFP flags indicates a non | |
659 | * atomic allocation is allowed. | |
660 | * | |
661 | * Preemption is disabled to protect against CPUs going offline but not online. | |
662 | * CPUs going online during the call will not be seen or sent an IPI. | |
663 | * | |
664 | * You must not call this function with disabled interrupts or | |
665 | * from a hardware interrupt handler or from a bottom half handler. | |
666 | */ | |
7d49b28a | 667 | void on_each_cpu_cond_mask(bool (*cond_func)(int cpu, void *info), |
b3a7e98e | 668 | smp_call_func_t func, void *info, bool wait, |
7d49b28a | 669 | gfp_t gfp_flags, const struct cpumask *mask) |
b3a7e98e GBY |
670 | { |
671 | cpumask_var_t cpus; | |
672 | int cpu, ret; | |
673 | ||
d0164adc | 674 | might_sleep_if(gfpflags_allow_blocking(gfp_flags)); |
b3a7e98e GBY |
675 | |
676 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { | |
677 | preempt_disable(); | |
7d49b28a | 678 | for_each_cpu(cpu, mask) |
b3a7e98e | 679 | if (cond_func(cpu, info)) |
c3f7f2c7 | 680 | __cpumask_set_cpu(cpu, cpus); |
b3a7e98e GBY |
681 | on_each_cpu_mask(cpus, func, info, wait); |
682 | preempt_enable(); | |
683 | free_cpumask_var(cpus); | |
684 | } else { | |
685 | /* | |
686 | * No free cpumask, bother. No matter, we'll | |
687 | * just have to IPI them one by one. | |
688 | */ | |
689 | preempt_disable(); | |
7d49b28a | 690 | for_each_cpu(cpu, mask) |
b3a7e98e GBY |
691 | if (cond_func(cpu, info)) { |
692 | ret = smp_call_function_single(cpu, func, | |
693 | info, wait); | |
618fde87 | 694 | WARN_ON_ONCE(ret); |
b3a7e98e GBY |
695 | } |
696 | preempt_enable(); | |
697 | } | |
698 | } | |
7d49b28a RR |
699 | EXPORT_SYMBOL(on_each_cpu_cond_mask); |
700 | ||
701 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), | |
702 | smp_call_func_t func, void *info, bool wait, | |
703 | gfp_t gfp_flags) | |
704 | { | |
705 | on_each_cpu_cond_mask(cond_func, func, info, wait, gfp_flags, | |
706 | cpu_online_mask); | |
707 | } | |
b3a7e98e | 708 | EXPORT_SYMBOL(on_each_cpu_cond); |
f37f435f TG |
709 | |
710 | static void do_nothing(void *unused) | |
711 | { | |
712 | } | |
713 | ||
714 | /** | |
715 | * kick_all_cpus_sync - Force all cpus out of idle | |
716 | * | |
717 | * Used to synchronize the update of pm_idle function pointer. It's | |
718 | * called after the pointer is updated and returns after the dummy | |
719 | * callback function has been executed on all cpus. The execution of | |
720 | * the function can only happen on the remote cpus after they have | |
721 | * left the idle function which had been called via pm_idle function | |
722 | * pointer. So it's guaranteed that nothing uses the previous pointer | |
723 | * anymore. | |
724 | */ | |
725 | void kick_all_cpus_sync(void) | |
726 | { | |
727 | /* Make sure the change is visible before we kick the cpus */ | |
728 | smp_mb(); | |
729 | smp_call_function(do_nothing, NULL, 1); | |
730 | } | |
731 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); | |
c6f4459f CL |
732 | |
733 | /** | |
734 | * wake_up_all_idle_cpus - break all cpus out of idle | |
735 | * wake_up_all_idle_cpus try to break all cpus which is in idle state even | |
736 | * including idle polling cpus, for non-idle cpus, we will do nothing | |
737 | * for them. | |
738 | */ | |
739 | void wake_up_all_idle_cpus(void) | |
740 | { | |
741 | int cpu; | |
742 | ||
743 | preempt_disable(); | |
744 | for_each_online_cpu(cpu) { | |
745 | if (cpu == smp_processor_id()) | |
746 | continue; | |
747 | ||
748 | wake_up_if_idle(cpu); | |
749 | } | |
750 | preempt_enable(); | |
751 | } | |
752 | EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); | |
df8ce9d7 JG |
753 | |
754 | /** | |
755 | * smp_call_on_cpu - Call a function on a specific cpu | |
756 | * | |
757 | * Used to call a function on a specific cpu and wait for it to return. | |
758 | * Optionally make sure the call is done on a specified physical cpu via vcpu | |
759 | * pinning in order to support virtualized environments. | |
760 | */ | |
761 | struct smp_call_on_cpu_struct { | |
762 | struct work_struct work; | |
763 | struct completion done; | |
764 | int (*func)(void *); | |
765 | void *data; | |
766 | int ret; | |
767 | int cpu; | |
768 | }; | |
769 | ||
770 | static void smp_call_on_cpu_callback(struct work_struct *work) | |
771 | { | |
772 | struct smp_call_on_cpu_struct *sscs; | |
773 | ||
774 | sscs = container_of(work, struct smp_call_on_cpu_struct, work); | |
775 | if (sscs->cpu >= 0) | |
776 | hypervisor_pin_vcpu(sscs->cpu); | |
777 | sscs->ret = sscs->func(sscs->data); | |
778 | if (sscs->cpu >= 0) | |
779 | hypervisor_pin_vcpu(-1); | |
780 | ||
781 | complete(&sscs->done); | |
782 | } | |
783 | ||
784 | int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys) | |
785 | { | |
786 | struct smp_call_on_cpu_struct sscs = { | |
df8ce9d7 JG |
787 | .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), |
788 | .func = func, | |
789 | .data = par, | |
790 | .cpu = phys ? cpu : -1, | |
791 | }; | |
792 | ||
8db54949 PZ |
793 | INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback); |
794 | ||
df8ce9d7 JG |
795 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
796 | return -ENXIO; | |
797 | ||
798 | queue_work_on(cpu, system_wq, &sscs.work); | |
799 | wait_for_completion(&sscs.done); | |
800 | ||
801 | return sscs.ret; | |
802 | } | |
803 | EXPORT_SYMBOL_GPL(smp_call_on_cpu); |