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Commit | Line | Data |
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3d442233 JA |
1 | /* |
2 | * Generic helpers for smp ipi calls | |
3 | * | |
4 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 | |
3d442233 | 5 | */ |
ca7dfdbb ME |
6 | |
7 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
8 | ||
47885016 | 9 | #include <linux/irq_work.h> |
3d442233 | 10 | #include <linux/rcupdate.h> |
59190f42 | 11 | #include <linux/rculist.h> |
641cd4cf | 12 | #include <linux/kernel.h> |
9984de1a | 13 | #include <linux/export.h> |
0b13fda1 IM |
14 | #include <linux/percpu.h> |
15 | #include <linux/init.h> | |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
3d442233 | 17 | #include <linux/smp.h> |
8969a5ed | 18 | #include <linux/cpu.h> |
c6f4459f | 19 | #include <linux/sched.h> |
47ae4b05 | 20 | #include <linux/hypervisor.h> |
3d442233 | 21 | |
3bb5d2ee SS |
22 | #include "smpboot.h" |
23 | ||
3d442233 | 24 | enum { |
6e275637 | 25 | CSD_FLAG_LOCK = 0x01, |
8053871d | 26 | CSD_FLAG_SYNCHRONOUS = 0x02, |
3d442233 JA |
27 | }; |
28 | ||
29 | struct call_function_data { | |
9a46ad6d | 30 | struct call_single_data __percpu *csd; |
0b13fda1 | 31 | cpumask_var_t cpumask; |
3d442233 JA |
32 | }; |
33 | ||
e03bcb68 MM |
34 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); |
35 | ||
6897fc22 | 36 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); |
8969a5ed | 37 | |
8d056c48 SB |
38 | static void flush_smp_call_function_queue(bool warn_cpu_offline); |
39 | ||
31487f83 | 40 | int smpcfd_prepare_cpu(unsigned int cpu) |
8969a5ed | 41 | { |
8969a5ed PZ |
42 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
43 | ||
31487f83 RW |
44 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, |
45 | cpu_to_node(cpu))) | |
46 | return -ENOMEM; | |
47 | cfd->csd = alloc_percpu(struct call_single_data); | |
48 | if (!cfd->csd) { | |
8969a5ed | 49 | free_cpumask_var(cfd->cpumask); |
31487f83 RW |
50 | return -ENOMEM; |
51 | } | |
52 | ||
53 | return 0; | |
8969a5ed PZ |
54 | } |
55 | ||
31487f83 RW |
56 | int smpcfd_dead_cpu(unsigned int cpu) |
57 | { | |
58 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); | |
59 | ||
60 | free_cpumask_var(cfd->cpumask); | |
61 | free_percpu(cfd->csd); | |
62 | return 0; | |
63 | } | |
64 | ||
65 | int smpcfd_dying_cpu(unsigned int cpu) | |
66 | { | |
67 | /* | |
68 | * The IPIs for the smp-call-function callbacks queued by other | |
69 | * CPUs might arrive late, either due to hardware latencies or | |
70 | * because this CPU disabled interrupts (inside stop-machine) | |
71 | * before the IPIs were sent. So flush out any pending callbacks | |
72 | * explicitly (without waiting for the IPIs to arrive), to | |
73 | * ensure that the outgoing CPU doesn't go offline with work | |
74 | * still pending. | |
75 | */ | |
76 | flush_smp_call_function_queue(false); | |
77 | return 0; | |
78 | } | |
8969a5ed | 79 | |
d8ad7d11 | 80 | void __init call_function_init(void) |
3d442233 JA |
81 | { |
82 | int i; | |
83 | ||
6897fc22 CH |
84 | for_each_possible_cpu(i) |
85 | init_llist_head(&per_cpu(call_single_queue, i)); | |
8969a5ed | 86 | |
31487f83 | 87 | smpcfd_prepare_cpu(smp_processor_id()); |
3d442233 JA |
88 | } |
89 | ||
8969a5ed PZ |
90 | /* |
91 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources | |
92 | * | |
0b13fda1 IM |
93 | * For non-synchronous ipi calls the csd can still be in use by the |
94 | * previous function call. For multi-cpu calls its even more interesting | |
95 | * as we'll have to ensure no other cpu is observing our csd. | |
8969a5ed | 96 | */ |
90d10984 | 97 | static __always_inline void csd_lock_wait(struct call_single_data *csd) |
8969a5ed | 98 | { |
1f03e8d2 | 99 | smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK)); |
6e275637 PZ |
100 | } |
101 | ||
90d10984 | 102 | static __always_inline void csd_lock(struct call_single_data *csd) |
6e275637 | 103 | { |
e1d12f32 AM |
104 | csd_lock_wait(csd); |
105 | csd->flags |= CSD_FLAG_LOCK; | |
8969a5ed PZ |
106 | |
107 | /* | |
0b13fda1 IM |
108 | * prevent CPU from reordering the above assignment |
109 | * to ->flags with any subsequent assignments to other | |
110 | * fields of the specified call_single_data structure: | |
8969a5ed | 111 | */ |
8053871d | 112 | smp_wmb(); |
8969a5ed PZ |
113 | } |
114 | ||
90d10984 | 115 | static __always_inline void csd_unlock(struct call_single_data *csd) |
8969a5ed | 116 | { |
8053871d | 117 | WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); |
0b13fda1 | 118 | |
8969a5ed | 119 | /* |
0b13fda1 | 120 | * ensure we're all done before releasing data: |
8969a5ed | 121 | */ |
8053871d | 122 | smp_store_release(&csd->flags, 0); |
3d442233 JA |
123 | } |
124 | ||
8b28499a FW |
125 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data); |
126 | ||
3d442233 | 127 | /* |
0b13fda1 IM |
128 | * Insert a previously allocated call_single_data element |
129 | * for execution on the given CPU. data must already have | |
130 | * ->func, ->info, and ->flags set. | |
3d442233 | 131 | */ |
8b28499a | 132 | static int generic_exec_single(int cpu, struct call_single_data *csd, |
8053871d | 133 | smp_call_func_t func, void *info) |
3d442233 | 134 | { |
8b28499a | 135 | if (cpu == smp_processor_id()) { |
8053871d LT |
136 | unsigned long flags; |
137 | ||
138 | /* | |
139 | * We can unlock early even for the synchronous on-stack case, | |
140 | * since we're doing this from the same CPU.. | |
141 | */ | |
142 | csd_unlock(csd); | |
8b28499a FW |
143 | local_irq_save(flags); |
144 | func(info); | |
145 | local_irq_restore(flags); | |
146 | return 0; | |
147 | } | |
148 | ||
149 | ||
5224b961 LT |
150 | if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { |
151 | csd_unlock(csd); | |
8b28499a | 152 | return -ENXIO; |
5224b961 | 153 | } |
8b28499a | 154 | |
8b28499a FW |
155 | csd->func = func; |
156 | csd->info = info; | |
157 | ||
561920a0 | 158 | /* |
15d0d3b3 NP |
159 | * The list addition should be visible before sending the IPI |
160 | * handler locks the list to pull the entry off it because of | |
161 | * normal cache coherency rules implied by spinlocks. | |
162 | * | |
163 | * If IPIs can go out of order to the cache coherency protocol | |
164 | * in an architecture, sufficient synchronisation should be added | |
165 | * to arch code to make it appear to obey cache coherency WRT | |
0b13fda1 IM |
166 | * locking and barrier primitives. Generic code isn't really |
167 | * equipped to do the right thing... | |
561920a0 | 168 | */ |
6897fc22 | 169 | if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) |
3d442233 JA |
170 | arch_send_call_function_single_ipi(cpu); |
171 | ||
8b28499a | 172 | return 0; |
3d442233 JA |
173 | } |
174 | ||
8d056c48 SB |
175 | /** |
176 | * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks | |
177 | * | |
178 | * Invoked by arch to handle an IPI for call function single. | |
179 | * Must be called with interrupts disabled. | |
3d442233 JA |
180 | */ |
181 | void generic_smp_call_function_single_interrupt(void) | |
182 | { | |
8d056c48 SB |
183 | flush_smp_call_function_queue(true); |
184 | } | |
185 | ||
186 | /** | |
187 | * flush_smp_call_function_queue - Flush pending smp-call-function callbacks | |
188 | * | |
189 | * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an | |
190 | * offline CPU. Skip this check if set to 'false'. | |
191 | * | |
192 | * Flush any pending smp-call-function callbacks queued on this CPU. This is | |
193 | * invoked by the generic IPI handler, as well as by a CPU about to go offline, | |
194 | * to ensure that all pending IPI callbacks are run before it goes completely | |
195 | * offline. | |
196 | * | |
197 | * Loop through the call_single_queue and run all the queued callbacks. | |
198 | * Must be called with interrupts disabled. | |
199 | */ | |
200 | static void flush_smp_call_function_queue(bool warn_cpu_offline) | |
201 | { | |
202 | struct llist_head *head; | |
5fd77595 JK |
203 | struct llist_node *entry; |
204 | struct call_single_data *csd, *csd_next; | |
a219ccf4 SB |
205 | static bool warned; |
206 | ||
8d056c48 SB |
207 | WARN_ON(!irqs_disabled()); |
208 | ||
bb964a92 | 209 | head = this_cpu_ptr(&call_single_queue); |
8d056c48 | 210 | entry = llist_del_all(head); |
a219ccf4 | 211 | entry = llist_reverse_order(entry); |
3d442233 | 212 | |
8d056c48 SB |
213 | /* There shouldn't be any pending callbacks on an offline CPU. */ |
214 | if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && | |
215 | !warned && !llist_empty(head))) { | |
a219ccf4 SB |
216 | warned = true; |
217 | WARN(1, "IPI on offline CPU %d\n", smp_processor_id()); | |
218 | ||
219 | /* | |
220 | * We don't have to use the _safe() variant here | |
221 | * because we are not invoking the IPI handlers yet. | |
222 | */ | |
223 | llist_for_each_entry(csd, entry, llist) | |
224 | pr_warn("IPI callback %pS sent to offline CPU\n", | |
225 | csd->func); | |
226 | } | |
3d442233 | 227 | |
5fd77595 | 228 | llist_for_each_entry_safe(csd, csd_next, entry, llist) { |
8053871d LT |
229 | smp_call_func_t func = csd->func; |
230 | void *info = csd->info; | |
231 | ||
232 | /* Do we wait until *after* callback? */ | |
233 | if (csd->flags & CSD_FLAG_SYNCHRONOUS) { | |
234 | func(info); | |
235 | csd_unlock(csd); | |
236 | } else { | |
237 | csd_unlock(csd); | |
238 | func(info); | |
239 | } | |
3d442233 | 240 | } |
47885016 FW |
241 | |
242 | /* | |
243 | * Handle irq works queued remotely by irq_work_queue_on(). | |
244 | * Smp functions above are typically synchronous so they | |
245 | * better run first since some other CPUs may be busy waiting | |
246 | * for them. | |
247 | */ | |
248 | irq_work_run(); | |
3d442233 JA |
249 | } |
250 | ||
251 | /* | |
252 | * smp_call_function_single - Run a function on a specific CPU | |
253 | * @func: The function to run. This must be fast and non-blocking. | |
254 | * @info: An arbitrary pointer to pass to the function. | |
3d442233 JA |
255 | * @wait: If true, wait until function has completed on other CPUs. |
256 | * | |
72f279b2 | 257 | * Returns 0 on success, else a negative status code. |
3d442233 | 258 | */ |
3a5f65df | 259 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
8691e5a8 | 260 | int wait) |
3d442233 | 261 | { |
8053871d LT |
262 | struct call_single_data *csd; |
263 | struct call_single_data csd_stack = { .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS }; | |
0b13fda1 | 264 | int this_cpu; |
8b28499a | 265 | int err; |
3d442233 | 266 | |
0b13fda1 IM |
267 | /* |
268 | * prevent preemption and reschedule on another processor, | |
269 | * as well as CPU removal | |
270 | */ | |
271 | this_cpu = get_cpu(); | |
272 | ||
269c861b SS |
273 | /* |
274 | * Can deadlock when called with interrupts disabled. | |
275 | * We allow cpu's that are not yet online though, as no one else can | |
276 | * send smp call function interrupt to this cpu and as such deadlocks | |
277 | * can't happen. | |
278 | */ | |
279 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
280 | && !oops_in_progress); | |
3d442233 | 281 | |
8053871d LT |
282 | csd = &csd_stack; |
283 | if (!wait) { | |
284 | csd = this_cpu_ptr(&csd_data); | |
285 | csd_lock(csd); | |
286 | } | |
287 | ||
288 | err = generic_exec_single(cpu, csd, func, info); | |
289 | ||
290 | if (wait) | |
291 | csd_lock_wait(csd); | |
3d442233 JA |
292 | |
293 | put_cpu(); | |
0b13fda1 | 294 | |
f73be6de | 295 | return err; |
3d442233 JA |
296 | } |
297 | EXPORT_SYMBOL(smp_call_function_single); | |
298 | ||
d7877c03 | 299 | /** |
c46fff2a FW |
300 | * smp_call_function_single_async(): Run an asynchronous function on a |
301 | * specific CPU. | |
d7877c03 FW |
302 | * @cpu: The CPU to run on. |
303 | * @csd: Pre-allocated and setup data structure | |
d7877c03 | 304 | * |
c46fff2a FW |
305 | * Like smp_call_function_single(), but the call is asynchonous and |
306 | * can thus be done from contexts with disabled interrupts. | |
307 | * | |
308 | * The caller passes his own pre-allocated data structure | |
309 | * (ie: embedded in an object) and is responsible for synchronizing it | |
310 | * such that the IPIs performed on the @csd are strictly serialized. | |
311 | * | |
312 | * NOTE: Be careful, there is unfortunately no current debugging facility to | |
313 | * validate the correctness of this serialization. | |
d7877c03 | 314 | */ |
c46fff2a | 315 | int smp_call_function_single_async(int cpu, struct call_single_data *csd) |
d7877c03 FW |
316 | { |
317 | int err = 0; | |
d7877c03 | 318 | |
fce8ad15 | 319 | preempt_disable(); |
8053871d LT |
320 | |
321 | /* We could deadlock if we have to wait here with interrupts disabled! */ | |
322 | if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK)) | |
323 | csd_lock_wait(csd); | |
324 | ||
325 | csd->flags = CSD_FLAG_LOCK; | |
326 | smp_wmb(); | |
327 | ||
328 | err = generic_exec_single(cpu, csd, csd->func, csd->info); | |
fce8ad15 | 329 | preempt_enable(); |
d7877c03 FW |
330 | |
331 | return err; | |
332 | } | |
c46fff2a | 333 | EXPORT_SYMBOL_GPL(smp_call_function_single_async); |
d7877c03 | 334 | |
2ea6dec4 RR |
335 | /* |
336 | * smp_call_function_any - Run a function on any of the given cpus | |
337 | * @mask: The mask of cpus it can run on. | |
338 | * @func: The function to run. This must be fast and non-blocking. | |
339 | * @info: An arbitrary pointer to pass to the function. | |
340 | * @wait: If true, wait until function has completed. | |
341 | * | |
342 | * Returns 0 on success, else a negative status code (if no cpus were online). | |
2ea6dec4 RR |
343 | * |
344 | * Selection preference: | |
345 | * 1) current cpu if in @mask | |
346 | * 2) any cpu of current node if in @mask | |
347 | * 3) any other online cpu in @mask | |
348 | */ | |
349 | int smp_call_function_any(const struct cpumask *mask, | |
3a5f65df | 350 | smp_call_func_t func, void *info, int wait) |
2ea6dec4 RR |
351 | { |
352 | unsigned int cpu; | |
353 | const struct cpumask *nodemask; | |
354 | int ret; | |
355 | ||
356 | /* Try for same CPU (cheapest) */ | |
357 | cpu = get_cpu(); | |
358 | if (cpumask_test_cpu(cpu, mask)) | |
359 | goto call; | |
360 | ||
361 | /* Try for same node. */ | |
af2422c4 | 362 | nodemask = cpumask_of_node(cpu_to_node(cpu)); |
2ea6dec4 RR |
363 | for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; |
364 | cpu = cpumask_next_and(cpu, nodemask, mask)) { | |
365 | if (cpu_online(cpu)) | |
366 | goto call; | |
367 | } | |
368 | ||
369 | /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ | |
370 | cpu = cpumask_any_and(mask, cpu_online_mask); | |
371 | call: | |
372 | ret = smp_call_function_single(cpu, func, info, wait); | |
373 | put_cpu(); | |
374 | return ret; | |
375 | } | |
376 | EXPORT_SYMBOL_GPL(smp_call_function_any); | |
377 | ||
3d442233 | 378 | /** |
54b11e6d RR |
379 | * smp_call_function_many(): Run a function on a set of other CPUs. |
380 | * @mask: The set of cpus to run on (only runs on online subset). | |
3d442233 JA |
381 | * @func: The function to run. This must be fast and non-blocking. |
382 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
383 | * @wait: If true, wait (atomically) until function has completed |
384 | * on other CPUs. | |
3d442233 | 385 | * |
72f279b2 | 386 | * If @wait is true, then returns once @func has returned. |
3d442233 JA |
387 | * |
388 | * You must not call this function with disabled interrupts or from a | |
389 | * hardware interrupt handler or from a bottom half handler. Preemption | |
390 | * must be disabled when calling this function. | |
391 | */ | |
54b11e6d | 392 | void smp_call_function_many(const struct cpumask *mask, |
3a5f65df | 393 | smp_call_func_t func, void *info, bool wait) |
3d442233 | 394 | { |
e1d12f32 | 395 | struct call_function_data *cfd; |
9a46ad6d | 396 | int cpu, next_cpu, this_cpu = smp_processor_id(); |
3d442233 | 397 | |
269c861b SS |
398 | /* |
399 | * Can deadlock when called with interrupts disabled. | |
400 | * We allow cpu's that are not yet online though, as no one else can | |
401 | * send smp call function interrupt to this cpu and as such deadlocks | |
402 | * can't happen. | |
403 | */ | |
404 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
bd924e8c | 405 | && !oops_in_progress && !early_boot_irqs_disabled); |
3d442233 | 406 | |
723aae25 | 407 | /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ |
54b11e6d | 408 | cpu = cpumask_first_and(mask, cpu_online_mask); |
0b13fda1 | 409 | if (cpu == this_cpu) |
54b11e6d | 410 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); |
0b13fda1 | 411 | |
54b11e6d RR |
412 | /* No online cpus? We're done. */ |
413 | if (cpu >= nr_cpu_ids) | |
414 | return; | |
415 | ||
416 | /* Do we have another CPU which isn't us? */ | |
417 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
0b13fda1 | 418 | if (next_cpu == this_cpu) |
54b11e6d RR |
419 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); |
420 | ||
421 | /* Fastpath: do that cpu by itself. */ | |
422 | if (next_cpu >= nr_cpu_ids) { | |
423 | smp_call_function_single(cpu, func, info, wait); | |
424 | return; | |
3d442233 JA |
425 | } |
426 | ||
bb964a92 | 427 | cfd = this_cpu_ptr(&cfd_data); |
45a57919 | 428 | |
e1d12f32 AM |
429 | cpumask_and(cfd->cpumask, mask, cpu_online_mask); |
430 | cpumask_clear_cpu(this_cpu, cfd->cpumask); | |
723aae25 MM |
431 | |
432 | /* Some callers race with other cpus changing the passed mask */ | |
e1d12f32 | 433 | if (unlikely(!cpumask_weight(cfd->cpumask))) |
723aae25 | 434 | return; |
3d442233 | 435 | |
e1d12f32 AM |
436 | for_each_cpu(cpu, cfd->cpumask) { |
437 | struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); | |
9a46ad6d SL |
438 | |
439 | csd_lock(csd); | |
8053871d LT |
440 | if (wait) |
441 | csd->flags |= CSD_FLAG_SYNCHRONOUS; | |
9a46ad6d SL |
442 | csd->func = func; |
443 | csd->info = info; | |
6897fc22 | 444 | llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)); |
9a46ad6d | 445 | } |
561920a0 | 446 | |
3d442233 | 447 | /* Send a message to all CPUs in the map */ |
73f94550 | 448 | arch_send_call_function_ipi_mask(cfd->cpumask); |
3d442233 | 449 | |
9a46ad6d | 450 | if (wait) { |
e1d12f32 AM |
451 | for_each_cpu(cpu, cfd->cpumask) { |
452 | struct call_single_data *csd; | |
453 | ||
454 | csd = per_cpu_ptr(cfd->csd, cpu); | |
9a46ad6d SL |
455 | csd_lock_wait(csd); |
456 | } | |
457 | } | |
3d442233 | 458 | } |
54b11e6d | 459 | EXPORT_SYMBOL(smp_call_function_many); |
3d442233 JA |
460 | |
461 | /** | |
462 | * smp_call_function(): Run a function on all other CPUs. | |
463 | * @func: The function to run. This must be fast and non-blocking. | |
464 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
465 | * @wait: If true, wait (atomically) until function has completed |
466 | * on other CPUs. | |
3d442233 | 467 | * |
54b11e6d | 468 | * Returns 0. |
3d442233 JA |
469 | * |
470 | * If @wait is true, then returns once @func has returned; otherwise | |
72f279b2 | 471 | * it returns just before the target cpu calls @func. |
3d442233 JA |
472 | * |
473 | * You must not call this function with disabled interrupts or from a | |
474 | * hardware interrupt handler or from a bottom half handler. | |
475 | */ | |
3a5f65df | 476 | int smp_call_function(smp_call_func_t func, void *info, int wait) |
3d442233 | 477 | { |
3d442233 | 478 | preempt_disable(); |
54b11e6d | 479 | smp_call_function_many(cpu_online_mask, func, info, wait); |
3d442233 | 480 | preempt_enable(); |
0b13fda1 | 481 | |
54b11e6d | 482 | return 0; |
3d442233 JA |
483 | } |
484 | EXPORT_SYMBOL(smp_call_function); | |
351f8f8e | 485 | |
34db18a0 AW |
486 | /* Setup configured maximum number of CPUs to activate */ |
487 | unsigned int setup_max_cpus = NR_CPUS; | |
488 | EXPORT_SYMBOL(setup_max_cpus); | |
489 | ||
490 | ||
491 | /* | |
492 | * Setup routine for controlling SMP activation | |
493 | * | |
494 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP | |
495 | * activation entirely (the MPS table probe still happens, though). | |
496 | * | |
497 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer | |
498 | * greater than 0, limits the maximum number of CPUs activated in | |
499 | * SMP mode to <NUM>. | |
500 | */ | |
501 | ||
502 | void __weak arch_disable_smp_support(void) { } | |
503 | ||
504 | static int __init nosmp(char *str) | |
505 | { | |
506 | setup_max_cpus = 0; | |
507 | arch_disable_smp_support(); | |
508 | ||
509 | return 0; | |
510 | } | |
511 | ||
512 | early_param("nosmp", nosmp); | |
513 | ||
514 | /* this is hard limit */ | |
515 | static int __init nrcpus(char *str) | |
516 | { | |
517 | int nr_cpus; | |
518 | ||
519 | get_option(&str, &nr_cpus); | |
520 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) | |
521 | nr_cpu_ids = nr_cpus; | |
522 | ||
523 | return 0; | |
524 | } | |
525 | ||
526 | early_param("nr_cpus", nrcpus); | |
527 | ||
528 | static int __init maxcpus(char *str) | |
529 | { | |
530 | get_option(&str, &setup_max_cpus); | |
531 | if (setup_max_cpus == 0) | |
532 | arch_disable_smp_support(); | |
533 | ||
534 | return 0; | |
535 | } | |
536 | ||
537 | early_param("maxcpus", maxcpus); | |
538 | ||
539 | /* Setup number of possible processor ids */ | |
540 | int nr_cpu_ids __read_mostly = NR_CPUS; | |
541 | EXPORT_SYMBOL(nr_cpu_ids); | |
542 | ||
543 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ | |
544 | void __init setup_nr_cpu_ids(void) | |
545 | { | |
546 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; | |
547 | } | |
548 | ||
549 | /* Called by boot processor to activate the rest. */ | |
550 | void __init smp_init(void) | |
551 | { | |
92b23278 | 552 | int num_nodes, num_cpus; |
34db18a0 AW |
553 | unsigned int cpu; |
554 | ||
3bb5d2ee | 555 | idle_threads_init(); |
4cb28ced | 556 | cpuhp_threads_init(); |
3bb5d2ee | 557 | |
51111dce ME |
558 | pr_info("Bringing up secondary CPUs ...\n"); |
559 | ||
34db18a0 AW |
560 | /* FIXME: This should be done in userspace --RR */ |
561 | for_each_present_cpu(cpu) { | |
562 | if (num_online_cpus() >= setup_max_cpus) | |
563 | break; | |
564 | if (!cpu_online(cpu)) | |
565 | cpu_up(cpu); | |
566 | } | |
567 | ||
92b23278 ME |
568 | num_nodes = num_online_nodes(); |
569 | num_cpus = num_online_cpus(); | |
570 | pr_info("Brought up %d node%s, %d CPU%s\n", | |
571 | num_nodes, (num_nodes > 1 ? "s" : ""), | |
572 | num_cpus, (num_cpus > 1 ? "s" : "")); | |
573 | ||
34db18a0 | 574 | /* Any cleanup work */ |
34db18a0 AW |
575 | smp_cpus_done(setup_max_cpus); |
576 | } | |
577 | ||
351f8f8e | 578 | /* |
bd924e8c TH |
579 | * Call a function on all processors. May be used during early boot while |
580 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead | |
581 | * of local_irq_disable/enable(). | |
351f8f8e AW |
582 | */ |
583 | int on_each_cpu(void (*func) (void *info), void *info, int wait) | |
584 | { | |
bd924e8c | 585 | unsigned long flags; |
351f8f8e AW |
586 | int ret = 0; |
587 | ||
588 | preempt_disable(); | |
589 | ret = smp_call_function(func, info, wait); | |
bd924e8c | 590 | local_irq_save(flags); |
351f8f8e | 591 | func(info); |
bd924e8c | 592 | local_irq_restore(flags); |
351f8f8e AW |
593 | preempt_enable(); |
594 | return ret; | |
595 | } | |
596 | EXPORT_SYMBOL(on_each_cpu); | |
3fc498f1 GBY |
597 | |
598 | /** | |
599 | * on_each_cpu_mask(): Run a function on processors specified by | |
600 | * cpumask, which may include the local processor. | |
601 | * @mask: The set of cpus to run on (only runs on online subset). | |
602 | * @func: The function to run. This must be fast and non-blocking. | |
603 | * @info: An arbitrary pointer to pass to the function. | |
604 | * @wait: If true, wait (atomically) until function has completed | |
605 | * on other CPUs. | |
606 | * | |
607 | * If @wait is true, then returns once @func has returned. | |
608 | * | |
202da400 DD |
609 | * You must not call this function with disabled interrupts or from a |
610 | * hardware interrupt handler or from a bottom half handler. The | |
611 | * exception is that it may be used during early boot while | |
612 | * early_boot_irqs_disabled is set. | |
3fc498f1 GBY |
613 | */ |
614 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, | |
615 | void *info, bool wait) | |
616 | { | |
617 | int cpu = get_cpu(); | |
618 | ||
619 | smp_call_function_many(mask, func, info, wait); | |
620 | if (cpumask_test_cpu(cpu, mask)) { | |
202da400 DD |
621 | unsigned long flags; |
622 | local_irq_save(flags); | |
3fc498f1 | 623 | func(info); |
202da400 | 624 | local_irq_restore(flags); |
3fc498f1 GBY |
625 | } |
626 | put_cpu(); | |
627 | } | |
628 | EXPORT_SYMBOL(on_each_cpu_mask); | |
b3a7e98e GBY |
629 | |
630 | /* | |
631 | * on_each_cpu_cond(): Call a function on each processor for which | |
632 | * the supplied function cond_func returns true, optionally waiting | |
633 | * for all the required CPUs to finish. This may include the local | |
634 | * processor. | |
635 | * @cond_func: A callback function that is passed a cpu id and | |
636 | * the the info parameter. The function is called | |
637 | * with preemption disabled. The function should | |
638 | * return a blooean value indicating whether to IPI | |
639 | * the specified CPU. | |
640 | * @func: The function to run on all applicable CPUs. | |
641 | * This must be fast and non-blocking. | |
642 | * @info: An arbitrary pointer to pass to both functions. | |
643 | * @wait: If true, wait (atomically) until function has | |
644 | * completed on other CPUs. | |
645 | * @gfp_flags: GFP flags to use when allocating the cpumask | |
646 | * used internally by the function. | |
647 | * | |
648 | * The function might sleep if the GFP flags indicates a non | |
649 | * atomic allocation is allowed. | |
650 | * | |
651 | * Preemption is disabled to protect against CPUs going offline but not online. | |
652 | * CPUs going online during the call will not be seen or sent an IPI. | |
653 | * | |
654 | * You must not call this function with disabled interrupts or | |
655 | * from a hardware interrupt handler or from a bottom half handler. | |
656 | */ | |
657 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), | |
658 | smp_call_func_t func, void *info, bool wait, | |
659 | gfp_t gfp_flags) | |
660 | { | |
661 | cpumask_var_t cpus; | |
662 | int cpu, ret; | |
663 | ||
d0164adc | 664 | might_sleep_if(gfpflags_allow_blocking(gfp_flags)); |
b3a7e98e GBY |
665 | |
666 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { | |
667 | preempt_disable(); | |
668 | for_each_online_cpu(cpu) | |
669 | if (cond_func(cpu, info)) | |
670 | cpumask_set_cpu(cpu, cpus); | |
671 | on_each_cpu_mask(cpus, func, info, wait); | |
672 | preempt_enable(); | |
673 | free_cpumask_var(cpus); | |
674 | } else { | |
675 | /* | |
676 | * No free cpumask, bother. No matter, we'll | |
677 | * just have to IPI them one by one. | |
678 | */ | |
679 | preempt_disable(); | |
680 | for_each_online_cpu(cpu) | |
681 | if (cond_func(cpu, info)) { | |
682 | ret = smp_call_function_single(cpu, func, | |
683 | info, wait); | |
618fde87 | 684 | WARN_ON_ONCE(ret); |
b3a7e98e GBY |
685 | } |
686 | preempt_enable(); | |
687 | } | |
688 | } | |
689 | EXPORT_SYMBOL(on_each_cpu_cond); | |
f37f435f TG |
690 | |
691 | static void do_nothing(void *unused) | |
692 | { | |
693 | } | |
694 | ||
695 | /** | |
696 | * kick_all_cpus_sync - Force all cpus out of idle | |
697 | * | |
698 | * Used to synchronize the update of pm_idle function pointer. It's | |
699 | * called after the pointer is updated and returns after the dummy | |
700 | * callback function has been executed on all cpus. The execution of | |
701 | * the function can only happen on the remote cpus after they have | |
702 | * left the idle function which had been called via pm_idle function | |
703 | * pointer. So it's guaranteed that nothing uses the previous pointer | |
704 | * anymore. | |
705 | */ | |
706 | void kick_all_cpus_sync(void) | |
707 | { | |
708 | /* Make sure the change is visible before we kick the cpus */ | |
709 | smp_mb(); | |
710 | smp_call_function(do_nothing, NULL, 1); | |
711 | } | |
712 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); | |
c6f4459f CL |
713 | |
714 | /** | |
715 | * wake_up_all_idle_cpus - break all cpus out of idle | |
716 | * wake_up_all_idle_cpus try to break all cpus which is in idle state even | |
717 | * including idle polling cpus, for non-idle cpus, we will do nothing | |
718 | * for them. | |
719 | */ | |
720 | void wake_up_all_idle_cpus(void) | |
721 | { | |
722 | int cpu; | |
723 | ||
724 | preempt_disable(); | |
725 | for_each_online_cpu(cpu) { | |
726 | if (cpu == smp_processor_id()) | |
727 | continue; | |
728 | ||
729 | wake_up_if_idle(cpu); | |
730 | } | |
731 | preempt_enable(); | |
732 | } | |
733 | EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); | |
df8ce9d7 JG |
734 | |
735 | /** | |
736 | * smp_call_on_cpu - Call a function on a specific cpu | |
737 | * | |
738 | * Used to call a function on a specific cpu and wait for it to return. | |
739 | * Optionally make sure the call is done on a specified physical cpu via vcpu | |
740 | * pinning in order to support virtualized environments. | |
741 | */ | |
742 | struct smp_call_on_cpu_struct { | |
743 | struct work_struct work; | |
744 | struct completion done; | |
745 | int (*func)(void *); | |
746 | void *data; | |
747 | int ret; | |
748 | int cpu; | |
749 | }; | |
750 | ||
751 | static void smp_call_on_cpu_callback(struct work_struct *work) | |
752 | { | |
753 | struct smp_call_on_cpu_struct *sscs; | |
754 | ||
755 | sscs = container_of(work, struct smp_call_on_cpu_struct, work); | |
756 | if (sscs->cpu >= 0) | |
757 | hypervisor_pin_vcpu(sscs->cpu); | |
758 | sscs->ret = sscs->func(sscs->data); | |
759 | if (sscs->cpu >= 0) | |
760 | hypervisor_pin_vcpu(-1); | |
761 | ||
762 | complete(&sscs->done); | |
763 | } | |
764 | ||
765 | int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys) | |
766 | { | |
767 | struct smp_call_on_cpu_struct sscs = { | |
df8ce9d7 JG |
768 | .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), |
769 | .func = func, | |
770 | .data = par, | |
771 | .cpu = phys ? cpu : -1, | |
772 | }; | |
773 | ||
8db54949 PZ |
774 | INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback); |
775 | ||
df8ce9d7 JG |
776 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
777 | return -ENXIO; | |
778 | ||
779 | queue_work_on(cpu, system_wq, &sscs.work); | |
780 | wait_for_completion(&sscs.done); | |
781 | ||
782 | return sscs.ret; | |
783 | } | |
784 | EXPORT_SYMBOL_GPL(smp_call_on_cpu); |