1/*
  2 * Copyright 2015 Advanced Micro Devices, Inc.
  3 *
  4 * Permission is hereby granted, free of charge, to any person obtaining a
  5 * copy of this software and associated documentation files (the "Software"),
  6 * to deal in the Software without restriction, including without limitation
  7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  8 * and/or sell copies of the Software, and to permit persons to whom the
  9 * Software is furnished to do so, subject to the following conditions:
 10 *
 11 * The above copyright notice and this permission notice shall be included in
 12 * all copies or substantial portions of the Software.
 13 *
 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 20 * OTHER DEALINGS IN THE SOFTWARE.
 21 *
 22 */
 23
 24#include <linux/kthread.h>
 25#include <linux/slab.h>
 26#include <linux/completion.h>
 27
 28#include <drm/drm_print.h>
 29#include <drm/gpu_scheduler.h>
 30
 31#include "gpu_scheduler_trace.h"
 32
 33#define to_drm_sched_job(sched_job)		\
 34		container_of((sched_job), struct drm_sched_job, queue_node)
 35
 36/**
 37 * drm_sched_entity_init - Init a context entity used by scheduler when
 38 * submit to HW ring.
 39 *
 40 * @entity: scheduler entity to init
 41 * @priority: priority of the entity
 42 * @sched_list: the list of drm scheds on which jobs from this
 43 *           entity can be submitted
 44 * @num_sched_list: number of drm sched in sched_list
 45 * @guilty: atomic_t set to 1 when a job on this queue
 46 *          is found to be guilty causing a timeout
 47 *
 48 * Note that the &sched_list must have at least one element to schedule the entity.
 49 *
 50 * For changing @priority later on at runtime see
 51 * drm_sched_entity_set_priority(). For changing the set of schedulers
 52 * @sched_list at runtime see drm_sched_entity_modify_sched().
 53 *
 54 * An entity is cleaned up by callind drm_sched_entity_fini(). See also
 55 * drm_sched_entity_destroy().
 56 *
 57 * Returns 0 on success or a negative error code on failure.
 58 */
 59int drm_sched_entity_init(struct drm_sched_entity *entity,
 60			  enum drm_sched_priority priority,
 61			  struct drm_gpu_scheduler **sched_list,
 62			  unsigned int num_sched_list,
 63			  atomic_t *guilty)
 64{
 65	if (!(entity && sched_list && (num_sched_list == 0 || sched_list[0])))
 66		return -EINVAL;
 67
 68	memset(entity, 0, sizeof(struct drm_sched_entity));
 69	INIT_LIST_HEAD(&entity->list);
 70	entity->rq = NULL;
 71	entity->guilty = guilty;
 72	entity->num_sched_list = num_sched_list;
 73	entity->priority = priority;
 74	entity->sched_list = num_sched_list > 1 ? sched_list : NULL;
 75	RCU_INIT_POINTER(entity->last_scheduled, NULL);
 76	RB_CLEAR_NODE(&entity->rb_tree_node);
 77
 78	if (!sched_list[0]->sched_rq) {
 79		/* Warn drivers not to do this and to fix their DRM
 80		 * calling order.
 81		 */
 82		pr_warn("%s: called with uninitialized scheduler\n", __func__);
 83	} else if (num_sched_list) {
 84		/* The "priority" of an entity cannot exceed the number of run-queues of a
 85		 * scheduler. Protect against num_rqs being 0, by converting to signed. Choose
 86		 * the lowest priority available.
 87		 */
 88		if (entity->priority >= sched_list[0]->num_rqs) {
 89			drm_err(sched_list[0], "entity with out-of-bounds priority:%u num_rqs:%u\n",
 90				entity->priority, sched_list[0]->num_rqs);
 91			entity->priority = max_t(s32, (s32) sched_list[0]->num_rqs - 1,
 92						 (s32) DRM_SCHED_PRIORITY_KERNEL);
 93		}
 94		entity->rq = sched_list[0]->sched_rq[entity->priority];
 95	}
 96
 97	init_completion(&entity->entity_idle);
 98
 99	/* We start in an idle state. */
100	complete_all(&entity->entity_idle);
101
102	spin_lock_init(&entity->rq_lock);
103	spsc_queue_init(&entity->job_queue);
104
105	atomic_set(&entity->fence_seq, 0);
106	entity->fence_context = dma_fence_context_alloc(2);
107
108	return 0;
109}
110EXPORT_SYMBOL(drm_sched_entity_init);
111
112/**
113 * drm_sched_entity_modify_sched - Modify sched of an entity
114 * @entity: scheduler entity to init
115 * @sched_list: the list of new drm scheds which will replace
116 *		 existing entity->sched_list
117 * @num_sched_list: number of drm sched in sched_list
118 *
119 * Note that this must be called under the same common lock for @entity as
120 * drm_sched_job_arm() and drm_sched_entity_push_job(), or the driver needs to
121 * guarantee through some other means that this is never called while new jobs
122 * can be pushed to @entity.
123 */
124void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
125				    struct drm_gpu_scheduler **sched_list,
126				    unsigned int num_sched_list)
127{
128	WARN_ON(!num_sched_list || !sched_list);
129
130	entity->sched_list = sched_list;
131	entity->num_sched_list = num_sched_list;
132}
133EXPORT_SYMBOL(drm_sched_entity_modify_sched);
134
135static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
136{
137	rmb(); /* for list_empty to work without lock */
138
139	if (list_empty(&entity->list) ||
140	    spsc_queue_count(&entity->job_queue) == 0 ||
141	    entity->stopped)
142		return true;
143
144	return false;
145}
146
147/* Return true if entity could provide a job. */
148bool drm_sched_entity_is_ready(struct drm_sched_entity *entity)
149{
150	if (spsc_queue_peek(&entity->job_queue) == NULL)
151		return false;
152
153	if (READ_ONCE(entity->dependency))
154		return false;
155
156	return true;
157}
158
159/**
160 * drm_sched_entity_error - return error of last scheduled job
161 * @entity: scheduler entity to check
162 *
163 * Opportunistically return the error of the last scheduled job. Result can
164 * change any time when new jobs are pushed to the hw.
165 */
166int drm_sched_entity_error(struct drm_sched_entity *entity)
167{
168	struct dma_fence *fence;
169	int r;
170
171	rcu_read_lock();
172	fence = rcu_dereference(entity->last_scheduled);
173	r = fence ? fence->error : 0;
174	rcu_read_unlock();
175
176	return r;
177}
178EXPORT_SYMBOL(drm_sched_entity_error);
179
180static void drm_sched_entity_kill_jobs_work(struct work_struct *wrk)
181{
182	struct drm_sched_job *job = container_of(wrk, typeof(*job), work);
183
184	drm_sched_fence_finished(job->s_fence, -ESRCH);
185	WARN_ON(job->s_fence->parent);
186	job->sched->ops->free_job(job);
187}
188
189/* Signal the scheduler finished fence when the entity in question is killed. */
190static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
191					  struct dma_fence_cb *cb)
192{
193	struct drm_sched_job *job = container_of(cb, struct drm_sched_job,
194						 finish_cb);
195	unsigned long index;
196
197	dma_fence_put(f);
198
199	/* Wait for all dependencies to avoid data corruptions */
200	xa_for_each(&job->dependencies, index, f) {
201		struct drm_sched_fence *s_fence = to_drm_sched_fence(f);
202
203		if (s_fence && f == &s_fence->scheduled) {
204			/* The dependencies array had a reference on the scheduled
205			 * fence, and the finished fence refcount might have
206			 * dropped to zero. Use dma_fence_get_rcu() so we get
207			 * a NULL fence in that case.
208			 */
209			f = dma_fence_get_rcu(&s_fence->finished);
210
211			/* Now that we have a reference on the finished fence,
212			 * we can release the reference the dependencies array
213			 * had on the scheduled fence.
214			 */
215			dma_fence_put(&s_fence->scheduled);
216		}
217
218		xa_erase(&job->dependencies, index);
219		if (f && !dma_fence_add_callback(f, &job->finish_cb,
220						 drm_sched_entity_kill_jobs_cb))
221			return;
222
223		dma_fence_put(f);
224	}
225
226	INIT_WORK(&job->work, drm_sched_entity_kill_jobs_work);
227	schedule_work(&job->work);
228}
229
230/* Remove the entity from the scheduler and kill all pending jobs */
231static void drm_sched_entity_kill(struct drm_sched_entity *entity)
232{
233	struct drm_sched_job *job;
234	struct dma_fence *prev;
235
236	if (!entity->rq)
237		return;
238
239	spin_lock(&entity->rq_lock);
240	entity->stopped = true;
241	drm_sched_rq_remove_entity(entity->rq, entity);
242	spin_unlock(&entity->rq_lock);
243
244	/* Make sure this entity is not used by the scheduler at the moment */
245	wait_for_completion(&entity->entity_idle);
246
247	/* The entity is guaranteed to not be used by the scheduler */
248	prev = rcu_dereference_check(entity->last_scheduled, true);
249	dma_fence_get(prev);
250	while ((job = to_drm_sched_job(spsc_queue_pop(&entity->job_queue)))) {
251		struct drm_sched_fence *s_fence = job->s_fence;
252
253		dma_fence_get(&s_fence->finished);
254		if (!prev || dma_fence_add_callback(prev, &job->finish_cb,
255					   drm_sched_entity_kill_jobs_cb))
256			drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb);
257
258		prev = &s_fence->finished;
259	}
260	dma_fence_put(prev);
261}
262
263/**
264 * drm_sched_entity_flush - Flush a context entity
265 *
266 * @entity: scheduler entity
267 * @timeout: time to wait in for Q to become empty in jiffies.
268 *
269 * Splitting drm_sched_entity_fini() into two functions, The first one does the
270 * waiting, removes the entity from the runqueue and returns an error when the
271 * process was killed.
272 *
273 * Returns the remaining time in jiffies left from the input timeout
274 */
275long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
276{
277	struct drm_gpu_scheduler *sched;
278	struct task_struct *last_user;
279	long ret = timeout;
280
281	if (!entity->rq)
282		return 0;
283
284	sched = entity->rq->sched;
285	/**
286	 * The client will not queue more IBs during this fini, consume existing
287	 * queued IBs or discard them on SIGKILL
288	 */
289	if (current->flags & PF_EXITING) {
290		if (timeout)
291			ret = wait_event_timeout(
292					sched->job_scheduled,
293					drm_sched_entity_is_idle(entity),
294					timeout);
295	} else {
296		wait_event_killable(sched->job_scheduled,
297				    drm_sched_entity_is_idle(entity));
298	}
299
300	/* For killed process disable any more IBs enqueue right now */
301	last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);
302	if ((!last_user || last_user == current->group_leader) &&
303	    (current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
304		drm_sched_entity_kill(entity);
305
306	return ret;
307}
308EXPORT_SYMBOL(drm_sched_entity_flush);
309
310/**
311 * drm_sched_entity_fini - Destroy a context entity
312 *
313 * @entity: scheduler entity
314 *
315 * Cleanups up @entity which has been initialized by drm_sched_entity_init().
316 *
317 * If there are potentially job still in flight or getting newly queued
318 * drm_sched_entity_flush() must be called first. This function then goes over
319 * the entity and signals all jobs with an error code if the process was killed.
320 */
321void drm_sched_entity_fini(struct drm_sched_entity *entity)
322{
323	/*
324	 * If consumption of existing IBs wasn't completed. Forcefully remove
325	 * them here. Also makes sure that the scheduler won't touch this entity
326	 * any more.
327	 */
328	drm_sched_entity_kill(entity);
329
330	if (entity->dependency) {
331		dma_fence_remove_callback(entity->dependency, &entity->cb);
332		dma_fence_put(entity->dependency);
333		entity->dependency = NULL;
334	}
335
336	dma_fence_put(rcu_dereference_check(entity->last_scheduled, true));
337	RCU_INIT_POINTER(entity->last_scheduled, NULL);
338}
339EXPORT_SYMBOL(drm_sched_entity_fini);
340
341/**
342 * drm_sched_entity_destroy - Destroy a context entity
343 * @entity: scheduler entity
344 *
345 * Calls drm_sched_entity_flush() and drm_sched_entity_fini() as a
346 * convenience wrapper.
347 */
348void drm_sched_entity_destroy(struct drm_sched_entity *entity)
349{
350	drm_sched_entity_flush(entity, MAX_WAIT_SCHED_ENTITY_Q_EMPTY);
351	drm_sched_entity_fini(entity);
352}
353EXPORT_SYMBOL(drm_sched_entity_destroy);
354
355/* drm_sched_entity_clear_dep - callback to clear the entities dependency */
356static void drm_sched_entity_clear_dep(struct dma_fence *f,
357				       struct dma_fence_cb *cb)
358{
359	struct drm_sched_entity *entity =
360		container_of(cb, struct drm_sched_entity, cb);
361
362	entity->dependency = NULL;
363	dma_fence_put(f);
364}
365
366/*
367 * drm_sched_entity_clear_dep - callback to clear the entities dependency and
368 * wake up scheduler
369 */
370static void drm_sched_entity_wakeup(struct dma_fence *f,
371				    struct dma_fence_cb *cb)
372{
373	struct drm_sched_entity *entity =
374		container_of(cb, struct drm_sched_entity, cb);
375
376	drm_sched_entity_clear_dep(f, cb);
377	drm_sched_wakeup(entity->rq->sched, entity);
378}
379
380/**
381 * drm_sched_entity_set_priority - Sets priority of the entity
382 *
383 * @entity: scheduler entity
384 * @priority: scheduler priority
385 *
386 * Update the priority of runqueus used for the entity.
387 */
388void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
389				   enum drm_sched_priority priority)
390{
391	spin_lock(&entity->rq_lock);
392	entity->priority = priority;
393	spin_unlock(&entity->rq_lock);
394}
395EXPORT_SYMBOL(drm_sched_entity_set_priority);
396
397/*
398 * Add a callback to the current dependency of the entity to wake up the
399 * scheduler when the entity becomes available.
400 */
401static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
402{
403	struct drm_gpu_scheduler *sched = entity->rq->sched;
404	struct dma_fence *fence = entity->dependency;
405	struct drm_sched_fence *s_fence;
406
407	if (fence->context == entity->fence_context ||
408	    fence->context == entity->fence_context + 1) {
409		/*
410		 * Fence is a scheduled/finished fence from a job
411		 * which belongs to the same entity, we can ignore
412		 * fences from ourself
413		 */
414		dma_fence_put(entity->dependency);
415		return false;
416	}
417
418	s_fence = to_drm_sched_fence(fence);
419	if (!fence->error && s_fence && s_fence->sched == sched &&
420	    !test_bit(DRM_SCHED_FENCE_DONT_PIPELINE, &fence->flags)) {
421
422		/*
423		 * Fence is from the same scheduler, only need to wait for
424		 * it to be scheduled
425		 */
426		fence = dma_fence_get(&s_fence->scheduled);
427		dma_fence_put(entity->dependency);
428		entity->dependency = fence;
429		if (!dma_fence_add_callback(fence, &entity->cb,
430					    drm_sched_entity_clear_dep))
431			return true;
432
433		/* Ignore it when it is already scheduled */
434		dma_fence_put(fence);
435		return false;
436	}
437
438	if (!dma_fence_add_callback(entity->dependency, &entity->cb,
439				    drm_sched_entity_wakeup))
440		return true;
441
442	dma_fence_put(entity->dependency);
443	return false;
444}
445
446static struct dma_fence *
447drm_sched_job_dependency(struct drm_sched_job *job,
448			 struct drm_sched_entity *entity)
449{
450	struct dma_fence *f;
451
452	/* We keep the fence around, so we can iterate over all dependencies
453	 * in drm_sched_entity_kill_jobs_cb() to ensure all deps are signaled
454	 * before killing the job.
455	 */
456	f = xa_load(&job->dependencies, job->last_dependency);
457	if (f) {
458		job->last_dependency++;
459		return dma_fence_get(f);
460	}
461
462	if (job->sched->ops->prepare_job)
463		return job->sched->ops->prepare_job(job, entity);
464
465	return NULL;
466}
467
468struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
469{
470	struct drm_sched_job *sched_job;
471
472	sched_job = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
473	if (!sched_job)
474		return NULL;
475
476	while ((entity->dependency =
477			drm_sched_job_dependency(sched_job, entity))) {
478		trace_drm_sched_job_wait_dep(sched_job, entity->dependency);
479
480		if (drm_sched_entity_add_dependency_cb(entity))
481			return NULL;
482	}
483
484	/* skip jobs from entity that marked guilty */
485	if (entity->guilty && atomic_read(entity->guilty))
486		dma_fence_set_error(&sched_job->s_fence->finished, -ECANCELED);
487
488	dma_fence_put(rcu_dereference_check(entity->last_scheduled, true));
489	rcu_assign_pointer(entity->last_scheduled,
490			   dma_fence_get(&sched_job->s_fence->finished));
491
492	/*
493	 * If the queue is empty we allow drm_sched_entity_select_rq() to
494	 * locklessly access ->last_scheduled. This only works if we set the
495	 * pointer before we dequeue and if we a write barrier here.
496	 */
497	smp_wmb();
498
499	spsc_queue_pop(&entity->job_queue);
500
501	/*
502	 * Update the entity's location in the min heap according to
503	 * the timestamp of the next job, if any.
504	 */
505	if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) {
506		struct drm_sched_job *next;
507
508		next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
509		if (next)
510			drm_sched_rq_update_fifo(entity, next->submit_ts);
511	}
512
513	/* Jobs and entities might have different lifecycles. Since we're
514	 * removing the job from the entities queue, set the jobs entity pointer
515	 * to NULL to prevent any future access of the entity through this job.
516	 */
517	sched_job->entity = NULL;
518
519	return sched_job;
520}
521
522void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
523{
524	struct dma_fence *fence;
525	struct drm_gpu_scheduler *sched;
526	struct drm_sched_rq *rq;
527
528	/* single possible engine and already selected */
529	if (!entity->sched_list)
530		return;
531
532	/* queue non-empty, stay on the same engine */
533	if (spsc_queue_count(&entity->job_queue))
534		return;
535
536	/*
537	 * Only when the queue is empty are we guaranteed that the scheduler
538	 * thread cannot change ->last_scheduled. To enforce ordering we need
539	 * a read barrier here. See drm_sched_entity_pop_job() for the other
540	 * side.
541	 */
542	smp_rmb();
543
544	fence = rcu_dereference_check(entity->last_scheduled, true);
545
546	/* stay on the same engine if the previous job hasn't finished */
547	if (fence && !dma_fence_is_signaled(fence))
548		return;
549
550	spin_lock(&entity->rq_lock);
551	sched = drm_sched_pick_best(entity->sched_list, entity->num_sched_list);
552	rq = sched ? sched->sched_rq[entity->priority] : NULL;
553	if (rq != entity->rq) {
554		drm_sched_rq_remove_entity(entity->rq, entity);
555		entity->rq = rq;
556	}
557	spin_unlock(&entity->rq_lock);
558
559	if (entity->num_sched_list == 1)
560		entity->sched_list = NULL;
561}
562
563/**
564 * drm_sched_entity_push_job - Submit a job to the entity's job queue
565 * @sched_job: job to submit
566 *
567 * Note: To guarantee that the order of insertion to queue matches the job's
568 * fence sequence number this function should be called with drm_sched_job_arm()
569 * under common lock for the struct drm_sched_entity that was set up for
570 * @sched_job in drm_sched_job_init().
571 *
572 * Returns 0 for success, negative error code otherwise.
573 */
574void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
575{
576	struct drm_sched_entity *entity = sched_job->entity;
577	bool first;
578	ktime_t submit_ts;
579
580	trace_drm_sched_job(sched_job, entity);
581	atomic_inc(entity->rq->sched->score);
582	WRITE_ONCE(entity->last_user, current->group_leader);
583
584	/*
585	 * After the sched_job is pushed into the entity queue, it may be
586	 * completed and freed up at any time. We can no longer access it.
587	 * Make sure to set the submit_ts first, to avoid a race.
588	 */
589	sched_job->submit_ts = submit_ts = ktime_get();
590	first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
591
592	/* first job wakes up scheduler */
593	if (first) {
594		/* Add the entity to the run queue */
595		spin_lock(&entity->rq_lock);
596		if (entity->stopped) {
597			spin_unlock(&entity->rq_lock);
598
599			DRM_ERROR("Trying to push to a killed entity\n");
600			return;
601		}
602
603		drm_sched_rq_add_entity(entity->rq, entity);
604		spin_unlock(&entity->rq_lock);
605
606		if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
607			drm_sched_rq_update_fifo(entity, submit_ts);
608
609		drm_sched_wakeup(entity->rq->sched, entity);
610	}
611}
612EXPORT_SYMBOL(drm_sched_entity_push_job);