1/*
   2 * Copyright © 2008-2015 Intel Corporation
   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 (including the next
  12 * paragraph) shall be included in all copies or substantial portions of the
  13 * Software.
  14 *
  15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21 * IN THE SOFTWARE.
  22 *
  23 */
  24
  25#include <linux/dma-fence-array.h>
  26#include <linux/dma-fence-chain.h>
  27#include <linux/irq_work.h>
  28#include <linux/prefetch.h>
  29#include <linux/sched.h>
  30#include <linux/sched/clock.h>
  31#include <linux/sched/signal.h>
  32
  33#include "gem/i915_gem_context.h"
  34#include "gt/intel_breadcrumbs.h"
  35#include "gt/intel_context.h"
  36#include "gt/intel_engine.h"
  37#include "gt/intel_engine_heartbeat.h"
  38#include "gt/intel_gpu_commands.h"
  39#include "gt/intel_reset.h"
  40#include "gt/intel_ring.h"
  41#include "gt/intel_rps.h"
  42
  43#include "i915_active.h"
  44#include "i915_drv.h"
  45#include "i915_globals.h"
  46#include "i915_trace.h"
  47#include "intel_pm.h"
  48
  49struct execute_cb {
  50	struct irq_work work;
  51	struct i915_sw_fence *fence;
  52	void (*hook)(struct i915_request *rq, struct dma_fence *signal);
  53	struct i915_request *signal;
  54};
  55
  56static struct i915_global_request {
  57	struct i915_global base;
  58	struct kmem_cache *slab_requests;
  59	struct kmem_cache *slab_execute_cbs;
  60} global;
  61
  62static const char *i915_fence_get_driver_name(struct dma_fence *fence)
  63{
  64	return dev_name(to_request(fence)->engine->i915->drm.dev);
  65}
  66
  67static const char *i915_fence_get_timeline_name(struct dma_fence *fence)
  68{
  69	const struct i915_gem_context *ctx;
  70
  71	/*
  72	 * The timeline struct (as part of the ppgtt underneath a context)
  73	 * may be freed when the request is no longer in use by the GPU.
  74	 * We could extend the life of a context to beyond that of all
  75	 * fences, possibly keeping the hw resource around indefinitely,
  76	 * or we just give them a false name. Since
  77	 * dma_fence_ops.get_timeline_name is a debug feature, the occasional
  78	 * lie seems justifiable.
  79	 */
  80	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
  81		return "signaled";
  82
  83	ctx = i915_request_gem_context(to_request(fence));
  84	if (!ctx)
  85		return "[" DRIVER_NAME "]";
  86
  87	return ctx->name;
  88}
  89
  90static bool i915_fence_signaled(struct dma_fence *fence)
  91{
  92	return i915_request_completed(to_request(fence));
  93}
  94
  95static bool i915_fence_enable_signaling(struct dma_fence *fence)
  96{
  97	return i915_request_enable_breadcrumb(to_request(fence));
  98}
  99
 100static signed long i915_fence_wait(struct dma_fence *fence,
 101				   bool interruptible,
 102				   signed long timeout)
 103{
 104	return i915_request_wait(to_request(fence),
 105				 interruptible | I915_WAIT_PRIORITY,
 106				 timeout);
 107}
 108
 109struct kmem_cache *i915_request_slab_cache(void)
 110{
 111	return global.slab_requests;
 112}
 113
 114static void i915_fence_release(struct dma_fence *fence)
 115{
 116	struct i915_request *rq = to_request(fence);
 117
 118	/*
 119	 * The request is put onto a RCU freelist (i.e. the address
 120	 * is immediately reused), mark the fences as being freed now.
 121	 * Otherwise the debugobjects for the fences are only marked as
 122	 * freed when the slab cache itself is freed, and so we would get
 123	 * caught trying to reuse dead objects.
 124	 */
 125	i915_sw_fence_fini(&rq->submit);
 126	i915_sw_fence_fini(&rq->semaphore);
 127
 128	/*
 129	 * Keep one request on each engine for reserved use under mempressure
 130	 *
 131	 * We do not hold a reference to the engine here and so have to be
 132	 * very careful in what rq->engine we poke. The virtual engine is
 133	 * referenced via the rq->context and we released that ref during
 134	 * i915_request_retire(), ergo we must not dereference a virtual
 135	 * engine here. Not that we would want to, as the only consumer of
 136	 * the reserved engine->request_pool is the power management parking,
 137	 * which must-not-fail, and that is only run on the physical engines.
 138	 *
 139	 * Since the request must have been executed to be have completed,
 140	 * we know that it will have been processed by the HW and will
 141	 * not be unsubmitted again, so rq->engine and rq->execution_mask
 142	 * at this point is stable. rq->execution_mask will be a single
 143	 * bit if the last and _only_ engine it could execution on was a
 144	 * physical engine, if it's multiple bits then it started on and
 145	 * could still be on a virtual engine. Thus if the mask is not a
 146	 * power-of-two we assume that rq->engine may still be a virtual
 147	 * engine and so a dangling invalid pointer that we cannot dereference
 148	 *
 149	 * For example, consider the flow of a bonded request through a virtual
 150	 * engine. The request is created with a wide engine mask (all engines
 151	 * that we might execute on). On processing the bond, the request mask
 152	 * is reduced to one or more engines. If the request is subsequently
 153	 * bound to a single engine, it will then be constrained to only
 154	 * execute on that engine and never returned to the virtual engine
 155	 * after timeslicing away, see __unwind_incomplete_requests(). Thus we
 156	 * know that if the rq->execution_mask is a single bit, rq->engine
 157	 * can be a physical engine with the exact corresponding mask.
 158	 */
 159	if (is_power_of_2(rq->execution_mask) &&
 160	    !cmpxchg(&rq->engine->request_pool, NULL, rq))
 161		return;
 162
 163	kmem_cache_free(global.slab_requests, rq);
 164}
 165
 166const struct dma_fence_ops i915_fence_ops = {
 167	.get_driver_name = i915_fence_get_driver_name,
 168	.get_timeline_name = i915_fence_get_timeline_name,
 169	.enable_signaling = i915_fence_enable_signaling,
 170	.signaled = i915_fence_signaled,
 171	.wait = i915_fence_wait,
 172	.release = i915_fence_release,
 173};
 174
 175static void irq_execute_cb(struct irq_work *wrk)
 176{
 177	struct execute_cb *cb = container_of(wrk, typeof(*cb), work);
 178
 179	i915_sw_fence_complete(cb->fence);
 180	kmem_cache_free(global.slab_execute_cbs, cb);
 181}
 182
 183static void irq_execute_cb_hook(struct irq_work *wrk)
 184{
 185	struct execute_cb *cb = container_of(wrk, typeof(*cb), work);
 186
 187	cb->hook(container_of(cb->fence, struct i915_request, submit),
 188		 &cb->signal->fence);
 189	i915_request_put(cb->signal);
 190
 191	irq_execute_cb(wrk);
 192}
 193
 194static __always_inline void
 195__notify_execute_cb(struct i915_request *rq, bool (*fn)(struct irq_work *wrk))
 196{
 197	struct execute_cb *cb, *cn;
 198
 
 
 
 199	if (llist_empty(&rq->execute_cb))
 200		return;
 201
 202	llist_for_each_entry_safe(cb, cn,
 203				  llist_del_all(&rq->execute_cb),
 204				  work.node.llist)
 205		fn(&cb->work);
 206}
 207
 208static void __notify_execute_cb_irq(struct i915_request *rq)
 209{
 210	__notify_execute_cb(rq, irq_work_queue);
 
 
 
 
 
 
 
 
 211}
 212
 213static bool irq_work_imm(struct irq_work *wrk)
 
 214{
 215	wrk->func(wrk);
 216	return false;
 217}
 218
 219static void __notify_execute_cb_imm(struct i915_request *rq)
 220{
 221	__notify_execute_cb(rq, irq_work_imm);
 
 
 
 
 
 
 
 
 222}
 223
 224static void free_capture_list(struct i915_request *request)
 225{
 226	struct i915_capture_list *capture;
 227
 228	capture = fetch_and_zero(&request->capture_list);
 229	while (capture) {
 230		struct i915_capture_list *next = capture->next;
 231
 232		kfree(capture);
 233		capture = next;
 234	}
 235}
 236
 237static void __i915_request_fill(struct i915_request *rq, u8 val)
 238{
 239	void *vaddr = rq->ring->vaddr;
 240	u32 head;
 241
 242	head = rq->infix;
 243	if (rq->postfix < head) {
 244		memset(vaddr + head, val, rq->ring->size - head);
 245		head = 0;
 246	}
 247	memset(vaddr + head, val, rq->postfix - head);
 248}
 249
 250/**
 251 * i915_request_active_engine
 252 * @rq: request to inspect
 253 * @active: pointer in which to return the active engine
 254 *
 255 * Fills the currently active engine to the @active pointer if the request
 256 * is active and still not completed.
 257 *
 258 * Returns true if request was active or false otherwise.
 259 */
 260bool
 261i915_request_active_engine(struct i915_request *rq,
 262			   struct intel_engine_cs **active)
 263{
 264	struct intel_engine_cs *engine, *locked;
 265	bool ret = false;
 266
 267	/*
 268	 * Serialise with __i915_request_submit() so that it sees
 269	 * is-banned?, or we know the request is already inflight.
 270	 *
 271	 * Note that rq->engine is unstable, and so we double
 272	 * check that we have acquired the lock on the final engine.
 273	 */
 274	locked = READ_ONCE(rq->engine);
 275	spin_lock_irq(&locked->active.lock);
 276	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
 277		spin_unlock(&locked->active.lock);
 278		locked = engine;
 279		spin_lock(&locked->active.lock);
 280	}
 281
 282	if (i915_request_is_active(rq)) {
 283		if (!__i915_request_is_complete(rq))
 284			*active = locked;
 285		ret = true;
 286	}
 287
 288	spin_unlock_irq(&locked->active.lock);
 289
 290	return ret;
 291}
 292
 293
 294static void remove_from_engine(struct i915_request *rq)
 295{
 296	struct intel_engine_cs *engine, *locked;
 297
 298	/*
 299	 * Virtual engines complicate acquiring the engine timeline lock,
 300	 * as their rq->engine pointer is not stable until under that
 301	 * engine lock. The simple ploy we use is to take the lock then
 302	 * check that the rq still belongs to the newly locked engine.
 303	 */
 304	locked = READ_ONCE(rq->engine);
 305	spin_lock_irq(&locked->active.lock);
 306	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
 307		spin_unlock(&locked->active.lock);
 308		spin_lock(&engine->active.lock);
 309		locked = engine;
 310	}
 311	list_del_init(&rq->sched.link);
 312
 313	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
 314	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
 315
 316	/* Prevent further __await_execution() registering a cb, then flush */
 317	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
 318
 319	spin_unlock_irq(&locked->active.lock);
 320
 321	__notify_execute_cb_imm(rq);
 322}
 323
 324static void __rq_init_watchdog(struct i915_request *rq)
 325{
 326	rq->watchdog.timer.function = NULL;
 327}
 328
 329static enum hrtimer_restart __rq_watchdog_expired(struct hrtimer *hrtimer)
 330{
 331	struct i915_request *rq =
 332		container_of(hrtimer, struct i915_request, watchdog.timer);
 333	struct intel_gt *gt = rq->engine->gt;
 334
 335	if (!i915_request_completed(rq)) {
 336		if (llist_add(&rq->watchdog.link, &gt->watchdog.list))
 337			schedule_work(&gt->watchdog.work);
 338	} else {
 339		i915_request_put(rq);
 340	}
 341
 342	return HRTIMER_NORESTART;
 343}
 344
 345static void __rq_arm_watchdog(struct i915_request *rq)
 346{
 347	struct i915_request_watchdog *wdg = &rq->watchdog;
 348	struct intel_context *ce = rq->context;
 349
 350	if (!ce->watchdog.timeout_us)
 351		return;
 352
 353	i915_request_get(rq);
 354
 355	hrtimer_init(&wdg->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 356	wdg->timer.function = __rq_watchdog_expired;
 357	hrtimer_start_range_ns(&wdg->timer,
 358			       ns_to_ktime(ce->watchdog.timeout_us *
 359					   NSEC_PER_USEC),
 360			       NSEC_PER_MSEC,
 361			       HRTIMER_MODE_REL);
 362}
 363
 364static void __rq_cancel_watchdog(struct i915_request *rq)
 365{
 366	struct i915_request_watchdog *wdg = &rq->watchdog;
 367
 368	if (wdg->timer.function && hrtimer_try_to_cancel(&wdg->timer) > 0)
 369		i915_request_put(rq);
 370}
 371
 372bool i915_request_retire(struct i915_request *rq)
 373{
 374	if (!__i915_request_is_complete(rq))
 375		return false;
 376
 377	RQ_TRACE(rq, "\n");
 378
 379	GEM_BUG_ON(!i915_sw_fence_signaled(&rq->submit));
 380	trace_i915_request_retire(rq);
 381	i915_request_mark_complete(rq);
 382
 383	__rq_cancel_watchdog(rq);
 384
 385	/*
 386	 * We know the GPU must have read the request to have
 387	 * sent us the seqno + interrupt, so use the position
 388	 * of tail of the request to update the last known position
 389	 * of the GPU head.
 390	 *
 391	 * Note this requires that we are always called in request
 392	 * completion order.
 393	 */
 394	GEM_BUG_ON(!list_is_first(&rq->link,
 395				  &i915_request_timeline(rq)->requests));
 396	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
 397		/* Poison before we release our space in the ring */
 398		__i915_request_fill(rq, POISON_FREE);
 399	rq->ring->head = rq->postfix;
 400
 401	if (!i915_request_signaled(rq)) {
 402		spin_lock_irq(&rq->lock);
 403		dma_fence_signal_locked(&rq->fence);
 404		spin_unlock_irq(&rq->lock);
 405	}
 406
 407	if (test_and_set_bit(I915_FENCE_FLAG_BOOST, &rq->fence.flags))
 408		atomic_dec(&rq->engine->gt->rps.num_waiters);
 409
 410	/*
 411	 * We only loosely track inflight requests across preemption,
 412	 * and so we may find ourselves attempting to retire a _completed_
 413	 * request that we have removed from the HW and put back on a run
 414	 * queue.
 415	 *
 416	 * As we set I915_FENCE_FLAG_ACTIVE on the request, this should be
 417	 * after removing the breadcrumb and signaling it, so that we do not
 418	 * inadvertently attach the breadcrumb to a completed request.
 419	 */
 420	if (!list_empty(&rq->sched.link))
 421		remove_from_engine(rq);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 422	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
 
 423
 
 424	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
 425
 426	intel_context_exit(rq->context);
 427	intel_context_unpin(rq->context);
 428
 429	free_capture_list(rq);
 430	i915_sched_node_fini(&rq->sched);
 431	i915_request_put(rq);
 432
 433	return true;
 434}
 435
 436void i915_request_retire_upto(struct i915_request *rq)
 437{
 438	struct intel_timeline * const tl = i915_request_timeline(rq);
 439	struct i915_request *tmp;
 440
 441	RQ_TRACE(rq, "\n");
 442	GEM_BUG_ON(!__i915_request_is_complete(rq));
 
 443
 444	do {
 445		tmp = list_first_entry(&tl->requests, typeof(*tmp), link);
 446	} while (i915_request_retire(tmp) && tmp != rq);
 447}
 448
 
 
 
 
 
 
 449static struct i915_request * const *
 450__engine_active(struct intel_engine_cs *engine)
 451{
 452	return READ_ONCE(engine->execlists.active);
 453}
 454
 455static bool __request_in_flight(const struct i915_request *signal)
 456{
 457	struct i915_request * const *port, *rq;
 458	bool inflight = false;
 459
 460	if (!i915_request_is_ready(signal))
 461		return false;
 462
 463	/*
 464	 * Even if we have unwound the request, it may still be on
 465	 * the GPU (preempt-to-busy). If that request is inside an
 466	 * unpreemptible critical section, it will not be removed. Some
 467	 * GPU functions may even be stuck waiting for the paired request
 468	 * (__await_execution) to be submitted and cannot be preempted
 469	 * until the bond is executing.
 470	 *
 471	 * As we know that there are always preemption points between
 472	 * requests, we know that only the currently executing request
 473	 * may be still active even though we have cleared the flag.
 474	 * However, we can't rely on our tracking of ELSP[0] to know
 475	 * which request is currently active and so maybe stuck, as
 476	 * the tracking maybe an event behind. Instead assume that
 477	 * if the context is still inflight, then it is still active
 478	 * even if the active flag has been cleared.
 479	 *
 480	 * To further complicate matters, if there a pending promotion, the HW
 481	 * may either perform a context switch to the second inflight execlists,
 482	 * or it may switch to the pending set of execlists. In the case of the
 483	 * latter, it may send the ACK and we process the event copying the
 484	 * pending[] over top of inflight[], _overwriting_ our *active. Since
 485	 * this implies the HW is arbitrating and not struck in *active, we do
 486	 * not worry about complete accuracy, but we do require no read/write
 487	 * tearing of the pointer [the read of the pointer must be valid, even
 488	 * as the array is being overwritten, for which we require the writes
 489	 * to avoid tearing.]
 490	 *
 491	 * Note that the read of *execlists->active may race with the promotion
 492	 * of execlists->pending[] to execlists->inflight[], overwritting
 493	 * the value at *execlists->active. This is fine. The promotion implies
 494	 * that we received an ACK from the HW, and so the context is not
 495	 * stuck -- if we do not see ourselves in *active, the inflight status
 496	 * is valid. If instead we see ourselves being copied into *active,
 497	 * we are inflight and may signal the callback.
 498	 */
 499	if (!intel_context_inflight(signal->context))
 500		return false;
 501
 502	rcu_read_lock();
 503	for (port = __engine_active(signal->engine);
 504	     (rq = READ_ONCE(*port)); /* may race with promotion of pending[] */
 505	     port++) {
 506		if (rq->context == signal->context) {
 507			inflight = i915_seqno_passed(rq->fence.seqno,
 508						     signal->fence.seqno);
 509			break;
 510		}
 511	}
 512	rcu_read_unlock();
 513
 514	return inflight;
 515}
 516
 517static int
 518__await_execution(struct i915_request *rq,
 519		  struct i915_request *signal,
 520		  void (*hook)(struct i915_request *rq,
 521			       struct dma_fence *signal),
 522		  gfp_t gfp)
 523{
 524	struct execute_cb *cb;
 525
 526	if (i915_request_is_active(signal)) {
 527		if (hook)
 528			hook(rq, &signal->fence);
 529		return 0;
 530	}
 531
 532	cb = kmem_cache_alloc(global.slab_execute_cbs, gfp);
 533	if (!cb)
 534		return -ENOMEM;
 535
 536	cb->fence = &rq->submit;
 537	i915_sw_fence_await(cb->fence);
 538	init_irq_work(&cb->work, irq_execute_cb);
 539
 540	if (hook) {
 541		cb->hook = hook;
 542		cb->signal = i915_request_get(signal);
 543		cb->work.func = irq_execute_cb_hook;
 544	}
 545
 546	/*
 547	 * Register the callback first, then see if the signaler is already
 548	 * active. This ensures that if we race with the
 549	 * __notify_execute_cb from i915_request_submit() and we are not
 550	 * included in that list, we get a second bite of the cherry and
 551	 * execute it ourselves. After this point, a future
 552	 * i915_request_submit() will notify us.
 553	 *
 554	 * In i915_request_retire() we set the ACTIVE bit on a completed
 555	 * request (then flush the execute_cb). So by registering the
 556	 * callback first, then checking the ACTIVE bit, we serialise with
 557	 * the completed/retired request.
 558	 */
 559	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
 560		if (i915_request_is_active(signal) ||
 561		    __request_in_flight(signal))
 562			__notify_execute_cb_imm(signal);
 563	}
 
 564
 565	return 0;
 566}
 567
 568static bool fatal_error(int error)
 569{
 570	switch (error) {
 571	case 0: /* not an error! */
 572	case -EAGAIN: /* innocent victim of a GT reset (__i915_request_reset) */
 573	case -ETIMEDOUT: /* waiting for Godot (timer_i915_sw_fence_wake) */
 574		return false;
 575	default:
 576		return true;
 577	}
 578}
 579
 580void __i915_request_skip(struct i915_request *rq)
 581{
 582	GEM_BUG_ON(!fatal_error(rq->fence.error));
 583
 584	if (rq->infix == rq->postfix)
 585		return;
 586
 587	RQ_TRACE(rq, "error: %d\n", rq->fence.error);
 588
 589	/*
 590	 * As this request likely depends on state from the lost
 591	 * context, clear out all the user operations leaving the
 592	 * breadcrumb at the end (so we get the fence notifications).
 593	 */
 594	__i915_request_fill(rq, 0);
 595	rq->infix = rq->postfix;
 596}
 597
 598bool i915_request_set_error_once(struct i915_request *rq, int error)
 599{
 600	int old;
 601
 602	GEM_BUG_ON(!IS_ERR_VALUE((long)error));
 603
 604	if (i915_request_signaled(rq))
 605		return false;
 606
 607	old = READ_ONCE(rq->fence.error);
 608	do {
 609		if (fatal_error(old))
 610			return false;
 611	} while (!try_cmpxchg(&rq->fence.error, &old, error));
 612
 613	return true;
 614}
 615
 616struct i915_request *i915_request_mark_eio(struct i915_request *rq)
 617{
 618	if (__i915_request_is_complete(rq))
 619		return NULL;
 620
 621	GEM_BUG_ON(i915_request_signaled(rq));
 622
 623	/* As soon as the request is completed, it may be retired */
 624	rq = i915_request_get(rq);
 625
 626	i915_request_set_error_once(rq, -EIO);
 627	i915_request_mark_complete(rq);
 628
 629	return rq;
 630}
 631
 632bool __i915_request_submit(struct i915_request *request)
 633{
 634	struct intel_engine_cs *engine = request->engine;
 635	bool result = false;
 636
 637	RQ_TRACE(request, "\n");
 638
 639	GEM_BUG_ON(!irqs_disabled());
 640	lockdep_assert_held(&engine->active.lock);
 641
 642	/*
 643	 * With the advent of preempt-to-busy, we frequently encounter
 644	 * requests that we have unsubmitted from HW, but left running
 645	 * until the next ack and so have completed in the meantime. On
 646	 * resubmission of that completed request, we can skip
 647	 * updating the payload, and execlists can even skip submitting
 648	 * the request.
 649	 *
 650	 * We must remove the request from the caller's priority queue,
 651	 * and the caller must only call us when the request is in their
 652	 * priority queue, under the active.lock. This ensures that the
 653	 * request has *not* yet been retired and we can safely move
 654	 * the request into the engine->active.list where it will be
 655	 * dropped upon retiring. (Otherwise if resubmit a *retired*
 656	 * request, this would be a horrible use-after-free.)
 657	 */
 658	if (__i915_request_is_complete(request)) {
 659		list_del_init(&request->sched.link);
 660		goto active;
 661	}
 662
 663	if (unlikely(intel_context_is_banned(request->context)))
 664		i915_request_set_error_once(request, -EIO);
 665
 666	if (unlikely(fatal_error(request->fence.error)))
 667		__i915_request_skip(request);
 668
 669	/*
 670	 * Are we using semaphores when the gpu is already saturated?
 671	 *
 672	 * Using semaphores incurs a cost in having the GPU poll a
 673	 * memory location, busywaiting for it to change. The continual
 674	 * memory reads can have a noticeable impact on the rest of the
 675	 * system with the extra bus traffic, stalling the cpu as it too
 676	 * tries to access memory across the bus (perf stat -e bus-cycles).
 677	 *
 678	 * If we installed a semaphore on this request and we only submit
 679	 * the request after the signaler completed, that indicates the
 680	 * system is overloaded and using semaphores at this time only
 681	 * increases the amount of work we are doing. If so, we disable
 682	 * further use of semaphores until we are idle again, whence we
 683	 * optimistically try again.
 684	 */
 685	if (request->sched.semaphores &&
 686	    i915_sw_fence_signaled(&request->semaphore))
 687		engine->saturated |= request->sched.semaphores;
 688
 689	engine->emit_fini_breadcrumb(request,
 690				     request->ring->vaddr + request->postfix);
 691
 692	trace_i915_request_execute(request);
 693	engine->serial++;
 694	result = true;
 695
 696	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
 697	list_move_tail(&request->sched.link, &engine->active.requests);
 698active:
 699	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
 700	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
 701
 702	/*
 703	 * XXX Rollback bonded-execution on __i915_request_unsubmit()?
 704	 *
 705	 * In the future, perhaps when we have an active time-slicing scheduler,
 706	 * it will be interesting to unsubmit parallel execution and remove
 707	 * busywaits from the GPU until their master is restarted. This is
 708	 * quite hairy, we have to carefully rollback the fence and do a
 709	 * preempt-to-idle cycle on the target engine, all the while the
 710	 * master execute_cb may refire.
 711	 */
 712	__notify_execute_cb_irq(request);
 713
 714	/* We may be recursing from the signal callback of another i915 fence */
 715	if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &request->fence.flags))
 716		i915_request_enable_breadcrumb(request);
 
 
 
 
 
 
 
 
 
 
 717
 718	return result;
 719}
 720
 721void i915_request_submit(struct i915_request *request)
 722{
 723	struct intel_engine_cs *engine = request->engine;
 724	unsigned long flags;
 725
 726	/* Will be called from irq-context when using foreign fences. */
 727	spin_lock_irqsave(&engine->active.lock, flags);
 728
 729	__i915_request_submit(request);
 730
 731	spin_unlock_irqrestore(&engine->active.lock, flags);
 732}
 733
 734void __i915_request_unsubmit(struct i915_request *request)
 735{
 736	struct intel_engine_cs *engine = request->engine;
 737
 738	/*
 739	 * Only unwind in reverse order, required so that the per-context list
 740	 * is kept in seqno/ring order.
 741	 */
 742	RQ_TRACE(request, "\n");
 743
 744	GEM_BUG_ON(!irqs_disabled());
 745	lockdep_assert_held(&engine->active.lock);
 746
 747	/*
 748	 * Before we remove this breadcrumb from the signal list, we have
 749	 * to ensure that a concurrent dma_fence_enable_signaling() does not
 750	 * attach itself. We first mark the request as no longer active and
 751	 * make sure that is visible to other cores, and then remove the
 752	 * breadcrumb if attached.
 753	 */
 754	GEM_BUG_ON(!test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
 755	clear_bit_unlock(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
 
 
 756	if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &request->fence.flags))
 757		i915_request_cancel_breadcrumb(request);
 758
 
 
 
 
 
 759	/* We've already spun, don't charge on resubmitting. */
 760	if (request->sched.semaphores && __i915_request_has_started(request))
 761		request->sched.semaphores = 0;
 762
 763	/*
 764	 * We don't need to wake_up any waiters on request->execute, they
 765	 * will get woken by any other event or us re-adding this request
 766	 * to the engine timeline (__i915_request_submit()). The waiters
 767	 * should be quite adapt at finding that the request now has a new
 768	 * global_seqno to the one they went to sleep on.
 769	 */
 770}
 771
 772void i915_request_unsubmit(struct i915_request *request)
 773{
 774	struct intel_engine_cs *engine = request->engine;
 775	unsigned long flags;
 776
 777	/* Will be called from irq-context when using foreign fences. */
 778	spin_lock_irqsave(&engine->active.lock, flags);
 779
 780	__i915_request_unsubmit(request);
 781
 782	spin_unlock_irqrestore(&engine->active.lock, flags);
 783}
 784
 785static void __cancel_request(struct i915_request *rq)
 786{
 787	struct intel_engine_cs *engine = NULL;
 788
 789	i915_request_active_engine(rq, &engine);
 790
 791	if (engine && intel_engine_pulse(engine))
 792		intel_gt_handle_error(engine->gt, engine->mask, 0,
 793				      "request cancellation by %s",
 794				      current->comm);
 795}
 796
 797void i915_request_cancel(struct i915_request *rq, int error)
 798{
 799	if (!i915_request_set_error_once(rq, error))
 800		return;
 801
 802	set_bit(I915_FENCE_FLAG_SENTINEL, &rq->fence.flags);
 803
 804	__cancel_request(rq);
 805}
 806
 807static int __i915_sw_fence_call
 808submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
 809{
 810	struct i915_request *request =
 811		container_of(fence, typeof(*request), submit);
 812
 813	switch (state) {
 814	case FENCE_COMPLETE:
 815		trace_i915_request_submit(request);
 816
 817		if (unlikely(fence->error))
 818			i915_request_set_error_once(request, fence->error);
 819		else
 820			__rq_arm_watchdog(request);
 821
 822		/*
 823		 * We need to serialize use of the submit_request() callback
 824		 * with its hotplugging performed during an emergency
 825		 * i915_gem_set_wedged().  We use the RCU mechanism to mark the
 826		 * critical section in order to force i915_gem_set_wedged() to
 827		 * wait until the submit_request() is completed before
 828		 * proceeding.
 829		 */
 830		rcu_read_lock();
 831		request->engine->submit_request(request);
 832		rcu_read_unlock();
 833		break;
 834
 835	case FENCE_FREE:
 836		i915_request_put(request);
 837		break;
 838	}
 839
 840	return NOTIFY_DONE;
 841}
 842
 843static int __i915_sw_fence_call
 844semaphore_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
 845{
 846	struct i915_request *rq = container_of(fence, typeof(*rq), semaphore);
 847
 848	switch (state) {
 849	case FENCE_COMPLETE:
 850		break;
 851
 852	case FENCE_FREE:
 853		i915_request_put(rq);
 854		break;
 855	}
 856
 857	return NOTIFY_DONE;
 858}
 859
 860static void retire_requests(struct intel_timeline *tl)
 861{
 862	struct i915_request *rq, *rn;
 863
 864	list_for_each_entry_safe(rq, rn, &tl->requests, link)
 865		if (!i915_request_retire(rq))
 866			break;
 867}
 868
 869static noinline struct i915_request *
 870request_alloc_slow(struct intel_timeline *tl,
 871		   struct i915_request **rsvd,
 872		   gfp_t gfp)
 873{
 874	struct i915_request *rq;
 875
 876	/* If we cannot wait, dip into our reserves */
 877	if (!gfpflags_allow_blocking(gfp)) {
 878		rq = xchg(rsvd, NULL);
 879		if (!rq) /* Use the normal failure path for one final WARN */
 880			goto out;
 881
 882		return rq;
 883	}
 884
 885	if (list_empty(&tl->requests))
 886		goto out;
 887
 888	/* Move our oldest request to the slab-cache (if not in use!) */
 889	rq = list_first_entry(&tl->requests, typeof(*rq), link);
 890	i915_request_retire(rq);
 891
 892	rq = kmem_cache_alloc(global.slab_requests,
 893			      gfp | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
 894	if (rq)
 895		return rq;
 896
 897	/* Ratelimit ourselves to prevent oom from malicious clients */
 898	rq = list_last_entry(&tl->requests, typeof(*rq), link);
 899	cond_synchronize_rcu(rq->rcustate);
 900
 901	/* Retire our old requests in the hope that we free some */
 902	retire_requests(tl);
 903
 904out:
 905	return kmem_cache_alloc(global.slab_requests, gfp);
 906}
 907
 908static void __i915_request_ctor(void *arg)
 909{
 910	struct i915_request *rq = arg;
 911
 912	spin_lock_init(&rq->lock);
 913	i915_sched_node_init(&rq->sched);
 914	i915_sw_fence_init(&rq->submit, submit_notify);
 915	i915_sw_fence_init(&rq->semaphore, semaphore_notify);
 916
 
 
 
 917	rq->capture_list = NULL;
 918
 919	init_llist_head(&rq->execute_cb);
 920}
 921
 922struct i915_request *
 923__i915_request_create(struct intel_context *ce, gfp_t gfp)
 924{
 925	struct intel_timeline *tl = ce->timeline;
 926	struct i915_request *rq;
 927	u32 seqno;
 928	int ret;
 929
 930	might_alloc(gfp);
 931
 932	/* Check that the caller provided an already pinned context */
 933	__intel_context_pin(ce);
 934
 935	/*
 936	 * Beware: Dragons be flying overhead.
 937	 *
 938	 * We use RCU to look up requests in flight. The lookups may
 939	 * race with the request being allocated from the slab freelist.
 940	 * That is the request we are writing to here, may be in the process
 941	 * of being read by __i915_active_request_get_rcu(). As such,
 942	 * we have to be very careful when overwriting the contents. During
 943	 * the RCU lookup, we change chase the request->engine pointer,
 944	 * read the request->global_seqno and increment the reference count.
 945	 *
 946	 * The reference count is incremented atomically. If it is zero,
 947	 * the lookup knows the request is unallocated and complete. Otherwise,
 948	 * it is either still in use, or has been reallocated and reset
 949	 * with dma_fence_init(). This increment is safe for release as we
 950	 * check that the request we have a reference to and matches the active
 951	 * request.
 952	 *
 953	 * Before we increment the refcount, we chase the request->engine
 954	 * pointer. We must not call kmem_cache_zalloc() or else we set
 955	 * that pointer to NULL and cause a crash during the lookup. If
 956	 * we see the request is completed (based on the value of the
 957	 * old engine and seqno), the lookup is complete and reports NULL.
 958	 * If we decide the request is not completed (new engine or seqno),
 959	 * then we grab a reference and double check that it is still the
 960	 * active request - which it won't be and restart the lookup.
 961	 *
 962	 * Do not use kmem_cache_zalloc() here!
 963	 */
 964	rq = kmem_cache_alloc(global.slab_requests,
 965			      gfp | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
 966	if (unlikely(!rq)) {
 967		rq = request_alloc_slow(tl, &ce->engine->request_pool, gfp);
 968		if (!rq) {
 969			ret = -ENOMEM;
 970			goto err_unreserve;
 971		}
 972	}
 973
 974	rq->context = ce;
 975	rq->engine = ce->engine;
 976	rq->ring = ce->ring;
 977	rq->execution_mask = ce->engine->mask;
 978
 
 
 
 
 
 979	ret = intel_timeline_get_seqno(tl, rq, &seqno);
 980	if (ret)
 981		goto err_free;
 982
 983	dma_fence_init(&rq->fence, &i915_fence_ops, &rq->lock,
 984		       tl->fence_context, seqno);
 985
 986	RCU_INIT_POINTER(rq->timeline, tl);
 
 987	rq->hwsp_seqno = tl->hwsp_seqno;
 988	GEM_BUG_ON(__i915_request_is_complete(rq));
 989
 990	rq->rcustate = get_state_synchronize_rcu(); /* acts as smp_mb() */
 991
 992	/* We bump the ref for the fence chain */
 993	i915_sw_fence_reinit(&i915_request_get(rq)->submit);
 994	i915_sw_fence_reinit(&i915_request_get(rq)->semaphore);
 995
 996	i915_sched_node_reinit(&rq->sched);
 997
 998	/* No zalloc, everything must be cleared after use */
 999	rq->batch = NULL;
1000	__rq_init_watchdog(rq);
1001	GEM_BUG_ON(rq->capture_list);
1002	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
1003
1004	/*
1005	 * Reserve space in the ring buffer for all the commands required to
1006	 * eventually emit this request. This is to guarantee that the
1007	 * i915_request_add() call can't fail. Note that the reserve may need
1008	 * to be redone if the request is not actually submitted straight
1009	 * away, e.g. because a GPU scheduler has deferred it.
1010	 *
1011	 * Note that due to how we add reserved_space to intel_ring_begin()
1012	 * we need to double our request to ensure that if we need to wrap
1013	 * around inside i915_request_add() there is sufficient space at
1014	 * the beginning of the ring as well.
1015	 */
1016	rq->reserved_space =
1017		2 * rq->engine->emit_fini_breadcrumb_dw * sizeof(u32);
1018
1019	/*
1020	 * Record the position of the start of the request so that
1021	 * should we detect the updated seqno part-way through the
1022	 * GPU processing the request, we never over-estimate the
1023	 * position of the head.
1024	 */
1025	rq->head = rq->ring->emit;
1026
1027	ret = rq->engine->request_alloc(rq);
1028	if (ret)
1029		goto err_unwind;
1030
1031	rq->infix = rq->ring->emit; /* end of header; start of user payload */
1032
1033	intel_context_mark_active(ce);
1034	list_add_tail_rcu(&rq->link, &tl->requests);
1035
1036	return rq;
1037
1038err_unwind:
1039	ce->ring->emit = rq->head;
1040
1041	/* Make sure we didn't add ourselves to external state before freeing */
1042	GEM_BUG_ON(!list_empty(&rq->sched.signalers_list));
1043	GEM_BUG_ON(!list_empty(&rq->sched.waiters_list));
1044
1045err_free:
1046	kmem_cache_free(global.slab_requests, rq);
1047err_unreserve:
1048	intel_context_unpin(ce);
1049	return ERR_PTR(ret);
1050}
1051
1052struct i915_request *
1053i915_request_create(struct intel_context *ce)
1054{
1055	struct i915_request *rq;
1056	struct intel_timeline *tl;
1057
1058	tl = intel_context_timeline_lock(ce);
1059	if (IS_ERR(tl))
1060		return ERR_CAST(tl);
1061
1062	/* Move our oldest request to the slab-cache (if not in use!) */
1063	rq = list_first_entry(&tl->requests, typeof(*rq), link);
1064	if (!list_is_last(&rq->link, &tl->requests))
1065		i915_request_retire(rq);
1066
1067	intel_context_enter(ce);
1068	rq = __i915_request_create(ce, GFP_KERNEL);
1069	intel_context_exit(ce); /* active reference transferred to request */
1070	if (IS_ERR(rq))
1071		goto err_unlock;
1072
1073	/* Check that we do not interrupt ourselves with a new request */
1074	rq->cookie = lockdep_pin_lock(&tl->mutex);
1075
1076	return rq;
1077
1078err_unlock:
1079	intel_context_timeline_unlock(tl);
1080	return rq;
1081}
1082
1083static int
1084i915_request_await_start(struct i915_request *rq, struct i915_request *signal)
1085{
1086	struct dma_fence *fence;
1087	int err;
1088
1089	if (i915_request_timeline(rq) == rcu_access_pointer(signal->timeline))
1090		return 0;
1091
1092	if (i915_request_started(signal))
1093		return 0;
1094
1095	/*
1096	 * The caller holds a reference on @signal, but we do not serialise
1097	 * against it being retired and removed from the lists.
1098	 *
1099	 * We do not hold a reference to the request before @signal, and
1100	 * so must be very careful to ensure that it is not _recycled_ as
1101	 * we follow the link backwards.
1102	 */
1103	fence = NULL;
1104	rcu_read_lock();
 
1105	do {
1106		struct list_head *pos = READ_ONCE(signal->link.prev);
1107		struct i915_request *prev;
1108
1109		/* Confirm signal has not been retired, the link is valid */
1110		if (unlikely(__i915_request_has_started(signal)))
1111			break;
1112
1113		/* Is signal the earliest request on its timeline? */
1114		if (pos == &rcu_dereference(signal->timeline)->requests)
1115			break;
1116
1117		/*
1118		 * Peek at the request before us in the timeline. That
1119		 * request will only be valid before it is retired, so
1120		 * after acquiring a reference to it, confirm that it is
1121		 * still part of the signaler's timeline.
1122		 */
1123		prev = list_entry(pos, typeof(*prev), link);
1124		if (!i915_request_get_rcu(prev))
1125			break;
1126
1127		/* After the strong barrier, confirm prev is still attached */
1128		if (unlikely(READ_ONCE(prev->link.next) != &signal->link)) {
1129			i915_request_put(prev);
1130			break;
1131		}
1132
1133		fence = &prev->fence;
1134	} while (0);
 
1135	rcu_read_unlock();
1136	if (!fence)
1137		return 0;
1138
1139	err = 0;
1140	if (!intel_timeline_sync_is_later(i915_request_timeline(rq), fence))
1141		err = i915_sw_fence_await_dma_fence(&rq->submit,
1142						    fence, 0,
1143						    I915_FENCE_GFP);
1144	dma_fence_put(fence);
1145
1146	return err;
1147}
1148
1149static intel_engine_mask_t
1150already_busywaiting(struct i915_request *rq)
1151{
1152	/*
1153	 * Polling a semaphore causes bus traffic, delaying other users of
1154	 * both the GPU and CPU. We want to limit the impact on others,
1155	 * while taking advantage of early submission to reduce GPU
1156	 * latency. Therefore we restrict ourselves to not using more
1157	 * than one semaphore from each source, and not using a semaphore
1158	 * if we have detected the engine is saturated (i.e. would not be
1159	 * submitted early and cause bus traffic reading an already passed
1160	 * semaphore).
1161	 *
1162	 * See the are-we-too-late? check in __i915_request_submit().
1163	 */
1164	return rq->sched.semaphores | READ_ONCE(rq->engine->saturated);
1165}
1166
1167static int
1168__emit_semaphore_wait(struct i915_request *to,
1169		      struct i915_request *from,
1170		      u32 seqno)
1171{
1172	const int has_token = GRAPHICS_VER(to->engine->i915) >= 12;
1173	u32 hwsp_offset;
1174	int len, err;
1175	u32 *cs;
1176
1177	GEM_BUG_ON(GRAPHICS_VER(to->engine->i915) < 8);
1178	GEM_BUG_ON(i915_request_has_initial_breadcrumb(to));
1179
1180	/* We need to pin the signaler's HWSP until we are finished reading. */
1181	err = intel_timeline_read_hwsp(from, to, &hwsp_offset);
1182	if (err)
1183		return err;
1184
1185	len = 4;
1186	if (has_token)
1187		len += 2;
1188
1189	cs = intel_ring_begin(to, len);
1190	if (IS_ERR(cs))
1191		return PTR_ERR(cs);
1192
1193	/*
1194	 * Using greater-than-or-equal here means we have to worry
1195	 * about seqno wraparound. To side step that issue, we swap
1196	 * the timeline HWSP upon wrapping, so that everyone listening
1197	 * for the old (pre-wrap) values do not see the much smaller
1198	 * (post-wrap) values than they were expecting (and so wait
1199	 * forever).
1200	 */
1201	*cs++ = (MI_SEMAPHORE_WAIT |
1202		 MI_SEMAPHORE_GLOBAL_GTT |
1203		 MI_SEMAPHORE_POLL |
1204		 MI_SEMAPHORE_SAD_GTE_SDD) +
1205		has_token;
1206	*cs++ = seqno;
1207	*cs++ = hwsp_offset;
1208	*cs++ = 0;
1209	if (has_token) {
1210		*cs++ = 0;
1211		*cs++ = MI_NOOP;
1212	}
1213
1214	intel_ring_advance(to, cs);
1215	return 0;
1216}
1217
1218static int
1219emit_semaphore_wait(struct i915_request *to,
1220		    struct i915_request *from,
1221		    gfp_t gfp)
1222{
1223	const intel_engine_mask_t mask = READ_ONCE(from->engine)->mask;
1224	struct i915_sw_fence *wait = &to->submit;
1225
1226	if (!intel_context_use_semaphores(to->context))
1227		goto await_fence;
1228
1229	if (i915_request_has_initial_breadcrumb(to))
1230		goto await_fence;
1231
 
 
 
1232	/*
1233	 * If this or its dependents are waiting on an external fence
1234	 * that may fail catastrophically, then we want to avoid using
1235	 * sempahores as they bypass the fence signaling metadata, and we
1236	 * lose the fence->error propagation.
1237	 */
1238	if (from->sched.flags & I915_SCHED_HAS_EXTERNAL_CHAIN)
1239		goto await_fence;
1240
1241	/* Just emit the first semaphore we see as request space is limited. */
1242	if (already_busywaiting(to) & mask)
1243		goto await_fence;
1244
1245	if (i915_request_await_start(to, from) < 0)
1246		goto await_fence;
1247
1248	/* Only submit our spinner after the signaler is running! */
1249	if (__await_execution(to, from, NULL, gfp))
1250		goto await_fence;
1251
1252	if (__emit_semaphore_wait(to, from, from->fence.seqno))
1253		goto await_fence;
1254
1255	to->sched.semaphores |= mask;
1256	wait = &to->semaphore;
1257
1258await_fence:
1259	return i915_sw_fence_await_dma_fence(wait,
1260					     &from->fence, 0,
1261					     I915_FENCE_GFP);
1262}
1263
1264static bool intel_timeline_sync_has_start(struct intel_timeline *tl,
1265					  struct dma_fence *fence)
1266{
1267	return __intel_timeline_sync_is_later(tl,
1268					      fence->context,
1269					      fence->seqno - 1);
1270}
1271
1272static int intel_timeline_sync_set_start(struct intel_timeline *tl,
1273					 const struct dma_fence *fence)
1274{
1275	return __intel_timeline_sync_set(tl, fence->context, fence->seqno - 1);
1276}
1277
1278static int
1279__i915_request_await_execution(struct i915_request *to,
1280			       struct i915_request *from,
1281			       void (*hook)(struct i915_request *rq,
1282					    struct dma_fence *signal))
1283{
1284	int err;
1285
1286	GEM_BUG_ON(intel_context_is_barrier(from->context));
1287
1288	/* Submit both requests at the same time */
1289	err = __await_execution(to, from, hook, I915_FENCE_GFP);
1290	if (err)
1291		return err;
1292
1293	/* Squash repeated depenendices to the same timelines */
1294	if (intel_timeline_sync_has_start(i915_request_timeline(to),
1295					  &from->fence))
1296		return 0;
1297
1298	/*
1299	 * Wait until the start of this request.
1300	 *
1301	 * The execution cb fires when we submit the request to HW. But in
1302	 * many cases this may be long before the request itself is ready to
1303	 * run (consider that we submit 2 requests for the same context, where
1304	 * the request of interest is behind an indefinite spinner). So we hook
1305	 * up to both to reduce our queues and keep the execution lag minimised
1306	 * in the worst case, though we hope that the await_start is elided.
1307	 */
1308	err = i915_request_await_start(to, from);
1309	if (err < 0)
1310		return err;
1311
1312	/*
1313	 * Ensure both start together [after all semaphores in signal]
1314	 *
1315	 * Now that we are queued to the HW at roughly the same time (thanks
1316	 * to the execute cb) and are ready to run at roughly the same time
1317	 * (thanks to the await start), our signaler may still be indefinitely
1318	 * delayed by waiting on a semaphore from a remote engine. If our
1319	 * signaler depends on a semaphore, so indirectly do we, and we do not
1320	 * want to start our payload until our signaler also starts theirs.
1321	 * So we wait.
1322	 *
1323	 * However, there is also a second condition for which we need to wait
1324	 * for the precise start of the signaler. Consider that the signaler
1325	 * was submitted in a chain of requests following another context
1326	 * (with just an ordinary intra-engine fence dependency between the
1327	 * two). In this case the signaler is queued to HW, but not for
1328	 * immediate execution, and so we must wait until it reaches the
1329	 * active slot.
1330	 */
1331	if (intel_engine_has_semaphores(to->engine) &&
1332	    !i915_request_has_initial_breadcrumb(to)) {
1333		err = __emit_semaphore_wait(to, from, from->fence.seqno - 1);
1334		if (err < 0)
1335			return err;
1336	}
1337
1338	/* Couple the dependency tree for PI on this exposed to->fence */
1339	if (to->engine->schedule) {
1340		err = i915_sched_node_add_dependency(&to->sched,
1341						     &from->sched,
1342						     I915_DEPENDENCY_WEAK);
1343		if (err < 0)
1344			return err;
1345	}
1346
1347	return intel_timeline_sync_set_start(i915_request_timeline(to),
1348					     &from->fence);
1349}
1350
1351static void mark_external(struct i915_request *rq)
1352{
1353	/*
1354	 * The downside of using semaphores is that we lose metadata passing
1355	 * along the signaling chain. This is particularly nasty when we
1356	 * need to pass along a fatal error such as EFAULT or EDEADLK. For
1357	 * fatal errors we want to scrub the request before it is executed,
1358	 * which means that we cannot preload the request onto HW and have
1359	 * it wait upon a semaphore.
1360	 */
1361	rq->sched.flags |= I915_SCHED_HAS_EXTERNAL_CHAIN;
1362}
1363
1364static int
1365__i915_request_await_external(struct i915_request *rq, struct dma_fence *fence)
1366{
1367	mark_external(rq);
1368	return i915_sw_fence_await_dma_fence(&rq->submit, fence,
1369					     i915_fence_context_timeout(rq->engine->i915,
1370									fence->context),
1371					     I915_FENCE_GFP);
1372}
1373
1374static int
1375i915_request_await_external(struct i915_request *rq, struct dma_fence *fence)
1376{
1377	struct dma_fence *iter;
1378	int err = 0;
1379
1380	if (!to_dma_fence_chain(fence))
1381		return __i915_request_await_external(rq, fence);
1382
1383	dma_fence_chain_for_each(iter, fence) {
1384		struct dma_fence_chain *chain = to_dma_fence_chain(iter);
1385
1386		if (!dma_fence_is_i915(chain->fence)) {
1387			err = __i915_request_await_external(rq, iter);
1388			break;
1389		}
1390
1391		err = i915_request_await_dma_fence(rq, chain->fence);
1392		if (err < 0)
1393			break;
1394	}
1395
1396	dma_fence_put(iter);
1397	return err;
1398}
1399
1400int
1401i915_request_await_execution(struct i915_request *rq,
1402			     struct dma_fence *fence,
1403			     void (*hook)(struct i915_request *rq,
1404					  struct dma_fence *signal))
1405{
1406	struct dma_fence **child = &fence;
1407	unsigned int nchild = 1;
1408	int ret;
1409
1410	if (dma_fence_is_array(fence)) {
1411		struct dma_fence_array *array = to_dma_fence_array(fence);
1412
1413		/* XXX Error for signal-on-any fence arrays */
1414
1415		child = array->fences;
1416		nchild = array->num_fences;
1417		GEM_BUG_ON(!nchild);
1418	}
1419
1420	do {
1421		fence = *child++;
1422		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 
1423			continue;
 
1424
1425		if (fence->context == rq->fence.context)
1426			continue;
1427
1428		/*
1429		 * We don't squash repeated fence dependencies here as we
1430		 * want to run our callback in all cases.
1431		 */
1432
1433		if (dma_fence_is_i915(fence))
1434			ret = __i915_request_await_execution(rq,
1435							     to_request(fence),
1436							     hook);
1437		else
1438			ret = i915_request_await_external(rq, fence);
1439		if (ret < 0)
1440			return ret;
1441	} while (--nchild);
1442
1443	return 0;
1444}
1445
1446static int
1447await_request_submit(struct i915_request *to, struct i915_request *from)
1448{
1449	/*
1450	 * If we are waiting on a virtual engine, then it may be
1451	 * constrained to execute on a single engine *prior* to submission.
1452	 * When it is submitted, it will be first submitted to the virtual
1453	 * engine and then passed to the physical engine. We cannot allow
1454	 * the waiter to be submitted immediately to the physical engine
1455	 * as it may then bypass the virtual request.
1456	 */
1457	if (to->engine == READ_ONCE(from->engine))
1458		return i915_sw_fence_await_sw_fence_gfp(&to->submit,
1459							&from->submit,
1460							I915_FENCE_GFP);
1461	else
1462		return __i915_request_await_execution(to, from, NULL);
1463}
1464
1465static int
1466i915_request_await_request(struct i915_request *to, struct i915_request *from)
1467{
1468	int ret;
1469
1470	GEM_BUG_ON(to == from);
1471	GEM_BUG_ON(to->timeline == from->timeline);
1472
1473	if (i915_request_completed(from)) {
1474		i915_sw_fence_set_error_once(&to->submit, from->fence.error);
1475		return 0;
1476	}
1477
1478	if (to->engine->schedule) {
1479		ret = i915_sched_node_add_dependency(&to->sched,
1480						     &from->sched,
1481						     I915_DEPENDENCY_EXTERNAL);
1482		if (ret < 0)
1483			return ret;
1484	}
1485
1486	if (is_power_of_2(to->execution_mask | READ_ONCE(from->execution_mask)))
1487		ret = await_request_submit(to, from);
1488	else
1489		ret = emit_semaphore_wait(to, from, I915_FENCE_GFP);
1490	if (ret < 0)
1491		return ret;
1492
1493	return 0;
1494}
1495
1496int
1497i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence)
1498{
1499	struct dma_fence **child = &fence;
1500	unsigned int nchild = 1;
1501	int ret;
1502
1503	/*
1504	 * Note that if the fence-array was created in signal-on-any mode,
1505	 * we should *not* decompose it into its individual fences. However,
1506	 * we don't currently store which mode the fence-array is operating
1507	 * in. Fortunately, the only user of signal-on-any is private to
1508	 * amdgpu and we should not see any incoming fence-array from
1509	 * sync-file being in signal-on-any mode.
1510	 */
1511	if (dma_fence_is_array(fence)) {
1512		struct dma_fence_array *array = to_dma_fence_array(fence);
1513
1514		child = array->fences;
1515		nchild = array->num_fences;
1516		GEM_BUG_ON(!nchild);
1517	}
1518
1519	do {
1520		fence = *child++;
1521		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 
1522			continue;
 
1523
1524		/*
1525		 * Requests on the same timeline are explicitly ordered, along
1526		 * with their dependencies, by i915_request_add() which ensures
1527		 * that requests are submitted in-order through each ring.
1528		 */
1529		if (fence->context == rq->fence.context)
1530			continue;
1531
1532		/* Squash repeated waits to the same timelines */
1533		if (fence->context &&
1534		    intel_timeline_sync_is_later(i915_request_timeline(rq),
1535						 fence))
1536			continue;
1537
1538		if (dma_fence_is_i915(fence))
1539			ret = i915_request_await_request(rq, to_request(fence));
1540		else
1541			ret = i915_request_await_external(rq, fence);
1542		if (ret < 0)
1543			return ret;
1544
1545		/* Record the latest fence used against each timeline */
1546		if (fence->context)
1547			intel_timeline_sync_set(i915_request_timeline(rq),
1548						fence);
1549	} while (--nchild);
1550
1551	return 0;
1552}
1553
1554/**
1555 * i915_request_await_object - set this request to (async) wait upon a bo
1556 * @to: request we are wishing to use
1557 * @obj: object which may be in use on another ring.
1558 * @write: whether the wait is on behalf of a writer
1559 *
1560 * This code is meant to abstract object synchronization with the GPU.
1561 * Conceptually we serialise writes between engines inside the GPU.
1562 * We only allow one engine to write into a buffer at any time, but
1563 * multiple readers. To ensure each has a coherent view of memory, we must:
1564 *
1565 * - If there is an outstanding write request to the object, the new
1566 *   request must wait for it to complete (either CPU or in hw, requests
1567 *   on the same ring will be naturally ordered).
1568 *
1569 * - If we are a write request (pending_write_domain is set), the new
1570 *   request must wait for outstanding read requests to complete.
1571 *
1572 * Returns 0 if successful, else propagates up the lower layer error.
1573 */
1574int
1575i915_request_await_object(struct i915_request *to,
1576			  struct drm_i915_gem_object *obj,
1577			  bool write)
1578{
1579	struct dma_fence *excl;
1580	int ret = 0;
1581
1582	if (write) {
1583		struct dma_fence **shared;
1584		unsigned int count, i;
1585
1586		ret = dma_resv_get_fences(obj->base.resv, &excl, &count,
1587					  &shared);
1588		if (ret)
1589			return ret;
1590
1591		for (i = 0; i < count; i++) {
1592			ret = i915_request_await_dma_fence(to, shared[i]);
1593			if (ret)
1594				break;
1595
1596			dma_fence_put(shared[i]);
1597		}
1598
1599		for (; i < count; i++)
1600			dma_fence_put(shared[i]);
1601		kfree(shared);
1602	} else {
1603		excl = dma_resv_get_excl_unlocked(obj->base.resv);
1604	}
1605
1606	if (excl) {
1607		if (ret == 0)
1608			ret = i915_request_await_dma_fence(to, excl);
1609
1610		dma_fence_put(excl);
1611	}
1612
1613	return ret;
1614}
1615
1616static struct i915_request *
1617__i915_request_add_to_timeline(struct i915_request *rq)
1618{
1619	struct intel_timeline *timeline = i915_request_timeline(rq);
1620	struct i915_request *prev;
1621
1622	/*
1623	 * Dependency tracking and request ordering along the timeline
1624	 * is special cased so that we can eliminate redundant ordering
1625	 * operations while building the request (we know that the timeline
1626	 * itself is ordered, and here we guarantee it).
1627	 *
1628	 * As we know we will need to emit tracking along the timeline,
1629	 * we embed the hooks into our request struct -- at the cost of
1630	 * having to have specialised no-allocation interfaces (which will
1631	 * be beneficial elsewhere).
1632	 *
1633	 * A second benefit to open-coding i915_request_await_request is
1634	 * that we can apply a slight variant of the rules specialised
1635	 * for timelines that jump between engines (such as virtual engines).
1636	 * If we consider the case of virtual engine, we must emit a dma-fence
1637	 * to prevent scheduling of the second request until the first is
1638	 * complete (to maximise our greedy late load balancing) and this
1639	 * precludes optimising to use semaphores serialisation of a single
1640	 * timeline across engines.
1641	 */
1642	prev = to_request(__i915_active_fence_set(&timeline->last_request,
1643						  &rq->fence));
1644	if (prev && !__i915_request_is_complete(prev)) {
1645		/*
1646		 * The requests are supposed to be kept in order. However,
1647		 * we need to be wary in case the timeline->last_request
1648		 * is used as a barrier for external modification to this
1649		 * context.
1650		 */
1651		GEM_BUG_ON(prev->context == rq->context &&
1652			   i915_seqno_passed(prev->fence.seqno,
1653					     rq->fence.seqno));
1654
1655		if (is_power_of_2(READ_ONCE(prev->engine)->mask | rq->engine->mask))
1656			i915_sw_fence_await_sw_fence(&rq->submit,
1657						     &prev->submit,
1658						     &rq->submitq);
1659		else
1660			__i915_sw_fence_await_dma_fence(&rq->submit,
1661							&prev->fence,
1662							&rq->dmaq);
1663		if (rq->engine->schedule)
1664			__i915_sched_node_add_dependency(&rq->sched,
1665							 &prev->sched,
1666							 &rq->dep,
1667							 0);
1668	}
1669
1670	/*
1671	 * Make sure that no request gazumped us - if it was allocated after
1672	 * our i915_request_alloc() and called __i915_request_add() before
1673	 * us, the timeline will hold its seqno which is later than ours.
1674	 */
1675	GEM_BUG_ON(timeline->seqno != rq->fence.seqno);
1676
1677	return prev;
1678}
1679
1680/*
1681 * NB: This function is not allowed to fail. Doing so would mean the the
1682 * request is not being tracked for completion but the work itself is
1683 * going to happen on the hardware. This would be a Bad Thing(tm).
1684 */
1685struct i915_request *__i915_request_commit(struct i915_request *rq)
1686{
1687	struct intel_engine_cs *engine = rq->engine;
1688	struct intel_ring *ring = rq->ring;
1689	u32 *cs;
1690
1691	RQ_TRACE(rq, "\n");
1692
1693	/*
1694	 * To ensure that this call will not fail, space for its emissions
1695	 * should already have been reserved in the ring buffer. Let the ring
1696	 * know that it is time to use that space up.
1697	 */
1698	GEM_BUG_ON(rq->reserved_space > ring->space);
1699	rq->reserved_space = 0;
1700	rq->emitted_jiffies = jiffies;
1701
1702	/*
1703	 * Record the position of the start of the breadcrumb so that
1704	 * should we detect the updated seqno part-way through the
1705	 * GPU processing the request, we never over-estimate the
1706	 * position of the ring's HEAD.
1707	 */
1708	cs = intel_ring_begin(rq, engine->emit_fini_breadcrumb_dw);
1709	GEM_BUG_ON(IS_ERR(cs));
1710	rq->postfix = intel_ring_offset(rq, cs);
1711
1712	return __i915_request_add_to_timeline(rq);
1713}
1714
1715void __i915_request_queue_bh(struct i915_request *rq)
1716{
1717	i915_sw_fence_commit(&rq->semaphore);
1718	i915_sw_fence_commit(&rq->submit);
1719}
1720
1721void __i915_request_queue(struct i915_request *rq,
1722			  const struct i915_sched_attr *attr)
1723{
1724	/*
1725	 * Let the backend know a new request has arrived that may need
1726	 * to adjust the existing execution schedule due to a high priority
1727	 * request - i.e. we may want to preempt the current request in order
1728	 * to run a high priority dependency chain *before* we can execute this
1729	 * request.
1730	 *
1731	 * This is called before the request is ready to run so that we can
1732	 * decide whether to preempt the entire chain so that it is ready to
1733	 * run at the earliest possible convenience.
1734	 */
1735	if (attr && rq->engine->schedule)
1736		rq->engine->schedule(rq, attr);
1737
1738	local_bh_disable();
1739	__i915_request_queue_bh(rq);
1740	local_bh_enable(); /* kick tasklets */
1741}
1742
1743void i915_request_add(struct i915_request *rq)
1744{
1745	struct intel_timeline * const tl = i915_request_timeline(rq);
1746	struct i915_sched_attr attr = {};
1747	struct i915_gem_context *ctx;
1748
1749	lockdep_assert_held(&tl->mutex);
1750	lockdep_unpin_lock(&tl->mutex, rq->cookie);
1751
1752	trace_i915_request_add(rq);
1753	__i915_request_commit(rq);
1754
1755	/* XXX placeholder for selftests */
1756	rcu_read_lock();
1757	ctx = rcu_dereference(rq->context->gem_context);
1758	if (ctx)
1759		attr = ctx->sched;
1760	rcu_read_unlock();
1761
1762	__i915_request_queue(rq, &attr);
1763
1764	mutex_unlock(&tl->mutex);
1765}
1766
1767static unsigned long local_clock_ns(unsigned int *cpu)
1768{
1769	unsigned long t;
1770
1771	/*
1772	 * Cheaply and approximately convert from nanoseconds to microseconds.
1773	 * The result and subsequent calculations are also defined in the same
1774	 * approximate microseconds units. The principal source of timing
1775	 * error here is from the simple truncation.
1776	 *
1777	 * Note that local_clock() is only defined wrt to the current CPU;
1778	 * the comparisons are no longer valid if we switch CPUs. Instead of
1779	 * blocking preemption for the entire busywait, we can detect the CPU
1780	 * switch and use that as indicator of system load and a reason to
1781	 * stop busywaiting, see busywait_stop().
1782	 */
1783	*cpu = get_cpu();
1784	t = local_clock();
1785	put_cpu();
1786
1787	return t;
1788}
1789
1790static bool busywait_stop(unsigned long timeout, unsigned int cpu)
1791{
1792	unsigned int this_cpu;
1793
1794	if (time_after(local_clock_ns(&this_cpu), timeout))
1795		return true;
1796
1797	return this_cpu != cpu;
1798}
1799
1800static bool __i915_spin_request(struct i915_request * const rq, int state)
1801{
1802	unsigned long timeout_ns;
1803	unsigned int cpu;
1804
1805	/*
1806	 * Only wait for the request if we know it is likely to complete.
1807	 *
1808	 * We don't track the timestamps around requests, nor the average
1809	 * request length, so we do not have a good indicator that this
1810	 * request will complete within the timeout. What we do know is the
1811	 * order in which requests are executed by the context and so we can
1812	 * tell if the request has been started. If the request is not even
1813	 * running yet, it is a fair assumption that it will not complete
1814	 * within our relatively short timeout.
1815	 */
1816	if (!i915_request_is_running(rq))
1817		return false;
1818
1819	/*
1820	 * When waiting for high frequency requests, e.g. during synchronous
1821	 * rendering split between the CPU and GPU, the finite amount of time
1822	 * required to set up the irq and wait upon it limits the response
1823	 * rate. By busywaiting on the request completion for a short while we
1824	 * can service the high frequency waits as quick as possible. However,
1825	 * if it is a slow request, we want to sleep as quickly as possible.
1826	 * The tradeoff between waiting and sleeping is roughly the time it
1827	 * takes to sleep on a request, on the order of a microsecond.
1828	 */
1829
1830	timeout_ns = READ_ONCE(rq->engine->props.max_busywait_duration_ns);
1831	timeout_ns += local_clock_ns(&cpu);
1832	do {
1833		if (dma_fence_is_signaled(&rq->fence))
1834			return true;
1835
1836		if (signal_pending_state(state, current))
1837			break;
1838
1839		if (busywait_stop(timeout_ns, cpu))
1840			break;
1841
1842		cpu_relax();
1843	} while (!need_resched());
1844
1845	return false;
1846}
1847
1848struct request_wait {
1849	struct dma_fence_cb cb;
1850	struct task_struct *tsk;
1851};
1852
1853static void request_wait_wake(struct dma_fence *fence, struct dma_fence_cb *cb)
1854{
1855	struct request_wait *wait = container_of(cb, typeof(*wait), cb);
1856
1857	wake_up_process(fetch_and_zero(&wait->tsk));
1858}
1859
1860/**
1861 * i915_request_wait - wait until execution of request has finished
1862 * @rq: the request to wait upon
1863 * @flags: how to wait
1864 * @timeout: how long to wait in jiffies
1865 *
1866 * i915_request_wait() waits for the request to be completed, for a
1867 * maximum of @timeout jiffies (with MAX_SCHEDULE_TIMEOUT implying an
1868 * unbounded wait).
1869 *
1870 * Returns the remaining time (in jiffies) if the request completed, which may
1871 * be zero or -ETIME if the request is unfinished after the timeout expires.
1872 * May return -EINTR is called with I915_WAIT_INTERRUPTIBLE and a signal is
1873 * pending before the request completes.
1874 */
1875long i915_request_wait(struct i915_request *rq,
1876		       unsigned int flags,
1877		       long timeout)
1878{
1879	const int state = flags & I915_WAIT_INTERRUPTIBLE ?
1880		TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
1881	struct request_wait wait;
1882
1883	might_sleep();
1884	GEM_BUG_ON(timeout < 0);
1885
1886	if (dma_fence_is_signaled(&rq->fence))
1887		return timeout;
1888
1889	if (!timeout)
1890		return -ETIME;
1891
1892	trace_i915_request_wait_begin(rq, flags);
1893
1894	/*
1895	 * We must never wait on the GPU while holding a lock as we
1896	 * may need to perform a GPU reset. So while we don't need to
1897	 * serialise wait/reset with an explicit lock, we do want
1898	 * lockdep to detect potential dependency cycles.
1899	 */
1900	mutex_acquire(&rq->engine->gt->reset.mutex.dep_map, 0, 0, _THIS_IP_);
1901
1902	/*
1903	 * Optimistic spin before touching IRQs.
1904	 *
1905	 * We may use a rather large value here to offset the penalty of
1906	 * switching away from the active task. Frequently, the client will
1907	 * wait upon an old swapbuffer to throttle itself to remain within a
1908	 * frame of the gpu. If the client is running in lockstep with the gpu,
1909	 * then it should not be waiting long at all, and a sleep now will incur
1910	 * extra scheduler latency in producing the next frame. To try to
1911	 * avoid adding the cost of enabling/disabling the interrupt to the
1912	 * short wait, we first spin to see if the request would have completed
1913	 * in the time taken to setup the interrupt.
1914	 *
1915	 * We need upto 5us to enable the irq, and upto 20us to hide the
1916	 * scheduler latency of a context switch, ignoring the secondary
1917	 * impacts from a context switch such as cache eviction.
1918	 *
1919	 * The scheme used for low-latency IO is called "hybrid interrupt
1920	 * polling". The suggestion there is to sleep until just before you
1921	 * expect to be woken by the device interrupt and then poll for its
1922	 * completion. That requires having a good predictor for the request
1923	 * duration, which we currently lack.
1924	 */
1925	if (IS_ACTIVE(CONFIG_DRM_I915_MAX_REQUEST_BUSYWAIT) &&
1926	    __i915_spin_request(rq, state))
 
1927		goto out;
 
1928
1929	/*
1930	 * This client is about to stall waiting for the GPU. In many cases
1931	 * this is undesirable and limits the throughput of the system, as
1932	 * many clients cannot continue processing user input/output whilst
1933	 * blocked. RPS autotuning may take tens of milliseconds to respond
1934	 * to the GPU load and thus incurs additional latency for the client.
1935	 * We can circumvent that by promoting the GPU frequency to maximum
1936	 * before we sleep. This makes the GPU throttle up much more quickly
1937	 * (good for benchmarks and user experience, e.g. window animations),
1938	 * but at a cost of spending more power processing the workload
1939	 * (bad for battery).
1940	 */
1941	if (flags & I915_WAIT_PRIORITY && !i915_request_started(rq))
1942		intel_rps_boost(rq);
 
 
 
1943
1944	wait.tsk = current;
1945	if (dma_fence_add_callback(&rq->fence, &wait.cb, request_wait_wake))
1946		goto out;
1947
1948	/*
1949	 * Flush the submission tasklet, but only if it may help this request.
1950	 *
1951	 * We sometimes experience some latency between the HW interrupts and
1952	 * tasklet execution (mostly due to ksoftirqd latency, but it can also
1953	 * be due to lazy CS events), so lets run the tasklet manually if there
1954	 * is a chance it may submit this request. If the request is not ready
1955	 * to run, as it is waiting for other fences to be signaled, flushing
1956	 * the tasklet is busy work without any advantage for this client.
1957	 *
1958	 * If the HW is being lazy, this is the last chance before we go to
1959	 * sleep to catch any pending events. We will check periodically in
1960	 * the heartbeat to flush the submission tasklets as a last resort
1961	 * for unhappy HW.
1962	 */
1963	if (i915_request_is_ready(rq))
1964		__intel_engine_flush_submission(rq->engine, false);
1965
1966	for (;;) {
1967		set_current_state(state);
1968
1969		if (dma_fence_is_signaled(&rq->fence))
 
1970			break;
 
 
 
1971
1972		if (signal_pending_state(state, current)) {
1973			timeout = -ERESTARTSYS;
1974			break;
1975		}
1976
1977		if (!timeout) {
1978			timeout = -ETIME;
1979			break;
1980		}
1981
1982		timeout = io_schedule_timeout(timeout);
1983	}
1984	__set_current_state(TASK_RUNNING);
1985
1986	if (READ_ONCE(wait.tsk))
1987		dma_fence_remove_callback(&rq->fence, &wait.cb);
1988	GEM_BUG_ON(!list_empty(&wait.cb.node));
1989
1990out:
1991	mutex_release(&rq->engine->gt->reset.mutex.dep_map, _THIS_IP_);
1992	trace_i915_request_wait_end(rq);
1993	return timeout;
1994}
1995
1996static int print_sched_attr(const struct i915_sched_attr *attr,
1997			    char *buf, int x, int len)
1998{
1999	if (attr->priority == I915_PRIORITY_INVALID)
2000		return x;
2001
2002	x += snprintf(buf + x, len - x,
2003		      " prio=%d", attr->priority);
2004
2005	return x;
2006}
2007
2008static char queue_status(const struct i915_request *rq)
2009{
2010	if (i915_request_is_active(rq))
2011		return 'E';
2012
2013	if (i915_request_is_ready(rq))
2014		return intel_engine_is_virtual(rq->engine) ? 'V' : 'R';
2015
2016	return 'U';
2017}
2018
2019static const char *run_status(const struct i915_request *rq)
2020{
2021	if (__i915_request_is_complete(rq))
2022		return "!";
2023
2024	if (__i915_request_has_started(rq))
2025		return "*";
2026
2027	if (!i915_sw_fence_signaled(&rq->semaphore))
2028		return "&";
2029
2030	return "";
2031}
2032
2033static const char *fence_status(const struct i915_request *rq)
2034{
2035	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &rq->fence.flags))
2036		return "+";
2037
2038	if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &rq->fence.flags))
2039		return "-";
2040
2041	return "";
2042}
2043
2044void i915_request_show(struct drm_printer *m,
2045		       const struct i915_request *rq,
2046		       const char *prefix,
2047		       int indent)
2048{
2049	const char *name = rq->fence.ops->get_timeline_name((struct dma_fence *)&rq->fence);
2050	char buf[80] = "";
2051	int x = 0;
2052
2053	/*
2054	 * The prefix is used to show the queue status, for which we use
2055	 * the following flags:
2056	 *
2057	 *  U [Unready]
2058	 *    - initial status upon being submitted by the user
2059	 *
2060	 *    - the request is not ready for execution as it is waiting
2061	 *      for external fences
2062	 *
2063	 *  R [Ready]
2064	 *    - all fences the request was waiting on have been signaled,
2065	 *      and the request is now ready for execution and will be
2066	 *      in a backend queue
2067	 *
2068	 *    - a ready request may still need to wait on semaphores
2069	 *      [internal fences]
2070	 *
2071	 *  V [Ready/virtual]
2072	 *    - same as ready, but queued over multiple backends
2073	 *
2074	 *  E [Executing]
2075	 *    - the request has been transferred from the backend queue and
2076	 *      submitted for execution on HW
2077	 *
2078	 *    - a completed request may still be regarded as executing, its
2079	 *      status may not be updated until it is retired and removed
2080	 *      from the lists
2081	 */
2082
2083	x = print_sched_attr(&rq->sched.attr, buf, x, sizeof(buf));
2084
2085	drm_printf(m, "%s%.*s%c %llx:%lld%s%s %s @ %dms: %s\n",
2086		   prefix, indent, "                ",
2087		   queue_status(rq),
2088		   rq->fence.context, rq->fence.seqno,
2089		   run_status(rq),
2090		   fence_status(rq),
2091		   buf,
2092		   jiffies_to_msecs(jiffies - rq->emitted_jiffies),
2093		   name);
2094}
2095
2096#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
2097#include "selftests/mock_request.c"
2098#include "selftests/i915_request.c"
2099#endif
2100
2101static void i915_global_request_shrink(void)
2102{
2103	kmem_cache_shrink(global.slab_execute_cbs);
2104	kmem_cache_shrink(global.slab_requests);
2105}
2106
2107static void i915_global_request_exit(void)
2108{
2109	kmem_cache_destroy(global.slab_execute_cbs);
2110	kmem_cache_destroy(global.slab_requests);
2111}
2112
2113static struct i915_global_request global = { {
2114	.shrink = i915_global_request_shrink,
2115	.exit = i915_global_request_exit,
2116} };
2117
2118int __init i915_global_request_init(void)
2119{
2120	global.slab_requests =
2121		kmem_cache_create("i915_request",
2122				  sizeof(struct i915_request),
2123				  __alignof__(struct i915_request),
2124				  SLAB_HWCACHE_ALIGN |
2125				  SLAB_RECLAIM_ACCOUNT |
2126				  SLAB_TYPESAFE_BY_RCU,
2127				  __i915_request_ctor);
2128	if (!global.slab_requests)
2129		return -ENOMEM;
2130
2131	global.slab_execute_cbs = KMEM_CACHE(execute_cb,
2132					     SLAB_HWCACHE_ALIGN |
2133					     SLAB_RECLAIM_ACCOUNT |
2134					     SLAB_TYPESAFE_BY_RCU);
2135	if (!global.slab_execute_cbs)
2136		goto err_requests;
2137
2138	i915_global_register(&global.base);
2139	return 0;
2140
2141err_requests:
2142	kmem_cache_destroy(global.slab_requests);
2143	return -ENOMEM;
2144}