xref: /openbmc/linux/drivers/gpu/drm/i915/gt/intel_reset.c (revision b9221f71)
1 // SPDX-License-Identifier: MIT
2 /*
3  * Copyright © 2008-2018 Intel Corporation
4  */
5 
6 #include <linux/sched/mm.h>
7 #include <linux/stop_machine.h>
8 
9 #include "display/intel_display_types.h"
10 #include "display/intel_overlay.h"
11 
12 #include "gem/i915_gem_context.h"
13 
14 #include "i915_drv.h"
15 #include "i915_gpu_error.h"
16 #include "i915_irq.h"
17 #include "intel_breadcrumbs.h"
18 #include "intel_engine_pm.h"
19 #include "intel_gt.h"
20 #include "intel_gt_pm.h"
21 #include "intel_gt_requests.h"
22 #include "intel_reset.h"
23 
24 #include "uc/intel_guc.h"
25 
26 #define RESET_MAX_RETRIES 3
27 
28 /* XXX How to handle concurrent GGTT updates using tiling registers? */
29 #define RESET_UNDER_STOP_MACHINE 0
30 
31 static void rmw_set_fw(struct intel_uncore *uncore, i915_reg_t reg, u32 set)
32 {
33 	intel_uncore_rmw_fw(uncore, reg, 0, set);
34 }
35 
36 static void rmw_clear_fw(struct intel_uncore *uncore, i915_reg_t reg, u32 clr)
37 {
38 	intel_uncore_rmw_fw(uncore, reg, clr, 0);
39 }
40 
41 static void client_mark_guilty(struct i915_gem_context *ctx, bool banned)
42 {
43 	struct drm_i915_file_private *file_priv = ctx->file_priv;
44 	unsigned long prev_hang;
45 	unsigned int score;
46 
47 	if (IS_ERR_OR_NULL(file_priv))
48 		return;
49 
50 	score = 0;
51 	if (banned)
52 		score = I915_CLIENT_SCORE_CONTEXT_BAN;
53 
54 	prev_hang = xchg(&file_priv->hang_timestamp, jiffies);
55 	if (time_before(jiffies, prev_hang + I915_CLIENT_FAST_HANG_JIFFIES))
56 		score += I915_CLIENT_SCORE_HANG_FAST;
57 
58 	if (score) {
59 		atomic_add(score, &file_priv->ban_score);
60 
61 		drm_dbg(&ctx->i915->drm,
62 			"client %s: gained %u ban score, now %u\n",
63 			ctx->name, score,
64 			atomic_read(&file_priv->ban_score));
65 	}
66 }
67 
68 static bool mark_guilty(struct i915_request *rq)
69 {
70 	struct i915_gem_context *ctx;
71 	unsigned long prev_hang;
72 	bool banned;
73 	int i;
74 
75 	if (intel_context_is_closed(rq->context))
76 		return true;
77 
78 	rcu_read_lock();
79 	ctx = rcu_dereference(rq->context->gem_context);
80 	if (ctx && !kref_get_unless_zero(&ctx->ref))
81 		ctx = NULL;
82 	rcu_read_unlock();
83 	if (!ctx)
84 		return intel_context_is_banned(rq->context);
85 
86 	atomic_inc(&ctx->guilty_count);
87 
88 	/* Cool contexts are too cool to be banned! (Used for reset testing.) */
89 	if (!i915_gem_context_is_bannable(ctx)) {
90 		banned = false;
91 		goto out;
92 	}
93 
94 	drm_notice(&ctx->i915->drm,
95 		   "%s context reset due to GPU hang\n",
96 		   ctx->name);
97 
98 	/* Record the timestamp for the last N hangs */
99 	prev_hang = ctx->hang_timestamp[0];
100 	for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp) - 1; i++)
101 		ctx->hang_timestamp[i] = ctx->hang_timestamp[i + 1];
102 	ctx->hang_timestamp[i] = jiffies;
103 
104 	/* If we have hung N+1 times in rapid succession, we ban the context! */
105 	banned = !i915_gem_context_is_recoverable(ctx);
106 	if (time_before(jiffies, prev_hang + CONTEXT_FAST_HANG_JIFFIES))
107 		banned = true;
108 	if (banned)
109 		drm_dbg(&ctx->i915->drm, "context %s: guilty %d, banned\n",
110 			ctx->name, atomic_read(&ctx->guilty_count));
111 
112 	client_mark_guilty(ctx, banned);
113 
114 out:
115 	i915_gem_context_put(ctx);
116 	return banned;
117 }
118 
119 static void mark_innocent(struct i915_request *rq)
120 {
121 	struct i915_gem_context *ctx;
122 
123 	rcu_read_lock();
124 	ctx = rcu_dereference(rq->context->gem_context);
125 	if (ctx)
126 		atomic_inc(&ctx->active_count);
127 	rcu_read_unlock();
128 }
129 
130 void __i915_request_reset(struct i915_request *rq, bool guilty)
131 {
132 	bool banned = false;
133 
134 	RQ_TRACE(rq, "guilty? %s\n", yesno(guilty));
135 	GEM_BUG_ON(__i915_request_is_complete(rq));
136 
137 	rcu_read_lock(); /* protect the GEM context */
138 	if (guilty) {
139 		i915_request_set_error_once(rq, -EIO);
140 		__i915_request_skip(rq);
141 		banned = mark_guilty(rq);
142 	} else {
143 		i915_request_set_error_once(rq, -EAGAIN);
144 		mark_innocent(rq);
145 	}
146 	rcu_read_unlock();
147 
148 	if (banned)
149 		intel_context_ban(rq->context, rq);
150 }
151 
152 static bool i915_in_reset(struct pci_dev *pdev)
153 {
154 	u8 gdrst;
155 
156 	pci_read_config_byte(pdev, I915_GDRST, &gdrst);
157 	return gdrst & GRDOM_RESET_STATUS;
158 }
159 
160 static int i915_do_reset(struct intel_gt *gt,
161 			 intel_engine_mask_t engine_mask,
162 			 unsigned int retry)
163 {
164 	struct pci_dev *pdev = to_pci_dev(gt->i915->drm.dev);
165 	int err;
166 
167 	/* Assert reset for at least 20 usec, and wait for acknowledgement. */
168 	pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
169 	udelay(50);
170 	err = wait_for_atomic(i915_in_reset(pdev), 50);
171 
172 	/* Clear the reset request. */
173 	pci_write_config_byte(pdev, I915_GDRST, 0);
174 	udelay(50);
175 	if (!err)
176 		err = wait_for_atomic(!i915_in_reset(pdev), 50);
177 
178 	return err;
179 }
180 
181 static bool g4x_reset_complete(struct pci_dev *pdev)
182 {
183 	u8 gdrst;
184 
185 	pci_read_config_byte(pdev, I915_GDRST, &gdrst);
186 	return (gdrst & GRDOM_RESET_ENABLE) == 0;
187 }
188 
189 static int g33_do_reset(struct intel_gt *gt,
190 			intel_engine_mask_t engine_mask,
191 			unsigned int retry)
192 {
193 	struct pci_dev *pdev = to_pci_dev(gt->i915->drm.dev);
194 
195 	pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
196 	return wait_for_atomic(g4x_reset_complete(pdev), 50);
197 }
198 
199 static int g4x_do_reset(struct intel_gt *gt,
200 			intel_engine_mask_t engine_mask,
201 			unsigned int retry)
202 {
203 	struct pci_dev *pdev = to_pci_dev(gt->i915->drm.dev);
204 	struct intel_uncore *uncore = gt->uncore;
205 	int ret;
206 
207 	/* WaVcpClkGateDisableForMediaReset:ctg,elk */
208 	rmw_set_fw(uncore, VDECCLK_GATE_D, VCP_UNIT_CLOCK_GATE_DISABLE);
209 	intel_uncore_posting_read_fw(uncore, VDECCLK_GATE_D);
210 
211 	pci_write_config_byte(pdev, I915_GDRST,
212 			      GRDOM_MEDIA | GRDOM_RESET_ENABLE);
213 	ret =  wait_for_atomic(g4x_reset_complete(pdev), 50);
214 	if (ret) {
215 		GT_TRACE(gt, "Wait for media reset failed\n");
216 		goto out;
217 	}
218 
219 	pci_write_config_byte(pdev, I915_GDRST,
220 			      GRDOM_RENDER | GRDOM_RESET_ENABLE);
221 	ret =  wait_for_atomic(g4x_reset_complete(pdev), 50);
222 	if (ret) {
223 		GT_TRACE(gt, "Wait for render reset failed\n");
224 		goto out;
225 	}
226 
227 out:
228 	pci_write_config_byte(pdev, I915_GDRST, 0);
229 
230 	rmw_clear_fw(uncore, VDECCLK_GATE_D, VCP_UNIT_CLOCK_GATE_DISABLE);
231 	intel_uncore_posting_read_fw(uncore, VDECCLK_GATE_D);
232 
233 	return ret;
234 }
235 
236 static int ilk_do_reset(struct intel_gt *gt, intel_engine_mask_t engine_mask,
237 			unsigned int retry)
238 {
239 	struct intel_uncore *uncore = gt->uncore;
240 	int ret;
241 
242 	intel_uncore_write_fw(uncore, ILK_GDSR,
243 			      ILK_GRDOM_RENDER | ILK_GRDOM_RESET_ENABLE);
244 	ret = __intel_wait_for_register_fw(uncore, ILK_GDSR,
245 					   ILK_GRDOM_RESET_ENABLE, 0,
246 					   5000, 0,
247 					   NULL);
248 	if (ret) {
249 		GT_TRACE(gt, "Wait for render reset failed\n");
250 		goto out;
251 	}
252 
253 	intel_uncore_write_fw(uncore, ILK_GDSR,
254 			      ILK_GRDOM_MEDIA | ILK_GRDOM_RESET_ENABLE);
255 	ret = __intel_wait_for_register_fw(uncore, ILK_GDSR,
256 					   ILK_GRDOM_RESET_ENABLE, 0,
257 					   5000, 0,
258 					   NULL);
259 	if (ret) {
260 		GT_TRACE(gt, "Wait for media reset failed\n");
261 		goto out;
262 	}
263 
264 out:
265 	intel_uncore_write_fw(uncore, ILK_GDSR, 0);
266 	intel_uncore_posting_read_fw(uncore, ILK_GDSR);
267 	return ret;
268 }
269 
270 /* Reset the hardware domains (GENX_GRDOM_*) specified by mask */
271 static int gen6_hw_domain_reset(struct intel_gt *gt, u32 hw_domain_mask)
272 {
273 	struct intel_uncore *uncore = gt->uncore;
274 	int err;
275 
276 	/*
277 	 * GEN6_GDRST is not in the gt power well, no need to check
278 	 * for fifo space for the write or forcewake the chip for
279 	 * the read
280 	 */
281 	intel_uncore_write_fw(uncore, GEN6_GDRST, hw_domain_mask);
282 
283 	/* Wait for the device to ack the reset requests */
284 	err = __intel_wait_for_register_fw(uncore,
285 					   GEN6_GDRST, hw_domain_mask, 0,
286 					   500, 0,
287 					   NULL);
288 	if (err)
289 		GT_TRACE(gt,
290 			 "Wait for 0x%08x engines reset failed\n",
291 			 hw_domain_mask);
292 
293 	return err;
294 }
295 
296 static int gen6_reset_engines(struct intel_gt *gt,
297 			      intel_engine_mask_t engine_mask,
298 			      unsigned int retry)
299 {
300 	static const u32 hw_engine_mask[] = {
301 		[RCS0]  = GEN6_GRDOM_RENDER,
302 		[BCS0]  = GEN6_GRDOM_BLT,
303 		[VCS0]  = GEN6_GRDOM_MEDIA,
304 		[VCS1]  = GEN8_GRDOM_MEDIA2,
305 		[VECS0] = GEN6_GRDOM_VECS,
306 	};
307 	struct intel_engine_cs *engine;
308 	u32 hw_mask;
309 
310 	if (engine_mask == ALL_ENGINES) {
311 		hw_mask = GEN6_GRDOM_FULL;
312 	} else {
313 		intel_engine_mask_t tmp;
314 
315 		hw_mask = 0;
316 		for_each_engine_masked(engine, gt, engine_mask, tmp) {
317 			GEM_BUG_ON(engine->id >= ARRAY_SIZE(hw_engine_mask));
318 			hw_mask |= hw_engine_mask[engine->id];
319 		}
320 	}
321 
322 	return gen6_hw_domain_reset(gt, hw_mask);
323 }
324 
325 static struct intel_engine_cs *find_sfc_paired_vecs_engine(struct intel_engine_cs *engine)
326 {
327 	int vecs_id;
328 
329 	GEM_BUG_ON(engine->class != VIDEO_DECODE_CLASS);
330 
331 	vecs_id = _VECS((engine->instance) / 2);
332 
333 	return engine->gt->engine[vecs_id];
334 }
335 
336 struct sfc_lock_data {
337 	i915_reg_t lock_reg;
338 	i915_reg_t ack_reg;
339 	i915_reg_t usage_reg;
340 	u32 lock_bit;
341 	u32 ack_bit;
342 	u32 usage_bit;
343 	u32 reset_bit;
344 };
345 
346 static void get_sfc_forced_lock_data(struct intel_engine_cs *engine,
347 				     struct sfc_lock_data *sfc_lock)
348 {
349 	switch (engine->class) {
350 	default:
351 		MISSING_CASE(engine->class);
352 		fallthrough;
353 	case VIDEO_DECODE_CLASS:
354 		sfc_lock->lock_reg = GEN11_VCS_SFC_FORCED_LOCK(engine);
355 		sfc_lock->lock_bit = GEN11_VCS_SFC_FORCED_LOCK_BIT;
356 
357 		sfc_lock->ack_reg = GEN11_VCS_SFC_LOCK_STATUS(engine);
358 		sfc_lock->ack_bit  = GEN11_VCS_SFC_LOCK_ACK_BIT;
359 
360 		sfc_lock->usage_reg = GEN11_VCS_SFC_LOCK_STATUS(engine);
361 		sfc_lock->usage_bit = GEN11_VCS_SFC_USAGE_BIT;
362 		sfc_lock->reset_bit = GEN11_VCS_SFC_RESET_BIT(engine->instance);
363 
364 		break;
365 	case VIDEO_ENHANCEMENT_CLASS:
366 		sfc_lock->lock_reg = GEN11_VECS_SFC_FORCED_LOCK(engine);
367 		sfc_lock->lock_bit = GEN11_VECS_SFC_FORCED_LOCK_BIT;
368 
369 		sfc_lock->ack_reg = GEN11_VECS_SFC_LOCK_ACK(engine);
370 		sfc_lock->ack_bit  = GEN11_VECS_SFC_LOCK_ACK_BIT;
371 
372 		sfc_lock->usage_reg = GEN11_VECS_SFC_USAGE(engine);
373 		sfc_lock->usage_bit = GEN11_VECS_SFC_USAGE_BIT;
374 		sfc_lock->reset_bit = GEN11_VECS_SFC_RESET_BIT(engine->instance);
375 
376 		break;
377 	}
378 }
379 
380 static int gen11_lock_sfc(struct intel_engine_cs *engine,
381 			  u32 *reset_mask,
382 			  u32 *unlock_mask)
383 {
384 	struct intel_uncore *uncore = engine->uncore;
385 	u8 vdbox_sfc_access = engine->gt->info.vdbox_sfc_access;
386 	struct sfc_lock_data sfc_lock;
387 	bool lock_obtained, lock_to_other = false;
388 	int ret;
389 
390 	switch (engine->class) {
391 	case VIDEO_DECODE_CLASS:
392 		if ((BIT(engine->instance) & vdbox_sfc_access) == 0)
393 			return 0;
394 
395 		fallthrough;
396 	case VIDEO_ENHANCEMENT_CLASS:
397 		get_sfc_forced_lock_data(engine, &sfc_lock);
398 
399 		break;
400 	default:
401 		return 0;
402 	}
403 
404 	if (!(intel_uncore_read_fw(uncore, sfc_lock.usage_reg) & sfc_lock.usage_bit)) {
405 		struct intel_engine_cs *paired_vecs;
406 
407 		if (engine->class != VIDEO_DECODE_CLASS ||
408 		    GRAPHICS_VER(engine->i915) != 12)
409 			return 0;
410 
411 		/*
412 		 * Wa_14010733141
413 		 *
414 		 * If the VCS-MFX isn't using the SFC, we also need to check
415 		 * whether VCS-HCP is using it.  If so, we need to issue a *VE*
416 		 * forced lock on the VE engine that shares the same SFC.
417 		 */
418 		if (!(intel_uncore_read_fw(uncore,
419 					   GEN12_HCP_SFC_LOCK_STATUS(engine)) &
420 		      GEN12_HCP_SFC_USAGE_BIT))
421 			return 0;
422 
423 		paired_vecs = find_sfc_paired_vecs_engine(engine);
424 		get_sfc_forced_lock_data(paired_vecs, &sfc_lock);
425 		lock_to_other = true;
426 		*unlock_mask |= paired_vecs->mask;
427 	} else {
428 		*unlock_mask |= engine->mask;
429 	}
430 
431 	/*
432 	 * If the engine is using an SFC, tell the engine that a software reset
433 	 * is going to happen. The engine will then try to force lock the SFC.
434 	 * If SFC ends up being locked to the engine we want to reset, we have
435 	 * to reset it as well (we will unlock it once the reset sequence is
436 	 * completed).
437 	 */
438 	rmw_set_fw(uncore, sfc_lock.lock_reg, sfc_lock.lock_bit);
439 
440 	ret = __intel_wait_for_register_fw(uncore,
441 					   sfc_lock.ack_reg,
442 					   sfc_lock.ack_bit,
443 					   sfc_lock.ack_bit,
444 					   1000, 0, NULL);
445 
446 	/*
447 	 * Was the SFC released while we were trying to lock it?
448 	 *
449 	 * We should reset both the engine and the SFC if:
450 	 *  - We were locking the SFC to this engine and the lock succeeded
451 	 *       OR
452 	 *  - We were locking the SFC to a different engine (Wa_14010733141)
453 	 *    but the SFC was released before the lock was obtained.
454 	 *
455 	 * Otherwise we need only reset the engine by itself and we can
456 	 * leave the SFC alone.
457 	 */
458 	lock_obtained = (intel_uncore_read_fw(uncore, sfc_lock.usage_reg) &
459 			sfc_lock.usage_bit) != 0;
460 	if (lock_obtained == lock_to_other)
461 		return 0;
462 
463 	if (ret) {
464 		ENGINE_TRACE(engine, "Wait for SFC forced lock ack failed\n");
465 		return ret;
466 	}
467 
468 	*reset_mask |= sfc_lock.reset_bit;
469 	return 0;
470 }
471 
472 static void gen11_unlock_sfc(struct intel_engine_cs *engine)
473 {
474 	struct intel_uncore *uncore = engine->uncore;
475 	u8 vdbox_sfc_access = engine->gt->info.vdbox_sfc_access;
476 	struct sfc_lock_data sfc_lock = {};
477 
478 	if (engine->class != VIDEO_DECODE_CLASS &&
479 	    engine->class != VIDEO_ENHANCEMENT_CLASS)
480 		return;
481 
482 	if (engine->class == VIDEO_DECODE_CLASS &&
483 	    (BIT(engine->instance) & vdbox_sfc_access) == 0)
484 		return;
485 
486 	get_sfc_forced_lock_data(engine, &sfc_lock);
487 
488 	rmw_clear_fw(uncore, sfc_lock.lock_reg, sfc_lock.lock_bit);
489 }
490 
491 static int gen11_reset_engines(struct intel_gt *gt,
492 			       intel_engine_mask_t engine_mask,
493 			       unsigned int retry)
494 {
495 	static const u32 hw_engine_mask[] = {
496 		[RCS0]  = GEN11_GRDOM_RENDER,
497 		[BCS0]  = GEN11_GRDOM_BLT,
498 		[VCS0]  = GEN11_GRDOM_MEDIA,
499 		[VCS1]  = GEN11_GRDOM_MEDIA2,
500 		[VCS2]  = GEN11_GRDOM_MEDIA3,
501 		[VCS3]  = GEN11_GRDOM_MEDIA4,
502 		[VCS4]  = GEN11_GRDOM_MEDIA5,
503 		[VCS5]  = GEN11_GRDOM_MEDIA6,
504 		[VCS6]  = GEN11_GRDOM_MEDIA7,
505 		[VCS7]  = GEN11_GRDOM_MEDIA8,
506 		[VECS0] = GEN11_GRDOM_VECS,
507 		[VECS1] = GEN11_GRDOM_VECS2,
508 		[VECS2] = GEN11_GRDOM_VECS3,
509 		[VECS3] = GEN11_GRDOM_VECS4,
510 	};
511 	struct intel_engine_cs *engine;
512 	intel_engine_mask_t tmp;
513 	u32 reset_mask, unlock_mask = 0;
514 	int ret;
515 
516 	if (engine_mask == ALL_ENGINES) {
517 		reset_mask = GEN11_GRDOM_FULL;
518 	} else {
519 		reset_mask = 0;
520 		for_each_engine_masked(engine, gt, engine_mask, tmp) {
521 			GEM_BUG_ON(engine->id >= ARRAY_SIZE(hw_engine_mask));
522 			reset_mask |= hw_engine_mask[engine->id];
523 			ret = gen11_lock_sfc(engine, &reset_mask, &unlock_mask);
524 			if (ret)
525 				goto sfc_unlock;
526 		}
527 	}
528 
529 	ret = gen6_hw_domain_reset(gt, reset_mask);
530 
531 sfc_unlock:
532 	/*
533 	 * We unlock the SFC based on the lock status and not the result of
534 	 * gen11_lock_sfc to make sure that we clean properly if something
535 	 * wrong happened during the lock (e.g. lock acquired after timeout
536 	 * expiration).
537 	 *
538 	 * Due to Wa_14010733141, we may have locked an SFC to an engine that
539 	 * wasn't being reset.  So instead of calling gen11_unlock_sfc()
540 	 * on engine_mask, we instead call it on the mask of engines that our
541 	 * gen11_lock_sfc() calls told us actually had locks attempted.
542 	 */
543 	for_each_engine_masked(engine, gt, unlock_mask, tmp)
544 		gen11_unlock_sfc(engine);
545 
546 	return ret;
547 }
548 
549 static int gen8_engine_reset_prepare(struct intel_engine_cs *engine)
550 {
551 	struct intel_uncore *uncore = engine->uncore;
552 	const i915_reg_t reg = RING_RESET_CTL(engine->mmio_base);
553 	u32 request, mask, ack;
554 	int ret;
555 
556 	if (I915_SELFTEST_ONLY(should_fail(&engine->reset_timeout, 1)))
557 		return -ETIMEDOUT;
558 
559 	ack = intel_uncore_read_fw(uncore, reg);
560 	if (ack & RESET_CTL_CAT_ERROR) {
561 		/*
562 		 * For catastrophic errors, ready-for-reset sequence
563 		 * needs to be bypassed: HAS#396813
564 		 */
565 		request = RESET_CTL_CAT_ERROR;
566 		mask = RESET_CTL_CAT_ERROR;
567 
568 		/* Catastrophic errors need to be cleared by HW */
569 		ack = 0;
570 	} else if (!(ack & RESET_CTL_READY_TO_RESET)) {
571 		request = RESET_CTL_REQUEST_RESET;
572 		mask = RESET_CTL_READY_TO_RESET;
573 		ack = RESET_CTL_READY_TO_RESET;
574 	} else {
575 		return 0;
576 	}
577 
578 	intel_uncore_write_fw(uncore, reg, _MASKED_BIT_ENABLE(request));
579 	ret = __intel_wait_for_register_fw(uncore, reg, mask, ack,
580 					   700, 0, NULL);
581 	if (ret)
582 		drm_err(&engine->i915->drm,
583 			"%s reset request timed out: {request: %08x, RESET_CTL: %08x}\n",
584 			engine->name, request,
585 			intel_uncore_read_fw(uncore, reg));
586 
587 	return ret;
588 }
589 
590 static void gen8_engine_reset_cancel(struct intel_engine_cs *engine)
591 {
592 	intel_uncore_write_fw(engine->uncore,
593 			      RING_RESET_CTL(engine->mmio_base),
594 			      _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET));
595 }
596 
597 static int gen8_reset_engines(struct intel_gt *gt,
598 			      intel_engine_mask_t engine_mask,
599 			      unsigned int retry)
600 {
601 	struct intel_engine_cs *engine;
602 	const bool reset_non_ready = retry >= 1;
603 	intel_engine_mask_t tmp;
604 	int ret;
605 
606 	for_each_engine_masked(engine, gt, engine_mask, tmp) {
607 		ret = gen8_engine_reset_prepare(engine);
608 		if (ret && !reset_non_ready)
609 			goto skip_reset;
610 
611 		/*
612 		 * If this is not the first failed attempt to prepare,
613 		 * we decide to proceed anyway.
614 		 *
615 		 * By doing so we risk context corruption and with
616 		 * some gens (kbl), possible system hang if reset
617 		 * happens during active bb execution.
618 		 *
619 		 * We rather take context corruption instead of
620 		 * failed reset with a wedged driver/gpu. And
621 		 * active bb execution case should be covered by
622 		 * stop_engines() we have before the reset.
623 		 */
624 	}
625 
626 	if (GRAPHICS_VER(gt->i915) >= 11)
627 		ret = gen11_reset_engines(gt, engine_mask, retry);
628 	else
629 		ret = gen6_reset_engines(gt, engine_mask, retry);
630 
631 skip_reset:
632 	for_each_engine_masked(engine, gt, engine_mask, tmp)
633 		gen8_engine_reset_cancel(engine);
634 
635 	return ret;
636 }
637 
638 static int mock_reset(struct intel_gt *gt,
639 		      intel_engine_mask_t mask,
640 		      unsigned int retry)
641 {
642 	return 0;
643 }
644 
645 typedef int (*reset_func)(struct intel_gt *,
646 			  intel_engine_mask_t engine_mask,
647 			  unsigned int retry);
648 
649 static reset_func intel_get_gpu_reset(const struct intel_gt *gt)
650 {
651 	struct drm_i915_private *i915 = gt->i915;
652 
653 	if (is_mock_gt(gt))
654 		return mock_reset;
655 	else if (GRAPHICS_VER(i915) >= 8)
656 		return gen8_reset_engines;
657 	else if (GRAPHICS_VER(i915) >= 6)
658 		return gen6_reset_engines;
659 	else if (GRAPHICS_VER(i915) >= 5)
660 		return ilk_do_reset;
661 	else if (IS_G4X(i915))
662 		return g4x_do_reset;
663 	else if (IS_G33(i915) || IS_PINEVIEW(i915))
664 		return g33_do_reset;
665 	else if (GRAPHICS_VER(i915) >= 3)
666 		return i915_do_reset;
667 	else
668 		return NULL;
669 }
670 
671 int __intel_gt_reset(struct intel_gt *gt, intel_engine_mask_t engine_mask)
672 {
673 	const int retries = engine_mask == ALL_ENGINES ? RESET_MAX_RETRIES : 1;
674 	reset_func reset;
675 	int ret = -ETIMEDOUT;
676 	int retry;
677 
678 	reset = intel_get_gpu_reset(gt);
679 	if (!reset)
680 		return -ENODEV;
681 
682 	/*
683 	 * If the power well sleeps during the reset, the reset
684 	 * request may be dropped and never completes (causing -EIO).
685 	 */
686 	intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_ALL);
687 	for (retry = 0; ret == -ETIMEDOUT && retry < retries; retry++) {
688 		GT_TRACE(gt, "engine_mask=%x\n", engine_mask);
689 		preempt_disable();
690 		ret = reset(gt, engine_mask, retry);
691 		preempt_enable();
692 	}
693 	intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_ALL);
694 
695 	return ret;
696 }
697 
698 bool intel_has_gpu_reset(const struct intel_gt *gt)
699 {
700 	if (!gt->i915->params.reset)
701 		return NULL;
702 
703 	return intel_get_gpu_reset(gt);
704 }
705 
706 bool intel_has_reset_engine(const struct intel_gt *gt)
707 {
708 	if (gt->i915->params.reset < 2)
709 		return false;
710 
711 	return INTEL_INFO(gt->i915)->has_reset_engine;
712 }
713 
714 int intel_reset_guc(struct intel_gt *gt)
715 {
716 	u32 guc_domain =
717 		GRAPHICS_VER(gt->i915) >= 11 ? GEN11_GRDOM_GUC : GEN9_GRDOM_GUC;
718 	int ret;
719 
720 	GEM_BUG_ON(!HAS_GT_UC(gt->i915));
721 
722 	intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_ALL);
723 	ret = gen6_hw_domain_reset(gt, guc_domain);
724 	intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_ALL);
725 
726 	return ret;
727 }
728 
729 /*
730  * Ensure irq handler finishes, and not run again.
731  * Also return the active request so that we only search for it once.
732  */
733 static void reset_prepare_engine(struct intel_engine_cs *engine)
734 {
735 	/*
736 	 * During the reset sequence, we must prevent the engine from
737 	 * entering RC6. As the context state is undefined until we restart
738 	 * the engine, if it does enter RC6 during the reset, the state
739 	 * written to the powercontext is undefined and so we may lose
740 	 * GPU state upon resume, i.e. fail to restart after a reset.
741 	 */
742 	intel_uncore_forcewake_get(engine->uncore, FORCEWAKE_ALL);
743 	if (engine->reset.prepare)
744 		engine->reset.prepare(engine);
745 }
746 
747 static void revoke_mmaps(struct intel_gt *gt)
748 {
749 	int i;
750 
751 	for (i = 0; i < gt->ggtt->num_fences; i++) {
752 		struct drm_vma_offset_node *node;
753 		struct i915_vma *vma;
754 		u64 vma_offset;
755 
756 		vma = READ_ONCE(gt->ggtt->fence_regs[i].vma);
757 		if (!vma)
758 			continue;
759 
760 		if (!i915_vma_has_userfault(vma))
761 			continue;
762 
763 		GEM_BUG_ON(vma->fence != &gt->ggtt->fence_regs[i]);
764 
765 		if (!vma->mmo)
766 			continue;
767 
768 		node = &vma->mmo->vma_node;
769 		vma_offset = vma->ggtt_view.partial.offset << PAGE_SHIFT;
770 
771 		unmap_mapping_range(gt->i915->drm.anon_inode->i_mapping,
772 				    drm_vma_node_offset_addr(node) + vma_offset,
773 				    vma->size,
774 				    1);
775 	}
776 }
777 
778 static intel_engine_mask_t reset_prepare(struct intel_gt *gt)
779 {
780 	struct intel_engine_cs *engine;
781 	intel_engine_mask_t awake = 0;
782 	enum intel_engine_id id;
783 
784 	for_each_engine(engine, gt, id) {
785 		if (intel_engine_pm_get_if_awake(engine))
786 			awake |= engine->mask;
787 		reset_prepare_engine(engine);
788 	}
789 
790 	intel_uc_reset_prepare(&gt->uc);
791 
792 	return awake;
793 }
794 
795 static void gt_revoke(struct intel_gt *gt)
796 {
797 	revoke_mmaps(gt);
798 }
799 
800 static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
801 {
802 	struct intel_engine_cs *engine;
803 	enum intel_engine_id id;
804 	int err;
805 
806 	/*
807 	 * Everything depends on having the GTT running, so we need to start
808 	 * there.
809 	 */
810 	err = i915_ggtt_enable_hw(gt->i915);
811 	if (err)
812 		return err;
813 
814 	local_bh_disable();
815 	for_each_engine(engine, gt, id)
816 		__intel_engine_reset(engine, stalled_mask & engine->mask);
817 	local_bh_enable();
818 
819 	intel_uc_reset(&gt->uc, true);
820 
821 	intel_ggtt_restore_fences(gt->ggtt);
822 
823 	return err;
824 }
825 
826 static void reset_finish_engine(struct intel_engine_cs *engine)
827 {
828 	if (engine->reset.finish)
829 		engine->reset.finish(engine);
830 	intel_uncore_forcewake_put(engine->uncore, FORCEWAKE_ALL);
831 
832 	intel_engine_signal_breadcrumbs(engine);
833 }
834 
835 static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
836 {
837 	struct intel_engine_cs *engine;
838 	enum intel_engine_id id;
839 
840 	for_each_engine(engine, gt, id) {
841 		reset_finish_engine(engine);
842 		if (awake & engine->mask)
843 			intel_engine_pm_put(engine);
844 	}
845 
846 	intel_uc_reset_finish(&gt->uc);
847 }
848 
849 static void nop_submit_request(struct i915_request *request)
850 {
851 	RQ_TRACE(request, "-EIO\n");
852 
853 	request = i915_request_mark_eio(request);
854 	if (request) {
855 		i915_request_submit(request);
856 		intel_engine_signal_breadcrumbs(request->engine);
857 
858 		i915_request_put(request);
859 	}
860 }
861 
862 static void __intel_gt_set_wedged(struct intel_gt *gt)
863 {
864 	struct intel_engine_cs *engine;
865 	intel_engine_mask_t awake;
866 	enum intel_engine_id id;
867 
868 	if (test_bit(I915_WEDGED, &gt->reset.flags))
869 		return;
870 
871 	GT_TRACE(gt, "start\n");
872 
873 	/*
874 	 * First, stop submission to hw, but do not yet complete requests by
875 	 * rolling the global seqno forward (since this would complete requests
876 	 * for which we haven't set the fence error to EIO yet).
877 	 */
878 	awake = reset_prepare(gt);
879 
880 	/* Even if the GPU reset fails, it should still stop the engines */
881 	if (!INTEL_INFO(gt->i915)->gpu_reset_clobbers_display)
882 		__intel_gt_reset(gt, ALL_ENGINES);
883 
884 	for_each_engine(engine, gt, id)
885 		engine->submit_request = nop_submit_request;
886 
887 	/*
888 	 * Make sure no request can slip through without getting completed by
889 	 * either this call here to intel_engine_write_global_seqno, or the one
890 	 * in nop_submit_request.
891 	 */
892 	synchronize_rcu_expedited();
893 	set_bit(I915_WEDGED, &gt->reset.flags);
894 
895 	/* Mark all executing requests as skipped */
896 	local_bh_disable();
897 	for_each_engine(engine, gt, id)
898 		if (engine->reset.cancel)
899 			engine->reset.cancel(engine);
900 	intel_uc_cancel_requests(&gt->uc);
901 	local_bh_enable();
902 
903 	reset_finish(gt, awake);
904 
905 	GT_TRACE(gt, "end\n");
906 }
907 
908 void intel_gt_set_wedged(struct intel_gt *gt)
909 {
910 	intel_wakeref_t wakeref;
911 
912 	if (test_bit(I915_WEDGED, &gt->reset.flags))
913 		return;
914 
915 	wakeref = intel_runtime_pm_get(gt->uncore->rpm);
916 	mutex_lock(&gt->reset.mutex);
917 
918 	if (GEM_SHOW_DEBUG()) {
919 		struct drm_printer p = drm_debug_printer(__func__);
920 		struct intel_engine_cs *engine;
921 		enum intel_engine_id id;
922 
923 		drm_printf(&p, "called from %pS\n", (void *)_RET_IP_);
924 		for_each_engine(engine, gt, id) {
925 			if (intel_engine_is_idle(engine))
926 				continue;
927 
928 			intel_engine_dump(engine, &p, "%s\n", engine->name);
929 		}
930 	}
931 
932 	__intel_gt_set_wedged(gt);
933 
934 	mutex_unlock(&gt->reset.mutex);
935 	intel_runtime_pm_put(gt->uncore->rpm, wakeref);
936 }
937 
938 static bool __intel_gt_unset_wedged(struct intel_gt *gt)
939 {
940 	struct intel_gt_timelines *timelines = &gt->timelines;
941 	struct intel_timeline *tl;
942 	bool ok;
943 
944 	if (!test_bit(I915_WEDGED, &gt->reset.flags))
945 		return true;
946 
947 	/* Never fully initialised, recovery impossible */
948 	if (intel_gt_has_unrecoverable_error(gt))
949 		return false;
950 
951 	GT_TRACE(gt, "start\n");
952 
953 	/*
954 	 * Before unwedging, make sure that all pending operations
955 	 * are flushed and errored out - we may have requests waiting upon
956 	 * third party fences. We marked all inflight requests as EIO, and
957 	 * every execbuf since returned EIO, for consistency we want all
958 	 * the currently pending requests to also be marked as EIO, which
959 	 * is done inside our nop_submit_request - and so we must wait.
960 	 *
961 	 * No more can be submitted until we reset the wedged bit.
962 	 */
963 	spin_lock(&timelines->lock);
964 	list_for_each_entry(tl, &timelines->active_list, link) {
965 		struct dma_fence *fence;
966 
967 		fence = i915_active_fence_get(&tl->last_request);
968 		if (!fence)
969 			continue;
970 
971 		spin_unlock(&timelines->lock);
972 
973 		/*
974 		 * All internal dependencies (i915_requests) will have
975 		 * been flushed by the set-wedge, but we may be stuck waiting
976 		 * for external fences. These should all be capped to 10s
977 		 * (I915_FENCE_TIMEOUT) so this wait should not be unbounded
978 		 * in the worst case.
979 		 */
980 		dma_fence_default_wait(fence, false, MAX_SCHEDULE_TIMEOUT);
981 		dma_fence_put(fence);
982 
983 		/* Restart iteration after droping lock */
984 		spin_lock(&timelines->lock);
985 		tl = list_entry(&timelines->active_list, typeof(*tl), link);
986 	}
987 	spin_unlock(&timelines->lock);
988 
989 	/* We must reset pending GPU events before restoring our submission */
990 	ok = !HAS_EXECLISTS(gt->i915); /* XXX better agnosticism desired */
991 	if (!INTEL_INFO(gt->i915)->gpu_reset_clobbers_display)
992 		ok = __intel_gt_reset(gt, ALL_ENGINES) == 0;
993 	if (!ok) {
994 		/*
995 		 * Warn CI about the unrecoverable wedged condition.
996 		 * Time for a reboot.
997 		 */
998 		add_taint_for_CI(gt->i915, TAINT_WARN);
999 		return false;
1000 	}
1001 
1002 	/*
1003 	 * Undo nop_submit_request. We prevent all new i915 requests from
1004 	 * being queued (by disallowing execbuf whilst wedged) so having
1005 	 * waited for all active requests above, we know the system is idle
1006 	 * and do not have to worry about a thread being inside
1007 	 * engine->submit_request() as we swap over. So unlike installing
1008 	 * the nop_submit_request on reset, we can do this from normal
1009 	 * context and do not require stop_machine().
1010 	 */
1011 	intel_engines_reset_default_submission(gt);
1012 
1013 	GT_TRACE(gt, "end\n");
1014 
1015 	smp_mb__before_atomic(); /* complete takeover before enabling execbuf */
1016 	clear_bit(I915_WEDGED, &gt->reset.flags);
1017 
1018 	return true;
1019 }
1020 
1021 bool intel_gt_unset_wedged(struct intel_gt *gt)
1022 {
1023 	bool result;
1024 
1025 	mutex_lock(&gt->reset.mutex);
1026 	result = __intel_gt_unset_wedged(gt);
1027 	mutex_unlock(&gt->reset.mutex);
1028 
1029 	return result;
1030 }
1031 
1032 static int do_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
1033 {
1034 	int err, i;
1035 
1036 	err = __intel_gt_reset(gt, ALL_ENGINES);
1037 	for (i = 0; err && i < RESET_MAX_RETRIES; i++) {
1038 		msleep(10 * (i + 1));
1039 		err = __intel_gt_reset(gt, ALL_ENGINES);
1040 	}
1041 	if (err)
1042 		return err;
1043 
1044 	return gt_reset(gt, stalled_mask);
1045 }
1046 
1047 static int resume(struct intel_gt *gt)
1048 {
1049 	struct intel_engine_cs *engine;
1050 	enum intel_engine_id id;
1051 	int ret;
1052 
1053 	for_each_engine(engine, gt, id) {
1054 		ret = intel_engine_resume(engine);
1055 		if (ret)
1056 			return ret;
1057 	}
1058 
1059 	return 0;
1060 }
1061 
1062 /**
1063  * intel_gt_reset - reset chip after a hang
1064  * @gt: #intel_gt to reset
1065  * @stalled_mask: mask of the stalled engines with the guilty requests
1066  * @reason: user error message for why we are resetting
1067  *
1068  * Reset the chip.  Useful if a hang is detected. Marks the device as wedged
1069  * on failure.
1070  *
1071  * Procedure is fairly simple:
1072  *   - reset the chip using the reset reg
1073  *   - re-init context state
1074  *   - re-init hardware status page
1075  *   - re-init ring buffer
1076  *   - re-init interrupt state
1077  *   - re-init display
1078  */
1079 void intel_gt_reset(struct intel_gt *gt,
1080 		    intel_engine_mask_t stalled_mask,
1081 		    const char *reason)
1082 {
1083 	intel_engine_mask_t awake;
1084 	int ret;
1085 
1086 	GT_TRACE(gt, "flags=%lx\n", gt->reset.flags);
1087 
1088 	might_sleep();
1089 	GEM_BUG_ON(!test_bit(I915_RESET_BACKOFF, &gt->reset.flags));
1090 
1091 	/*
1092 	 * FIXME: Revoking cpu mmap ptes cannot be done from a dma_fence
1093 	 * critical section like gpu reset.
1094 	 */
1095 	gt_revoke(gt);
1096 
1097 	mutex_lock(&gt->reset.mutex);
1098 
1099 	/* Clear any previous failed attempts at recovery. Time to try again. */
1100 	if (!__intel_gt_unset_wedged(gt))
1101 		goto unlock;
1102 
1103 	if (reason)
1104 		drm_notice(&gt->i915->drm,
1105 			   "Resetting chip for %s\n", reason);
1106 	atomic_inc(&gt->i915->gpu_error.reset_count);
1107 
1108 	awake = reset_prepare(gt);
1109 
1110 	if (!intel_has_gpu_reset(gt)) {
1111 		if (gt->i915->params.reset)
1112 			drm_err(&gt->i915->drm, "GPU reset not supported\n");
1113 		else
1114 			drm_dbg(&gt->i915->drm, "GPU reset disabled\n");
1115 		goto error;
1116 	}
1117 
1118 	if (INTEL_INFO(gt->i915)->gpu_reset_clobbers_display)
1119 		intel_runtime_pm_disable_interrupts(gt->i915);
1120 
1121 	if (do_reset(gt, stalled_mask)) {
1122 		drm_err(&gt->i915->drm, "Failed to reset chip\n");
1123 		goto taint;
1124 	}
1125 
1126 	if (INTEL_INFO(gt->i915)->gpu_reset_clobbers_display)
1127 		intel_runtime_pm_enable_interrupts(gt->i915);
1128 
1129 	intel_overlay_reset(gt->i915);
1130 
1131 	/*
1132 	 * Next we need to restore the context, but we don't use those
1133 	 * yet either...
1134 	 *
1135 	 * Ring buffer needs to be re-initialized in the KMS case, or if X
1136 	 * was running at the time of the reset (i.e. we weren't VT
1137 	 * switched away).
1138 	 */
1139 	ret = intel_gt_init_hw(gt);
1140 	if (ret) {
1141 		drm_err(&gt->i915->drm,
1142 			"Failed to initialise HW following reset (%d)\n",
1143 			ret);
1144 		goto taint;
1145 	}
1146 
1147 	ret = resume(gt);
1148 	if (ret)
1149 		goto taint;
1150 
1151 finish:
1152 	reset_finish(gt, awake);
1153 unlock:
1154 	mutex_unlock(&gt->reset.mutex);
1155 	return;
1156 
1157 taint:
1158 	/*
1159 	 * History tells us that if we cannot reset the GPU now, we
1160 	 * never will. This then impacts everything that is run
1161 	 * subsequently. On failing the reset, we mark the driver
1162 	 * as wedged, preventing further execution on the GPU.
1163 	 * We also want to go one step further and add a taint to the
1164 	 * kernel so that any subsequent faults can be traced back to
1165 	 * this failure. This is important for CI, where if the
1166 	 * GPU/driver fails we would like to reboot and restart testing
1167 	 * rather than continue on into oblivion. For everyone else,
1168 	 * the system should still plod along, but they have been warned!
1169 	 */
1170 	add_taint_for_CI(gt->i915, TAINT_WARN);
1171 error:
1172 	__intel_gt_set_wedged(gt);
1173 	goto finish;
1174 }
1175 
1176 static int intel_gt_reset_engine(struct intel_engine_cs *engine)
1177 {
1178 	return __intel_gt_reset(engine->gt, engine->mask);
1179 }
1180 
1181 int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
1182 {
1183 	struct intel_gt *gt = engine->gt;
1184 	int ret;
1185 
1186 	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
1187 	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
1188 
1189 	if (intel_engine_uses_guc(engine))
1190 		return -ENODEV;
1191 
1192 	if (!intel_engine_pm_get_if_awake(engine))
1193 		return 0;
1194 
1195 	reset_prepare_engine(engine);
1196 
1197 	if (msg)
1198 		drm_notice(&engine->i915->drm,
1199 			   "Resetting %s for %s\n", engine->name, msg);
1200 	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
1201 
1202 	ret = intel_gt_reset_engine(engine);
1203 	if (ret) {
1204 		/* If we fail here, we expect to fallback to a global reset */
1205 		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
1206 		goto out;
1207 	}
1208 
1209 	/*
1210 	 * The request that caused the hang is stuck on elsp, we know the
1211 	 * active request and can drop it, adjust head to skip the offending
1212 	 * request to resume executing remaining requests in the queue.
1213 	 */
1214 	__intel_engine_reset(engine, true);
1215 
1216 	/*
1217 	 * The engine and its registers (and workarounds in case of render)
1218 	 * have been reset to their default values. Follow the init_ring
1219 	 * process to program RING_MODE, HWSP and re-enable submission.
1220 	 */
1221 	ret = intel_engine_resume(engine);
1222 
1223 out:
1224 	intel_engine_cancel_stop_cs(engine);
1225 	reset_finish_engine(engine);
1226 	intel_engine_pm_put_async(engine);
1227 	return ret;
1228 }
1229 
1230 /**
1231  * intel_engine_reset - reset GPU engine to recover from a hang
1232  * @engine: engine to reset
1233  * @msg: reason for GPU reset; or NULL for no drm_notice()
1234  *
1235  * Reset a specific GPU engine. Useful if a hang is detected.
1236  * Returns zero on successful reset or otherwise an error code.
1237  *
1238  * Procedure is:
1239  *  - identifies the request that caused the hang and it is dropped
1240  *  - reset engine (which will force the engine to idle)
1241  *  - re-init/configure engine
1242  */
1243 int intel_engine_reset(struct intel_engine_cs *engine, const char *msg)
1244 {
1245 	int err;
1246 
1247 	local_bh_disable();
1248 	err = __intel_engine_reset_bh(engine, msg);
1249 	local_bh_enable();
1250 
1251 	return err;
1252 }
1253 
1254 static void intel_gt_reset_global(struct intel_gt *gt,
1255 				  u32 engine_mask,
1256 				  const char *reason)
1257 {
1258 	struct kobject *kobj = &gt->i915->drm.primary->kdev->kobj;
1259 	char *error_event[] = { I915_ERROR_UEVENT "=1", NULL };
1260 	char *reset_event[] = { I915_RESET_UEVENT "=1", NULL };
1261 	char *reset_done_event[] = { I915_ERROR_UEVENT "=0", NULL };
1262 	struct intel_wedge_me w;
1263 
1264 	kobject_uevent_env(kobj, KOBJ_CHANGE, error_event);
1265 
1266 	GT_TRACE(gt, "resetting chip, engines=%x\n", engine_mask);
1267 	kobject_uevent_env(kobj, KOBJ_CHANGE, reset_event);
1268 
1269 	/* Use a watchdog to ensure that our reset completes */
1270 	intel_wedge_on_timeout(&w, gt, 5 * HZ) {
1271 		intel_display_prepare_reset(gt->i915);
1272 
1273 		/* Flush everyone using a resource about to be clobbered */
1274 		synchronize_srcu_expedited(&gt->reset.backoff_srcu);
1275 
1276 		intel_gt_reset(gt, engine_mask, reason);
1277 
1278 		intel_display_finish_reset(gt->i915);
1279 	}
1280 
1281 	if (!test_bit(I915_WEDGED, &gt->reset.flags))
1282 		kobject_uevent_env(kobj, KOBJ_CHANGE, reset_done_event);
1283 }
1284 
1285 /**
1286  * intel_gt_handle_error - handle a gpu error
1287  * @gt: the intel_gt
1288  * @engine_mask: mask representing engines that are hung
1289  * @flags: control flags
1290  * @fmt: Error message format string
1291  *
1292  * Do some basic checking of register state at error time and
1293  * dump it to the syslog.  Also call i915_capture_error_state() to make
1294  * sure we get a record and make it available in debugfs.  Fire a uevent
1295  * so userspace knows something bad happened (should trigger collection
1296  * of a ring dump etc.).
1297  */
1298 void intel_gt_handle_error(struct intel_gt *gt,
1299 			   intel_engine_mask_t engine_mask,
1300 			   unsigned long flags,
1301 			   const char *fmt, ...)
1302 {
1303 	struct intel_engine_cs *engine;
1304 	intel_wakeref_t wakeref;
1305 	intel_engine_mask_t tmp;
1306 	char error_msg[80];
1307 	char *msg = NULL;
1308 
1309 	if (fmt) {
1310 		va_list args;
1311 
1312 		va_start(args, fmt);
1313 		vscnprintf(error_msg, sizeof(error_msg), fmt, args);
1314 		va_end(args);
1315 
1316 		msg = error_msg;
1317 	}
1318 
1319 	/*
1320 	 * In most cases it's guaranteed that we get here with an RPM
1321 	 * reference held, for example because there is a pending GPU
1322 	 * request that won't finish until the reset is done. This
1323 	 * isn't the case at least when we get here by doing a
1324 	 * simulated reset via debugfs, so get an RPM reference.
1325 	 */
1326 	wakeref = intel_runtime_pm_get(gt->uncore->rpm);
1327 
1328 	engine_mask &= gt->info.engine_mask;
1329 
1330 	if (flags & I915_ERROR_CAPTURE) {
1331 		i915_capture_error_state(gt, engine_mask);
1332 		intel_gt_clear_error_registers(gt, engine_mask);
1333 	}
1334 
1335 	/*
1336 	 * Try engine reset when available. We fall back to full reset if
1337 	 * single reset fails.
1338 	 */
1339 	if (!intel_uc_uses_guc_submission(&gt->uc) &&
1340 	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
1341 		local_bh_disable();
1342 		for_each_engine_masked(engine, gt, engine_mask, tmp) {
1343 			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
1344 			if (test_and_set_bit(I915_RESET_ENGINE + engine->id,
1345 					     &gt->reset.flags))
1346 				continue;
1347 
1348 			if (__intel_engine_reset_bh(engine, msg) == 0)
1349 				engine_mask &= ~engine->mask;
1350 
1351 			clear_and_wake_up_bit(I915_RESET_ENGINE + engine->id,
1352 					      &gt->reset.flags);
1353 		}
1354 		local_bh_enable();
1355 	}
1356 
1357 	if (!engine_mask)
1358 		goto out;
1359 
1360 	/* Full reset needs the mutex, stop any other user trying to do so. */
1361 	if (test_and_set_bit(I915_RESET_BACKOFF, &gt->reset.flags)) {
1362 		wait_event(gt->reset.queue,
1363 			   !test_bit(I915_RESET_BACKOFF, &gt->reset.flags));
1364 		goto out; /* piggy-back on the other reset */
1365 	}
1366 
1367 	/* Make sure i915_reset_trylock() sees the I915_RESET_BACKOFF */
1368 	synchronize_rcu_expedited();
1369 
1370 	/* Prevent any other reset-engine attempt. */
1371 	for_each_engine(engine, gt, tmp) {
1372 		while (test_and_set_bit(I915_RESET_ENGINE + engine->id,
1373 					&gt->reset.flags))
1374 			wait_on_bit(&gt->reset.flags,
1375 				    I915_RESET_ENGINE + engine->id,
1376 				    TASK_UNINTERRUPTIBLE);
1377 	}
1378 
1379 	intel_gt_reset_global(gt, engine_mask, msg);
1380 
1381 	for_each_engine(engine, gt, tmp)
1382 		clear_bit_unlock(I915_RESET_ENGINE + engine->id,
1383 				 &gt->reset.flags);
1384 	clear_bit_unlock(I915_RESET_BACKOFF, &gt->reset.flags);
1385 	smp_mb__after_atomic();
1386 	wake_up_all(&gt->reset.queue);
1387 
1388 out:
1389 	intel_runtime_pm_put(gt->uncore->rpm, wakeref);
1390 }
1391 
1392 int intel_gt_reset_trylock(struct intel_gt *gt, int *srcu)
1393 {
1394 	might_lock(&gt->reset.backoff_srcu);
1395 	might_sleep();
1396 
1397 	rcu_read_lock();
1398 	while (test_bit(I915_RESET_BACKOFF, &gt->reset.flags)) {
1399 		rcu_read_unlock();
1400 
1401 		if (wait_event_interruptible(gt->reset.queue,
1402 					     !test_bit(I915_RESET_BACKOFF,
1403 						       &gt->reset.flags)))
1404 			return -EINTR;
1405 
1406 		rcu_read_lock();
1407 	}
1408 	*srcu = srcu_read_lock(&gt->reset.backoff_srcu);
1409 	rcu_read_unlock();
1410 
1411 	return 0;
1412 }
1413 
1414 void intel_gt_reset_unlock(struct intel_gt *gt, int tag)
1415 __releases(&gt->reset.backoff_srcu)
1416 {
1417 	srcu_read_unlock(&gt->reset.backoff_srcu, tag);
1418 }
1419 
1420 int intel_gt_terminally_wedged(struct intel_gt *gt)
1421 {
1422 	might_sleep();
1423 
1424 	if (!intel_gt_is_wedged(gt))
1425 		return 0;
1426 
1427 	if (intel_gt_has_unrecoverable_error(gt))
1428 		return -EIO;
1429 
1430 	/* Reset still in progress? Maybe we will recover? */
1431 	if (wait_event_interruptible(gt->reset.queue,
1432 				     !test_bit(I915_RESET_BACKOFF,
1433 					       &gt->reset.flags)))
1434 		return -EINTR;
1435 
1436 	return intel_gt_is_wedged(gt) ? -EIO : 0;
1437 }
1438 
1439 void intel_gt_set_wedged_on_init(struct intel_gt *gt)
1440 {
1441 	BUILD_BUG_ON(I915_RESET_ENGINE + I915_NUM_ENGINES >
1442 		     I915_WEDGED_ON_INIT);
1443 	intel_gt_set_wedged(gt);
1444 	set_bit(I915_WEDGED_ON_INIT, &gt->reset.flags);
1445 
1446 	/* Wedged on init is non-recoverable */
1447 	add_taint_for_CI(gt->i915, TAINT_WARN);
1448 }
1449 
1450 void intel_gt_set_wedged_on_fini(struct intel_gt *gt)
1451 {
1452 	intel_gt_set_wedged(gt);
1453 	set_bit(I915_WEDGED_ON_FINI, &gt->reset.flags);
1454 	intel_gt_retire_requests(gt); /* cleanup any wedged requests */
1455 }
1456 
1457 void intel_gt_init_reset(struct intel_gt *gt)
1458 {
1459 	init_waitqueue_head(&gt->reset.queue);
1460 	mutex_init(&gt->reset.mutex);
1461 	init_srcu_struct(&gt->reset.backoff_srcu);
1462 
1463 	/*
1464 	 * While undesirable to wait inside the shrinker, complain anyway.
1465 	 *
1466 	 * If we have to wait during shrinking, we guarantee forward progress
1467 	 * by forcing the reset. Therefore during the reset we must not
1468 	 * re-enter the shrinker. By declaring that we take the reset mutex
1469 	 * within the shrinker, we forbid ourselves from performing any
1470 	 * fs-reclaim or taking related locks during reset.
1471 	 */
1472 	i915_gem_shrinker_taints_mutex(gt->i915, &gt->reset.mutex);
1473 
1474 	/* no GPU until we are ready! */
1475 	__set_bit(I915_WEDGED, &gt->reset.flags);
1476 }
1477 
1478 void intel_gt_fini_reset(struct intel_gt *gt)
1479 {
1480 	cleanup_srcu_struct(&gt->reset.backoff_srcu);
1481 }
1482 
1483 static void intel_wedge_me(struct work_struct *work)
1484 {
1485 	struct intel_wedge_me *w = container_of(work, typeof(*w), work.work);
1486 
1487 	drm_err(&w->gt->i915->drm,
1488 		"%s timed out, cancelling all in-flight rendering.\n",
1489 		w->name);
1490 	intel_gt_set_wedged(w->gt);
1491 }
1492 
1493 void __intel_init_wedge(struct intel_wedge_me *w,
1494 			struct intel_gt *gt,
1495 			long timeout,
1496 			const char *name)
1497 {
1498 	w->gt = gt;
1499 	w->name = name;
1500 
1501 	INIT_DELAYED_WORK_ONSTACK(&w->work, intel_wedge_me);
1502 	schedule_delayed_work(&w->work, timeout);
1503 }
1504 
1505 void __intel_fini_wedge(struct intel_wedge_me *w)
1506 {
1507 	cancel_delayed_work_sync(&w->work);
1508 	destroy_delayed_work_on_stack(&w->work);
1509 	w->gt = NULL;
1510 }
1511 
1512 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
1513 #include "selftest_reset.c"
1514 #include "selftest_hangcheck.c"
1515 #endif
1516