1 // SPDX-License-Identifier: MIT
2 /*
3  * Copyright © 2019 Intel Corporation
4  */
5 
6 #include "i915_drv.h"
7 #include "i915_request.h"
8 
9 #include "intel_context.h"
10 #include "intel_engine_heartbeat.h"
11 #include "intel_engine_pm.h"
12 #include "intel_engine.h"
13 #include "intel_gt.h"
14 #include "intel_reset.h"
15 
16 /*
17  * While the engine is active, we send a periodic pulse along the engine
18  * to check on its health and to flush any idle-barriers. If that request
19  * is stuck, and we fail to preempt it, we declare the engine hung and
20  * issue a reset -- in the hope that restores progress.
21  */
22 
23 static bool next_heartbeat(struct intel_engine_cs *engine)
24 {
25 	long delay;
26 
27 	delay = READ_ONCE(engine->props.heartbeat_interval_ms);
28 	if (!delay)
29 		return false;
30 
31 	delay = msecs_to_jiffies_timeout(delay);
32 	if (delay >= HZ)
33 		delay = round_jiffies_up_relative(delay);
34 	mod_delayed_work(system_highpri_wq, &engine->heartbeat.work, delay + 1);
35 
36 	return true;
37 }
38 
39 static struct i915_request *
40 heartbeat_create(struct intel_context *ce, gfp_t gfp)
41 {
42 	struct i915_request *rq;
43 
44 	intel_context_enter(ce);
45 	rq = __i915_request_create(ce, gfp);
46 	intel_context_exit(ce);
47 
48 	return rq;
49 }
50 
51 static void idle_pulse(struct intel_engine_cs *engine, struct i915_request *rq)
52 {
53 	engine->wakeref_serial = READ_ONCE(engine->serial) + 1;
54 	i915_request_add_active_barriers(rq);
55 	if (!engine->heartbeat.systole && intel_engine_has_heartbeat(engine))
56 		engine->heartbeat.systole = i915_request_get(rq);
57 }
58 
59 static void heartbeat_commit(struct i915_request *rq,
60 			     const struct i915_sched_attr *attr)
61 {
62 	idle_pulse(rq->engine, rq);
63 
64 	__i915_request_commit(rq);
65 	__i915_request_queue(rq, attr);
66 }
67 
68 static void show_heartbeat(const struct i915_request *rq,
69 			   struct intel_engine_cs *engine)
70 {
71 	struct drm_printer p = drm_debug_printer("heartbeat");
72 
73 	if (!rq) {
74 		intel_engine_dump(engine, &p,
75 				  "%s heartbeat not ticking\n",
76 				  engine->name);
77 	} else {
78 		intel_engine_dump(engine, &p,
79 				  "%s heartbeat {seqno:%llx:%lld, prio:%d} not ticking\n",
80 				  engine->name,
81 				  rq->fence.context,
82 				  rq->fence.seqno,
83 				  rq->sched.attr.priority);
84 	}
85 }
86 
87 static void
88 reset_engine(struct intel_engine_cs *engine, struct i915_request *rq)
89 {
90 	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
91 		show_heartbeat(rq, engine);
92 
93 	if (intel_engine_uses_guc(engine))
94 		/*
95 		 * GuC itself is toast or GuC's hang detection
96 		 * is disabled. Either way, need to find the
97 		 * hang culprit manually.
98 		 */
99 		intel_guc_find_hung_context(engine);
100 
101 	intel_gt_handle_error(engine->gt, engine->mask,
102 			      I915_ERROR_CAPTURE,
103 			      "stopped heartbeat on %s",
104 			      engine->name);
105 }
106 
107 static void heartbeat(struct work_struct *wrk)
108 {
109 	struct i915_sched_attr attr = { .priority = I915_PRIORITY_MIN };
110 	struct intel_engine_cs *engine =
111 		container_of(wrk, typeof(*engine), heartbeat.work.work);
112 	struct intel_context *ce = engine->kernel_context;
113 	struct i915_request *rq;
114 	unsigned long serial;
115 
116 	/* Just in case everything has gone horribly wrong, give it a kick */
117 	intel_engine_flush_submission(engine);
118 
119 	rq = engine->heartbeat.systole;
120 	if (rq && i915_request_completed(rq)) {
121 		i915_request_put(rq);
122 		engine->heartbeat.systole = NULL;
123 	}
124 
125 	if (!intel_engine_pm_get_if_awake(engine))
126 		return;
127 
128 	if (intel_gt_is_wedged(engine->gt))
129 		goto out;
130 
131 	if (i915_sched_engine_disabled(engine->sched_engine)) {
132 		reset_engine(engine, engine->heartbeat.systole);
133 		goto out;
134 	}
135 
136 	if (engine->heartbeat.systole) {
137 		long delay = READ_ONCE(engine->props.heartbeat_interval_ms);
138 
139 		/* Safeguard against too-fast worker invocations */
140 		if (!time_after(jiffies,
141 				rq->emitted_jiffies + msecs_to_jiffies(delay)))
142 			goto out;
143 
144 		if (!i915_sw_fence_signaled(&rq->submit)) {
145 			/*
146 			 * Not yet submitted, system is stalled.
147 			 *
148 			 * This more often happens for ring submission,
149 			 * where all contexts are funnelled into a common
150 			 * ringbuffer. If one context is blocked on an
151 			 * external fence, not only is it not submitted,
152 			 * but all other contexts, including the kernel
153 			 * context are stuck waiting for the signal.
154 			 */
155 		} else if (engine->sched_engine->schedule &&
156 			   rq->sched.attr.priority < I915_PRIORITY_BARRIER) {
157 			/*
158 			 * Gradually raise the priority of the heartbeat to
159 			 * give high priority work [which presumably desires
160 			 * low latency and no jitter] the chance to naturally
161 			 * complete before being preempted.
162 			 */
163 			attr.priority = 0;
164 			if (rq->sched.attr.priority >= attr.priority)
165 				attr.priority = I915_PRIORITY_HEARTBEAT;
166 			if (rq->sched.attr.priority >= attr.priority)
167 				attr.priority = I915_PRIORITY_BARRIER;
168 
169 			local_bh_disable();
170 			engine->sched_engine->schedule(rq, &attr);
171 			local_bh_enable();
172 		} else {
173 			reset_engine(engine, rq);
174 		}
175 
176 		rq->emitted_jiffies = jiffies;
177 		goto out;
178 	}
179 
180 	serial = READ_ONCE(engine->serial);
181 	if (engine->wakeref_serial == serial)
182 		goto out;
183 
184 	if (!mutex_trylock(&ce->timeline->mutex)) {
185 		/* Unable to lock the kernel timeline, is the engine stuck? */
186 		if (xchg(&engine->heartbeat.blocked, serial) == serial)
187 			intel_gt_handle_error(engine->gt, engine->mask,
188 					      I915_ERROR_CAPTURE,
189 					      "no heartbeat on %s",
190 					      engine->name);
191 		goto out;
192 	}
193 
194 	rq = heartbeat_create(ce, GFP_NOWAIT | __GFP_NOWARN);
195 	if (IS_ERR(rq))
196 		goto unlock;
197 
198 	heartbeat_commit(rq, &attr);
199 
200 unlock:
201 	mutex_unlock(&ce->timeline->mutex);
202 out:
203 	if (!engine->i915->params.enable_hangcheck || !next_heartbeat(engine))
204 		i915_request_put(fetch_and_zero(&engine->heartbeat.systole));
205 	intel_engine_pm_put(engine);
206 }
207 
208 void intel_engine_unpark_heartbeat(struct intel_engine_cs *engine)
209 {
210 	if (!IS_ACTIVE(CONFIG_DRM_I915_HEARTBEAT_INTERVAL))
211 		return;
212 
213 	next_heartbeat(engine);
214 }
215 
216 void intel_engine_park_heartbeat(struct intel_engine_cs *engine)
217 {
218 	if (cancel_delayed_work(&engine->heartbeat.work))
219 		i915_request_put(fetch_and_zero(&engine->heartbeat.systole));
220 }
221 
222 void intel_gt_unpark_heartbeats(struct intel_gt *gt)
223 {
224 	struct intel_engine_cs *engine;
225 	enum intel_engine_id id;
226 
227 	for_each_engine(engine, gt, id)
228 		if (intel_engine_pm_is_awake(engine))
229 			intel_engine_unpark_heartbeat(engine);
230 }
231 
232 void intel_gt_park_heartbeats(struct intel_gt *gt)
233 {
234 	struct intel_engine_cs *engine;
235 	enum intel_engine_id id;
236 
237 	for_each_engine(engine, gt, id)
238 		intel_engine_park_heartbeat(engine);
239 }
240 
241 void intel_engine_init_heartbeat(struct intel_engine_cs *engine)
242 {
243 	INIT_DELAYED_WORK(&engine->heartbeat.work, heartbeat);
244 }
245 
246 static int __intel_engine_pulse(struct intel_engine_cs *engine)
247 {
248 	struct i915_sched_attr attr = { .priority = I915_PRIORITY_BARRIER };
249 	struct intel_context *ce = engine->kernel_context;
250 	struct i915_request *rq;
251 
252 	lockdep_assert_held(&ce->timeline->mutex);
253 	GEM_BUG_ON(!intel_engine_has_preemption(engine));
254 	GEM_BUG_ON(!intel_engine_pm_is_awake(engine));
255 
256 	rq = heartbeat_create(ce, GFP_NOWAIT | __GFP_NOWARN);
257 	if (IS_ERR(rq))
258 		return PTR_ERR(rq);
259 
260 	__set_bit(I915_FENCE_FLAG_SENTINEL, &rq->fence.flags);
261 
262 	heartbeat_commit(rq, &attr);
263 	GEM_BUG_ON(rq->sched.attr.priority < I915_PRIORITY_BARRIER);
264 
265 	return 0;
266 }
267 
268 static unsigned long set_heartbeat(struct intel_engine_cs *engine,
269 				   unsigned long delay)
270 {
271 	unsigned long old;
272 
273 	old = xchg(&engine->props.heartbeat_interval_ms, delay);
274 	if (delay)
275 		intel_engine_unpark_heartbeat(engine);
276 	else
277 		intel_engine_park_heartbeat(engine);
278 
279 	return old;
280 }
281 
282 int intel_engine_set_heartbeat(struct intel_engine_cs *engine,
283 			       unsigned long delay)
284 {
285 	struct intel_context *ce = engine->kernel_context;
286 	int err = 0;
287 
288 	if (!delay && !intel_engine_has_preempt_reset(engine))
289 		return -ENODEV;
290 
291 	intel_engine_pm_get(engine);
292 
293 	err = mutex_lock_interruptible(&ce->timeline->mutex);
294 	if (err)
295 		goto out_rpm;
296 
297 	if (delay != engine->props.heartbeat_interval_ms) {
298 		unsigned long saved = set_heartbeat(engine, delay);
299 
300 		/* recheck current execution */
301 		if (intel_engine_has_preemption(engine)) {
302 			err = __intel_engine_pulse(engine);
303 			if (err)
304 				set_heartbeat(engine, saved);
305 		}
306 	}
307 
308 	mutex_unlock(&ce->timeline->mutex);
309 
310 out_rpm:
311 	intel_engine_pm_put(engine);
312 	return err;
313 }
314 
315 int intel_engine_pulse(struct intel_engine_cs *engine)
316 {
317 	struct intel_context *ce = engine->kernel_context;
318 	int err;
319 
320 	if (!intel_engine_has_preemption(engine))
321 		return -ENODEV;
322 
323 	if (!intel_engine_pm_get_if_awake(engine))
324 		return 0;
325 
326 	err = -EINTR;
327 	if (!mutex_lock_interruptible(&ce->timeline->mutex)) {
328 		err = __intel_engine_pulse(engine);
329 		mutex_unlock(&ce->timeline->mutex);
330 	}
331 
332 	intel_engine_flush_submission(engine);
333 	intel_engine_pm_put(engine);
334 	return err;
335 }
336 
337 int intel_engine_flush_barriers(struct intel_engine_cs *engine)
338 {
339 	struct i915_sched_attr attr = { .priority = I915_PRIORITY_MIN };
340 	struct intel_context *ce = engine->kernel_context;
341 	struct i915_request *rq;
342 	int err;
343 
344 	if (llist_empty(&engine->barrier_tasks))
345 		return 0;
346 
347 	if (!intel_engine_pm_get_if_awake(engine))
348 		return 0;
349 
350 	if (mutex_lock_interruptible(&ce->timeline->mutex)) {
351 		err = -EINTR;
352 		goto out_rpm;
353 	}
354 
355 	rq = heartbeat_create(ce, GFP_KERNEL);
356 	if (IS_ERR(rq)) {
357 		err = PTR_ERR(rq);
358 		goto out_unlock;
359 	}
360 
361 	heartbeat_commit(rq, &attr);
362 
363 	err = 0;
364 out_unlock:
365 	mutex_unlock(&ce->timeline->mutex);
366 out_rpm:
367 	intel_engine_pm_put(engine);
368 	return err;
369 }
370 
371 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
372 #include "selftest_engine_heartbeat.c"
373 #endif
374