1/* 2 * Copyright © 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/kthread.h> 26#include <trace/events/dma_fence.h> 27#include <uapi/linux/sched/types.h> 28 29#include "i915_drv.h" 30#include "i915_trace.h" 31#include "intel_breadcrumbs.h" 32#include "intel_context.h" 33#include "intel_engine_pm.h" 34#include "intel_gt_pm.h" 35#include "intel_gt_requests.h" 36 37static bool irq_enable(struct intel_engine_cs *engine) 38{ 39 if (!engine->irq_enable) 40 return false; 41 42 /* Caller disables interrupts */ 43 spin_lock(&engine->gt->irq_lock); 44 engine->irq_enable(engine); 45 spin_unlock(&engine->gt->irq_lock); 46 47 return true; 48} 49 50static void irq_disable(struct intel_engine_cs *engine) 51{ 52 if (!engine->irq_disable) 53 return; 54 55 /* Caller disables interrupts */ 56 spin_lock(&engine->gt->irq_lock); 57 engine->irq_disable(engine); 58 spin_unlock(&engine->gt->irq_lock); 59} 60 61static void __intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b) 62{ 63 /* 64 * Since we are waiting on a request, the GPU should be busy 65 * and should have its own rpm reference. 66 */ 67 if (GEM_WARN_ON(!intel_gt_pm_get_if_awake(b->irq_engine->gt))) 68 return; 69 70 /* 71 * The breadcrumb irq will be disarmed on the interrupt after the 72 * waiters are signaled. This gives us a single interrupt window in 73 * which we can add a new waiter and avoid the cost of re-enabling 74 * the irq. 75 */ 76 WRITE_ONCE(b->irq_armed, true); 77 78 /* Requests may have completed before we could enable the interrupt. */ 79 if (!b->irq_enabled++ && irq_enable(b->irq_engine)) 80 irq_work_queue(&b->irq_work); 81} 82 83static void intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b) 84{ 85 if (!b->irq_engine) 86 return; 87 88 spin_lock(&b->irq_lock); 89 if (!b->irq_armed) 90 __intel_breadcrumbs_arm_irq(b); 91 spin_unlock(&b->irq_lock); 92} 93 94static void __intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b) 95{ 96 GEM_BUG_ON(!b->irq_enabled); 97 if (!--b->irq_enabled) 98 irq_disable(b->irq_engine); 99 100 WRITE_ONCE(b->irq_armed, false); 101 intel_gt_pm_put_async(b->irq_engine->gt); 102} 103 104static void intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b) 105{ 106 spin_lock(&b->irq_lock); 107 if (b->irq_armed) 108 __intel_breadcrumbs_disarm_irq(b); 109 spin_unlock(&b->irq_lock); 110} 111 112static void add_signaling_context(struct intel_breadcrumbs *b, 113 struct intel_context *ce) 114{ 115 lockdep_assert_held(&ce->signal_lock); 116 117 spin_lock(&b->signalers_lock); 118 list_add_rcu(&ce->signal_link, &b->signalers); 119 spin_unlock(&b->signalers_lock); 120} 121 122static bool remove_signaling_context(struct intel_breadcrumbs *b, 123 struct intel_context *ce) 124{ 125 lockdep_assert_held(&ce->signal_lock); 126 127 if (!list_empty(&ce->signals)) 128 return false; 129 130 spin_lock(&b->signalers_lock); 131 list_del_rcu(&ce->signal_link); 132 spin_unlock(&b->signalers_lock); 133 134 return true; 135} 136 137__maybe_unused static bool 138check_signal_order(struct intel_context *ce, struct i915_request *rq) 139{ 140 if (rq->context != ce) 141 return false; 142 143 if (!list_is_last(&rq->signal_link, &ce->signals) && 144 i915_seqno_passed(rq->fence.seqno, 145 list_next_entry(rq, signal_link)->fence.seqno)) 146 return false; 147 148 if (!list_is_first(&rq->signal_link, &ce->signals) && 149 i915_seqno_passed(list_prev_entry(rq, signal_link)->fence.seqno, 150 rq->fence.seqno)) 151 return false; 152 153 return true; 154} 155 156static bool 157__dma_fence_signal(struct dma_fence *fence) 158{ 159 return !test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags); 160} 161 162static void 163__dma_fence_signal__timestamp(struct dma_fence *fence, ktime_t timestamp) 164{ 165 fence->timestamp = timestamp; 166 set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags); 167 trace_dma_fence_signaled(fence); 168} 169 170static void 171__dma_fence_signal__notify(struct dma_fence *fence, 172 const struct list_head *list) 173{ 174 struct dma_fence_cb *cur, *tmp; 175 176 lockdep_assert_held(fence->lock); 177 178 list_for_each_entry_safe(cur, tmp, list, node) { 179 INIT_LIST_HEAD(&cur->node); 180 cur->func(fence, cur); 181 } 182} 183 184static void add_retire(struct intel_breadcrumbs *b, struct intel_timeline *tl) 185{ 186 if (b->irq_engine) 187 intel_engine_add_retire(b->irq_engine, tl); 188} 189 190static bool __signal_request(struct i915_request *rq) 191{ 192 GEM_BUG_ON(test_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags)); 193 194 if (!__dma_fence_signal(&rq->fence)) { 195 i915_request_put(rq); 196 return false; 197 } 198 199 return true; 200} 201 202static struct llist_node * 203slist_add(struct llist_node *node, struct llist_node *head) 204{ 205 node->next = head; 206 return node; 207} 208 209static void signal_irq_work(struct irq_work *work) 210{ 211 struct intel_breadcrumbs *b = container_of(work, typeof(*b), irq_work); 212 const ktime_t timestamp = ktime_get(); 213 struct llist_node *signal, *sn; 214 struct intel_context *ce; 215 216 signal = NULL; 217 if (unlikely(!llist_empty(&b->signaled_requests))) 218 signal = llist_del_all(&b->signaled_requests); 219 220 /* 221 * Keep the irq armed until the interrupt after all listeners are gone. 222 * 223 * Enabling/disabling the interrupt is rather costly, roughly a couple 224 * of hundred microseconds. If we are proactive and enable/disable 225 * the interrupt around every request that wants a breadcrumb, we 226 * quickly drown in the extra orders of magnitude of latency imposed 227 * on request submission. 228 * 229 * So we try to be lazy, and keep the interrupts enabled until no 230 * more listeners appear within a breadcrumb interrupt interval (that 231 * is until a request completes that no one cares about). The 232 * observation is that listeners come in batches, and will often 233 * listen to a bunch of requests in succession. Though note on icl+, 234 * interrupts are always enabled due to concerns with rc6 being 235 * dysfunctional with per-engine interrupt masking. 236 * 237 * We also try to avoid raising too many interrupts, as they may 238 * be generated by userspace batches and it is unfortunately rather 239 * too easy to drown the CPU under a flood of GPU interrupts. Thus 240 * whenever no one appears to be listening, we turn off the interrupts. 241 * Fewer interrupts should conserve power -- at the very least, fewer 242 * interrupt draw less ire from other users of the system and tools 243 * like powertop. 244 */ 245 if (!signal && READ_ONCE(b->irq_armed) && list_empty(&b->signalers)) 246 intel_breadcrumbs_disarm_irq(b); 247 248 rcu_read_lock(); 249 list_for_each_entry_rcu(ce, &b->signalers, signal_link) { 250 struct i915_request *rq; 251 252 list_for_each_entry_rcu(rq, &ce->signals, signal_link) { 253 bool release; 254 255 if (!__i915_request_is_complete(rq)) 256 break; 257 258 if (!test_and_clear_bit(I915_FENCE_FLAG_SIGNAL, 259 &rq->fence.flags)) 260 break; 261 262 /* 263 * Queue for execution after dropping the signaling 264 * spinlock as the callback chain may end up adding 265 * more signalers to the same context or engine. 266 */ 267 spin_lock(&ce->signal_lock); 268 list_del_rcu(&rq->signal_link); 269 release = remove_signaling_context(b, ce); 270 spin_unlock(&ce->signal_lock); 271 272 if (__signal_request(rq)) 273 /* We own signal_node now, xfer to local list */ 274 signal = slist_add(&rq->signal_node, signal); 275 276 if (release) { 277 add_retire(b, ce->timeline); 278 intel_context_put(ce); 279 } 280 } 281 } 282 rcu_read_unlock(); 283 284 llist_for_each_safe(signal, sn, signal) { 285 struct i915_request *rq = 286 llist_entry(signal, typeof(*rq), signal_node); 287 struct list_head cb_list; 288 289 spin_lock(&rq->lock); 290 list_replace(&rq->fence.cb_list, &cb_list); 291 __dma_fence_signal__timestamp(&rq->fence, timestamp); 292 __dma_fence_signal__notify(&rq->fence, &cb_list); 293 spin_unlock(&rq->lock); 294 295 i915_request_put(rq); 296 } 297 298 if (!READ_ONCE(b->irq_armed) && !list_empty(&b->signalers)) 299 intel_breadcrumbs_arm_irq(b); 300} 301 302struct intel_breadcrumbs * 303intel_breadcrumbs_create(struct intel_engine_cs *irq_engine) 304{ 305 struct intel_breadcrumbs *b; 306 307 b = kzalloc(sizeof(*b), GFP_KERNEL); 308 if (!b) 309 return NULL; 310 311 b->irq_engine = irq_engine; 312 313 spin_lock_init(&b->signalers_lock); 314 INIT_LIST_HEAD(&b->signalers); 315 init_llist_head(&b->signaled_requests); 316 317 spin_lock_init(&b->irq_lock); 318 init_irq_work(&b->irq_work, signal_irq_work); 319 320 return b; 321} 322 323void intel_breadcrumbs_reset(struct intel_breadcrumbs *b) 324{ 325 unsigned long flags; 326 327 if (!b->irq_engine) 328 return; 329 330 spin_lock_irqsave(&b->irq_lock, flags); 331 332 if (b->irq_enabled) 333 irq_enable(b->irq_engine); 334 else 335 irq_disable(b->irq_engine); 336 337 spin_unlock_irqrestore(&b->irq_lock, flags); 338} 339 340void intel_breadcrumbs_park(struct intel_breadcrumbs *b) 341{ 342 /* Kick the work once more to drain the signalers */ 343 irq_work_sync(&b->irq_work); 344 while (unlikely(READ_ONCE(b->irq_armed))) { 345 local_irq_disable(); 346 signal_irq_work(&b->irq_work); 347 local_irq_enable(); 348 cond_resched(); 349 } 350 GEM_BUG_ON(!list_empty(&b->signalers)); 351} 352 353void intel_breadcrumbs_free(struct intel_breadcrumbs *b) 354{ 355 irq_work_sync(&b->irq_work); 356 GEM_BUG_ON(!list_empty(&b->signalers)); 357 GEM_BUG_ON(b->irq_armed); 358 kfree(b); 359} 360 361static void insert_breadcrumb(struct i915_request *rq) 362{ 363 struct intel_breadcrumbs *b = READ_ONCE(rq->engine)->breadcrumbs; 364 struct intel_context *ce = rq->context; 365 struct list_head *pos; 366 367 if (test_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags)) 368 return; 369 370 i915_request_get(rq); 371 372 /* 373 * If the request is already completed, we can transfer it 374 * straight onto a signaled list, and queue the irq worker for 375 * its signal completion. 376 */ 377 if (__i915_request_is_complete(rq)) { 378 if (__signal_request(rq) && 379 llist_add(&rq->signal_node, &b->signaled_requests)) 380 irq_work_queue(&b->irq_work); 381 return; 382 } 383 384 if (list_empty(&ce->signals)) { 385 intel_context_get(ce); 386 add_signaling_context(b, ce); 387 pos = &ce->signals; 388 } else { 389 /* 390 * We keep the seqno in retirement order, so we can break 391 * inside intel_engine_signal_breadcrumbs as soon as we've 392 * passed the last completed request (or seen a request that 393 * hasn't event started). We could walk the timeline->requests, 394 * but keeping a separate signalers_list has the advantage of 395 * hopefully being much smaller than the full list and so 396 * provides faster iteration and detection when there are no 397 * more interrupts required for this context. 398 * 399 * We typically expect to add new signalers in order, so we 400 * start looking for our insertion point from the tail of 401 * the list. 402 */ 403 list_for_each_prev(pos, &ce->signals) { 404 struct i915_request *it = 405 list_entry(pos, typeof(*it), signal_link); 406 407 if (i915_seqno_passed(rq->fence.seqno, it->fence.seqno)) 408 break; 409 } 410 } 411 list_add_rcu(&rq->signal_link, pos); 412 GEM_BUG_ON(!check_signal_order(ce, rq)); 413 GEM_BUG_ON(test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &rq->fence.flags)); 414 set_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags); 415 416 /* 417 * Defer enabling the interrupt to after HW submission and recheck 418 * the request as it may have completed and raised the interrupt as 419 * we were attaching it into the lists. 420 */ 421 irq_work_queue(&b->irq_work); 422} 423 424bool i915_request_enable_breadcrumb(struct i915_request *rq) 425{ 426 struct intel_context *ce = rq->context; 427 428 /* Serialises with i915_request_retire() using rq->lock */ 429 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &rq->fence.flags)) 430 return true; 431 432 /* 433 * Peek at i915_request_submit()/i915_request_unsubmit() status. 434 * 435 * If the request is not yet active (and not signaled), we will 436 * attach the breadcrumb later. 437 */ 438 if (!test_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags)) 439 return true; 440 441 spin_lock(&ce->signal_lock); 442 if (test_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags)) 443 insert_breadcrumb(rq); 444 spin_unlock(&ce->signal_lock); 445 446 return true; 447} 448 449void i915_request_cancel_breadcrumb(struct i915_request *rq) 450{ 451 struct intel_context *ce = rq->context; 452 bool release; 453 454 spin_lock(&ce->signal_lock); 455 if (!test_and_clear_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags)) { 456 spin_unlock(&ce->signal_lock); 457 return; 458 } 459 460 list_del_rcu(&rq->signal_link); 461 release = remove_signaling_context(rq->engine->breadcrumbs, ce); 462 spin_unlock(&ce->signal_lock); 463 if (release) 464 intel_context_put(ce); 465 466 i915_request_put(rq); 467} 468 469static void print_signals(struct intel_breadcrumbs *b, struct drm_printer *p) 470{ 471 struct intel_context *ce; 472 struct i915_request *rq; 473 474 drm_printf(p, "Signals:\n"); 475 476 rcu_read_lock(); 477 list_for_each_entry_rcu(ce, &b->signalers, signal_link) { 478 list_for_each_entry_rcu(rq, &ce->signals, signal_link) 479 drm_printf(p, "\t[%llx:%llx%s] @ %dms\n", 480 rq->fence.context, rq->fence.seqno, 481 i915_request_completed(rq) ? "!" : 482 i915_request_started(rq) ? "*" : 483 "", 484 jiffies_to_msecs(jiffies - rq->emitted_jiffies)); 485 } 486 rcu_read_unlock(); 487} 488 489void intel_engine_print_breadcrumbs(struct intel_engine_cs *engine, 490 struct drm_printer *p) 491{ 492 struct intel_breadcrumbs *b; 493 494 b = engine->breadcrumbs; 495 if (!b) 496 return; 497 498 drm_printf(p, "IRQ: %s\n", enableddisabled(b->irq_armed)); 499 if (!list_empty(&b->signalers)) 500 print_signals(b, p); 501} 502