drivers/gpu/drm/i915/gt/intel_context.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright © 2019 Intel Corporation
   4  */
   5
   6 #include "gem/i915_gem_context.h"
   7 #include "gem/i915_gem_pm.h"
   8
   9 #include "i915_drv.h"
  10 #include "i915_globals.h"
  11
  12 #include "intel_context.h"
  13 #include "intel_engine.h"
  14 #include "intel_engine_pm.h"
  15 #include "intel_ring.h"
  16
  17 static struct i915_global_context {
  18         struct i915_global base;
  19         struct kmem_cache *slab_ce;
  20 } global;
  21
  22 static struct intel_context *intel_context_alloc(void)
  23 {
  24         return kmem_cache_zalloc(global.slab_ce, GFP_KERNEL);
  25 }
  26
  27 static void rcu_context_free(struct rcu_head *rcu)
  28 {
  29         struct intel_context *ce = container_of(rcu, typeof(*ce), rcu);
  30
  31         kmem_cache_free(global.slab_ce, ce);
  32 }
  33
  34 void intel_context_free(struct intel_context *ce)
  35 {
  36         call_rcu(&ce->rcu, rcu_context_free);
  37 }
  38
  39 struct intel_context *
  40 intel_context_create(struct intel_engine_cs *engine)
  41 {
  42         struct intel_context *ce;
  43
  44         ce = intel_context_alloc();
  45         if (!ce)
  46                 return ERR_PTR(-ENOMEM);
  47
  48         intel_context_init(ce, engine);
  49         return ce;
  50 }
  51
  52 int intel_context_alloc_state(struct intel_context *ce)
  53 {
  54         int err = 0;
  55
  56         if (mutex_lock_interruptible(&ce->pin_mutex))
  57                 return -EINTR;
  58
  59         if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
  60                 if (intel_context_is_banned(ce)) {
  61                         err = -EIO;
  62                         goto unlock;
  63                 }
  64
  65                 err = ce->ops->alloc(ce);
  66                 if (unlikely(err))
  67                         goto unlock;
  68
  69                 set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
  70         }
  71
  72 unlock:
  73         mutex_unlock(&ce->pin_mutex);
  74         return err;
  75 }
  76
  77 static int intel_context_active_acquire(struct intel_context *ce)
  78 {
  79         int err;
  80
  81         __i915_active_acquire(&ce->active);
  82
  83         if (intel_context_is_barrier(ce))
  84                 return 0;
  85
  86         /* Preallocate tracking nodes */
  87         err = i915_active_acquire_preallocate_barrier(&ce->active,
  88                                                       ce->engine);
  89         if (err)
  90                 i915_active_release(&ce->active);
  91
  92         return err;
  93 }
  94
  95 static void intel_context_active_release(struct intel_context *ce)
  96 {
  97         /* Nodes preallocated in intel_context_active() */
  98         i915_active_acquire_barrier(&ce->active);
  99         i915_active_release(&ce->active);
 100 }
 101
 102 static int __context_pin_state(struct i915_vma *vma, struct i915_gem_ww_ctx *ww)
 103 {
 104         unsigned int bias = i915_ggtt_pin_bias(vma) | PIN_OFFSET_BIAS;
 105         int err;
 106
 107         err = i915_ggtt_pin(vma, ww, 0, bias | PIN_HIGH);
 108         if (err)
 109                 return err;
 110
 111         err = i915_active_acquire(&vma->active);
 112         if (err)
 113                 goto err_unpin;
 114
 115         /*
 116          * And mark it as a globally pinned object to let the shrinker know
 117          * it cannot reclaim the object until we release it.
 118          */
 119         i915_vma_make_unshrinkable(vma);
 120         vma->obj->mm.dirty = true;
 121
 122         return 0;
 123
 124 err_unpin:
 125         i915_vma_unpin(vma);
 126         return err;
 127 }
 128
 129 static void __context_unpin_state(struct i915_vma *vma)
 130 {
 131         i915_vma_make_shrinkable(vma);
 132         i915_active_release(&vma->active);
 133         __i915_vma_unpin(vma);
 134 }
 135
 136 static int __ring_active(struct intel_ring *ring,
 137                          struct i915_gem_ww_ctx *ww)
 138 {
 139         int err;
 140
 141         err = intel_ring_pin(ring, ww);
 142         if (err)
 143                 return err;
 144
 145         err = i915_active_acquire(&ring->vma->active);
 146         if (err)
 147                 goto err_pin;
 148
 149         return 0;
 150
 151 err_pin:
 152         intel_ring_unpin(ring);
 153         return err;
 154 }
 155
 156 static void __ring_retire(struct intel_ring *ring)
 157 {
 158         i915_active_release(&ring->vma->active);
 159         intel_ring_unpin(ring);
 160 }
 161
 162 static int intel_context_pre_pin(struct intel_context *ce,
 163                                  struct i915_gem_ww_ctx *ww)
 164 {
 165         int err;
 166
 167         CE_TRACE(ce, "active\n");
 168
 169         err = __ring_active(ce->ring, ww);
 170         if (err)
 171                 return err;
 172
 173         err = intel_timeline_pin(ce->timeline, ww);
 174         if (err)
 175                 goto err_ring;
 176
 177         if (!ce->state)
 178                 return 0;
 179
 180         err = __context_pin_state(ce->state, ww);
 181         if (err)
 182                 goto err_timeline;
 183
 184
 185         return 0;
 186
 187 err_timeline:
 188         intel_timeline_unpin(ce->timeline);
 189 err_ring:
 190         __ring_retire(ce->ring);
 191         return err;
 192 }
 193
 194 static void intel_context_post_unpin(struct intel_context *ce)
 195 {
 196         if (ce->state)
 197                 __context_unpin_state(ce->state);
 198
 199         intel_timeline_unpin(ce->timeline);
 200         __ring_retire(ce->ring);
 201 }
 202
 203 int __intel_context_do_pin_ww(struct intel_context *ce,
 204                               struct i915_gem_ww_ctx *ww)
 205 {
 206         bool handoff = false;
 207         void *vaddr;
 208         int err = 0;
 209
 210         if (unlikely(!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))) {
 211                 err = intel_context_alloc_state(ce);
 212                 if (err)
 213                         return err;
 214         }
 215
 216         /*
 217          * We always pin the context/ring/timeline here, to ensure a pin
 218          * refcount for __intel_context_active(), which prevent a lock
 219          * inversion of ce->pin_mutex vs dma_resv_lock().
 220          */
 221
 222         err = i915_gem_object_lock(ce->timeline->hwsp_ggtt->obj, ww);
 223         if (!err && ce->ring->vma->obj)
 224                 err = i915_gem_object_lock(ce->ring->vma->obj, ww);
 225         if (!err && ce->state)
 226                 err = i915_gem_object_lock(ce->state->obj, ww);
 227         if (!err)
 228                 err = intel_context_pre_pin(ce, ww);
 229         if (err)
 230                 return err;
 231
 232         err = i915_active_acquire(&ce->active);
 233         if (err)
 234                 goto err_ctx_unpin;
 235
 236         err = ce->ops->pre_pin(ce, ww, &vaddr);
 237         if (err)
 238                 goto err_release;
 239
 240         err = mutex_lock_interruptible(&ce->pin_mutex);
 241         if (err)
 242                 goto err_post_unpin;
 243
 244         if (unlikely(intel_context_is_closed(ce))) {
 245                 err = -ENOENT;
 246                 goto err_unlock;
 247         }
 248
 249         if (likely(!atomic_add_unless(&ce->pin_count, 1, 0))) {
 250                 err = intel_context_active_acquire(ce);
 251                 if (unlikely(err))
 252                         goto err_unlock;
 253
 254                 err = ce->ops->pin(ce, vaddr);
 255                 if (err) {
 256                         intel_context_active_release(ce);
 257                         goto err_unlock;
 258                 }
 259
 260                 CE_TRACE(ce, "pin ring:{start:%08x, head:%04x, tail:%04x}\n",
 261                          i915_ggtt_offset(ce->ring->vma),
 262                          ce->ring->head, ce->ring->tail);
 263
 264                 handoff = true;
 265                 smp_mb__before_atomic(); /* flush pin before it is visible */
 266                 atomic_inc(&ce->pin_count);
 267         }
 268
 269         GEM_BUG_ON(!intel_context_is_pinned(ce)); /* no overflow! */
 270
 271 err_unlock:
 272         mutex_unlock(&ce->pin_mutex);
 273 err_post_unpin:
 274         if (!handoff)
 275                 ce->ops->post_unpin(ce);
 276 err_release:
 277         i915_active_release(&ce->active);
 278 err_ctx_unpin:
 279         intel_context_post_unpin(ce);
 280
 281         /*
 282          * Unlock the hwsp_ggtt object since it's shared.
 283          * In principle we can unlock all the global state locked above
 284          * since it's pinned and doesn't need fencing, and will
 285          * thus remain resident until it is explicitly unpinned.
 286          */
 287         i915_gem_ww_unlock_single(ce->timeline->hwsp_ggtt->obj);
 288
 289         return err;
 290 }
 291
 292 int __intel_context_do_pin(struct intel_context *ce)
 293 {
 294         struct i915_gem_ww_ctx ww;
 295         int err;
 296
 297         i915_gem_ww_ctx_init(&ww, true);
 298 retry:
 299         err = __intel_context_do_pin_ww(ce, &ww);
 300         if (err == -EDEADLK) {
 301                 err = i915_gem_ww_ctx_backoff(&ww);
 302                 if (!err)
 303                         goto retry;
 304         }
 305         i915_gem_ww_ctx_fini(&ww);
 306         return err;
 307 }
 308
 309 void intel_context_unpin(struct intel_context *ce)
 310 {
 311         if (!atomic_dec_and_test(&ce->pin_count))
 312                 return;
 313
 314         CE_TRACE(ce, "unpin\n");
 315         ce->ops->unpin(ce);
 316         ce->ops->post_unpin(ce);
 317
 318         /*
 319          * Once released, we may asynchronously drop the active reference.
 320          * As that may be the only reference keeping the context alive,
 321          * take an extra now so that it is not freed before we finish
 322          * dereferencing it.
 323          */
 324         intel_context_get(ce);
 325         intel_context_active_release(ce);
 326         intel_context_put(ce);
 327 }
 328
 329 static void __intel_context_retire(struct i915_active *active)
 330 {
 331         struct intel_context *ce = container_of(active, typeof(*ce), active);
 332
 333         CE_TRACE(ce, "retire runtime: { total:%lluns, avg:%lluns }\n",
 334                  intel_context_get_total_runtime_ns(ce),
 335                  intel_context_get_avg_runtime_ns(ce));
 336
 337         set_bit(CONTEXT_VALID_BIT, &ce->flags);
 338         intel_context_post_unpin(ce);
 339         intel_context_put(ce);
 340 }
 341
 342 static int __intel_context_active(struct i915_active *active)
 343 {
 344         struct intel_context *ce = container_of(active, typeof(*ce), active);
 345
 346         intel_context_get(ce);
 347
 348         /* everything should already be activated by intel_context_pre_pin() */
 349         GEM_WARN_ON(!i915_active_acquire_if_busy(&ce->ring->vma->active));
 350         __intel_ring_pin(ce->ring);
 351
 352         __intel_timeline_pin(ce->timeline);
 353
 354         if (ce->state) {
 355                 GEM_WARN_ON(!i915_active_acquire_if_busy(&ce->state->active));
 356                 __i915_vma_pin(ce->state);
 357                 i915_vma_make_unshrinkable(ce->state);
 358         }
 359
 360         return 0;
 361 }
 362
 363 void
 364 intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 365 {
 366         GEM_BUG_ON(!engine->cops);
 367         GEM_BUG_ON(!engine->gt->vm);
 368
 369         kref_init(&ce->ref);
 370
 371         ce->engine = engine;
 372         ce->ops = engine->cops;
 373         ce->sseu = engine->sseu;
 374         ce->ring = NULL;
 375         ce->ring_size = SZ_4K;
 376
 377         ewma_runtime_init(&ce->runtime.avg);
 378
 379         ce->vm = i915_vm_get(engine->gt->vm);
 380
 381         /* NB ce->signal_link/lock is used under RCU */
 382         spin_lock_init(&ce->signal_lock);
 383         INIT_LIST_HEAD(&ce->signals);
 384
 385         mutex_init(&ce->pin_mutex);
 386
 387         i915_active_init(&ce->active,
 388                          __intel_context_active, __intel_context_retire, 0);
 389 }
 390
 391 void intel_context_fini(struct intel_context *ce)
 392 {
 393         if (ce->timeline)
 394                 intel_timeline_put(ce->timeline);
 395         i915_vm_put(ce->vm);
 396
 397         mutex_destroy(&ce->pin_mutex);
 398         i915_active_fini(&ce->active);
 399 }
 400
 401 static void i915_global_context_shrink(void)
 402 {
 403         kmem_cache_shrink(global.slab_ce);
 404 }
 405
 406 static void i915_global_context_exit(void)
 407 {
 408         kmem_cache_destroy(global.slab_ce);
 409 }
 410
 411 static struct i915_global_context global = { {
 412         .shrink = i915_global_context_shrink,
 413         .exit = i915_global_context_exit,
 414 } };
 415
 416 int __init i915_global_context_init(void)
 417 {
 418         global.slab_ce = KMEM_CACHE(intel_context, SLAB_HWCACHE_ALIGN);
 419         if (!global.slab_ce)
 420                 return -ENOMEM;
 421
 422         i915_global_register(&global.base);
 423         return 0;
 424 }
 425
 426 void intel_context_enter_engine(struct intel_context *ce)
 427 {
 428         intel_engine_pm_get(ce->engine);
 429         intel_timeline_enter(ce->timeline);
 430 }
 431
 432 void intel_context_exit_engine(struct intel_context *ce)
 433 {
 434         intel_timeline_exit(ce->timeline);
 435         intel_engine_pm_put(ce->engine);
 436 }
 437
 438 int intel_context_prepare_remote_request(struct intel_context *ce,
 439                                          struct i915_request *rq)
 440 {
 441         struct intel_timeline *tl = ce->timeline;
 442         int err;
 443
 444         /* Only suitable for use in remotely modifying this context */
 445         GEM_BUG_ON(rq->context == ce);
 446
 447         if (rcu_access_pointer(rq->timeline) != tl) { /* timeline sharing! */
 448                 /* Queue this switch after current activity by this context. */
 449                 err = i915_active_fence_set(&tl->last_request, rq);
 450                 if (err)
 451                         return err;
 452         }
 453
 454         /*
 455          * Guarantee context image and the timeline remains pinned until the
 456          * modifying request is retired by setting the ce activity tracker.
 457          *
 458          * But we only need to take one pin on the account of it. Or in other
 459          * words transfer the pinned ce object to tracked active request.
 460          */
 461         GEM_BUG_ON(i915_active_is_idle(&ce->active));
 462         return i915_active_add_request(&ce->active, rq);
 463 }
 464
 465 struct i915_request *intel_context_create_request(struct intel_context *ce)
 466 {
 467         struct i915_gem_ww_ctx ww;
 468         struct i915_request *rq;
 469         int err;
 470
 471         i915_gem_ww_ctx_init(&ww, true);
 472 retry:
 473         err = intel_context_pin_ww(ce, &ww);
 474         if (!err) {
 475                 rq = i915_request_create(ce);
 476                 intel_context_unpin(ce);
 477         } else if (err == -EDEADLK) {
 478                 err = i915_gem_ww_ctx_backoff(&ww);
 479                 if (!err)
 480                         goto retry;
 481                 rq = ERR_PTR(err);
 482         } else {
 483                 rq = ERR_PTR(err);
 484         }
 485
 486         i915_gem_ww_ctx_fini(&ww);
 487
 488         if (IS_ERR(rq))
 489                 return rq;
 490
 491         /*
 492          * timeline->mutex should be the inner lock, but is used as outer lock.
 493          * Hack around this to shut up lockdep in selftests..
 494          */
 495         lockdep_unpin_lock(&ce->timeline->mutex, rq->cookie);
 496         mutex_release(&ce->timeline->mutex.dep_map, _RET_IP_);
 497         mutex_acquire(&ce->timeline->mutex.dep_map, SINGLE_DEPTH_NESTING, 0, _RET_IP_);
 498         rq->cookie = lockdep_pin_lock(&ce->timeline->mutex);
 499
 500         return rq;
 501 }
 502
 503 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 504 #include "selftest_context.c"
 505 #endif