drivers/gpu/drm/i915/i915_vma_resource.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright © 2021 Intel Corporation
   4  */
   5
   6 #include <linux/interval_tree_generic.h>
   7 #include <linux/sched/mm.h>
   8
   9 #include "i915_sw_fence.h"
  10 #include "i915_vma_resource.h"
  11 #include "i915_drv.h"
  12 #include "intel_memory_region.h"
  13
  14 #include "gt/intel_gtt.h"
  15
  16 static struct kmem_cache *slab_vma_resources;
  17
  18 /**
  19  * DOC:
  20  * We use a per-vm interval tree to keep track of vma_resources
  21  * scheduled for unbind but not yet unbound. The tree is protected by
  22  * the vm mutex, and nodes are removed just after the unbind fence signals.
  23  * The removal takes the vm mutex from a kernel thread which we need to
  24  * keep in mind so that we don't grab the mutex and try to wait for all
  25  * pending unbinds to complete, because that will temporaryily block many
  26  * of the workqueue threads, and people will get angry.
  27  *
  28  * We should consider using a single ordered fence per VM instead but that
  29  * requires ordering the unbinds and might introduce unnecessary waiting
  30  * for unrelated unbinds. Amount of code will probably be roughly the same
  31  * due to the simplicity of using the interval tree interface.
  32  *
  33  * Another drawback of this interval tree is that the complexity of insertion
  34  * and removal of fences increases as O(ln(pending_unbinds)) instead of
  35  * O(1) for a single fence without interval tree.
  36  */
  37 #define VMA_RES_START(_node) ((_node)->start)
  38 #define VMA_RES_LAST(_node) ((_node)->start + (_node)->node_size - 1)
  39 INTERVAL_TREE_DEFINE(struct i915_vma_resource, rb,
  40                      u64, __subtree_last,
  41                      VMA_RES_START, VMA_RES_LAST, static, vma_res_itree);
  42
  43 /* Callbacks for the unbind dma-fence. */
  44
  45 /**
  46  * i915_vma_resource_alloc - Allocate a vma resource
  47  *
  48  * Return: A pointer to a cleared struct i915_vma_resource or
  49  * a -ENOMEM error pointer if allocation fails.
  50  */
  51 struct i915_vma_resource *i915_vma_resource_alloc(void)
  52 {
  53         struct i915_vma_resource *vma_res =
  54                 kmem_cache_zalloc(slab_vma_resources, GFP_KERNEL);
  55
  56         return vma_res ? vma_res : ERR_PTR(-ENOMEM);
  57 }
  58
  59 /**
  60  * i915_vma_resource_free - Free a vma resource
  61  * @vma_res: The vma resource to free.
  62  */
  63 void i915_vma_resource_free(struct i915_vma_resource *vma_res)
  64 {
  65         if (vma_res)
  66                 kmem_cache_free(slab_vma_resources, vma_res);
  67 }
  68
  69 static const char *get_driver_name(struct dma_fence *fence)
  70 {
  71         return "vma unbind fence";
  72 }
  73
  74 static const char *get_timeline_name(struct dma_fence *fence)
  75 {
  76         return "unbound";
  77 }
  78
  79 static void unbind_fence_free_rcu(struct rcu_head *head)
  80 {
  81         struct i915_vma_resource *vma_res =
  82                 container_of(head, typeof(*vma_res), unbind_fence.rcu);
  83
  84         i915_vma_resource_free(vma_res);
  85 }
  86
  87 static void unbind_fence_release(struct dma_fence *fence)
  88 {
  89         struct i915_vma_resource *vma_res =
  90                 container_of(fence, typeof(*vma_res), unbind_fence);
  91
  92         i915_sw_fence_fini(&vma_res->chain);
  93
  94         call_rcu(&fence->rcu, unbind_fence_free_rcu);
  95 }
  96
  97 static struct dma_fence_ops unbind_fence_ops = {
  98         .get_driver_name = get_driver_name,
  99         .get_timeline_name = get_timeline_name,
 100         .release = unbind_fence_release,
 101 };
 102
 103 static void __i915_vma_resource_unhold(struct i915_vma_resource *vma_res)
 104 {
 105         struct i915_address_space *vm;
 106
 107         if (!refcount_dec_and_test(&vma_res->hold_count))
 108                 return;
 109
 110         dma_fence_signal(&vma_res->unbind_fence);
 111
 112         vm = vma_res->vm;
 113         if (vma_res->wakeref)
 114                 intel_runtime_pm_put(&vm->i915->runtime_pm, vma_res->wakeref);
 115
 116         vma_res->vm = NULL;
 117         if (!RB_EMPTY_NODE(&vma_res->rb)) {
 118                 mutex_lock(&vm->mutex);
 119                 vma_res_itree_remove(vma_res, &vm->pending_unbind);
 120                 mutex_unlock(&vm->mutex);
 121         }
 122
 123         if (vma_res->bi.pages_rsgt)
 124                 i915_refct_sgt_put(vma_res->bi.pages_rsgt);
 125 }
 126
 127 /**
 128  * i915_vma_resource_unhold - Unhold the signaling of the vma resource unbind
 129  * fence.
 130  * @vma_res: The vma resource.
 131  * @lockdep_cookie: The lockdep cookie returned from i915_vma_resource_hold.
 132  *
 133  * The function may leave a dma_fence critical section.
 134  */
 135 void i915_vma_resource_unhold(struct i915_vma_resource *vma_res,
 136                               bool lockdep_cookie)
 137 {
 138         dma_fence_end_signalling(lockdep_cookie);
 139
 140         if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
 141                 unsigned long irq_flags;
 142
 143                 /* Inefficient open-coded might_lock_irqsave() */
 144                 spin_lock_irqsave(&vma_res->lock, irq_flags);
 145                 spin_unlock_irqrestore(&vma_res->lock, irq_flags);
 146         }
 147
 148         __i915_vma_resource_unhold(vma_res);
 149 }
 150
 151 /**
 152  * i915_vma_resource_hold - Hold the signaling of the vma resource unbind fence.
 153  * @vma_res: The vma resource.
 154  * @lockdep_cookie: Pointer to a bool serving as a lockdep cooke that should
 155  * be given as an argument to the pairing i915_vma_resource_unhold.
 156  *
 157  * If returning true, the function enters a dma_fence signalling critical
 158  * section if not in one already.
 159  *
 160  * Return: true if holding successful, false if not.
 161  */
 162 bool i915_vma_resource_hold(struct i915_vma_resource *vma_res,
 163                             bool *lockdep_cookie)
 164 {
 165         bool held = refcount_inc_not_zero(&vma_res->hold_count);
 166
 167         if (held)
 168                 *lockdep_cookie = dma_fence_begin_signalling();
 169
 170         return held;
 171 }
 172
 173 static void i915_vma_resource_unbind_work(struct work_struct *work)
 174 {
 175         struct i915_vma_resource *vma_res =
 176                 container_of(work, typeof(*vma_res), work);
 177         struct i915_address_space *vm = vma_res->vm;
 178         bool lockdep_cookie;
 179
 180         lockdep_cookie = dma_fence_begin_signalling();
 181         if (likely(!vma_res->skip_pte_rewrite))
 182                 vma_res->ops->unbind_vma(vm, vma_res);
 183
 184         dma_fence_end_signalling(lockdep_cookie);
 185         __i915_vma_resource_unhold(vma_res);
 186         i915_vma_resource_put(vma_res);
 187 }
 188
 189 static int
 190 i915_vma_resource_fence_notify(struct i915_sw_fence *fence,
 191                                enum i915_sw_fence_notify state)
 192 {
 193         struct i915_vma_resource *vma_res =
 194                 container_of(fence, typeof(*vma_res), chain);
 195         struct dma_fence *unbind_fence =
 196                 &vma_res->unbind_fence;
 197
 198         switch (state) {
 199         case FENCE_COMPLETE:
 200                 dma_fence_get(unbind_fence);
 201                 if (vma_res->immediate_unbind) {
 202                         i915_vma_resource_unbind_work(&vma_res->work);
 203                 } else {
 204                         INIT_WORK(&vma_res->work, i915_vma_resource_unbind_work);
 205                         queue_work(system_unbound_wq, &vma_res->work);
 206                 }
 207                 break;
 208         case FENCE_FREE:
 209                 i915_vma_resource_put(vma_res);
 210                 break;
 211         }
 212
 213         return NOTIFY_DONE;
 214 }
 215
 216 /**
 217  * i915_vma_resource_unbind - Unbind a vma resource
 218  * @vma_res: The vma resource to unbind.
 219  *
 220  * At this point this function does little more than publish a fence that
 221  * signals immediately unless signaling is held back.
 222  *
 223  * Return: A refcounted pointer to a dma-fence that signals when unbinding is
 224  * complete.
 225  */
 226 struct dma_fence *i915_vma_resource_unbind(struct i915_vma_resource *vma_res)
 227 {
 228         struct i915_address_space *vm = vma_res->vm;
 229
 230         /* Reference for the sw fence */
 231         i915_vma_resource_get(vma_res);
 232
 233         /* Caller must already have a wakeref in this case. */
 234         if (vma_res->needs_wakeref)
 235                 vma_res->wakeref = intel_runtime_pm_get_if_in_use(&vm->i915->runtime_pm);
 236
 237         if (atomic_read(&vma_res->chain.pending) <= 1) {
 238                 RB_CLEAR_NODE(&vma_res->rb);
 239                 vma_res->immediate_unbind = 1;
 240         } else {
 241                 vma_res_itree_insert(vma_res, &vma_res->vm->pending_unbind);
 242         }
 243
 244         i915_sw_fence_commit(&vma_res->chain);
 245
 246         return &vma_res->unbind_fence;
 247 }
 248
 249 /**
 250  * __i915_vma_resource_init - Initialize a vma resource.
 251  * @vma_res: The vma resource to initialize
 252  *
 253  * Initializes the private members of a vma resource.
 254  */
 255 void __i915_vma_resource_init(struct i915_vma_resource *vma_res)
 256 {
 257         spin_lock_init(&vma_res->lock);
 258         dma_fence_init(&vma_res->unbind_fence, &unbind_fence_ops,
 259                        &vma_res->lock, 0, 0);
 260         refcount_set(&vma_res->hold_count, 1);
 261         i915_sw_fence_init(&vma_res->chain, i915_vma_resource_fence_notify);
 262 }
 263
 264 static void
 265 i915_vma_resource_color_adjust_range(struct i915_address_space *vm,
 266                                      u64 *start,
 267                                      u64 *end)
 268 {
 269         if (i915_vm_has_cache_coloring(vm)) {
 270                 if (*start)
 271                         *start -= I915_GTT_PAGE_SIZE;
 272                 *end += I915_GTT_PAGE_SIZE;
 273         }
 274 }
 275
 276 /**
 277  * i915_vma_resource_bind_dep_sync - Wait for / sync all unbinds touching a
 278  * certain vm range.
 279  * @vm: The vm to look at.
 280  * @offset: The range start.
 281  * @size: The range size.
 282  * @intr: Whether to wait interrubtible.
 283  *
 284  * The function needs to be called with the vm lock held.
 285  *
 286  * Return: Zero on success, -ERESTARTSYS if interrupted and @intr==true
 287  */
 288 int i915_vma_resource_bind_dep_sync(struct i915_address_space *vm,
 289                                     u64 offset,
 290                                     u64 size,
 291                                     bool intr)
 292 {
 293         struct i915_vma_resource *node;
 294         u64 last = offset + size - 1;
 295
 296         lockdep_assert_held(&vm->mutex);
 297         might_sleep();
 298
 299         i915_vma_resource_color_adjust_range(vm, &offset, &last);
 300         node = vma_res_itree_iter_first(&vm->pending_unbind, offset, last);
 301         while (node) {
 302                 int ret = dma_fence_wait(&node->unbind_fence, intr);
 303
 304                 if (ret)
 305                         return ret;
 306
 307                 node = vma_res_itree_iter_next(node, offset, last);
 308         }
 309
 310         return 0;
 311 }
 312
 313 /**
 314  * i915_vma_resource_bind_dep_sync_all - Wait for / sync all unbinds of a vm,
 315  * releasing the vm lock while waiting.
 316  * @vm: The vm to look at.
 317  *
 318  * The function may not be called with the vm lock held.
 319  * Typically this is called at vm destruction to finish any pending
 320  * unbind operations. The vm mutex is released while waiting to avoid
 321  * stalling kernel workqueues trying to grab the mutex.
 322  */
 323 void i915_vma_resource_bind_dep_sync_all(struct i915_address_space *vm)
 324 {
 325         struct i915_vma_resource *node;
 326         struct dma_fence *fence;
 327
 328         do {
 329                 fence = NULL;
 330                 mutex_lock(&vm->mutex);
 331                 node = vma_res_itree_iter_first(&vm->pending_unbind, 0,
 332                                                 U64_MAX);
 333                 if (node)
 334                         fence = dma_fence_get_rcu(&node->unbind_fence);
 335                 mutex_unlock(&vm->mutex);
 336
 337                 if (fence) {
 338                         /*
 339                          * The wait makes sure the node eventually removes
 340                          * itself from the tree.
 341                          */
 342                         dma_fence_wait(fence, false);
 343                         dma_fence_put(fence);
 344                 }
 345         } while (node);
 346 }
 347
 348 /**
 349  * i915_vma_resource_bind_dep_await - Have a struct i915_sw_fence await all
 350  * pending unbinds in a certain range of a vm.
 351  * @vm: The vm to look at.
 352  * @sw_fence: The struct i915_sw_fence that will be awaiting the unbinds.
 353  * @offset: The range start.
 354  * @size: The range size.
 355  * @intr: Whether to wait interrubtible.
 356  * @gfp: Allocation mode for memory allocations.
 357  *
 358  * The function makes @sw_fence await all pending unbinds in a certain
 359  * vm range before calling the complete notifier. To be able to await
 360  * each individual unbind, the function needs to allocate memory using
 361  * the @gpf allocation mode. If that fails, the function will instead
 362  * wait for the unbind fence to signal, using @intr to judge whether to
 363  * wait interruptible or not. Note that @gfp should ideally be selected so
 364  * as to avoid any expensive memory allocation stalls and rather fail and
 365  * synchronize itself. For now the vm mutex is required when calling this
 366  * function with means that @gfp can't call into direct reclaim. In reality
 367  * this means that during heavy memory pressure, we will sync in this
 368  * function.
 369  *
 370  * Return: Zero on success, -ERESTARTSYS if interrupted and @intr==true
 371  */
 372 int i915_vma_resource_bind_dep_await(struct i915_address_space *vm,
 373                                      struct i915_sw_fence *sw_fence,
 374                                      u64 offset,
 375                                      u64 size,
 376                                      bool intr,
 377                                      gfp_t gfp)
 378 {
 379         struct i915_vma_resource *node;
 380         u64 last = offset + size - 1;
 381
 382         lockdep_assert_held(&vm->mutex);
 383         might_alloc(gfp);
 384         might_sleep();
 385
 386         i915_vma_resource_color_adjust_range(vm, &offset, &last);
 387         node = vma_res_itree_iter_first(&vm->pending_unbind, offset, last);
 388         while (node) {
 389                 int ret;
 390
 391                 ret = i915_sw_fence_await_dma_fence(sw_fence,
 392                                                     &node->unbind_fence,
 393                                                     0, gfp);
 394                 if (ret < 0) {
 395                         ret = dma_fence_wait(&node->unbind_fence, intr);
 396                         if (ret)
 397                                 return ret;
 398                 }
 399
 400                 node = vma_res_itree_iter_next(node, offset, last);
 401         }
 402
 403         return 0;
 404 }
 405
 406 void i915_vma_resource_module_exit(void)
 407 {
 408         kmem_cache_destroy(slab_vma_resources);
 409 }
 410
 411 int __init i915_vma_resource_module_init(void)
 412 {
 413         slab_vma_resources = KMEM_CACHE(i915_vma_resource, SLAB_HWCACHE_ALIGN);
 414         if (!slab_vma_resources)
 415                 return -ENOMEM;
 416
 417         return 0;
 418 }