1 /*
2 * Copyright © 2012-2014 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 <drm/drmP.h>
26 #include <drm/i915_drm.h>
27 #include "i915_drv.h"
28 #include "i915_trace.h"
29 #include "intel_drv.h"
30 #include <linux/mmu_context.h>
31 #include <linux/mmu_notifier.h>
32 #include <linux/mempolicy.h>
33 #include <linux/swap.h>
34 #include <linux/sched/mm.h>
35
36 struct i915_mm_struct {
37 struct mm_struct *mm;
38 struct drm_i915_private *i915;
39 struct i915_mmu_notifier *mn;
40 struct hlist_node node;
41 struct kref kref;
42 struct work_struct work;
43 };
44
45 #if defined(CONFIG_MMU_NOTIFIER)
46 #include <linux/interval_tree.h>
47
48 struct i915_mmu_notifier {
49 spinlock_t lock;
50 struct hlist_node node;
51 struct mmu_notifier mn;
52 struct rb_root objects;
53 struct workqueue_struct *wq;
54 };
55
56 struct i915_mmu_object {
57 struct i915_mmu_notifier *mn;
58 struct drm_i915_gem_object *obj;
59 struct interval_tree_node it;
60 struct list_head link;
61 struct work_struct work;
62 bool attached;
63 };
64
cancel_userptr(struct work_struct * work)65 static void cancel_userptr(struct work_struct *work)
66 {
67 struct i915_mmu_object *mo = container_of(work, typeof(*mo), work);
68 struct drm_i915_gem_object *obj = mo->obj;
69 struct work_struct *active;
70
71 /* Cancel any active worker and force us to re-evaluate gup */
72 mutex_lock(&obj->mm.lock);
73 active = fetch_and_zero(&obj->userptr.work);
74 mutex_unlock(&obj->mm.lock);
75 if (active)
76 goto out;
77
78 i915_gem_object_wait(obj, I915_WAIT_ALL, MAX_SCHEDULE_TIMEOUT, NULL);
79
80 mutex_lock(&obj->base.dev->struct_mutex);
81
82 /* We are inside a kthread context and can't be interrupted */
83 if (i915_gem_object_unbind(obj) == 0)
84 __i915_gem_object_put_pages(obj, I915_MM_NORMAL);
85 WARN_ONCE(i915_gem_object_has_pages(obj),
86 "Failed to release pages: bind_count=%d, pages_pin_count=%d, pin_global=%d\n",
87 obj->bind_count,
88 atomic_read(&obj->mm.pages_pin_count),
89 obj->pin_global);
90
91 mutex_unlock(&obj->base.dev->struct_mutex);
92
93 out:
94 i915_gem_object_put(obj);
95 }
96
add_object(struct i915_mmu_object * mo)97 static void add_object(struct i915_mmu_object *mo)
98 {
99 if (mo->attached)
100 return;
101
102 interval_tree_insert(&mo->it, &mo->mn->objects);
103 mo->attached = true;
104 }
105
del_object(struct i915_mmu_object * mo)106 static void del_object(struct i915_mmu_object *mo)
107 {
108 if (!mo->attached)
109 return;
110
111 interval_tree_remove(&mo->it, &mo->mn->objects);
112 mo->attached = false;
113 }
114
i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier * _mn,struct mm_struct * mm,unsigned long start,unsigned long end)115 static void i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier *_mn,
116 struct mm_struct *mm,
117 unsigned long start,
118 unsigned long end)
119 {
120 struct i915_mmu_notifier *mn =
121 container_of(_mn, struct i915_mmu_notifier, mn);
122 struct i915_mmu_object *mo;
123 struct interval_tree_node *it;
124 LINUX_LIST_HEAD(cancelled);
125
126 if (RB_EMPTY_ROOT(&mn->objects))
127 return;
128
129 /* interval ranges are inclusive, but invalidate range is exclusive */
130 end--;
131
132 lockmgr(&mn->lock, LK_EXCLUSIVE);
133 it = interval_tree_iter_first(&mn->objects, start, end);
134 while (it) {
135 /* The mmu_object is released late when destroying the
136 * GEM object so it is entirely possible to gain a
137 * reference on an object in the process of being freed
138 * since our serialisation is via the spinlock and not
139 * the struct_mutex - and consequently use it after it
140 * is freed and then double free it. To prevent that
141 * use-after-free we only acquire a reference on the
142 * object if it is not in the process of being destroyed.
143 */
144 mo = container_of(it, struct i915_mmu_object, it);
145 if (kref_get_unless_zero(&mo->obj->base.refcount))
146 queue_work(mn->wq, &mo->work);
147
148 list_add(&mo->link, &cancelled);
149 it = interval_tree_iter_next(it, start, end);
150 }
151 list_for_each_entry(mo, &cancelled, link)
152 del_object(mo);
153 lockmgr(&mn->lock, LK_RELEASE);
154
155 if (!list_empty(&cancelled))
156 flush_workqueue(mn->wq);
157 }
158
159 static const struct mmu_notifier_ops i915_gem_userptr_notifier = {
160 .invalidate_range_start = i915_gem_userptr_mn_invalidate_range_start,
161 };
162
163 static struct i915_mmu_notifier *
i915_mmu_notifier_create(struct mm_struct * mm)164 i915_mmu_notifier_create(struct mm_struct *mm)
165 {
166 struct i915_mmu_notifier *mn;
167
168 mn = kmalloc(sizeof(*mn), M_DRM, GFP_KERNEL);
169 if (mn == NULL)
170 return ERR_PTR(-ENOMEM);
171
172 spin_lock_init(&mn->lock);
173 mn->mn.ops = &i915_gem_userptr_notifier;
174 mn->objects = LINUX_RB_ROOT;
175 mn->wq = alloc_workqueue("i915-userptr-release",
176 WQ_UNBOUND | WQ_MEM_RECLAIM,
177 0);
178 if (mn->wq == NULL) {
179 kfree(mn);
180 return ERR_PTR(-ENOMEM);
181 }
182
183 return mn;
184 }
185
186 static void
i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object * obj)187 i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj)
188 {
189 struct i915_mmu_object *mo;
190
191 mo = obj->userptr.mmu_object;
192 if (mo == NULL)
193 return;
194
195 lockmgr(&mo->mn->lock, LK_EXCLUSIVE);
196 del_object(mo);
197 lockmgr(&mo->mn->lock, LK_RELEASE);
198 kfree(mo);
199
200 obj->userptr.mmu_object = NULL;
201 }
202
203 static struct i915_mmu_notifier *
i915_mmu_notifier_find(struct i915_mm_struct * mm)204 i915_mmu_notifier_find(struct i915_mm_struct *mm)
205 {
206 struct i915_mmu_notifier *mn;
207 int err = 0;
208
209 mn = mm->mn;
210 if (mn)
211 return mn;
212
213 mn = i915_mmu_notifier_create(mm->mm);
214 if (IS_ERR(mn))
215 err = PTR_ERR(mn);
216
217 down_write(&mm->mm->mmap_sem);
218 mutex_lock(&mm->i915->mm_lock);
219 if (mm->mn == NULL && !err) {
220 /* Protected by mmap_sem (write-lock) */
221 err = __mmu_notifier_register(&mn->mn, mm->mm);
222 if (!err) {
223 /* Protected by mm_lock */
224 mm->mn = fetch_and_zero(&mn);
225 }
226 } else if (mm->mn) {
227 /*
228 * Someone else raced and successfully installed the mmu
229 * notifier, we can cancel our own errors.
230 */
231 err = 0;
232 }
233 mutex_unlock(&mm->i915->mm_lock);
234 up_write(&mm->mm->mmap_sem);
235
236 if (mn && !IS_ERR(mn)) {
237 destroy_workqueue(mn->wq);
238 kfree(mn);
239 }
240
241 return err ? ERR_PTR(err) : mm->mn;
242 }
243
244 static int
i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object * obj,unsigned flags)245 i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj,
246 unsigned flags)
247 {
248 struct i915_mmu_notifier *mn;
249 struct i915_mmu_object *mo;
250
251 if (flags & I915_USERPTR_UNSYNCHRONIZED)
252 return capable(CAP_SYS_ADMIN) ? 0 : -EPERM;
253
254 if (WARN_ON(obj->userptr.mm == NULL))
255 return -EINVAL;
256
257 mn = i915_mmu_notifier_find(obj->userptr.mm);
258 if (IS_ERR(mn))
259 return PTR_ERR(mn);
260
261 mo = kzalloc(sizeof(*mo), GFP_KERNEL);
262 if (mo == NULL)
263 return -ENOMEM;
264
265 mo->mn = mn;
266 mo->obj = obj;
267 mo->it.start = obj->userptr.ptr;
268 mo->it.last = obj->userptr.ptr + obj->base.size - 1;
269 INIT_WORK(&mo->work, cancel_userptr);
270
271 obj->userptr.mmu_object = mo;
272 return 0;
273 }
274
275 static void
i915_mmu_notifier_free(struct i915_mmu_notifier * mn,struct mm_struct * mm)276 i915_mmu_notifier_free(struct i915_mmu_notifier *mn,
277 struct mm_struct *mm)
278 {
279 if (mn == NULL)
280 return;
281
282 mmu_notifier_unregister(&mn->mn, mm);
283 destroy_workqueue(mn->wq);
284 kfree(mn);
285 }
286
287 #else
288
289 static void
i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object * obj)290 i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj)
291 {
292 }
293
294 static int
i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object * obj,unsigned flags)295 i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj,
296 unsigned flags)
297 {
298 if ((flags & I915_USERPTR_UNSYNCHRONIZED) == 0)
299 return -ENODEV;
300
301 if (!capable(CAP_SYS_ADMIN))
302 return -EPERM;
303
304 return 0;
305 }
306
307 static void
i915_mmu_notifier_free(struct i915_mmu_notifier * mn,struct mm_struct * mm)308 i915_mmu_notifier_free(struct i915_mmu_notifier *mn,
309 struct mm_struct *mm)
310 {
311 }
312
313 #endif
314
315 static struct i915_mm_struct *
__i915_mm_struct_find(struct drm_i915_private * dev_priv,struct mm_struct * real)316 __i915_mm_struct_find(struct drm_i915_private *dev_priv, struct mm_struct *real)
317 {
318 struct i915_mm_struct *mm;
319
320 /* Protected by dev_priv->mm_lock */
321 hash_for_each_possible(dev_priv->mm_structs, mm, node, (unsigned long)real)
322 if (mm->mm == real)
323 return mm;
324
325 return NULL;
326 }
327
328 static int
i915_gem_userptr_init__mm_struct(struct drm_i915_gem_object * obj)329 i915_gem_userptr_init__mm_struct(struct drm_i915_gem_object *obj)
330 {
331 struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
332 struct i915_mm_struct *mm;
333 int ret = 0;
334
335 /* During release of the GEM object we hold the struct_mutex. This
336 * precludes us from calling mmput() at that time as that may be
337 * the last reference and so call exit_mmap(). exit_mmap() will
338 * attempt to reap the vma, and if we were holding a GTT mmap
339 * would then call drm_gem_vm_close() and attempt to reacquire
340 * the struct mutex. So in order to avoid that recursion, we have
341 * to defer releasing the mm reference until after we drop the
342 * struct_mutex, i.e. we need to schedule a worker to do the clean
343 * up.
344 */
345 mutex_lock(&dev_priv->mm_lock);
346 mm = __i915_mm_struct_find(dev_priv, current->mm);
347 if (mm == NULL) {
348 mm = kmalloc(sizeof(*mm), M_DRM, GFP_KERNEL);
349 if (mm == NULL) {
350 ret = -ENOMEM;
351 goto out;
352 }
353
354 kref_init(&mm->kref);
355 mm->i915 = to_i915(obj->base.dev);
356
357 mm->mm = current->mm;
358 mmgrab(current->mm);
359
360 mm->mn = NULL;
361
362 /* Protected by dev_priv->mm_lock */
363 hash_add(dev_priv->mm_structs,
364 &mm->node, (unsigned long)mm->mm);
365 } else
366 kref_get(&mm->kref);
367
368 obj->userptr.mm = mm;
369 out:
370 mutex_unlock(&dev_priv->mm_lock);
371 return ret;
372 }
373
374 static void
__i915_mm_struct_free__worker(struct work_struct * work)375 __i915_mm_struct_free__worker(struct work_struct *work)
376 {
377 struct i915_mm_struct *mm = container_of(work, typeof(*mm), work);
378 i915_mmu_notifier_free(mm->mn, mm->mm);
379 #if 0
380 mmdrop(mm->mm);
381 #endif
382 kfree(mm);
383 }
384
385 static void
__i915_mm_struct_free(struct kref * kref)386 __i915_mm_struct_free(struct kref *kref)
387 {
388 struct i915_mm_struct *mm = container_of(kref, typeof(*mm), kref);
389
390 /* Protected by dev_priv->mm_lock */
391 hash_del(&mm->node);
392 mutex_unlock(&mm->i915->mm_lock);
393
394 INIT_WORK(&mm->work, __i915_mm_struct_free__worker);
395 queue_work(mm->i915->mm.userptr_wq, &mm->work);
396 }
397
398 static void
i915_gem_userptr_release__mm_struct(struct drm_i915_gem_object * obj)399 i915_gem_userptr_release__mm_struct(struct drm_i915_gem_object *obj)
400 {
401 if (obj->userptr.mm == NULL)
402 return;
403
404 kref_put_mutex(&obj->userptr.mm->kref,
405 __i915_mm_struct_free,
406 &to_i915(obj->base.dev)->mm_lock);
407 obj->userptr.mm = NULL;
408 }
409
410 struct get_pages_work {
411 struct work_struct work;
412 struct drm_i915_gem_object *obj;
413 struct task_struct *task;
414 };
415
416 #if 0
417 static struct sg_table *
418 __i915_gem_userptr_alloc_pages(struct drm_i915_gem_object *obj,
419 struct page **pvec, int num_pages)
420 {
421 unsigned int max_segment = i915_sg_segment_size();
422 struct sg_table *st;
423 unsigned int sg_page_sizes;
424 int ret;
425
426 st = kmalloc(sizeof(*st), M_DRM, GFP_KERNEL);
427 if (!st)
428 return ERR_PTR(-ENOMEM);
429
430 alloc_table:
431 ret = __sg_alloc_table_from_pages(st, pvec, num_pages,
432 0, num_pages << PAGE_SHIFT,
433 max_segment,
434 GFP_KERNEL);
435 if (ret) {
436 kfree(st);
437 return ERR_PTR(ret);
438 }
439
440 ret = i915_gem_gtt_prepare_pages(obj, st);
441 if (ret) {
442 sg_free_table(st);
443
444 if (max_segment > PAGE_SIZE) {
445 max_segment = PAGE_SIZE;
446 goto alloc_table;
447 }
448
449 kfree(st);
450 return ERR_PTR(ret);
451 }
452
453 sg_page_sizes = i915_sg_page_sizes(st->sgl);
454
455 __i915_gem_object_set_pages(obj, st, sg_page_sizes);
456
457 return st;
458 }
459 #endif
460
461 static int
__i915_gem_userptr_set_active(struct drm_i915_gem_object * obj,bool value)462 __i915_gem_userptr_set_active(struct drm_i915_gem_object *obj,
463 bool value)
464 {
465 int ret = 0;
466
467 /* During mm_invalidate_range we need to cancel any userptr that
468 * overlaps the range being invalidated. Doing so requires the
469 * struct_mutex, and that risks recursion. In order to cause
470 * recursion, the user must alias the userptr address space with
471 * a GTT mmapping (possible with a MAP_FIXED) - then when we have
472 * to invalidate that mmaping, mm_invalidate_range is called with
473 * the userptr address *and* the struct_mutex held. To prevent that
474 * we set a flag under the i915_mmu_notifier spinlock to indicate
475 * whether this object is valid.
476 */
477 #if defined(CONFIG_MMU_NOTIFIER)
478 if (obj->userptr.mmu_object == NULL)
479 return 0;
480
481 lockmgr(&obj->userptr.mmu_object->mn->lock, LK_EXCLUSIVE);
482 /* In order to serialise get_pages with an outstanding
483 * cancel_userptr, we must drop the struct_mutex and try again.
484 */
485 if (!value)
486 del_object(obj->userptr.mmu_object);
487 else if (!work_pending(&obj->userptr.mmu_object->work))
488 add_object(obj->userptr.mmu_object);
489 else
490 ret = -EAGAIN;
491 lockmgr(&obj->userptr.mmu_object->mn->lock, LK_RELEASE);
492 #endif
493
494 return ret;
495 }
496
497 #if 0
498 static void
499 __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
500 {
501 struct get_pages_work *work = container_of(_work, typeof(*work), work);
502 struct drm_i915_gem_object *obj = work->obj;
503 const int npages = obj->base.size >> PAGE_SHIFT;
504 struct page **pvec;
505 int pinned, ret;
506
507 ret = -ENOMEM;
508 pinned = 0;
509
510 pvec = kvmalloc_array(npages, sizeof(struct page *), GFP_TEMPORARY);
511 if (pvec != NULL) {
512 struct mm_struct *mm = obj->userptr.mm->mm;
513 unsigned int flags = 0;
514
515 if (!obj->userptr.read_only)
516 flags |= FOLL_WRITE;
517
518 ret = -EFAULT;
519 if (mmget_not_zero(mm)) {
520 down_read(&mm->mmap_sem);
521 while (pinned < npages) {
522 ret = get_user_pages_remote
523 (work->task, mm,
524 obj->userptr.ptr + pinned * PAGE_SIZE,
525 npages - pinned,
526 flags,
527 pvec + pinned, NULL, NULL);
528 if (ret < 0)
529 break;
530
531 pinned += ret;
532 }
533 up_read(&mm->mmap_sem);
534 mmput(mm);
535 }
536 }
537
538 mutex_lock(&obj->mm.lock);
539 if (obj->userptr.work == &work->work) {
540 struct sg_table *pages = ERR_PTR(ret);
541
542 if (pinned == npages) {
543 pages = __i915_gem_userptr_alloc_pages(obj, pvec,
544 npages);
545 if (!IS_ERR(pages)) {
546 pinned = 0;
547 pages = NULL;
548 }
549 }
550
551 obj->userptr.work = ERR_CAST(pages);
552 if (IS_ERR(pages))
553 __i915_gem_userptr_set_active(obj, false);
554 }
555 mutex_unlock(&obj->mm.lock);
556
557 release_pages(pvec, pinned);
558 kvfree(pvec);
559
560 i915_gem_object_put(obj);
561 put_task_struct(work->task);
562 kfree(work);
563 }
564
565 static struct sg_table *
566 __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj)
567 {
568 struct get_pages_work *work;
569
570 /* Spawn a worker so that we can acquire the
571 * user pages without holding our mutex. Access
572 * to the user pages requires mmap_sem, and we have
573 * a strict lock ordering of mmap_sem, struct_mutex -
574 * we already hold struct_mutex here and so cannot
575 * call gup without encountering a lock inversion.
576 *
577 * Userspace will keep on repeating the operation
578 * (thanks to EAGAIN) until either we hit the fast
579 * path or the worker completes. If the worker is
580 * cancelled or superseded, the task is still run
581 * but the results ignored. (This leads to
582 * complications that we may have a stray object
583 * refcount that we need to be wary of when
584 * checking for existing objects during creation.)
585 * If the worker encounters an error, it reports
586 * that error back to this function through
587 * obj->userptr.work = ERR_PTR.
588 */
589 work = kmalloc(sizeof(*work), M_DRM, GFP_KERNEL);
590 if (work == NULL)
591 return ERR_PTR(-ENOMEM);
592
593 obj->userptr.work = &work->work;
594
595 work->obj = i915_gem_object_get(obj);
596
597 work->task = current;
598 get_task_struct(work->task);
599
600 INIT_WORK(&work->work, __i915_gem_userptr_get_pages_worker);
601 queue_work(to_i915(obj->base.dev)->mm.userptr_wq, &work->work);
602
603 return ERR_PTR(-EAGAIN);
604 }
605 #endif
606
i915_gem_userptr_get_pages(struct drm_i915_gem_object * obj)607 static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
608 {
609 #if 0
610 const int num_pages = obj->base.size >> PAGE_SHIFT;
611 struct mm_struct *mm = obj->userptr.mm->mm;
612 struct page **pvec;
613 struct sg_table *pages;
614 bool active;
615 int pinned;
616
617 /* If userspace should engineer that these pages are replaced in
618 * the vma between us binding this page into the GTT and completion
619 * of rendering... Their loss. If they change the mapping of their
620 * pages they need to create a new bo to point to the new vma.
621 *
622 * However, that still leaves open the possibility of the vma
623 * being copied upon fork. Which falls under the same userspace
624 * synchronisation issue as a regular bo, except that this time
625 * the process may not be expecting that a particular piece of
626 * memory is tied to the GPU.
627 *
628 * Fortunately, we can hook into the mmu_notifier in order to
629 * discard the page references prior to anything nasty happening
630 * to the vma (discard or cloning) which should prevent the more
631 * egregious cases from causing harm.
632 */
633
634 if (obj->userptr.work) {
635 /* active flag should still be held for the pending work */
636 if (IS_ERR(obj->userptr.work))
637 return PTR_ERR(obj->userptr.work);
638 else
639 return -EAGAIN;
640 }
641
642 pvec = NULL;
643 pinned = 0;
644
645 if (mm == current->mm) {
646 pvec = kvmalloc_array(num_pages, sizeof(struct page *),
647 GFP_KERNEL |
648 __GFP_NORETRY |
649 __GFP_NOWARN);
650 if (pvec) /* defer to worker if malloc fails */
651 pinned = __get_user_pages_fast(obj->userptr.ptr,
652 num_pages,
653 !obj->userptr.read_only,
654 pvec);
655 }
656
657 active = false;
658 if (pinned < 0) {
659 pages = ERR_PTR(pinned);
660 pinned = 0;
661 } else if (pinned < num_pages) {
662 pages = __i915_gem_userptr_get_pages_schedule(obj);
663 active = pages == ERR_PTR(-EAGAIN);
664 } else {
665 pages = __i915_gem_userptr_alloc_pages(obj, pvec, num_pages);
666 active = !IS_ERR(pages);
667 }
668 if (active)
669 __i915_gem_userptr_set_active(obj, true);
670
671 if (IS_ERR(pages))
672 release_pages(pvec, pinned);
673 kvfree(pvec);
674
675 return PTR_ERR_OR_ZERO(pages);
676 #endif
677 return -EINVAL;
678 }
679
680 static void
i915_gem_userptr_put_pages(struct drm_i915_gem_object * obj,struct sg_table * pages)681 i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
682 struct sg_table *pages)
683 {
684 struct sgt_iter sgt_iter;
685 struct page *page;
686
687 BUG_ON(obj->userptr.work != NULL);
688 __i915_gem_userptr_set_active(obj, false);
689
690 if (obj->mm.madv != I915_MADV_WILLNEED)
691 obj->mm.dirty = false;
692
693 i915_gem_gtt_finish_pages(obj, pages);
694
695 for_each_sgt_page(page, sgt_iter, pages) {
696 if (obj->mm.dirty)
697 set_page_dirty(page);
698
699 mark_page_accessed(page);
700 put_page(page);
701 }
702 obj->mm.dirty = false;
703
704 sg_free_table(pages);
705 kfree(pages);
706 }
707
708 static void
i915_gem_userptr_release(struct drm_i915_gem_object * obj)709 i915_gem_userptr_release(struct drm_i915_gem_object *obj)
710 {
711 i915_gem_userptr_release__mmu_notifier(obj);
712 i915_gem_userptr_release__mm_struct(obj);
713 }
714
715 static int
i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object * obj)716 i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj)
717 {
718 if (obj->userptr.mmu_object)
719 return 0;
720
721 return i915_gem_userptr_init__mmu_notifier(obj, 0);
722 }
723
724 static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = {
725 .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE |
726 I915_GEM_OBJECT_IS_SHRINKABLE,
727 .get_pages = i915_gem_userptr_get_pages,
728 .put_pages = i915_gem_userptr_put_pages,
729 .dmabuf_export = i915_gem_userptr_dmabuf_export,
730 .release = i915_gem_userptr_release,
731 };
732
733 /**
734 * Creates a new mm object that wraps some normal memory from the process
735 * context - user memory.
736 *
737 * We impose several restrictions upon the memory being mapped
738 * into the GPU.
739 * 1. It must be page aligned (both start/end addresses, i.e ptr and size).
740 * 2. It must be normal system memory, not a pointer into another map of IO
741 * space (e.g. it must not be a GTT mmapping of another object).
742 * 3. We only allow a bo as large as we could in theory map into the GTT,
743 * that is we limit the size to the total size of the GTT.
744 * 4. The bo is marked as being snoopable. The backing pages are left
745 * accessible directly by the CPU, but reads and writes by the GPU may
746 * incur the cost of a snoop (unless you have an LLC architecture).
747 *
748 * Synchronisation between multiple users and the GPU is left to userspace
749 * through the normal set-domain-ioctl. The kernel will enforce that the
750 * GPU relinquishes the VMA before it is returned back to the system
751 * i.e. upon free(), munmap() or process termination. However, the userspace
752 * malloc() library may not immediately relinquish the VMA after free() and
753 * instead reuse it whilst the GPU is still reading and writing to the VMA.
754 * Caveat emptor.
755 *
756 * Also note, that the object created here is not currently a "first class"
757 * object, in that several ioctls are banned. These are the CPU access
758 * ioctls: mmap(), pwrite and pread. In practice, you are expected to use
759 * direct access via your pointer rather than use those ioctls. Another
760 * restriction is that we do not allow userptr surfaces to be pinned to the
761 * hardware and so we reject any attempt to create a framebuffer out of a
762 * userptr.
763 *
764 * If you think this is a good interface to use to pass GPU memory between
765 * drivers, please use dma-buf instead. In fact, wherever possible use
766 * dma-buf instead.
767 */
768 int
i915_gem_userptr_ioctl(struct drm_device * dev,void * data,struct drm_file * file)769 i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
770 {
771 struct drm_i915_private *dev_priv = to_i915(dev);
772 struct drm_i915_gem_userptr *args = data;
773 struct drm_i915_gem_object *obj;
774 int ret;
775 u32 handle;
776
777 if (!HAS_LLC(dev_priv) && !HAS_SNOOP(dev_priv)) {
778 /* We cannot support coherent userptr objects on hw without
779 * LLC and broken snooping.
780 */
781 return -ENODEV;
782 }
783
784 if (args->flags & ~(I915_USERPTR_READ_ONLY |
785 I915_USERPTR_UNSYNCHRONIZED))
786 return -EINVAL;
787
788 if (offset_in_page(args->user_ptr | args->user_size))
789 return -EINVAL;
790
791 #if 0
792 if (!access_ok(args->flags & I915_USERPTR_READ_ONLY ? VERIFY_READ : VERIFY_WRITE,
793 (char __user *)(unsigned long)args->user_ptr, args->user_size))
794 return -EFAULT;
795 #endif
796
797 if (args->flags & I915_USERPTR_READ_ONLY) {
798 /* On almost all of the current hw, we cannot tell the GPU that a
799 * page is readonly, so this is just a placeholder in the uAPI.
800 */
801 return -ENODEV;
802 }
803
804 obj = i915_gem_object_alloc(dev_priv);
805 if (obj == NULL)
806 return -ENOMEM;
807
808 drm_gem_private_object_init(dev, &obj->base, args->user_size);
809 i915_gem_object_init(obj, &i915_gem_userptr_ops);
810 obj->base.read_domains = I915_GEM_DOMAIN_CPU;
811 obj->base.write_domain = I915_GEM_DOMAIN_CPU;
812 i915_gem_object_set_cache_coherency(obj, I915_CACHE_LLC);
813
814 obj->userptr.ptr = args->user_ptr;
815 obj->userptr.read_only = !!(args->flags & I915_USERPTR_READ_ONLY);
816
817 /* And keep a pointer to the current->mm for resolving the user pages
818 * at binding. This means that we need to hook into the mmu_notifier
819 * in order to detect if the mmu is destroyed.
820 */
821 ret = i915_gem_userptr_init__mm_struct(obj);
822 if (ret == 0)
823 ret = i915_gem_userptr_init__mmu_notifier(obj, args->flags);
824 if (ret == 0)
825 ret = drm_gem_handle_create(file, &obj->base, &handle);
826
827 /* drop reference from allocate - handle holds it now */
828 i915_gem_object_put(obj);
829 if (ret)
830 return ret;
831
832 args->handle = handle;
833 return 0;
834 }
835
i915_gem_init_userptr(struct drm_i915_private * dev_priv)836 int i915_gem_init_userptr(struct drm_i915_private *dev_priv)
837 {
838 lockinit(&dev_priv->mm_lock, "i915dmm", 0, LK_CANRECURSE);
839 hash_init(dev_priv->mm_structs);
840
841 dev_priv->mm.userptr_wq =
842 alloc_workqueue("i915-userptr-acquire",
843 WQ_HIGHPRI | WQ_UNBOUND,
844 0);
845 if (!dev_priv->mm.userptr_wq)
846 return -ENOMEM;
847
848 return 0;
849 }
850
i915_gem_cleanup_userptr(struct drm_i915_private * dev_priv)851 void i915_gem_cleanup_userptr(struct drm_i915_private *dev_priv)
852 {
853 destroy_workqueue(dev_priv->mm.userptr_wq);
854 }
855