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 "drmP.h" 26#include "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 35struct i915_mm_struct { 36 struct mm_struct *mm; 37 struct drm_device *dev; 38 struct i915_mmu_notifier *mn; 39 struct hlist_node node; 40 struct kref kref; 41 struct work_struct work; 42}; 43 44#if defined(CONFIG_MMU_NOTIFIER) 45#include <linux/interval_tree.h> 46 47struct i915_mmu_notifier { 48 spinlock_t lock; 49 struct hlist_node node; 50 struct mmu_notifier mn; 51 struct rb_root objects; 52 struct list_head linear; 53 unsigned long serial; 54 bool has_linear; 55}; 56 57struct i915_mmu_object { 58 struct i915_mmu_notifier *mn; 59 struct interval_tree_node it; 60 struct list_head link; 61 struct drm_i915_gem_object *obj; 62 bool is_linear; 63}; 64 65static unsigned long cancel_userptr(struct drm_i915_gem_object *obj) 66{ 67 struct drm_device *dev = obj->base.dev; 68 unsigned long end; 69 70 mutex_lock(&dev->struct_mutex); 71 /* Cancel any active worker and force us to re-evaluate gup */ 72 obj->userptr.work = NULL; 73 74 if (obj->pages != NULL) { 75 struct drm_i915_private *dev_priv = to_i915(dev); 76 struct i915_vma *vma, *tmp; 77 bool was_interruptible; 78 79 was_interruptible = dev_priv->mm.interruptible; 80 dev_priv->mm.interruptible = false; 81 82 list_for_each_entry_safe(vma, tmp, &obj->vma_list, vma_link) { 83 int ret = i915_vma_unbind(vma); 84 WARN_ON(ret && ret != -EIO); 85 } 86 WARN_ON(i915_gem_object_put_pages(obj)); 87 88 dev_priv->mm.interruptible = was_interruptible; 89 } 90 91 end = obj->userptr.ptr + obj->base.size; 92 93 drm_gem_object_unreference(&obj->base); 94 mutex_unlock(&dev->struct_mutex); 95 96 return end; 97} 98 99static void *invalidate_range__linear(struct i915_mmu_notifier *mn, 100 struct mm_struct *mm, 101 unsigned long start, 102 unsigned long end) 103{ 104 struct i915_mmu_object *mo; 105 unsigned long serial; 106 107restart: 108 serial = mn->serial; 109 list_for_each_entry(mo, &mn->linear, link) { 110 struct drm_i915_gem_object *obj; 111 112 if (mo->it.last < start || mo->it.start > end) 113 continue; 114 115 obj = mo->obj; 116 drm_gem_object_reference(&obj->base); 117 spin_unlock(&mn->lock); 118 119 cancel_userptr(obj); 120 121 spin_lock(&mn->lock); 122 if (serial != mn->serial) 123 goto restart; 124 } 125 126 return NULL; 127} 128 129static void i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier *_mn, 130 struct mm_struct *mm, 131 unsigned long start, 132 unsigned long end) 133{ 134 struct i915_mmu_notifier *mn = container_of(_mn, struct i915_mmu_notifier, mn); 135 struct interval_tree_node *it = NULL; 136 unsigned long next = start; 137 unsigned long serial = 0; 138 139 end--; /* interval ranges are inclusive, but invalidate range is exclusive */ 140 while (next < end) { 141 struct drm_i915_gem_object *obj = NULL; 142 143 spin_lock(&mn->lock); 144 if (mn->has_linear) 145 it = invalidate_range__linear(mn, mm, start, end); 146 else if (serial == mn->serial) 147 it = interval_tree_iter_next(it, next, end); 148 else 149 it = interval_tree_iter_first(&mn->objects, start, end); 150 if (it != NULL) { 151 obj = container_of(it, struct i915_mmu_object, it)->obj; 152 drm_gem_object_reference(&obj->base); 153 serial = mn->serial; 154 } 155 spin_unlock(&mn->lock); 156 if (obj == NULL) 157 return; 158 159 next = cancel_userptr(obj); 160 } 161} 162 163static const struct mmu_notifier_ops i915_gem_userptr_notifier = { 164 .invalidate_range_start = i915_gem_userptr_mn_invalidate_range_start, 165}; 166 167static struct i915_mmu_notifier * 168i915_mmu_notifier_create(struct mm_struct *mm) 169{ 170 struct i915_mmu_notifier *mn; 171 int ret; 172 173 mn = kmalloc(sizeof(*mn), GFP_KERNEL); 174 if (mn == NULL) 175 return ERR_PTR(-ENOMEM); 176 177 spin_lock_init(&mn->lock); 178 mn->mn.ops = &i915_gem_userptr_notifier; 179 mn->objects = RB_ROOT; 180 mn->serial = 1; 181 INIT_LIST_HEAD(&mn->linear); 182 mn->has_linear = false; 183 184 /* Protected by mmap_sem (write-lock) */ 185 ret = __mmu_notifier_register(&mn->mn, mm); 186 if (ret) { 187 kfree(mn); 188 return ERR_PTR(ret); 189 } 190 191 return mn; 192} 193 194static void __i915_mmu_notifier_update_serial(struct i915_mmu_notifier *mn) 195{ 196 if (++mn->serial == 0) 197 mn->serial = 1; 198} 199 200static int 201i915_mmu_notifier_add(struct drm_device *dev, 202 struct i915_mmu_notifier *mn, 203 struct i915_mmu_object *mo) 204{ 205 struct interval_tree_node *it; 206 int ret; 207 208 ret = i915_mutex_lock_interruptible(dev); 209 if (ret) 210 return ret; 211 212 /* Make sure we drop the final active reference (and thereby 213 * remove the objects from the interval tree) before we do 214 * the check for overlapping objects. 215 */ 216 i915_gem_retire_requests(dev); 217 218 spin_lock(&mn->lock); 219 it = interval_tree_iter_first(&mn->objects, 220 mo->it.start, mo->it.last); 221 if (it) { 222 struct drm_i915_gem_object *obj; 223 224 /* We only need to check the first object in the range as it 225 * either has cancelled gup work queued and we need to 226 * return back to the user to give time for the gup-workers 227 * to flush their object references upon which the object will 228 * be removed from the interval-tree, or the the range is 229 * still in use by another client and the overlap is invalid. 230 * 231 * If we do have an overlap, we cannot use the interval tree 232 * for fast range invalidation. 233 */ 234 235 obj = container_of(it, struct i915_mmu_object, it)->obj; 236 if (!obj->userptr.workers) 237 mn->has_linear = mo->is_linear = true; 238 else 239 ret = -EAGAIN; 240 } else 241 interval_tree_insert(&mo->it, &mn->objects); 242 243 if (ret == 0) { 244 list_add(&mo->link, &mn->linear); 245 __i915_mmu_notifier_update_serial(mn); 246 } 247 spin_unlock(&mn->lock); 248 mutex_unlock(&dev->struct_mutex); 249 250 return ret; 251} 252 253static bool i915_mmu_notifier_has_linear(struct i915_mmu_notifier *mn) 254{ 255 struct i915_mmu_object *mo; 256 257 list_for_each_entry(mo, &mn->linear, link) 258 if (mo->is_linear) 259 return true; 260 261 return false; 262} 263 264static void 265i915_mmu_notifier_del(struct i915_mmu_notifier *mn, 266 struct i915_mmu_object *mo) 267{ 268 spin_lock(&mn->lock); 269 list_del(&mo->link); 270 if (mo->is_linear) 271 mn->has_linear = i915_mmu_notifier_has_linear(mn); 272 else 273 interval_tree_remove(&mo->it, &mn->objects); 274 __i915_mmu_notifier_update_serial(mn); 275 spin_unlock(&mn->lock); 276} 277 278static void 279i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj) 280{ 281 struct i915_mmu_object *mo; 282 283 mo = obj->userptr.mmu_object; 284 if (mo == NULL) 285 return; 286 287 i915_mmu_notifier_del(mo->mn, mo); 288 kfree(mo); 289 290 obj->userptr.mmu_object = NULL; 291} 292 293static struct i915_mmu_notifier * 294i915_mmu_notifier_find(struct i915_mm_struct *mm) 295{ 296 struct i915_mmu_notifier *mn = mm->mn; 297 298 mn = mm->mn; 299 if (mn) 300 return mn; 301 302 down_write(&mm->mm->mmap_sem); 303 mutex_lock(&to_i915(mm->dev)->mm_lock); 304 if ((mn = mm->mn) == NULL) { 305 mn = i915_mmu_notifier_create(mm->mm); 306 if (!IS_ERR(mn)) 307 mm->mn = mn; 308 } 309 mutex_unlock(&to_i915(mm->dev)->mm_lock); 310 up_write(&mm->mm->mmap_sem); 311 312 return mn; 313} 314 315static int 316i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj, 317 unsigned flags) 318{ 319 struct i915_mmu_notifier *mn; 320 struct i915_mmu_object *mo; 321 int ret; 322 323 if (flags & I915_USERPTR_UNSYNCHRONIZED) 324 return capable(CAP_SYS_ADMIN) ? 0 : -EPERM; 325 326 if (WARN_ON(obj->userptr.mm == NULL)) 327 return -EINVAL; 328 329 mn = i915_mmu_notifier_find(obj->userptr.mm); 330 if (IS_ERR(mn)) 331 return PTR_ERR(mn); 332 333 mo = kzalloc(sizeof(*mo), GFP_KERNEL); 334 if (mo == NULL) 335 return -ENOMEM; 336 337 mo->mn = mn; 338 mo->it.start = obj->userptr.ptr; 339 mo->it.last = mo->it.start + obj->base.size - 1; 340 mo->obj = obj; 341 342 ret = i915_mmu_notifier_add(obj->base.dev, mn, mo); 343 if (ret) { 344 kfree(mo); 345 return ret; 346 } 347 348 obj->userptr.mmu_object = mo; 349 return 0; 350} 351 352static void 353i915_mmu_notifier_free(struct i915_mmu_notifier *mn, 354 struct mm_struct *mm) 355{ 356 if (mn == NULL) 357 return; 358 359 mmu_notifier_unregister(&mn->mn, mm); 360 kfree(mn); 361} 362 363#else 364 365static void 366i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj) 367{ 368} 369 370static int 371i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj, 372 unsigned flags) 373{ 374 if ((flags & I915_USERPTR_UNSYNCHRONIZED) == 0) 375 return -ENODEV; 376 377 if (!capable(CAP_SYS_ADMIN)) 378 return -EPERM; 379 380 return 0; 381} 382 383static void 384i915_mmu_notifier_free(struct i915_mmu_notifier *mn, 385 struct mm_struct *mm) 386{ 387} 388 389#endif 390 391static struct i915_mm_struct * 392__i915_mm_struct_find(struct drm_i915_private *dev_priv, struct mm_struct *real) 393{ 394 struct i915_mm_struct *mm; 395 396 /* Protected by dev_priv->mm_lock */ 397 hash_for_each_possible(dev_priv->mm_structs, mm, node, (unsigned long)real) 398 if (mm->mm == real) 399 return mm; 400 401 return NULL; 402} 403 404static int 405i915_gem_userptr_init__mm_struct(struct drm_i915_gem_object *obj) 406{ 407 struct drm_i915_private *dev_priv = to_i915(obj->base.dev); 408 struct i915_mm_struct *mm; 409 int ret = 0; 410 411 /* During release of the GEM object we hold the struct_mutex. This 412 * precludes us from calling mmput() at that time as that may be 413 * the last reference and so call exit_mmap(). exit_mmap() will 414 * attempt to reap the vma, and if we were holding a GTT mmap 415 * would then call drm_gem_vm_close() and attempt to reacquire 416 * the struct mutex. So in order to avoid that recursion, we have 417 * to defer releasing the mm reference until after we drop the 418 * struct_mutex, i.e. we need to schedule a worker to do the clean 419 * up. 420 */ 421 mutex_lock(&dev_priv->mm_lock); 422 mm = __i915_mm_struct_find(dev_priv, current->mm); 423 if (mm == NULL) { 424 mm = kmalloc(sizeof(*mm), GFP_KERNEL); 425 if (mm == NULL) { 426 ret = -ENOMEM; 427 goto out; 428 } 429 430 kref_init(&mm->kref); 431 mm->dev = obj->base.dev; 432 433 mm->mm = current->mm; 434 atomic_inc(¤t->mm->mm_count); 435 436 mm->mn = NULL; 437 438 /* Protected by dev_priv->mm_lock */ 439 hash_add(dev_priv->mm_structs, 440 &mm->node, (unsigned long)mm->mm); 441 } else 442 kref_get(&mm->kref); 443 444 obj->userptr.mm = mm; 445out: 446 mutex_unlock(&dev_priv->mm_lock); 447 return ret; 448} 449 450static void 451__i915_mm_struct_free__worker(struct work_struct *work) 452{ 453 struct i915_mm_struct *mm = container_of(work, typeof(*mm), work); 454 i915_mmu_notifier_free(mm->mn, mm->mm); 455 mmdrop(mm->mm); 456 kfree(mm); 457} 458 459static void 460__i915_mm_struct_free(struct kref *kref) 461{ 462 struct i915_mm_struct *mm = container_of(kref, typeof(*mm), kref); 463 464 /* Protected by dev_priv->mm_lock */ 465 hash_del(&mm->node); 466 mutex_unlock(&to_i915(mm->dev)->mm_lock); 467 468 INIT_WORK(&mm->work, __i915_mm_struct_free__worker); 469 schedule_work(&mm->work); 470} 471 472static void 473i915_gem_userptr_release__mm_struct(struct drm_i915_gem_object *obj) 474{ 475 if (obj->userptr.mm == NULL) 476 return; 477 478 kref_put_mutex(&obj->userptr.mm->kref, 479 __i915_mm_struct_free, 480 &to_i915(obj->base.dev)->mm_lock); 481 obj->userptr.mm = NULL; 482} 483 484struct get_pages_work { 485 struct work_struct work; 486 struct drm_i915_gem_object *obj; 487 struct task_struct *task; 488}; 489 490#if IS_ENABLED(CONFIG_SWIOTLB) 491#define swiotlb_active() swiotlb_nr_tbl() 492#else 493#define swiotlb_active() 0 494#endif 495 496static int 497st_set_pages(struct sg_table **st, struct page **pvec, int num_pages) 498{ 499 struct scatterlist *sg; 500 int ret, n; 501 502 *st = kmalloc(sizeof(**st), GFP_KERNEL); 503 if (*st == NULL) 504 return -ENOMEM; 505 506 if (swiotlb_active()) { 507 ret = sg_alloc_table(*st, num_pages, GFP_KERNEL); 508 if (ret) 509 goto err; 510 511 for_each_sg((*st)->sgl, sg, num_pages, n) 512 sg_set_page(sg, pvec[n], PAGE_SIZE, 0); 513 } else { 514 ret = sg_alloc_table_from_pages(*st, pvec, num_pages, 515 0, num_pages << PAGE_SHIFT, 516 GFP_KERNEL); 517 if (ret) 518 goto err; 519 } 520 521 return 0; 522 523err: 524 kfree(*st); 525 *st = NULL; 526 return ret; 527} 528 529static void 530__i915_gem_userptr_get_pages_worker(struct work_struct *_work) 531{ 532 struct get_pages_work *work = container_of(_work, typeof(*work), work); 533 struct drm_i915_gem_object *obj = work->obj; 534 struct drm_device *dev = obj->base.dev; 535 const int num_pages = obj->base.size >> PAGE_SHIFT; 536 struct page **pvec; 537 int pinned, ret; 538 539 ret = -ENOMEM; 540 pinned = 0; 541 542 pvec = kmalloc(num_pages*sizeof(struct page *), 543 GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY); 544 if (pvec == NULL) 545 pvec = drm_malloc_ab(num_pages, sizeof(struct page *)); 546 if (pvec != NULL) { 547 struct mm_struct *mm = obj->userptr.mm->mm; 548 549 down_read(&mm->mmap_sem); 550 while (pinned < num_pages) { 551 ret = get_user_pages(work->task, mm, 552 obj->userptr.ptr + pinned * PAGE_SIZE, 553 num_pages - pinned, 554 !obj->userptr.read_only, 0, 555 pvec + pinned, NULL); 556 if (ret < 0) 557 break; 558 559 pinned += ret; 560 } 561 up_read(&mm->mmap_sem); 562 } 563 564 mutex_lock(&dev->struct_mutex); 565 if (obj->userptr.work != &work->work) { 566 ret = 0; 567 } else if (pinned == num_pages) { 568 ret = st_set_pages(&obj->pages, pvec, num_pages); 569 if (ret == 0) { 570 list_add_tail(&obj->global_list, &to_i915(dev)->mm.unbound_list); 571 pinned = 0; 572 } 573 } 574 575 obj->userptr.work = ERR_PTR(ret); 576 obj->userptr.workers--; 577 drm_gem_object_unreference(&obj->base); 578 mutex_unlock(&dev->struct_mutex); 579 580 release_pages(pvec, pinned, 0); 581 drm_free_large(pvec); 582 583 put_task_struct(work->task); 584 kfree(work); 585} 586 587static int 588i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) 589{ 590 const int num_pages = obj->base.size >> PAGE_SHIFT; 591 struct page **pvec; 592 int pinned, ret; 593 594 /* If userspace should engineer that these pages are replaced in 595 * the vma between us binding this page into the GTT and completion 596 * of rendering... Their loss. If they change the mapping of their 597 * pages they need to create a new bo to point to the new vma. 598 * 599 * However, that still leaves open the possibility of the vma 600 * being copied upon fork. Which falls under the same userspace 601 * synchronisation issue as a regular bo, except that this time 602 * the process may not be expecting that a particular piece of 603 * memory is tied to the GPU. 604 * 605 * Fortunately, we can hook into the mmu_notifier in order to 606 * discard the page references prior to anything nasty happening 607 * to the vma (discard or cloning) which should prevent the more 608 * egregious cases from causing harm. 609 */ 610 611 pvec = NULL; 612 pinned = 0; 613 if (obj->userptr.mm->mm == current->mm) { 614 pvec = kmalloc(num_pages*sizeof(struct page *), 615 GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY); 616 if (pvec == NULL) { 617 pvec = drm_malloc_ab(num_pages, sizeof(struct page *)); 618 if (pvec == NULL) 619 return -ENOMEM; 620 } 621 622 pinned = __get_user_pages_fast(obj->userptr.ptr, num_pages, 623 !obj->userptr.read_only, pvec); 624 } 625 if (pinned < num_pages) { 626 if (pinned < 0) { 627 ret = pinned; 628 pinned = 0; 629 } else { 630 /* Spawn a worker so that we can acquire the 631 * user pages without holding our mutex. Access 632 * to the user pages requires mmap_sem, and we have 633 * a strict lock ordering of mmap_sem, struct_mutex - 634 * we already hold struct_mutex here and so cannot 635 * call gup without encountering a lock inversion. 636 * 637 * Userspace will keep on repeating the operation 638 * (thanks to EAGAIN) until either we hit the fast 639 * path or the worker completes. If the worker is 640 * cancelled or superseded, the task is still run 641 * but the results ignored. (This leads to 642 * complications that we may have a stray object 643 * refcount that we need to be wary of when 644 * checking for existing objects during creation.) 645 * If the worker encounters an error, it reports 646 * that error back to this function through 647 * obj->userptr.work = ERR_PTR. 648 */ 649 ret = -EAGAIN; 650 if (obj->userptr.work == NULL && 651 obj->userptr.workers < I915_GEM_USERPTR_MAX_WORKERS) { 652 struct get_pages_work *work; 653 654 work = kmalloc(sizeof(*work), GFP_KERNEL); 655 if (work != NULL) { 656 obj->userptr.work = &work->work; 657 obj->userptr.workers++; 658 659 work->obj = obj; 660 drm_gem_object_reference(&obj->base); 661 662 work->task = current; 663 get_task_struct(work->task); 664 665 INIT_WORK(&work->work, __i915_gem_userptr_get_pages_worker); 666 schedule_work(&work->work); 667 } else 668 ret = -ENOMEM; 669 } else { 670 if (IS_ERR(obj->userptr.work)) { 671 ret = PTR_ERR(obj->userptr.work); 672 obj->userptr.work = NULL; 673 } 674 } 675 } 676 } else { 677 ret = st_set_pages(&obj->pages, pvec, num_pages); 678 if (ret == 0) { 679 obj->userptr.work = NULL; 680 pinned = 0; 681 } 682 } 683 684 release_pages(pvec, pinned, 0); 685 drm_free_large(pvec); 686 return ret; 687} 688 689static void 690i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj) 691{ 692 struct sg_page_iter sg_iter; 693 694 BUG_ON(obj->userptr.work != NULL); 695 696 if (obj->madv != I915_MADV_WILLNEED) 697 obj->dirty = 0; 698 699 for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) { 700 struct page *page = sg_page_iter_page(&sg_iter); 701 702 if (obj->dirty) 703 set_page_dirty(page); 704 705 mark_page_accessed(page); 706 page_cache_release(page); 707 } 708 obj->dirty = 0; 709 710 sg_free_table(obj->pages); 711 kfree(obj->pages); 712} 713 714static void 715i915_gem_userptr_release(struct drm_i915_gem_object *obj) 716{ 717 i915_gem_userptr_release__mmu_notifier(obj); 718 i915_gem_userptr_release__mm_struct(obj); 719} 720 721static int 722i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj) 723{ 724 if (obj->userptr.mmu_object) 725 return 0; 726 727 return i915_gem_userptr_init__mmu_notifier(obj, 0); 728} 729 730static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = { 731 .dmabuf_export = i915_gem_userptr_dmabuf_export, 732 .get_pages = i915_gem_userptr_get_pages, 733 .put_pages = i915_gem_userptr_put_pages, 734 .release = i915_gem_userptr_release, 735}; 736 737/** 738 * Creates a new mm object that wraps some normal memory from the process 739 * context - user memory. 740 * 741 * We impose several restrictions upon the memory being mapped 742 * into the GPU. 743 * 1. It must be page aligned (both start/end addresses, i.e ptr and size). 744 * 2. It must be normal system memory, not a pointer into another map of IO 745 * space (e.g. it must not be a GTT mmapping of another object). 746 * 3. We only allow a bo as large as we could in theory map into the GTT, 747 * that is we limit the size to the total size of the GTT. 748 * 4. The bo is marked as being snoopable. The backing pages are left 749 * accessible directly by the CPU, but reads and writes by the GPU may 750 * incur the cost of a snoop (unless you have an LLC architecture). 751 * 752 * Synchronisation between multiple users and the GPU is left to userspace 753 * through the normal set-domain-ioctl. The kernel will enforce that the 754 * GPU relinquishes the VMA before it is returned back to the system 755 * i.e. upon free(), munmap() or process termination. However, the userspace 756 * malloc() library may not immediately relinquish the VMA after free() and 757 * instead reuse it whilst the GPU is still reading and writing to the VMA. 758 * Caveat emptor. 759 * 760 * Also note, that the object created here is not currently a "first class" 761 * object, in that several ioctls are banned. These are the CPU access 762 * ioctls: mmap(), pwrite and pread. In practice, you are expected to use 763 * direct access via your pointer rather than use those ioctls. 764 * 765 * If you think this is a good interface to use to pass GPU memory between 766 * drivers, please use dma-buf instead. In fact, wherever possible use 767 * dma-buf instead. 768 */ 769int 770i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file) 771{ 772 struct drm_i915_private *dev_priv = dev->dev_private; 773 struct drm_i915_gem_userptr *args = data; 774 struct drm_i915_gem_object *obj; 775 int ret; 776 u32 handle; 777 778 if (args->flags & ~(I915_USERPTR_READ_ONLY | 779 I915_USERPTR_UNSYNCHRONIZED)) 780 return -EINVAL; 781 782 if (offset_in_page(args->user_ptr | args->user_size)) 783 return -EINVAL; 784 785 if (args->user_size > dev_priv->gtt.base.total) 786 return -E2BIG; 787 788 if (!access_ok(args->flags & I915_USERPTR_READ_ONLY ? VERIFY_READ : VERIFY_WRITE, 789 (char __user *)(unsigned long)args->user_ptr, args->user_size)) 790 return -EFAULT; 791 792 if (args->flags & I915_USERPTR_READ_ONLY) { 793 /* On almost all of the current hw, we cannot tell the GPU that a 794 * page is readonly, so this is just a placeholder in the uAPI. 795 */ 796 return -ENODEV; 797 } 798 799 obj = i915_gem_object_alloc(dev); 800 if (obj == NULL) 801 return -ENOMEM; 802 803 drm_gem_private_object_init(dev, &obj->base, args->user_size); 804 i915_gem_object_init(obj, &i915_gem_userptr_ops); 805 obj->cache_level = I915_CACHE_LLC; 806 obj->base.write_domain = I915_GEM_DOMAIN_CPU; 807 obj->base.read_domains = I915_GEM_DOMAIN_CPU; 808 809 obj->userptr.ptr = args->user_ptr; 810 obj->userptr.read_only = !!(args->flags & I915_USERPTR_READ_ONLY); 811 812 /* And keep a pointer to the current->mm for resolving the user pages 813 * at binding. This means that we need to hook into the mmu_notifier 814 * in order to detect if the mmu is destroyed. 815 */ 816 ret = i915_gem_userptr_init__mm_struct(obj); 817 if (ret == 0) 818 ret = i915_gem_userptr_init__mmu_notifier(obj, args->flags); 819 if (ret == 0) 820 ret = drm_gem_handle_create(file, &obj->base, &handle); 821 822 /* drop reference from allocate - handle holds it now */ 823 drm_gem_object_unreference_unlocked(&obj->base); 824 if (ret) 825 return ret; 826 827 args->handle = handle; 828 return 0; 829} 830 831int 832i915_gem_init_userptr(struct drm_device *dev) 833{ 834 struct drm_i915_private *dev_priv = to_i915(dev); 835 mutex_init(&dev_priv->mm_lock); 836 hash_init(dev_priv->mm_structs); 837 return 0; 838} 839