1 /* 2 * SPDX-License-Identifier: MIT 3 * 4 * Copyright © 2014-2016 Intel Corporation 5 */ 6 7 #include <linux/pagevec.h> 8 #include <linux/swap.h> 9 10 #include "gem/i915_gem_region.h" 11 #include "i915_drv.h" 12 #include "i915_gemfs.h" 13 #include "i915_gem_object.h" 14 #include "i915_scatterlist.h" 15 #include "i915_trace.h" 16 17 /* 18 * Move pages to appropriate lru and release the pagevec, decrementing the 19 * ref count of those pages. 20 */ 21 static void check_release_pagevec(struct pagevec *pvec) 22 { 23 check_move_unevictable_pages(pvec); 24 __pagevec_release(pvec); 25 cond_resched(); 26 } 27 28 static int shmem_get_pages(struct drm_i915_gem_object *obj) 29 { 30 struct drm_i915_private *i915 = to_i915(obj->base.dev); 31 struct intel_memory_region *mem = obj->mm.region; 32 const unsigned long page_count = obj->base.size / PAGE_SIZE; 33 unsigned long i; 34 struct address_space *mapping; 35 struct sg_table *st; 36 struct scatterlist *sg; 37 struct sgt_iter sgt_iter; 38 struct page *page; 39 unsigned long last_pfn = 0; /* suppress gcc warning */ 40 unsigned int max_segment = i915_sg_segment_size(); 41 unsigned int sg_page_sizes; 42 gfp_t noreclaim; 43 int ret; 44 45 /* 46 * Assert that the object is not currently in any GPU domain. As it 47 * wasn't in the GTT, there shouldn't be any way it could have been in 48 * a GPU cache 49 */ 50 GEM_BUG_ON(obj->read_domains & I915_GEM_GPU_DOMAINS); 51 GEM_BUG_ON(obj->write_domain & I915_GEM_GPU_DOMAINS); 52 53 /* 54 * If there's no chance of allocating enough pages for the whole 55 * object, bail early. 56 */ 57 if (obj->base.size > resource_size(&mem->region)) 58 return -ENOMEM; 59 60 st = kmalloc(sizeof(*st), GFP_KERNEL); 61 if (!st) 62 return -ENOMEM; 63 64 rebuild_st: 65 if (sg_alloc_table(st, page_count, GFP_KERNEL)) { 66 kfree(st); 67 return -ENOMEM; 68 } 69 70 /* 71 * Get the list of pages out of our struct file. They'll be pinned 72 * at this point until we release them. 73 * 74 * Fail silently without starting the shrinker 75 */ 76 mapping = obj->base.filp->f_mapping; 77 mapping_set_unevictable(mapping); 78 noreclaim = mapping_gfp_constraint(mapping, ~__GFP_RECLAIM); 79 noreclaim |= __GFP_NORETRY | __GFP_NOWARN; 80 81 sg = st->sgl; 82 st->nents = 0; 83 sg_page_sizes = 0; 84 for (i = 0; i < page_count; i++) { 85 const unsigned int shrink[] = { 86 I915_SHRINK_BOUND | I915_SHRINK_UNBOUND, 87 0, 88 }, *s = shrink; 89 gfp_t gfp = noreclaim; 90 91 do { 92 cond_resched(); 93 page = shmem_read_mapping_page_gfp(mapping, i, gfp); 94 if (!IS_ERR(page)) 95 break; 96 97 if (!*s) { 98 ret = PTR_ERR(page); 99 goto err_sg; 100 } 101 102 i915_gem_shrink(i915, 2 * page_count, NULL, *s++); 103 104 /* 105 * We've tried hard to allocate the memory by reaping 106 * our own buffer, now let the real VM do its job and 107 * go down in flames if truly OOM. 108 * 109 * However, since graphics tend to be disposable, 110 * defer the oom here by reporting the ENOMEM back 111 * to userspace. 112 */ 113 if (!*s) { 114 /* reclaim and warn, but no oom */ 115 gfp = mapping_gfp_mask(mapping); 116 117 /* 118 * Our bo are always dirty and so we require 119 * kswapd to reclaim our pages (direct reclaim 120 * does not effectively begin pageout of our 121 * buffers on its own). However, direct reclaim 122 * only waits for kswapd when under allocation 123 * congestion. So as a result __GFP_RECLAIM is 124 * unreliable and fails to actually reclaim our 125 * dirty pages -- unless you try over and over 126 * again with !__GFP_NORETRY. However, we still 127 * want to fail this allocation rather than 128 * trigger the out-of-memory killer and for 129 * this we want __GFP_RETRY_MAYFAIL. 130 */ 131 gfp |= __GFP_RETRY_MAYFAIL; 132 } 133 } while (1); 134 135 if (!i || 136 sg->length >= max_segment || 137 page_to_pfn(page) != last_pfn + 1) { 138 if (i) { 139 sg_page_sizes |= sg->length; 140 sg = sg_next(sg); 141 } 142 st->nents++; 143 sg_set_page(sg, page, PAGE_SIZE, 0); 144 } else { 145 sg->length += PAGE_SIZE; 146 } 147 last_pfn = page_to_pfn(page); 148 149 /* Check that the i965g/gm workaround works. */ 150 GEM_BUG_ON(gfp & __GFP_DMA32 && last_pfn >= 0x00100000UL); 151 } 152 if (sg) { /* loop terminated early; short sg table */ 153 sg_page_sizes |= sg->length; 154 sg_mark_end(sg); 155 } 156 157 /* Trim unused sg entries to avoid wasting memory. */ 158 i915_sg_trim(st); 159 160 ret = i915_gem_gtt_prepare_pages(obj, st); 161 if (ret) { 162 /* 163 * DMA remapping failed? One possible cause is that 164 * it could not reserve enough large entries, asking 165 * for PAGE_SIZE chunks instead may be helpful. 166 */ 167 if (max_segment > PAGE_SIZE) { 168 for_each_sgt_page(page, sgt_iter, st) 169 put_page(page); 170 sg_free_table(st); 171 172 max_segment = PAGE_SIZE; 173 goto rebuild_st; 174 } else { 175 dev_warn(&i915->drm.pdev->dev, 176 "Failed to DMA remap %lu pages\n", 177 page_count); 178 goto err_pages; 179 } 180 } 181 182 if (i915_gem_object_needs_bit17_swizzle(obj)) 183 i915_gem_object_do_bit_17_swizzle(obj, st); 184 185 __i915_gem_object_set_pages(obj, st, sg_page_sizes); 186 187 return 0; 188 189 err_sg: 190 sg_mark_end(sg); 191 err_pages: 192 mapping_clear_unevictable(mapping); 193 if (sg != st->sgl) { 194 struct pagevec pvec; 195 196 pagevec_init(&pvec); 197 for_each_sgt_page(page, sgt_iter, st) { 198 if (!pagevec_add(&pvec, page)) 199 check_release_pagevec(&pvec); 200 } 201 if (pagevec_count(&pvec)) 202 check_release_pagevec(&pvec); 203 } 204 sg_free_table(st); 205 kfree(st); 206 207 /* 208 * shmemfs first checks if there is enough memory to allocate the page 209 * and reports ENOSPC should there be insufficient, along with the usual 210 * ENOMEM for a genuine allocation failure. 211 * 212 * We use ENOSPC in our driver to mean that we have run out of aperture 213 * space and so want to translate the error from shmemfs back to our 214 * usual understanding of ENOMEM. 215 */ 216 if (ret == -ENOSPC) 217 ret = -ENOMEM; 218 219 return ret; 220 } 221 222 static void 223 shmem_truncate(struct drm_i915_gem_object *obj) 224 { 225 /* 226 * Our goal here is to return as much of the memory as 227 * is possible back to the system as we are called from OOM. 228 * To do this we must instruct the shmfs to drop all of its 229 * backing pages, *now*. 230 */ 231 shmem_truncate_range(file_inode(obj->base.filp), 0, (loff_t)-1); 232 obj->mm.madv = __I915_MADV_PURGED; 233 obj->mm.pages = ERR_PTR(-EFAULT); 234 } 235 236 static void 237 shmem_writeback(struct drm_i915_gem_object *obj) 238 { 239 struct address_space *mapping; 240 struct writeback_control wbc = { 241 .sync_mode = WB_SYNC_NONE, 242 .nr_to_write = SWAP_CLUSTER_MAX, 243 .range_start = 0, 244 .range_end = LLONG_MAX, 245 .for_reclaim = 1, 246 }; 247 unsigned long i; 248 249 /* 250 * Leave mmapings intact (GTT will have been revoked on unbinding, 251 * leaving only CPU mmapings around) and add those pages to the LRU 252 * instead of invoking writeback so they are aged and paged out 253 * as normal. 254 */ 255 mapping = obj->base.filp->f_mapping; 256 257 /* Begin writeback on each dirty page */ 258 for (i = 0; i < obj->base.size >> PAGE_SHIFT; i++) { 259 struct page *page; 260 261 page = find_lock_page(mapping, i); 262 if (!page) 263 continue; 264 265 if (!page_mapped(page) && clear_page_dirty_for_io(page)) { 266 int ret; 267 268 SetPageReclaim(page); 269 ret = mapping->a_ops->writepage(page, &wbc); 270 if (!PageWriteback(page)) 271 ClearPageReclaim(page); 272 if (!ret) 273 goto put; 274 } 275 unlock_page(page); 276 put: 277 put_page(page); 278 } 279 } 280 281 void 282 __i915_gem_object_release_shmem(struct drm_i915_gem_object *obj, 283 struct sg_table *pages, 284 bool needs_clflush) 285 { 286 GEM_BUG_ON(obj->mm.madv == __I915_MADV_PURGED); 287 288 if (obj->mm.madv == I915_MADV_DONTNEED) 289 obj->mm.dirty = false; 290 291 if (needs_clflush && 292 (obj->read_domains & I915_GEM_DOMAIN_CPU) == 0 && 293 !(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ)) 294 drm_clflush_sg(pages); 295 296 __start_cpu_write(obj); 297 } 298 299 static void 300 shmem_put_pages(struct drm_i915_gem_object *obj, struct sg_table *pages) 301 { 302 struct sgt_iter sgt_iter; 303 struct pagevec pvec; 304 struct page *page; 305 306 __i915_gem_object_release_shmem(obj, pages, true); 307 308 i915_gem_gtt_finish_pages(obj, pages); 309 310 if (i915_gem_object_needs_bit17_swizzle(obj)) 311 i915_gem_object_save_bit_17_swizzle(obj, pages); 312 313 mapping_clear_unevictable(file_inode(obj->base.filp)->i_mapping); 314 315 pagevec_init(&pvec); 316 for_each_sgt_page(page, sgt_iter, pages) { 317 if (obj->mm.dirty) 318 set_page_dirty(page); 319 320 if (obj->mm.madv == I915_MADV_WILLNEED) 321 mark_page_accessed(page); 322 323 if (!pagevec_add(&pvec, page)) 324 check_release_pagevec(&pvec); 325 } 326 if (pagevec_count(&pvec)) 327 check_release_pagevec(&pvec); 328 obj->mm.dirty = false; 329 330 sg_free_table(pages); 331 kfree(pages); 332 } 333 334 static int 335 shmem_pwrite(struct drm_i915_gem_object *obj, 336 const struct drm_i915_gem_pwrite *arg) 337 { 338 struct address_space *mapping = obj->base.filp->f_mapping; 339 char __user *user_data = u64_to_user_ptr(arg->data_ptr); 340 u64 remain, offset; 341 unsigned int pg; 342 343 /* Caller already validated user args */ 344 GEM_BUG_ON(!access_ok(user_data, arg->size)); 345 346 /* 347 * Before we instantiate/pin the backing store for our use, we 348 * can prepopulate the shmemfs filp efficiently using a write into 349 * the pagecache. We avoid the penalty of instantiating all the 350 * pages, important if the user is just writing to a few and never 351 * uses the object on the GPU, and using a direct write into shmemfs 352 * allows it to avoid the cost of retrieving a page (either swapin 353 * or clearing-before-use) before it is overwritten. 354 */ 355 if (i915_gem_object_has_pages(obj)) 356 return -ENODEV; 357 358 if (obj->mm.madv != I915_MADV_WILLNEED) 359 return -EFAULT; 360 361 /* 362 * Before the pages are instantiated the object is treated as being 363 * in the CPU domain. The pages will be clflushed as required before 364 * use, and we can freely write into the pages directly. If userspace 365 * races pwrite with any other operation; corruption will ensue - 366 * that is userspace's prerogative! 367 */ 368 369 remain = arg->size; 370 offset = arg->offset; 371 pg = offset_in_page(offset); 372 373 do { 374 unsigned int len, unwritten; 375 struct page *page; 376 void *data, *vaddr; 377 int err; 378 char c; 379 380 len = PAGE_SIZE - pg; 381 if (len > remain) 382 len = remain; 383 384 /* Prefault the user page to reduce potential recursion */ 385 err = __get_user(c, user_data); 386 if (err) 387 return err; 388 389 err = __get_user(c, user_data + len - 1); 390 if (err) 391 return err; 392 393 err = pagecache_write_begin(obj->base.filp, mapping, 394 offset, len, 0, 395 &page, &data); 396 if (err < 0) 397 return err; 398 399 vaddr = kmap_atomic(page); 400 unwritten = __copy_from_user_inatomic(vaddr + pg, 401 user_data, 402 len); 403 kunmap_atomic(vaddr); 404 405 err = pagecache_write_end(obj->base.filp, mapping, 406 offset, len, len - unwritten, 407 page, data); 408 if (err < 0) 409 return err; 410 411 /* We don't handle -EFAULT, leave it to the caller to check */ 412 if (unwritten) 413 return -ENODEV; 414 415 remain -= len; 416 user_data += len; 417 offset += len; 418 pg = 0; 419 } while (remain); 420 421 return 0; 422 } 423 424 static void shmem_release(struct drm_i915_gem_object *obj) 425 { 426 i915_gem_object_release_memory_region(obj); 427 428 fput(obj->base.filp); 429 } 430 431 const struct drm_i915_gem_object_ops i915_gem_shmem_ops = { 432 .name = "i915_gem_object_shmem", 433 .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE | 434 I915_GEM_OBJECT_IS_SHRINKABLE, 435 436 .get_pages = shmem_get_pages, 437 .put_pages = shmem_put_pages, 438 .truncate = shmem_truncate, 439 .writeback = shmem_writeback, 440 441 .pwrite = shmem_pwrite, 442 443 .release = shmem_release, 444 }; 445 446 static int __create_shmem(struct drm_i915_private *i915, 447 struct drm_gem_object *obj, 448 resource_size_t size) 449 { 450 unsigned long flags = VM_NORESERVE; 451 struct file *filp; 452 453 drm_gem_private_object_init(&i915->drm, obj, size); 454 455 if (i915->mm.gemfs) 456 filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size, 457 flags); 458 else 459 filp = shmem_file_setup("i915", size, flags); 460 if (IS_ERR(filp)) 461 return PTR_ERR(filp); 462 463 obj->filp = filp; 464 return 0; 465 } 466 467 static int shmem_object_init(struct intel_memory_region *mem, 468 struct drm_i915_gem_object *obj, 469 resource_size_t size, 470 unsigned int flags) 471 { 472 static struct lock_class_key lock_class; 473 struct drm_i915_private *i915 = mem->i915; 474 struct address_space *mapping; 475 unsigned int cache_level; 476 gfp_t mask; 477 int ret; 478 479 ret = __create_shmem(i915, &obj->base, size); 480 if (ret) 481 return ret; 482 483 mask = GFP_HIGHUSER | __GFP_RECLAIMABLE; 484 if (IS_I965GM(i915) || IS_I965G(i915)) { 485 /* 965gm cannot relocate objects above 4GiB. */ 486 mask &= ~__GFP_HIGHMEM; 487 mask |= __GFP_DMA32; 488 } 489 490 mapping = obj->base.filp->f_mapping; 491 mapping_set_gfp_mask(mapping, mask); 492 GEM_BUG_ON(!(mapping_gfp_mask(mapping) & __GFP_RECLAIM)); 493 494 i915_gem_object_init(obj, &i915_gem_shmem_ops, &lock_class); 495 496 obj->write_domain = I915_GEM_DOMAIN_CPU; 497 obj->read_domains = I915_GEM_DOMAIN_CPU; 498 499 if (HAS_LLC(i915)) 500 /* On some devices, we can have the GPU use the LLC (the CPU 501 * cache) for about a 10% performance improvement 502 * compared to uncached. Graphics requests other than 503 * display scanout are coherent with the CPU in 504 * accessing this cache. This means in this mode we 505 * don't need to clflush on the CPU side, and on the 506 * GPU side we only need to flush internal caches to 507 * get data visible to the CPU. 508 * 509 * However, we maintain the display planes as UC, and so 510 * need to rebind when first used as such. 511 */ 512 cache_level = I915_CACHE_LLC; 513 else 514 cache_level = I915_CACHE_NONE; 515 516 i915_gem_object_set_cache_coherency(obj, cache_level); 517 518 i915_gem_object_init_memory_region(obj, mem, 0); 519 520 return 0; 521 } 522 523 struct drm_i915_gem_object * 524 i915_gem_object_create_shmem(struct drm_i915_private *i915, 525 resource_size_t size) 526 { 527 return i915_gem_object_create_region(i915->mm.regions[INTEL_REGION_SMEM], 528 size, 0); 529 } 530 531 /* Allocate a new GEM object and fill it with the supplied data */ 532 struct drm_i915_gem_object * 533 i915_gem_object_create_shmem_from_data(struct drm_i915_private *dev_priv, 534 const void *data, resource_size_t size) 535 { 536 struct drm_i915_gem_object *obj; 537 struct file *file; 538 resource_size_t offset; 539 int err; 540 541 obj = i915_gem_object_create_shmem(dev_priv, round_up(size, PAGE_SIZE)); 542 if (IS_ERR(obj)) 543 return obj; 544 545 GEM_BUG_ON(obj->write_domain != I915_GEM_DOMAIN_CPU); 546 547 file = obj->base.filp; 548 offset = 0; 549 do { 550 unsigned int len = min_t(typeof(size), size, PAGE_SIZE); 551 struct page *page; 552 void *pgdata, *vaddr; 553 554 err = pagecache_write_begin(file, file->f_mapping, 555 offset, len, 0, 556 &page, &pgdata); 557 if (err < 0) 558 goto fail; 559 560 vaddr = kmap(page); 561 memcpy(vaddr, data, len); 562 kunmap(page); 563 564 err = pagecache_write_end(file, file->f_mapping, 565 offset, len, len, 566 page, pgdata); 567 if (err < 0) 568 goto fail; 569 570 size -= len; 571 data += len; 572 offset += len; 573 } while (size); 574 575 return obj; 576 577 fail: 578 i915_gem_object_put(obj); 579 return ERR_PTR(err); 580 } 581 582 static int init_shmem(struct intel_memory_region *mem) 583 { 584 int err; 585 586 err = i915_gemfs_init(mem->i915); 587 if (err) { 588 DRM_NOTE("Unable to create a private tmpfs mount, hugepage support will be disabled(%d).\n", 589 err); 590 } 591 592 intel_memory_region_set_name(mem, "system"); 593 594 return 0; /* Don't error, we can simply fallback to the kernel mnt */ 595 } 596 597 static void release_shmem(struct intel_memory_region *mem) 598 { 599 i915_gemfs_fini(mem->i915); 600 } 601 602 static const struct intel_memory_region_ops shmem_region_ops = { 603 .init = init_shmem, 604 .release = release_shmem, 605 .init_object = shmem_object_init, 606 }; 607 608 struct intel_memory_region *i915_gem_shmem_setup(struct drm_i915_private *i915) 609 { 610 return intel_memory_region_create(i915, 0, 611 totalram_pages() << PAGE_SHIFT, 612 PAGE_SIZE, 0, 613 &shmem_region_ops); 614 } 615 616 bool i915_gem_object_is_shmem(const struct drm_i915_gem_object *obj) 617 { 618 return obj->ops == &i915_gem_shmem_ops; 619 } 620