drivers/gpu/drm/i915/gem/i915_gem_shmem.c

   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 struct drm_i915_gem_object *
 468 create_shmem(struct intel_memory_region *mem,
 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 drm_i915_gem_object *obj;
 475         struct address_space *mapping;
 476         unsigned int cache_level;
 477         gfp_t mask;
 478         int ret;
 479
 480         obj = i915_gem_object_alloc();
 481         if (!obj)
 482                 return ERR_PTR(-ENOMEM);
 483
 484         ret = __create_shmem(i915, &obj->base, size);
 485         if (ret)
 486                 goto fail;
 487
 488         mask = GFP_HIGHUSER | __GFP_RECLAIMABLE;
 489         if (IS_I965GM(i915) || IS_I965G(i915)) {
 490                 /* 965gm cannot relocate objects above 4GiB. */
 491                 mask &= ~__GFP_HIGHMEM;
 492                 mask |= __GFP_DMA32;
 493         }
 494
 495         mapping = obj->base.filp->f_mapping;
 496         mapping_set_gfp_mask(mapping, mask);
 497         GEM_BUG_ON(!(mapping_gfp_mask(mapping) & __GFP_RECLAIM));
 498
 499         i915_gem_object_init(obj, &i915_gem_shmem_ops, &lock_class);
 500
 501         obj->write_domain = I915_GEM_DOMAIN_CPU;
 502         obj->read_domains = I915_GEM_DOMAIN_CPU;
 503
 504         if (HAS_LLC(i915))
 505                 /* On some devices, we can have the GPU use the LLC (the CPU
 506                  * cache) for about a 10% performance improvement
 507                  * compared to uncached.  Graphics requests other than
 508                  * display scanout are coherent with the CPU in
 509                  * accessing this cache.  This means in this mode we
 510                  * don't need to clflush on the CPU side, and on the
 511                  * GPU side we only need to flush internal caches to
 512                  * get data visible to the CPU.
 513                  *
 514                  * However, we maintain the display planes as UC, and so
 515                  * need to rebind when first used as such.
 516                  */
 517                 cache_level = I915_CACHE_LLC;
 518         else
 519                 cache_level = I915_CACHE_NONE;
 520
 521         i915_gem_object_set_cache_coherency(obj, cache_level);
 522
 523         i915_gem_object_init_memory_region(obj, mem, 0);
 524
 525         return obj;
 526
 527 fail:
 528         i915_gem_object_free(obj);
 529         return ERR_PTR(ret);
 530 }
 531
 532 struct drm_i915_gem_object *
 533 i915_gem_object_create_shmem(struct drm_i915_private *i915,
 534                              resource_size_t size)
 535 {
 536         return i915_gem_object_create_region(i915->mm.regions[INTEL_REGION_SMEM],
 537                                              size, 0);
 538 }
 539
 540 /* Allocate a new GEM object and fill it with the supplied data */
 541 struct drm_i915_gem_object *
 542 i915_gem_object_create_shmem_from_data(struct drm_i915_private *dev_priv,
 543                                        const void *data, resource_size_t size)
 544 {
 545         struct drm_i915_gem_object *obj;
 546         struct file *file;
 547         resource_size_t offset;
 548         int err;
 549
 550         obj = i915_gem_object_create_shmem(dev_priv, round_up(size, PAGE_SIZE));
 551         if (IS_ERR(obj))
 552                 return obj;
 553
 554         GEM_BUG_ON(obj->write_domain != I915_GEM_DOMAIN_CPU);
 555
 556         file = obj->base.filp;
 557         offset = 0;
 558         do {
 559                 unsigned int len = min_t(typeof(size), size, PAGE_SIZE);
 560                 struct page *page;
 561                 void *pgdata, *vaddr;
 562
 563                 err = pagecache_write_begin(file, file->f_mapping,
 564                                             offset, len, 0,
 565                                             &page, &pgdata);
 566                 if (err < 0)
 567                         goto fail;
 568
 569                 vaddr = kmap(page);
 570                 memcpy(vaddr, data, len);
 571                 kunmap(page);
 572
 573                 err = pagecache_write_end(file, file->f_mapping,
 574                                           offset, len, len,
 575                                           page, pgdata);
 576                 if (err < 0)
 577                         goto fail;
 578
 579                 size -= len;
 580                 data += len;
 581                 offset += len;
 582         } while (size);
 583
 584         return obj;
 585
 586 fail:
 587         i915_gem_object_put(obj);
 588         return ERR_PTR(err);
 589 }
 590
 591 static int init_shmem(struct intel_memory_region *mem)
 592 {
 593         int err;
 594
 595         err = i915_gemfs_init(mem->i915);
 596         if (err) {
 597                 DRM_NOTE("Unable to create a private tmpfs mount, hugepage support will be disabled(%d).\n",
 598                          err);
 599         }
 600
 601         intel_memory_region_set_name(mem, "system");
 602
 603         return 0; /* Don't error, we can simply fallback to the kernel mnt */
 604 }
 605
 606 static void release_shmem(struct intel_memory_region *mem)
 607 {
 608         i915_gemfs_fini(mem->i915);
 609 }
 610
 611 static const struct intel_memory_region_ops shmem_region_ops = {
 612         .init = init_shmem,
 613         .release = release_shmem,
 614         .create_object = create_shmem,
 615 };
 616
 617 struct intel_memory_region *i915_gem_shmem_setup(struct drm_i915_private *i915)
 618 {
 619         return intel_memory_region_create(i915, 0,
 620                                           totalram_pages() << PAGE_SHIFT,
 621                                           PAGE_SIZE, 0,
 622                                           &shmem_region_ops);
 623 }