mm/memremap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright(c) 2015 Intel Corporation. All rights reserved. */
   3 #include <linux/device.h>
   4 #include <linux/io.h>
   5 #include <linux/kasan.h>
   6 #include <linux/memory_hotplug.h>
   7 #include <linux/memremap.h>
   8 #include <linux/pfn_t.h>
   9 #include <linux/swap.h>
  10 #include <linux/mm.h>
  11 #include <linux/mmzone.h>
  12 #include <linux/swapops.h>
  13 #include <linux/types.h>
  14 #include <linux/wait_bit.h>
  15 #include <linux/xarray.h>
  16 #include "internal.h"
  17
  18 static DEFINE_XARRAY(pgmap_array);
  19
  20 /*
  21  * The memremap() and memremap_pages() interfaces are alternately used
  22  * to map persistent memory namespaces. These interfaces place different
  23  * constraints on the alignment and size of the mapping (namespace).
  24  * memremap() can map individual PAGE_SIZE pages. memremap_pages() can
  25  * only map subsections (2MB), and at least one architecture (PowerPC)
  26  * the minimum mapping granularity of memremap_pages() is 16MB.
  27  *
  28  * The role of memremap_compat_align() is to communicate the minimum
  29  * arch supported alignment of a namespace such that it can freely
  30  * switch modes without violating the arch constraint. Namely, do not
  31  * allow a namespace to be PAGE_SIZE aligned since that namespace may be
  32  * reconfigured into a mode that requires SUBSECTION_SIZE alignment.
  33  */
  34 #ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
  35 unsigned long memremap_compat_align(void)
  36 {
  37         return SUBSECTION_SIZE;
  38 }
  39 EXPORT_SYMBOL_GPL(memremap_compat_align);
  40 #endif
  41
  42 #ifdef CONFIG_FS_DAX
  43 DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
  44 EXPORT_SYMBOL(devmap_managed_key);
  45
  46 static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
  47 {
  48         if (pgmap->type == MEMORY_DEVICE_FS_DAX)
  49                 static_branch_dec(&devmap_managed_key);
  50 }
  51
  52 static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
  53 {
  54         if (pgmap->type == MEMORY_DEVICE_FS_DAX)
  55                 static_branch_inc(&devmap_managed_key);
  56 }
  57 #else
  58 static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
  59 {
  60 }
  61 static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
  62 {
  63 }
  64 #endif /* CONFIG_FS_DAX */
  65
  66 static void pgmap_array_delete(struct range *range)
  67 {
  68         xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end),
  69                         NULL, GFP_KERNEL);
  70         synchronize_rcu();
  71 }
  72
  73 static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id)
  74 {
  75         struct range *range = &pgmap->ranges[range_id];
  76         unsigned long pfn = PHYS_PFN(range->start);
  77
  78         if (range_id)
  79                 return pfn;
  80         return pfn + vmem_altmap_offset(pgmap_altmap(pgmap));
  81 }
  82
  83 bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
  84 {
  85         int i;
  86
  87         for (i = 0; i < pgmap->nr_range; i++) {
  88                 struct range *range = &pgmap->ranges[i];
  89
  90                 if (pfn >= PHYS_PFN(range->start) &&
  91                     pfn <= PHYS_PFN(range->end))
  92                         return pfn >= pfn_first(pgmap, i);
  93         }
  94
  95         return false;
  96 }
  97
  98 static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
  99 {
 100         const struct range *range = &pgmap->ranges[range_id];
 101
 102         return (range->start + range_len(range)) >> PAGE_SHIFT;
 103 }
 104
 105 static unsigned long pfn_len(struct dev_pagemap *pgmap, unsigned long range_id)
 106 {
 107         return (pfn_end(pgmap, range_id) -
 108                 pfn_first(pgmap, range_id)) >> pgmap->vmemmap_shift;
 109 }
 110
 111 static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
 112 {
 113         struct range *range = &pgmap->ranges[range_id];
 114         struct page *first_page;
 115
 116         /* make sure to access a memmap that was actually initialized */
 117         first_page = pfn_to_page(pfn_first(pgmap, range_id));
 118
 119         /* pages are dead and unused, undo the arch mapping */
 120         mem_hotplug_begin();
 121         remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
 122                                    PHYS_PFN(range_len(range)));
 123         if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
 124                 __remove_pages(PHYS_PFN(range->start),
 125                                PHYS_PFN(range_len(range)), NULL);
 126         } else {
 127                 arch_remove_memory(range->start, range_len(range),
 128                                 pgmap_altmap(pgmap));
 129                 kasan_remove_zero_shadow(__va(range->start), range_len(range));
 130         }
 131         mem_hotplug_done();
 132
 133         untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range), true);
 134         pgmap_array_delete(range);
 135 }
 136
 137 void memunmap_pages(struct dev_pagemap *pgmap)
 138 {
 139         int i;
 140
 141         percpu_ref_kill(&pgmap->ref);
 142         if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
 143             pgmap->type != MEMORY_DEVICE_COHERENT)
 144                 for (i = 0; i < pgmap->nr_range; i++)
 145                         percpu_ref_put_many(&pgmap->ref, pfn_len(pgmap, i));
 146
 147         wait_for_completion(&pgmap->done);
 148
 149         for (i = 0; i < pgmap->nr_range; i++)
 150                 pageunmap_range(pgmap, i);
 151         percpu_ref_exit(&pgmap->ref);
 152
 153         WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
 154         devmap_managed_enable_put(pgmap);
 155 }
 156 EXPORT_SYMBOL_GPL(memunmap_pages);
 157
 158 static void devm_memremap_pages_release(void *data)
 159 {
 160         memunmap_pages(data);
 161 }
 162
 163 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
 164 {
 165         struct dev_pagemap *pgmap = container_of(ref, struct dev_pagemap, ref);
 166
 167         complete(&pgmap->done);
 168 }
 169
 170 static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
 171                 int range_id, int nid)
 172 {
 173         const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
 174         struct range *range = &pgmap->ranges[range_id];
 175         struct dev_pagemap *conflict_pgmap;
 176         int error, is_ram;
 177
 178         if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0,
 179                                 "altmap not supported for multiple ranges\n"))
 180                 return -EINVAL;
 181
 182         conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
 183         if (conflict_pgmap) {
 184                 WARN(1, "Conflicting mapping in same section\n");
 185                 put_dev_pagemap(conflict_pgmap);
 186                 return -ENOMEM;
 187         }
 188
 189         conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
 190         if (conflict_pgmap) {
 191                 WARN(1, "Conflicting mapping in same section\n");
 192                 put_dev_pagemap(conflict_pgmap);
 193                 return -ENOMEM;
 194         }
 195
 196         is_ram = region_intersects(range->start, range_len(range),
 197                 IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 198
 199         if (is_ram != REGION_DISJOINT) {
 200                 WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n",
 201                                 is_ram == REGION_MIXED ? "mixed" : "ram",
 202                                 range->start, range->end);
 203                 return -ENXIO;
 204         }
 205
 206         error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start),
 207                                 PHYS_PFN(range->end), pgmap, GFP_KERNEL));
 208         if (error)
 209                 return error;
 210
 211         if (nid < 0)
 212                 nid = numa_mem_id();
 213
 214         error = track_pfn_remap(NULL, &params->pgprot, PHYS_PFN(range->start), 0,
 215                         range_len(range));
 216         if (error)
 217                 goto err_pfn_remap;
 218
 219         if (!mhp_range_allowed(range->start, range_len(range), !is_private)) {
 220                 error = -EINVAL;
 221                 goto err_kasan;
 222         }
 223
 224         mem_hotplug_begin();
 225
 226         /*
 227          * For device private memory we call add_pages() as we only need to
 228          * allocate and initialize struct page for the device memory. More-
 229          * over the device memory is un-accessible thus we do not want to
 230          * create a linear mapping for the memory like arch_add_memory()
 231          * would do.
 232          *
 233          * For all other device memory types, which are accessible by
 234          * the CPU, we do want the linear mapping and thus use
 235          * arch_add_memory().
 236          */
 237         if (is_private) {
 238                 error = add_pages(nid, PHYS_PFN(range->start),
 239                                 PHYS_PFN(range_len(range)), params);
 240         } else {
 241                 error = kasan_add_zero_shadow(__va(range->start), range_len(range));
 242                 if (error) {
 243                         mem_hotplug_done();
 244                         goto err_kasan;
 245                 }
 246
 247                 error = arch_add_memory(nid, range->start, range_len(range),
 248                                         params);
 249         }
 250
 251         if (!error) {
 252                 struct zone *zone;
 253
 254                 zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
 255                 move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
 256                                 PHYS_PFN(range_len(range)), params->altmap,
 257                                 MIGRATE_MOVABLE);
 258         }
 259
 260         mem_hotplug_done();
 261         if (error)
 262                 goto err_add_memory;
 263
 264         /*
 265          * Initialization of the pages has been deferred until now in order
 266          * to allow us to do the work while not holding the hotplug lock.
 267          */
 268         memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
 269                                 PHYS_PFN(range->start),
 270                                 PHYS_PFN(range_len(range)), pgmap);
 271         if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
 272             pgmap->type != MEMORY_DEVICE_COHERENT)
 273                 percpu_ref_get_many(&pgmap->ref, pfn_len(pgmap, range_id));
 274         return 0;
 275
 276 err_add_memory:
 277         if (!is_private)
 278                 kasan_remove_zero_shadow(__va(range->start), range_len(range));
 279 err_kasan:
 280         untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range), true);
 281 err_pfn_remap:
 282         pgmap_array_delete(range);
 283         return error;
 284 }
 285
 286
 287 /*
 288  * Not device managed version of devm_memremap_pages, undone by
 289  * memunmap_pages().  Please use devm_memremap_pages if you have a struct
 290  * device available.
 291  */
 292 void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 293 {
 294         struct mhp_params params = {
 295                 .altmap = pgmap_altmap(pgmap),
 296                 .pgmap = pgmap,
 297                 .pgprot = PAGE_KERNEL,
 298         };
 299         const int nr_range = pgmap->nr_range;
 300         int error, i;
 301
 302         if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
 303                 return ERR_PTR(-EINVAL);
 304
 305         switch (pgmap->type) {
 306         case MEMORY_DEVICE_PRIVATE:
 307                 if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
 308                         WARN(1, "Device private memory not supported\n");
 309                         return ERR_PTR(-EINVAL);
 310                 }
 311                 if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
 312                         WARN(1, "Missing migrate_to_ram method\n");
 313                         return ERR_PTR(-EINVAL);
 314                 }
 315                 if (!pgmap->ops->page_free) {
 316                         WARN(1, "Missing page_free method\n");
 317                         return ERR_PTR(-EINVAL);
 318                 }
 319                 if (!pgmap->owner) {
 320                         WARN(1, "Missing owner\n");
 321                         return ERR_PTR(-EINVAL);
 322                 }
 323                 break;
 324         case MEMORY_DEVICE_COHERENT:
 325                 if (!pgmap->ops->page_free) {
 326                         WARN(1, "Missing page_free method\n");
 327                         return ERR_PTR(-EINVAL);
 328                 }
 329                 if (!pgmap->owner) {
 330                         WARN(1, "Missing owner\n");
 331                         return ERR_PTR(-EINVAL);
 332                 }
 333                 break;
 334         case MEMORY_DEVICE_FS_DAX:
 335                 if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
 336                         WARN(1, "File system DAX not supported\n");
 337                         return ERR_PTR(-EINVAL);
 338                 }
 339                 params.pgprot = pgprot_decrypted(params.pgprot);
 340                 break;
 341         case MEMORY_DEVICE_GENERIC:
 342                 break;
 343         case MEMORY_DEVICE_PCI_P2PDMA:
 344                 params.pgprot = pgprot_noncached(params.pgprot);
 345                 break;
 346         default:
 347                 WARN(1, "Invalid pgmap type %d\n", pgmap->type);
 348                 break;
 349         }
 350
 351         init_completion(&pgmap->done);
 352         error = percpu_ref_init(&pgmap->ref, dev_pagemap_percpu_release, 0,
 353                                 GFP_KERNEL);
 354         if (error)
 355                 return ERR_PTR(error);
 356
 357         devmap_managed_enable_get(pgmap);
 358
 359         /*
 360          * Clear the pgmap nr_range as it will be incremented for each
 361          * successfully processed range. This communicates how many
 362          * regions to unwind in the abort case.
 363          */
 364         pgmap->nr_range = 0;
 365         error = 0;
 366         for (i = 0; i < nr_range; i++) {
 367                 error = pagemap_range(pgmap, &params, i, nid);
 368                 if (error)
 369                         break;
 370                 pgmap->nr_range++;
 371         }
 372
 373         if (i < nr_range) {
 374                 memunmap_pages(pgmap);
 375                 pgmap->nr_range = nr_range;
 376                 return ERR_PTR(error);
 377         }
 378
 379         return __va(pgmap->ranges[0].start);
 380 }
 381 EXPORT_SYMBOL_GPL(memremap_pages);
 382
 383 /**
 384  * devm_memremap_pages - remap and provide memmap backing for the given resource
 385  * @dev: hosting device for @res
 386  * @pgmap: pointer to a struct dev_pagemap
 387  *
 388  * Notes:
 389  * 1/ At a minimum the range and type members of @pgmap must be initialized
 390  *    by the caller before passing it to this function
 391  *
 392  * 2/ The altmap field may optionally be initialized, in which case
 393  *    PGMAP_ALTMAP_VALID must be set in pgmap->flags.
 394  *
 395  * 3/ The ref field may optionally be provided, in which pgmap->ref must be
 396  *    'live' on entry and will be killed and reaped at
 397  *    devm_memremap_pages_release() time, or if this routine fails.
 398  *
 399  * 4/ range is expected to be a host memory range that could feasibly be
 400  *    treated as a "System RAM" range, i.e. not a device mmio range, but
 401  *    this is not enforced.
 402  */
 403 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 404 {
 405         int error;
 406         void *ret;
 407
 408         ret = memremap_pages(pgmap, dev_to_node(dev));
 409         if (IS_ERR(ret))
 410                 return ret;
 411
 412         error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
 413                         pgmap);
 414         if (error)
 415                 return ERR_PTR(error);
 416         return ret;
 417 }
 418 EXPORT_SYMBOL_GPL(devm_memremap_pages);
 419
 420 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
 421 {
 422         devm_release_action(dev, devm_memremap_pages_release, pgmap);
 423 }
 424 EXPORT_SYMBOL_GPL(devm_memunmap_pages);
 425
 426 /**
 427  * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
 428  * @pfn: page frame number to lookup page_map
 429  * @pgmap: optional known pgmap that already has a reference
 430  *
 431  * If @pgmap is non-NULL and covers @pfn it will be returned as-is.  If @pgmap
 432  * is non-NULL but does not cover @pfn the reference to it will be released.
 433  */
 434 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 435                 struct dev_pagemap *pgmap)
 436 {
 437         resource_size_t phys = PFN_PHYS(pfn);
 438
 439         /*
 440          * In the cached case we're already holding a live reference.
 441          */
 442         if (pgmap) {
 443                 if (phys >= pgmap->range.start && phys <= pgmap->range.end)
 444                         return pgmap;
 445                 put_dev_pagemap(pgmap);
 446         }
 447
 448         /* fall back to slow path lookup */
 449         rcu_read_lock();
 450         pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
 451         if (pgmap && !percpu_ref_tryget_live_rcu(&pgmap->ref))
 452                 pgmap = NULL;
 453         rcu_read_unlock();
 454
 455         return pgmap;
 456 }
 457 EXPORT_SYMBOL_GPL(get_dev_pagemap);
 458
 459 void free_zone_device_folio(struct folio *folio)
 460 {
 461         if (WARN_ON_ONCE(!folio->page.pgmap->ops ||
 462                         !folio->page.pgmap->ops->page_free))
 463                 return;
 464
 465         mem_cgroup_uncharge(folio);
 466
 467         /*
 468          * Note: we don't expect anonymous compound pages yet. Once supported
 469          * and we could PTE-map them similar to THP, we'd have to clear
 470          * PG_anon_exclusive on all tail pages.
 471          */
 472         if (folio_test_anon(folio)) {
 473                 VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
 474                 __ClearPageAnonExclusive(folio_page(folio, 0));
 475         }
 476
 477         /*
 478          * When a device managed page is freed, the folio->mapping field
 479          * may still contain a (stale) mapping value. For example, the
 480          * lower bits of folio->mapping may still identify the folio as an
 481          * anonymous folio. Ultimately, this entire field is just stale
 482          * and wrong, and it will cause errors if not cleared.
 483          *
 484          * For other types of ZONE_DEVICE pages, migration is either
 485          * handled differently or not done at all, so there is no need
 486          * to clear folio->mapping.
 487          */
 488         folio->mapping = NULL;
 489         folio->page.pgmap->ops->page_free(folio_page(folio, 0));
 490
 491         if (folio->page.pgmap->type != MEMORY_DEVICE_PRIVATE &&
 492             folio->page.pgmap->type != MEMORY_DEVICE_COHERENT)
 493                 /*
 494                  * Reset the refcount to 1 to prepare for handing out the page
 495                  * again.
 496                  */
 497                 folio_set_count(folio, 1);
 498         else
 499                 put_dev_pagemap(folio->page.pgmap);
 500 }
 501
 502 void zone_device_page_init(struct page *page)
 503 {
 504         /*
 505          * Drivers shouldn't be allocating pages after calling
 506          * memunmap_pages().
 507          */
 508         WARN_ON_ONCE(!percpu_ref_tryget_live(&page->pgmap->ref));
 509         set_page_count(page, 1);
 510         lock_page(page);
 511 }
 512 EXPORT_SYMBOL_GPL(zone_device_page_init);
 513
 514 #ifdef CONFIG_FS_DAX
 515 bool __put_devmap_managed_folio_refs(struct folio *folio, int refs)
 516 {
 517         if (folio->page.pgmap->type != MEMORY_DEVICE_FS_DAX)
 518                 return false;
 519
 520         /*
 521          * fsdax page refcounts are 1-based, rather than 0-based: if
 522          * refcount is 1, then the page is free and the refcount is
 523          * stable because nobody holds a reference on the page.
 524          */
 525         if (folio_ref_sub_return(folio, refs) == 1)
 526                 wake_up_var(&folio->_refcount);
 527         return true;
 528 }
 529 EXPORT_SYMBOL(__put_devmap_managed_folio_refs);
 530 #endif /* CONFIG_FS_DAX */