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/mm.h>
   8 #include <linux/pfn_t.h>
   9 #include <linux/swap.h>
  10 #include <linux/mmzone.h>
  11 #include <linux/swapops.h>
  12 #include <linux/types.h>
  13 #include <linux/wait_bit.h>
  14 #include <linux/xarray.h>
  15
  16 static DEFINE_XARRAY(pgmap_array);
  17
  18 /*
  19  * The memremap() and memremap_pages() interfaces are alternately used
  20  * to map persistent memory namespaces. These interfaces place different
  21  * constraints on the alignment and size of the mapping (namespace).
  22  * memremap() can map individual PAGE_SIZE pages. memremap_pages() can
  23  * only map subsections (2MB), and at least one architecture (PowerPC)
  24  * the minimum mapping granularity of memremap_pages() is 16MB.
  25  *
  26  * The role of memremap_compat_align() is to communicate the minimum
  27  * arch supported alignment of a namespace such that it can freely
  28  * switch modes without violating the arch constraint. Namely, do not
  29  * allow a namespace to be PAGE_SIZE aligned since that namespace may be
  30  * reconfigured into a mode that requires SUBSECTION_SIZE alignment.
  31  */
  32 #ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
  33 unsigned long memremap_compat_align(void)
  34 {
  35         return SUBSECTION_SIZE;
  36 }
  37 EXPORT_SYMBOL_GPL(memremap_compat_align);
  38 #endif
  39
  40 #ifdef CONFIG_DEV_PAGEMAP_OPS
  41 DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
  42 EXPORT_SYMBOL(devmap_managed_key);
  43 static atomic_t devmap_managed_enable;
  44
  45 static void devmap_managed_enable_put(void)
  46 {
  47         if (atomic_dec_and_test(&devmap_managed_enable))
  48                 static_branch_disable(&devmap_managed_key);
  49 }
  50
  51 static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
  52 {
  53         if (pgmap->type == MEMORY_DEVICE_PRIVATE &&
  54             (!pgmap->ops || !pgmap->ops->page_free)) {
  55                 WARN(1, "Missing page_free method\n");
  56                 return -EINVAL;
  57         }
  58
  59         if (atomic_inc_return(&devmap_managed_enable) == 1)
  60                 static_branch_enable(&devmap_managed_key);
  61         return 0;
  62 }
  63 #else
  64 static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
  65 {
  66         return -EINVAL;
  67 }
  68 static void devmap_managed_enable_put(void)
  69 {
  70 }
  71 #endif /* CONFIG_DEV_PAGEMAP_OPS */
  72
  73 static void pgmap_array_delete(struct resource *res)
  74 {
  75         xa_store_range(&pgmap_array, PHYS_PFN(res->start), PHYS_PFN(res->end),
  76                         NULL, GFP_KERNEL);
  77         synchronize_rcu();
  78 }
  79
  80 static unsigned long pfn_first(struct dev_pagemap *pgmap)
  81 {
  82         return PHYS_PFN(pgmap->res.start) +
  83                 vmem_altmap_offset(pgmap_altmap(pgmap));
  84 }
  85
  86 static unsigned long pfn_end(struct dev_pagemap *pgmap)
  87 {
  88         const struct resource *res = &pgmap->res;
  89
  90         return (res->start + resource_size(res)) >> PAGE_SHIFT;
  91 }
  92
  93 static unsigned long pfn_next(unsigned long pfn)
  94 {
  95         if (pfn % 1024 == 0)
  96                 cond_resched();
  97         return pfn + 1;
  98 }
  99
 100 #define for_each_device_pfn(pfn, map) \
 101         for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn))
 102
 103 static void dev_pagemap_kill(struct dev_pagemap *pgmap)
 104 {
 105         if (pgmap->ops && pgmap->ops->kill)
 106                 pgmap->ops->kill(pgmap);
 107         else
 108                 percpu_ref_kill(pgmap->ref);
 109 }
 110
 111 static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
 112 {
 113         if (pgmap->ops && pgmap->ops->cleanup) {
 114                 pgmap->ops->cleanup(pgmap);
 115         } else {
 116                 wait_for_completion(&pgmap->done);
 117                 percpu_ref_exit(pgmap->ref);
 118         }
 119         /*
 120          * Undo the pgmap ref assignment for the internal case as the
 121          * caller may re-enable the same pgmap.
 122          */
 123         if (pgmap->ref == &pgmap->internal_ref)
 124                 pgmap->ref = NULL;
 125 }
 126
 127 void memunmap_pages(struct dev_pagemap *pgmap)
 128 {
 129         struct resource *res = &pgmap->res;
 130         struct page *first_page;
 131         unsigned long pfn;
 132         int nid;
 133
 134         dev_pagemap_kill(pgmap);
 135         for_each_device_pfn(pfn, pgmap)
 136                 put_page(pfn_to_page(pfn));
 137         dev_pagemap_cleanup(pgmap);
 138
 139         /* make sure to access a memmap that was actually initialized */
 140         first_page = pfn_to_page(pfn_first(pgmap));
 141
 142         /* pages are dead and unused, undo the arch mapping */
 143         nid = page_to_nid(first_page);
 144
 145         mem_hotplug_begin();
 146         remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(res->start),
 147                                    PHYS_PFN(resource_size(res)));
 148         if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
 149                 __remove_pages(PHYS_PFN(res->start),
 150                                PHYS_PFN(resource_size(res)), NULL);
 151         } else {
 152                 arch_remove_memory(nid, res->start, resource_size(res),
 153                                 pgmap_altmap(pgmap));
 154                 kasan_remove_zero_shadow(__va(res->start), resource_size(res));
 155         }
 156         mem_hotplug_done();
 157
 158         untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
 159         pgmap_array_delete(res);
 160         WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
 161         devmap_managed_enable_put();
 162 }
 163 EXPORT_SYMBOL_GPL(memunmap_pages);
 164
 165 static void devm_memremap_pages_release(void *data)
 166 {
 167         memunmap_pages(data);
 168 }
 169
 170 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
 171 {
 172         struct dev_pagemap *pgmap =
 173                 container_of(ref, struct dev_pagemap, internal_ref);
 174
 175         complete(&pgmap->done);
 176 }
 177
 178 /*
 179  * Not device managed version of dev_memremap_pages, undone by
 180  * memunmap_pages().  Please use dev_memremap_pages if you have a struct
 181  * device available.
 182  */
 183 void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 184 {
 185         struct resource *res = &pgmap->res;
 186         struct dev_pagemap *conflict_pgmap;
 187         struct mhp_params params = {
 188                 /*
 189                  * We do not want any optional features only our own memmap
 190                  */
 191                 .altmap = pgmap_altmap(pgmap),
 192                 .pgprot = PAGE_KERNEL,
 193         };
 194         int error, is_ram;
 195         bool need_devmap_managed = true;
 196
 197         switch (pgmap->type) {
 198         case MEMORY_DEVICE_PRIVATE:
 199                 if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
 200                         WARN(1, "Device private memory not supported\n");
 201                         return ERR_PTR(-EINVAL);
 202                 }
 203                 if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
 204                         WARN(1, "Missing migrate_to_ram method\n");
 205                         return ERR_PTR(-EINVAL);
 206                 }
 207                 if (!pgmap->owner) {
 208                         WARN(1, "Missing owner\n");
 209                         return ERR_PTR(-EINVAL);
 210                 }
 211                 break;
 212         case MEMORY_DEVICE_FS_DAX:
 213                 if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
 214                     IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
 215                         WARN(1, "File system DAX not supported\n");
 216                         return ERR_PTR(-EINVAL);
 217                 }
 218                 break;
 219         case MEMORY_DEVICE_DEVDAX:
 220                 need_devmap_managed = false;
 221                 break;
 222         case MEMORY_DEVICE_PCI_P2PDMA:
 223                 params.pgprot = pgprot_noncached(params.pgprot);
 224                 need_devmap_managed = false;
 225                 break;
 226         default:
 227                 WARN(1, "Invalid pgmap type %d\n", pgmap->type);
 228                 break;
 229         }
 230
 231         if (!pgmap->ref) {
 232                 if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup))
 233                         return ERR_PTR(-EINVAL);
 234
 235                 init_completion(&pgmap->done);
 236                 error = percpu_ref_init(&pgmap->internal_ref,
 237                                 dev_pagemap_percpu_release, 0, GFP_KERNEL);
 238                 if (error)
 239                         return ERR_PTR(error);
 240                 pgmap->ref = &pgmap->internal_ref;
 241         } else {
 242                 if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) {
 243                         WARN(1, "Missing reference count teardown definition\n");
 244                         return ERR_PTR(-EINVAL);
 245                 }
 246         }
 247
 248         if (need_devmap_managed) {
 249                 error = devmap_managed_enable_get(pgmap);
 250                 if (error)
 251                         return ERR_PTR(error);
 252         }
 253
 254         conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL);
 255         if (conflict_pgmap) {
 256                 WARN(1, "Conflicting mapping in same section\n");
 257                 put_dev_pagemap(conflict_pgmap);
 258                 error = -ENOMEM;
 259                 goto err_array;
 260         }
 261
 262         conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->end), NULL);
 263         if (conflict_pgmap) {
 264                 WARN(1, "Conflicting mapping in same section\n");
 265                 put_dev_pagemap(conflict_pgmap);
 266                 error = -ENOMEM;
 267                 goto err_array;
 268         }
 269
 270         is_ram = region_intersects(res->start, resource_size(res),
 271                 IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 272
 273         if (is_ram != REGION_DISJOINT) {
 274                 WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__,
 275                                 is_ram == REGION_MIXED ? "mixed" : "ram", res);
 276                 error = -ENXIO;
 277                 goto err_array;
 278         }
 279
 280         error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(res->start),
 281                                 PHYS_PFN(res->end), pgmap, GFP_KERNEL));
 282         if (error)
 283                 goto err_array;
 284
 285         if (nid < 0)
 286                 nid = numa_mem_id();
 287
 288         error = track_pfn_remap(NULL, &params.pgprot, PHYS_PFN(res->start),
 289                                 0, resource_size(res));
 290         if (error)
 291                 goto err_pfn_remap;
 292
 293         mem_hotplug_begin();
 294
 295         /*
 296          * For device private memory we call add_pages() as we only need to
 297          * allocate and initialize struct page for the device memory. More-
 298          * over the device memory is un-accessible thus we do not want to
 299          * create a linear mapping for the memory like arch_add_memory()
 300          * would do.
 301          *
 302          * For all other device memory types, which are accessible by
 303          * the CPU, we do want the linear mapping and thus use
 304          * arch_add_memory().
 305          */
 306         if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
 307                 error = add_pages(nid, PHYS_PFN(res->start),
 308                                 PHYS_PFN(resource_size(res)), &params);
 309         } else {
 310                 error = kasan_add_zero_shadow(__va(res->start), resource_size(res));
 311                 if (error) {
 312                         mem_hotplug_done();
 313                         goto err_kasan;
 314                 }
 315
 316                 error = arch_add_memory(nid, res->start, resource_size(res),
 317                                         &params);
 318         }
 319
 320         if (!error) {
 321                 struct zone *zone;
 322
 323                 zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
 324                 move_pfn_range_to_zone(zone, PHYS_PFN(res->start),
 325                                 PHYS_PFN(resource_size(res)), params.altmap);
 326         }
 327
 328         mem_hotplug_done();
 329         if (error)
 330                 goto err_add_memory;
 331
 332         /*
 333          * Initialization of the pages has been deferred until now in order
 334          * to allow us to do the work while not holding the hotplug lock.
 335          */
 336         memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
 337                                 PHYS_PFN(res->start),
 338                                 PHYS_PFN(resource_size(res)), pgmap);
 339         percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap));
 340         return __va(res->start);
 341
 342  err_add_memory:
 343         kasan_remove_zero_shadow(__va(res->start), resource_size(res));
 344  err_kasan:
 345         untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
 346  err_pfn_remap:
 347         pgmap_array_delete(res);
 348  err_array:
 349         dev_pagemap_kill(pgmap);
 350         dev_pagemap_cleanup(pgmap);
 351         devmap_managed_enable_put();
 352         return ERR_PTR(error);
 353 }
 354 EXPORT_SYMBOL_GPL(memremap_pages);
 355
 356 /**
 357  * devm_memremap_pages - remap and provide memmap backing for the given resource
 358  * @dev: hosting device for @res
 359  * @pgmap: pointer to a struct dev_pagemap
 360  *
 361  * Notes:
 362  * 1/ At a minimum the res and type members of @pgmap must be initialized
 363  *    by the caller before passing it to this function
 364  *
 365  * 2/ The altmap field may optionally be initialized, in which case
 366  *    PGMAP_ALTMAP_VALID must be set in pgmap->flags.
 367  *
 368  * 3/ The ref field may optionally be provided, in which pgmap->ref must be
 369  *    'live' on entry and will be killed and reaped at
 370  *    devm_memremap_pages_release() time, or if this routine fails.
 371  *
 372  * 4/ res is expected to be a host memory range that could feasibly be
 373  *    treated as a "System RAM" range, i.e. not a device mmio range, but
 374  *    this is not enforced.
 375  */
 376 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 377 {
 378         int error;
 379         void *ret;
 380
 381         ret = memremap_pages(pgmap, dev_to_node(dev));
 382         if (IS_ERR(ret))
 383                 return ret;
 384
 385         error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
 386                         pgmap);
 387         if (error)
 388                 return ERR_PTR(error);
 389         return ret;
 390 }
 391 EXPORT_SYMBOL_GPL(devm_memremap_pages);
 392
 393 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
 394 {
 395         devm_release_action(dev, devm_memremap_pages_release, pgmap);
 396 }
 397 EXPORT_SYMBOL_GPL(devm_memunmap_pages);
 398
 399 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
 400 {
 401         /* number of pfns from base where pfn_to_page() is valid */
 402         if (altmap)
 403                 return altmap->reserve + altmap->free;
 404         return 0;
 405 }
 406
 407 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
 408 {
 409         altmap->alloc -= nr_pfns;
 410 }
 411
 412 /**
 413  * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
 414  * @pfn: page frame number to lookup page_map
 415  * @pgmap: optional known pgmap that already has a reference
 416  *
 417  * If @pgmap is non-NULL and covers @pfn it will be returned as-is.  If @pgmap
 418  * is non-NULL but does not cover @pfn the reference to it will be released.
 419  */
 420 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 421                 struct dev_pagemap *pgmap)
 422 {
 423         resource_size_t phys = PFN_PHYS(pfn);
 424
 425         /*
 426          * In the cached case we're already holding a live reference.
 427          */
 428         if (pgmap) {
 429                 if (phys >= pgmap->res.start && phys <= pgmap->res.end)
 430                         return pgmap;
 431                 put_dev_pagemap(pgmap);
 432         }
 433
 434         /* fall back to slow path lookup */
 435         rcu_read_lock();
 436         pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
 437         if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
 438                 pgmap = NULL;
 439         rcu_read_unlock();
 440
 441         return pgmap;
 442 }
 443 EXPORT_SYMBOL_GPL(get_dev_pagemap);
 444
 445 #ifdef CONFIG_DEV_PAGEMAP_OPS
 446 void free_devmap_managed_page(struct page *page)
 447 {
 448         /* notify page idle for dax */
 449         if (!is_device_private_page(page)) {
 450                 wake_up_var(&page->_refcount);
 451                 return;
 452         }
 453
 454         /* Clear Active bit in case of parallel mark_page_accessed */
 455         __ClearPageActive(page);
 456         __ClearPageWaiters(page);
 457
 458         mem_cgroup_uncharge(page);
 459
 460         /*
 461          * When a device_private page is freed, the page->mapping field
 462          * may still contain a (stale) mapping value. For example, the
 463          * lower bits of page->mapping may still identify the page as an
 464          * anonymous page. Ultimately, this entire field is just stale
 465          * and wrong, and it will cause errors if not cleared.  One
 466          * example is:
 467          *
 468          *  migrate_vma_pages()
 469          *    migrate_vma_insert_page()
 470          *      page_add_new_anon_rmap()
 471          *        __page_set_anon_rmap()
 472          *          ...checks page->mapping, via PageAnon(page) call,
 473          *            and incorrectly concludes that the page is an
 474          *            anonymous page. Therefore, it incorrectly,
 475          *            silently fails to set up the new anon rmap.
 476          *
 477          * For other types of ZONE_DEVICE pages, migration is either
 478          * handled differently or not done at all, so there is no need
 479          * to clear page->mapping.
 480          */
 481         page->mapping = NULL;
 482         page->pgmap->ops->page_free(page);
 483 }
 484 #endif /* CONFIG_DEV_PAGEMAP_OPS */