1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright(c) 2015 Intel Corporation. All rights reserved. */
3 #include <linux/device.h>
5 #include <linux/kasan.h>
6 #include <linux/memory_hotplug.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>
16 static DEFINE_XARRAY(pgmap_array);
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.
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.
32 #ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
33 unsigned long memremap_compat_align(void)
35 return SUBSECTION_SIZE;
37 EXPORT_SYMBOL_GPL(memremap_compat_align);
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;
45 static void devmap_managed_enable_put(void)
47 if (atomic_dec_and_test(&devmap_managed_enable))
48 static_branch_disable(&devmap_managed_key);
51 static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
53 if (pgmap->type == MEMORY_DEVICE_PRIVATE &&
54 (!pgmap->ops || !pgmap->ops->page_free)) {
55 WARN(1, "Missing page_free method\n");
59 if (atomic_inc_return(&devmap_managed_enable) == 1)
60 static_branch_enable(&devmap_managed_key);
64 static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
68 static void devmap_managed_enable_put(void)
71 #endif /* CONFIG_DEV_PAGEMAP_OPS */
73 static void pgmap_array_delete(struct resource *res)
75 xa_store_range(&pgmap_array, PHYS_PFN(res->start), PHYS_PFN(res->end),
80 static unsigned long pfn_first(struct dev_pagemap *pgmap)
82 return PHYS_PFN(pgmap->res.start) +
83 vmem_altmap_offset(pgmap_altmap(pgmap));
86 static unsigned long pfn_end(struct dev_pagemap *pgmap)
88 const struct resource *res = &pgmap->res;
90 return (res->start + resource_size(res)) >> PAGE_SHIFT;
93 static unsigned long pfn_next(unsigned long pfn)
100 #define for_each_device_pfn(pfn, map) \
101 for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn))
103 static void dev_pagemap_kill(struct dev_pagemap *pgmap)
105 if (pgmap->ops && pgmap->ops->kill)
106 pgmap->ops->kill(pgmap);
108 percpu_ref_kill(pgmap->ref);
111 static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
113 if (pgmap->ops && pgmap->ops->cleanup) {
114 pgmap->ops->cleanup(pgmap);
116 wait_for_completion(&pgmap->done);
117 percpu_ref_exit(pgmap->ref);
120 * Undo the pgmap ref assignment for the internal case as the
121 * caller may re-enable the same pgmap.
123 if (pgmap->ref == &pgmap->internal_ref)
127 void memunmap_pages(struct dev_pagemap *pgmap)
129 struct resource *res = &pgmap->res;
130 struct page *first_page;
134 dev_pagemap_kill(pgmap);
135 for_each_device_pfn(pfn, pgmap)
136 put_page(pfn_to_page(pfn));
137 dev_pagemap_cleanup(pgmap);
139 /* make sure to access a memmap that was actually initialized */
140 first_page = pfn_to_page(pfn_first(pgmap));
142 /* pages are dead and unused, undo the arch mapping */
143 nid = page_to_nid(first_page);
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);
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));
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();
163 EXPORT_SYMBOL_GPL(memunmap_pages);
165 static void devm_memremap_pages_release(void *data)
167 memunmap_pages(data);
170 static void dev_pagemap_percpu_release(struct percpu_ref *ref)
172 struct dev_pagemap *pgmap =
173 container_of(ref, struct dev_pagemap, internal_ref);
175 complete(&pgmap->done);
179 * Not device managed version of dev_memremap_pages, undone by
180 * memunmap_pages(). Please use dev_memremap_pages if you have a struct
183 void *memremap_pages(struct dev_pagemap *pgmap, int nid)
185 struct resource *res = &pgmap->res;
186 struct dev_pagemap *conflict_pgmap;
187 struct mhp_restrictions restrictions = {
189 * We do not want any optional features only our own memmap
191 .altmap = pgmap_altmap(pgmap),
193 pgprot_t pgprot = PAGE_KERNEL;
195 bool need_devmap_managed = true;
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);
203 if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
204 WARN(1, "Missing migrate_to_ram method\n");
205 return ERR_PTR(-EINVAL);
208 WARN(1, "Missing owner\n");
209 return ERR_PTR(-EINVAL);
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);
219 case MEMORY_DEVICE_DEVDAX:
220 case MEMORY_DEVICE_PCI_P2PDMA:
221 need_devmap_managed = false;
224 WARN(1, "Invalid pgmap type %d\n", pgmap->type);
229 if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup))
230 return ERR_PTR(-EINVAL);
232 init_completion(&pgmap->done);
233 error = percpu_ref_init(&pgmap->internal_ref,
234 dev_pagemap_percpu_release, 0, GFP_KERNEL);
236 return ERR_PTR(error);
237 pgmap->ref = &pgmap->internal_ref;
239 if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) {
240 WARN(1, "Missing reference count teardown definition\n");
241 return ERR_PTR(-EINVAL);
245 if (need_devmap_managed) {
246 error = devmap_managed_enable_get(pgmap);
248 return ERR_PTR(error);
251 conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL);
252 if (conflict_pgmap) {
253 WARN(1, "Conflicting mapping in same section\n");
254 put_dev_pagemap(conflict_pgmap);
259 conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->end), NULL);
260 if (conflict_pgmap) {
261 WARN(1, "Conflicting mapping in same section\n");
262 put_dev_pagemap(conflict_pgmap);
267 is_ram = region_intersects(res->start, resource_size(res),
268 IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
270 if (is_ram != REGION_DISJOINT) {
271 WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__,
272 is_ram == REGION_MIXED ? "mixed" : "ram", res);
277 error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(res->start),
278 PHYS_PFN(res->end), pgmap, GFP_KERNEL));
285 error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(res->start), 0,
293 * For device private memory we call add_pages() as we only need to
294 * allocate and initialize struct page for the device memory. More-
295 * over the device memory is un-accessible thus we do not want to
296 * create a linear mapping for the memory like arch_add_memory()
299 * For all other device memory types, which are accessible by
300 * the CPU, we do want the linear mapping and thus use
303 if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
304 error = add_pages(nid, PHYS_PFN(res->start),
305 PHYS_PFN(resource_size(res)), &restrictions);
307 error = kasan_add_zero_shadow(__va(res->start), resource_size(res));
313 error = arch_add_memory(nid, res->start, resource_size(res),
320 zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
321 move_pfn_range_to_zone(zone, PHYS_PFN(res->start),
322 PHYS_PFN(resource_size(res)), restrictions.altmap);
330 * Initialization of the pages has been deferred until now in order
331 * to allow us to do the work while not holding the hotplug lock.
333 memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
334 PHYS_PFN(res->start),
335 PHYS_PFN(resource_size(res)), pgmap);
336 percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap));
337 return __va(res->start);
340 kasan_remove_zero_shadow(__va(res->start), resource_size(res));
342 untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
344 pgmap_array_delete(res);
346 dev_pagemap_kill(pgmap);
347 dev_pagemap_cleanup(pgmap);
348 devmap_managed_enable_put();
349 return ERR_PTR(error);
351 EXPORT_SYMBOL_GPL(memremap_pages);
354 * devm_memremap_pages - remap and provide memmap backing for the given resource
355 * @dev: hosting device for @res
356 * @pgmap: pointer to a struct dev_pagemap
359 * 1/ At a minimum the res and type members of @pgmap must be initialized
360 * by the caller before passing it to this function
362 * 2/ The altmap field may optionally be initialized, in which case
363 * PGMAP_ALTMAP_VALID must be set in pgmap->flags.
365 * 3/ The ref field may optionally be provided, in which pgmap->ref must be
366 * 'live' on entry and will be killed and reaped at
367 * devm_memremap_pages_release() time, or if this routine fails.
369 * 4/ res is expected to be a host memory range that could feasibly be
370 * treated as a "System RAM" range, i.e. not a device mmio range, but
371 * this is not enforced.
373 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
378 ret = memremap_pages(pgmap, dev_to_node(dev));
382 error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
385 return ERR_PTR(error);
388 EXPORT_SYMBOL_GPL(devm_memremap_pages);
390 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
392 devm_release_action(dev, devm_memremap_pages_release, pgmap);
394 EXPORT_SYMBOL_GPL(devm_memunmap_pages);
396 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
398 /* number of pfns from base where pfn_to_page() is valid */
400 return altmap->reserve + altmap->free;
404 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
406 altmap->alloc -= nr_pfns;
410 * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
411 * @pfn: page frame number to lookup page_map
412 * @pgmap: optional known pgmap that already has a reference
414 * If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap
415 * is non-NULL but does not cover @pfn the reference to it will be released.
417 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
418 struct dev_pagemap *pgmap)
420 resource_size_t phys = PFN_PHYS(pfn);
423 * In the cached case we're already holding a live reference.
426 if (phys >= pgmap->res.start && phys <= pgmap->res.end)
428 put_dev_pagemap(pgmap);
431 /* fall back to slow path lookup */
433 pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
434 if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
440 EXPORT_SYMBOL_GPL(get_dev_pagemap);
442 #ifdef CONFIG_DEV_PAGEMAP_OPS
443 void free_devmap_managed_page(struct page *page)
445 /* notify page idle for dax */
446 if (!is_device_private_page(page)) {
447 wake_up_var(&page->_refcount);
451 /* Clear Active bit in case of parallel mark_page_accessed */
452 __ClearPageActive(page);
453 __ClearPageWaiters(page);
455 mem_cgroup_uncharge(page);
458 * When a device_private page is freed, the page->mapping field
459 * may still contain a (stale) mapping value. For example, the
460 * lower bits of page->mapping may still identify the page as an
461 * anonymous page. Ultimately, this entire field is just stale
462 * and wrong, and it will cause errors if not cleared. One
465 * migrate_vma_pages()
466 * migrate_vma_insert_page()
467 * page_add_new_anon_rmap()
468 * __page_set_anon_rmap()
469 * ...checks page->mapping, via PageAnon(page) call,
470 * and incorrectly concludes that the page is an
471 * anonymous page. Therefore, it incorrectly,
472 * silently fails to set up the new anon rmap.
474 * For other types of ZONE_DEVICE pages, migration is either
475 * handled differently or not done at all, so there is no need
476 * to clear page->mapping.
478 page->mapping = NULL;
479 page->pgmap->ops->page_free(page);
481 #endif /* CONFIG_DEV_PAGEMAP_OPS */