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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/mmzone.h>
11#include <linux/swapops.h>
12#include <linux/types.h>
13#include <linux/wait_bit.h>
14#include <linux/xarray.h>
15#include "internal.h"
16
17static DEFINE_XARRAY(pgmap_array);
18
19/*
20 * The memremap() and memremap_pages() interfaces are alternately used
21 * to map persistent memory namespaces. These interfaces place different
22 * constraints on the alignment and size of the mapping (namespace).
23 * memremap() can map individual PAGE_SIZE pages. memremap_pages() can
24 * only map subsections (2MB), and at least one architecture (PowerPC)
25 * the minimum mapping granularity of memremap_pages() is 16MB.
26 *
27 * The role of memremap_compat_align() is to communicate the minimum
28 * arch supported alignment of a namespace such that it can freely
29 * switch modes without violating the arch constraint. Namely, do not
30 * allow a namespace to be PAGE_SIZE aligned since that namespace may be
31 * reconfigured into a mode that requires SUBSECTION_SIZE alignment.
32 */
33#ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
34unsigned long memremap_compat_align(void)
35{
36 return SUBSECTION_SIZE;
37}
38EXPORT_SYMBOL_GPL(memremap_compat_align);
39#endif
40
41#ifdef CONFIG_FS_DAX
42DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
43EXPORT_SYMBOL(devmap_managed_key);
44
45static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
46{
47 if (pgmap->type == MEMORY_DEVICE_FS_DAX)
48 static_branch_dec(&devmap_managed_key);
49}
50
51static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
52{
53 if (pgmap->type == MEMORY_DEVICE_FS_DAX)
54 static_branch_inc(&devmap_managed_key);
55}
56#else
57static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
58{
59}
60static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
61{
62}
63#endif /* CONFIG_FS_DAX */
64
65static void pgmap_array_delete(struct range *range)
66{
67 xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end),
68 NULL, GFP_KERNEL);
69 synchronize_rcu();
70}
71
72static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id)
73{
74 struct range *range = &pgmap->ranges[range_id];
75 unsigned long pfn = PHYS_PFN(range->start);
76
77 if (range_id)
78 return pfn;
79 return pfn + vmem_altmap_offset(pgmap_altmap(pgmap));
80}
81
82bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
83{
84 int i;
85
86 for (i = 0; i < pgmap->nr_range; i++) {
87 struct range *range = &pgmap->ranges[i];
88
89 if (pfn >= PHYS_PFN(range->start) &&
90 pfn <= PHYS_PFN(range->end))
91 return pfn >= pfn_first(pgmap, i);
92 }
93
94 return false;
95}
96
97static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
98{
99 const struct range *range = &pgmap->ranges[range_id];
100
101 return (range->start + range_len(range)) >> PAGE_SHIFT;
102}
103
104static unsigned long pfn_len(struct dev_pagemap *pgmap, unsigned long range_id)
105{
106 return (pfn_end(pgmap, range_id) -
107 pfn_first(pgmap, range_id)) >> pgmap->vmemmap_shift;
108}
109
110static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
111{
112 struct range *range = &pgmap->ranges[range_id];
113 struct page *first_page;
114
115 /* make sure to access a memmap that was actually initialized */
116 first_page = pfn_to_page(pfn_first(pgmap, range_id));
117
118 /* pages are dead and unused, undo the arch mapping */
119 mem_hotplug_begin();
120 remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
121 PHYS_PFN(range_len(range)));
122 if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
123 __remove_pages(PHYS_PFN(range->start),
124 PHYS_PFN(range_len(range)), NULL);
125 } else {
126 arch_remove_memory(range->start, range_len(range),
127 pgmap_altmap(pgmap));
128 kasan_remove_zero_shadow(__va(range->start), range_len(range));
129 }
130 mem_hotplug_done();
131
132 untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
133 pgmap_array_delete(range);
134}
135
136void memunmap_pages(struct dev_pagemap *pgmap)
137{
138 int i;
139
140 percpu_ref_kill(&pgmap->ref);
141 if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
142 pgmap->type != MEMORY_DEVICE_COHERENT)
143 for (i = 0; i < pgmap->nr_range; i++)
144 percpu_ref_put_many(&pgmap->ref, pfn_len(pgmap, i));
145
146 wait_for_completion(&pgmap->done);
147
148 for (i = 0; i < pgmap->nr_range; i++)
149 pageunmap_range(pgmap, i);
150 percpu_ref_exit(&pgmap->ref);
151
152 WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
153 devmap_managed_enable_put(pgmap);
154}
155EXPORT_SYMBOL_GPL(memunmap_pages);
156
157static void devm_memremap_pages_release(void *data)
158{
159 memunmap_pages(data);
160}
161
162static void dev_pagemap_percpu_release(struct percpu_ref *ref)
163{
164 struct dev_pagemap *pgmap = container_of(ref, struct dev_pagemap, ref);
165
166 complete(&pgmap->done);
167}
168
169static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
170 int range_id, int nid)
171{
172 const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
173 struct range *range = &pgmap->ranges[range_id];
174 struct dev_pagemap *conflict_pgmap;
175 int error, is_ram;
176
177 if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0,
178 "altmap not supported for multiple ranges\n"))
179 return -EINVAL;
180
181 conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
182 if (conflict_pgmap) {
183 WARN(1, "Conflicting mapping in same section\n");
184 put_dev_pagemap(conflict_pgmap);
185 return -ENOMEM;
186 }
187
188 conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
189 if (conflict_pgmap) {
190 WARN(1, "Conflicting mapping in same section\n");
191 put_dev_pagemap(conflict_pgmap);
192 return -ENOMEM;
193 }
194
195 is_ram = region_intersects(range->start, range_len(range),
196 IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
197
198 if (is_ram != REGION_DISJOINT) {
199 WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n",
200 is_ram == REGION_MIXED ? "mixed" : "ram",
201 range->start, range->end);
202 return -ENXIO;
203 }
204
205 error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start),
206 PHYS_PFN(range->end), pgmap, GFP_KERNEL));
207 if (error)
208 return error;
209
210 if (nid < 0)
211 nid = numa_mem_id();
212
213 error = track_pfn_remap(NULL, ¶ms->pgprot, PHYS_PFN(range->start), 0,
214 range_len(range));
215 if (error)
216 goto err_pfn_remap;
217
218 if (!mhp_range_allowed(range->start, range_len(range), !is_private)) {
219 error = -EINVAL;
220 goto err_kasan;
221 }
222
223 mem_hotplug_begin();
224
225 /*
226 * For device private memory we call add_pages() as we only need to
227 * allocate and initialize struct page for the device memory. More-
228 * over the device memory is un-accessible thus we do not want to
229 * create a linear mapping for the memory like arch_add_memory()
230 * would do.
231 *
232 * For all other device memory types, which are accessible by
233 * the CPU, we do want the linear mapping and thus use
234 * arch_add_memory().
235 */
236 if (is_private) {
237 error = add_pages(nid, PHYS_PFN(range->start),
238 PHYS_PFN(range_len(range)), params);
239 } else {
240 error = kasan_add_zero_shadow(__va(range->start), range_len(range));
241 if (error) {
242 mem_hotplug_done();
243 goto err_kasan;
244 }
245
246 error = arch_add_memory(nid, range->start, range_len(range),
247 params);
248 }
249
250 if (!error) {
251 struct zone *zone;
252
253 zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
254 move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
255 PHYS_PFN(range_len(range)), params->altmap,
256 MIGRATE_MOVABLE);
257 }
258
259 mem_hotplug_done();
260 if (error)
261 goto err_add_memory;
262
263 /*
264 * Initialization of the pages has been deferred until now in order
265 * to allow us to do the work while not holding the hotplug lock.
266 */
267 memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
268 PHYS_PFN(range->start),
269 PHYS_PFN(range_len(range)), pgmap);
270 if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
271 pgmap->type != MEMORY_DEVICE_COHERENT)
272 percpu_ref_get_many(&pgmap->ref, pfn_len(pgmap, range_id));
273 return 0;
274
275err_add_memory:
276 if (!is_private)
277 kasan_remove_zero_shadow(__va(range->start), range_len(range));
278err_kasan:
279 untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
280err_pfn_remap:
281 pgmap_array_delete(range);
282 return error;
283}
284
285
286/*
287 * Not device managed version of devm_memremap_pages, undone by
288 * memunmap_pages(). Please use devm_memremap_pages if you have a struct
289 * device available.
290 */
291void *memremap_pages(struct dev_pagemap *pgmap, int nid)
292{
293 struct mhp_params params = {
294 .altmap = pgmap_altmap(pgmap),
295 .pgmap = pgmap,
296 .pgprot = PAGE_KERNEL,
297 };
298 const int nr_range = pgmap->nr_range;
299 int error, i;
300
301 if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
302 return ERR_PTR(-EINVAL);
303
304 switch (pgmap->type) {
305 case MEMORY_DEVICE_PRIVATE:
306 if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
307 WARN(1, "Device private memory not supported\n");
308 return ERR_PTR(-EINVAL);
309 }
310 if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
311 WARN(1, "Missing migrate_to_ram method\n");
312 return ERR_PTR(-EINVAL);
313 }
314 if (!pgmap->ops->page_free) {
315 WARN(1, "Missing page_free method\n");
316 return ERR_PTR(-EINVAL);
317 }
318 if (!pgmap->owner) {
319 WARN(1, "Missing owner\n");
320 return ERR_PTR(-EINVAL);
321 }
322 break;
323 case MEMORY_DEVICE_COHERENT:
324 if (!pgmap->ops->page_free) {
325 WARN(1, "Missing page_free method\n");
326 return ERR_PTR(-EINVAL);
327 }
328 if (!pgmap->owner) {
329 WARN(1, "Missing owner\n");
330 return ERR_PTR(-EINVAL);
331 }
332 break;
333 case MEMORY_DEVICE_FS_DAX:
334 if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
335 WARN(1, "File system DAX not supported\n");
336 return ERR_PTR(-EINVAL);
337 }
338 params.pgprot = pgprot_decrypted(params.pgprot);
339 break;
340 case MEMORY_DEVICE_GENERIC:
341 break;
342 case MEMORY_DEVICE_PCI_P2PDMA:
343 params.pgprot = pgprot_noncached(params.pgprot);
344 break;
345 default:
346 WARN(1, "Invalid pgmap type %d\n", pgmap->type);
347 break;
348 }
349
350 init_completion(&pgmap->done);
351 error = percpu_ref_init(&pgmap->ref, dev_pagemap_percpu_release, 0,
352 GFP_KERNEL);
353 if (error)
354 return ERR_PTR(error);
355
356 devmap_managed_enable_get(pgmap);
357
358 /*
359 * Clear the pgmap nr_range as it will be incremented for each
360 * successfully processed range. This communicates how many
361 * regions to unwind in the abort case.
362 */
363 pgmap->nr_range = 0;
364 error = 0;
365 for (i = 0; i < nr_range; i++) {
366 error = pagemap_range(pgmap, ¶ms, i, nid);
367 if (error)
368 break;
369 pgmap->nr_range++;
370 }
371
372 if (i < nr_range) {
373 memunmap_pages(pgmap);
374 pgmap->nr_range = nr_range;
375 return ERR_PTR(error);
376 }
377
378 return __va(pgmap->ranges[0].start);
379}
380EXPORT_SYMBOL_GPL(memremap_pages);
381
382/**
383 * devm_memremap_pages - remap and provide memmap backing for the given resource
384 * @dev: hosting device for @res
385 * @pgmap: pointer to a struct dev_pagemap
386 *
387 * Notes:
388 * 1/ At a minimum the res and type members of @pgmap must be initialized
389 * by the caller before passing it to this function
390 *
391 * 2/ The altmap field may optionally be initialized, in which case
392 * PGMAP_ALTMAP_VALID must be set in pgmap->flags.
393 *
394 * 3/ The ref field may optionally be provided, in which pgmap->ref must be
395 * 'live' on entry and will be killed and reaped at
396 * devm_memremap_pages_release() time, or if this routine fails.
397 *
398 * 4/ range is expected to be a host memory range that could feasibly be
399 * treated as a "System RAM" range, i.e. not a device mmio range, but
400 * this is not enforced.
401 */
402void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
403{
404 int error;
405 void *ret;
406
407 ret = memremap_pages(pgmap, dev_to_node(dev));
408 if (IS_ERR(ret))
409 return ret;
410
411 error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
412 pgmap);
413 if (error)
414 return ERR_PTR(error);
415 return ret;
416}
417EXPORT_SYMBOL_GPL(devm_memremap_pages);
418
419void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
420{
421 devm_release_action(dev, devm_memremap_pages_release, pgmap);
422}
423EXPORT_SYMBOL_GPL(devm_memunmap_pages);
424
425unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
426{
427 /* number of pfns from base where pfn_to_page() is valid */
428 if (altmap)
429 return altmap->reserve + altmap->free;
430 return 0;
431}
432
433void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
434{
435 altmap->alloc -= nr_pfns;
436}
437
438/**
439 * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
440 * @pfn: page frame number to lookup page_map
441 * @pgmap: optional known pgmap that already has a reference
442 *
443 * If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap
444 * is non-NULL but does not cover @pfn the reference to it will be released.
445 */
446struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
447 struct dev_pagemap *pgmap)
448{
449 resource_size_t phys = PFN_PHYS(pfn);
450
451 /*
452 * In the cached case we're already holding a live reference.
453 */
454 if (pgmap) {
455 if (phys >= pgmap->range.start && phys <= pgmap->range.end)
456 return pgmap;
457 put_dev_pagemap(pgmap);
458 }
459
460 /* fall back to slow path lookup */
461 rcu_read_lock();
462 pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
463 if (pgmap && !percpu_ref_tryget_live_rcu(&pgmap->ref))
464 pgmap = NULL;
465 rcu_read_unlock();
466
467 return pgmap;
468}
469EXPORT_SYMBOL_GPL(get_dev_pagemap);
470
471void free_zone_device_page(struct page *page)
472{
473 if (WARN_ON_ONCE(!page->pgmap->ops || !page->pgmap->ops->page_free))
474 return;
475
476 mem_cgroup_uncharge(page_folio(page));
477
478 /*
479 * Note: we don't expect anonymous compound pages yet. Once supported
480 * and we could PTE-map them similar to THP, we'd have to clear
481 * PG_anon_exclusive on all tail pages.
482 */
483 VM_BUG_ON_PAGE(PageAnon(page) && PageCompound(page), page);
484 if (PageAnon(page))
485 __ClearPageAnonExclusive(page);
486
487 /*
488 * When a device managed page is freed, the page->mapping field
489 * may still contain a (stale) mapping value. For example, the
490 * lower bits of page->mapping may still identify the page as an
491 * anonymous page. Ultimately, this entire field is just stale
492 * and wrong, and it will cause errors if not cleared. One
493 * example is:
494 *
495 * migrate_vma_pages()
496 * migrate_vma_insert_page()
497 * page_add_new_anon_rmap()
498 * __page_set_anon_rmap()
499 * ...checks page->mapping, via PageAnon(page) call,
500 * and incorrectly concludes that the page is an
501 * anonymous page. Therefore, it incorrectly,
502 * silently fails to set up the new anon rmap.
503 *
504 * For other types of ZONE_DEVICE pages, migration is either
505 * handled differently or not done at all, so there is no need
506 * to clear page->mapping.
507 */
508 page->mapping = NULL;
509 page->pgmap->ops->page_free(page);
510
511 if (page->pgmap->type != MEMORY_DEVICE_PRIVATE &&
512 page->pgmap->type != MEMORY_DEVICE_COHERENT)
513 /*
514 * Reset the page count to 1 to prepare for handing out the page
515 * again.
516 */
517 set_page_count(page, 1);
518 else
519 put_dev_pagemap(page->pgmap);
520}
521
522void zone_device_page_init(struct page *page)
523{
524 /*
525 * Drivers shouldn't be allocating pages after calling
526 * memunmap_pages().
527 */
528 WARN_ON_ONCE(!percpu_ref_tryget_live(&page->pgmap->ref));
529 set_page_count(page, 1);
530 lock_page(page);
531}
532EXPORT_SYMBOL_GPL(zone_device_page_init);
533
534#ifdef CONFIG_FS_DAX
535bool __put_devmap_managed_page_refs(struct page *page, int refs)
536{
537 if (page->pgmap->type != MEMORY_DEVICE_FS_DAX)
538 return false;
539
540 /*
541 * fsdax page refcounts are 1-based, rather than 0-based: if
542 * refcount is 1, then the page is free and the refcount is
543 * stable because nobody holds a reference on the page.
544 */
545 if (page_ref_sub_return(page, refs) == 1)
546 wake_up_var(&page->_refcount);
547 return true;
548}
549EXPORT_SYMBOL(__put_devmap_managed_page_refs);
550#endif /* CONFIG_FS_DAX */