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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/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
16static 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
33unsigned long memremap_compat_align(void)
34{
35 return SUBSECTION_SIZE;
36}
37EXPORT_SYMBOL_GPL(memremap_compat_align);
38#endif
39
40#ifdef CONFIG_DEV_PAGEMAP_OPS
41DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
42EXPORT_SYMBOL(devmap_managed_key);
43
44static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
45{
46 if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
47 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_PRIVATE ||
54 pgmap->type == MEMORY_DEVICE_FS_DAX)
55 static_branch_inc(&devmap_managed_key);
56}
57#else
58static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
59{
60}
61static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
62{
63}
64#endif /* CONFIG_DEV_PAGEMAP_OPS */
65
66static 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
73static 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
83bool 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
98static 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
105static unsigned long pfn_next(unsigned long pfn)
106{
107 if (pfn % 1024 == 0)
108 cond_resched();
109 return pfn + 1;
110}
111
112#define for_each_device_pfn(pfn, map, i) \
113 for (pfn = pfn_first(map, i); pfn < pfn_end(map, i); pfn = pfn_next(pfn))
114
115static void dev_pagemap_kill(struct dev_pagemap *pgmap)
116{
117 if (pgmap->ops && pgmap->ops->kill)
118 pgmap->ops->kill(pgmap);
119 else
120 percpu_ref_kill(pgmap->ref);
121}
122
123static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
124{
125 if (pgmap->ops && pgmap->ops->cleanup) {
126 pgmap->ops->cleanup(pgmap);
127 } else {
128 wait_for_completion(&pgmap->done);
129 percpu_ref_exit(pgmap->ref);
130 }
131 /*
132 * Undo the pgmap ref assignment for the internal case as the
133 * caller may re-enable the same pgmap.
134 */
135 if (pgmap->ref == &pgmap->internal_ref)
136 pgmap->ref = NULL;
137}
138
139static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
140{
141 struct range *range = &pgmap->ranges[range_id];
142 struct page *first_page;
143 int nid;
144
145 /* make sure to access a memmap that was actually initialized */
146 first_page = pfn_to_page(pfn_first(pgmap, range_id));
147
148 /* pages are dead and unused, undo the arch mapping */
149 nid = page_to_nid(first_page);
150
151 mem_hotplug_begin();
152 remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
153 PHYS_PFN(range_len(range)));
154 if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
155 __remove_pages(PHYS_PFN(range->start),
156 PHYS_PFN(range_len(range)), NULL);
157 } else {
158 arch_remove_memory(nid, range->start, range_len(range),
159 pgmap_altmap(pgmap));
160 kasan_remove_zero_shadow(__va(range->start), range_len(range));
161 }
162 mem_hotplug_done();
163
164 untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
165 pgmap_array_delete(range);
166}
167
168void memunmap_pages(struct dev_pagemap *pgmap)
169{
170 unsigned long pfn;
171 int i;
172
173 dev_pagemap_kill(pgmap);
174 for (i = 0; i < pgmap->nr_range; i++)
175 for_each_device_pfn(pfn, pgmap, i)
176 put_page(pfn_to_page(pfn));
177 dev_pagemap_cleanup(pgmap);
178
179 for (i = 0; i < pgmap->nr_range; i++)
180 pageunmap_range(pgmap, i);
181
182 WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
183 devmap_managed_enable_put(pgmap);
184}
185EXPORT_SYMBOL_GPL(memunmap_pages);
186
187static void devm_memremap_pages_release(void *data)
188{
189 memunmap_pages(data);
190}
191
192static void dev_pagemap_percpu_release(struct percpu_ref *ref)
193{
194 struct dev_pagemap *pgmap =
195 container_of(ref, struct dev_pagemap, internal_ref);
196
197 complete(&pgmap->done);
198}
199
200static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
201 int range_id, int nid)
202{
203 const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
204 struct range *range = &pgmap->ranges[range_id];
205 struct dev_pagemap *conflict_pgmap;
206 int error, is_ram;
207
208 if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0,
209 "altmap not supported for multiple ranges\n"))
210 return -EINVAL;
211
212 conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
213 if (conflict_pgmap) {
214 WARN(1, "Conflicting mapping in same section\n");
215 put_dev_pagemap(conflict_pgmap);
216 return -ENOMEM;
217 }
218
219 conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
220 if (conflict_pgmap) {
221 WARN(1, "Conflicting mapping in same section\n");
222 put_dev_pagemap(conflict_pgmap);
223 return -ENOMEM;
224 }
225
226 is_ram = region_intersects(range->start, range_len(range),
227 IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
228
229 if (is_ram != REGION_DISJOINT) {
230 WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n",
231 is_ram == REGION_MIXED ? "mixed" : "ram",
232 range->start, range->end);
233 return -ENXIO;
234 }
235
236 error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start),
237 PHYS_PFN(range->end), pgmap, GFP_KERNEL));
238 if (error)
239 return error;
240
241 if (nid < 0)
242 nid = numa_mem_id();
243
244 error = track_pfn_remap(NULL, ¶ms->pgprot, PHYS_PFN(range->start), 0,
245 range_len(range));
246 if (error)
247 goto err_pfn_remap;
248
249 if (!mhp_range_allowed(range->start, range_len(range), !is_private)) {
250 error = -EINVAL;
251 goto err_pfn_remap;
252 }
253
254 mem_hotplug_begin();
255
256 /*
257 * For device private memory we call add_pages() as we only need to
258 * allocate and initialize struct page for the device memory. More-
259 * over the device memory is un-accessible thus we do not want to
260 * create a linear mapping for the memory like arch_add_memory()
261 * would do.
262 *
263 * For all other device memory types, which are accessible by
264 * the CPU, we do want the linear mapping and thus use
265 * arch_add_memory().
266 */
267 if (is_private) {
268 error = add_pages(nid, PHYS_PFN(range->start),
269 PHYS_PFN(range_len(range)), params);
270 } else {
271 error = kasan_add_zero_shadow(__va(range->start), range_len(range));
272 if (error) {
273 mem_hotplug_done();
274 goto err_kasan;
275 }
276
277 error = arch_add_memory(nid, range->start, range_len(range),
278 params);
279 }
280
281 if (!error) {
282 struct zone *zone;
283
284 zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
285 move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
286 PHYS_PFN(range_len(range)), params->altmap,
287 MIGRATE_MOVABLE);
288 }
289
290 mem_hotplug_done();
291 if (error)
292 goto err_add_memory;
293
294 /*
295 * Initialization of the pages has been deferred until now in order
296 * to allow us to do the work while not holding the hotplug lock.
297 */
298 memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
299 PHYS_PFN(range->start),
300 PHYS_PFN(range_len(range)), pgmap);
301 percpu_ref_get_many(pgmap->ref, pfn_end(pgmap, range_id)
302 - pfn_first(pgmap, range_id));
303 return 0;
304
305err_add_memory:
306 kasan_remove_zero_shadow(__va(range->start), range_len(range));
307err_kasan:
308 untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
309err_pfn_remap:
310 pgmap_array_delete(range);
311 return error;
312}
313
314
315/*
316 * Not device managed version of dev_memremap_pages, undone by
317 * memunmap_pages(). Please use dev_memremap_pages if you have a struct
318 * device available.
319 */
320void *memremap_pages(struct dev_pagemap *pgmap, int nid)
321{
322 struct mhp_params params = {
323 .altmap = pgmap_altmap(pgmap),
324 .pgprot = PAGE_KERNEL,
325 };
326 const int nr_range = pgmap->nr_range;
327 int error, i;
328
329 if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
330 return ERR_PTR(-EINVAL);
331
332 switch (pgmap->type) {
333 case MEMORY_DEVICE_PRIVATE:
334 if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
335 WARN(1, "Device private memory not supported\n");
336 return ERR_PTR(-EINVAL);
337 }
338 if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
339 WARN(1, "Missing migrate_to_ram method\n");
340 return ERR_PTR(-EINVAL);
341 }
342 if (!pgmap->ops->page_free) {
343 WARN(1, "Missing page_free method\n");
344 return ERR_PTR(-EINVAL);
345 }
346 if (!pgmap->owner) {
347 WARN(1, "Missing owner\n");
348 return ERR_PTR(-EINVAL);
349 }
350 break;
351 case MEMORY_DEVICE_FS_DAX:
352 if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
353 IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
354 WARN(1, "File system DAX not supported\n");
355 return ERR_PTR(-EINVAL);
356 }
357 break;
358 case MEMORY_DEVICE_GENERIC:
359 break;
360 case MEMORY_DEVICE_PCI_P2PDMA:
361 params.pgprot = pgprot_noncached(params.pgprot);
362 break;
363 default:
364 WARN(1, "Invalid pgmap type %d\n", pgmap->type);
365 break;
366 }
367
368 if (!pgmap->ref) {
369 if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup))
370 return ERR_PTR(-EINVAL);
371
372 init_completion(&pgmap->done);
373 error = percpu_ref_init(&pgmap->internal_ref,
374 dev_pagemap_percpu_release, 0, GFP_KERNEL);
375 if (error)
376 return ERR_PTR(error);
377 pgmap->ref = &pgmap->internal_ref;
378 } else {
379 if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) {
380 WARN(1, "Missing reference count teardown definition\n");
381 return ERR_PTR(-EINVAL);
382 }
383 }
384
385 devmap_managed_enable_get(pgmap);
386
387 /*
388 * Clear the pgmap nr_range as it will be incremented for each
389 * successfully processed range. This communicates how many
390 * regions to unwind in the abort case.
391 */
392 pgmap->nr_range = 0;
393 error = 0;
394 for (i = 0; i < nr_range; i++) {
395 error = pagemap_range(pgmap, ¶ms, i, nid);
396 if (error)
397 break;
398 pgmap->nr_range++;
399 }
400
401 if (i < nr_range) {
402 memunmap_pages(pgmap);
403 pgmap->nr_range = nr_range;
404 return ERR_PTR(error);
405 }
406
407 return __va(pgmap->ranges[0].start);
408}
409EXPORT_SYMBOL_GPL(memremap_pages);
410
411/**
412 * devm_memremap_pages - remap and provide memmap backing for the given resource
413 * @dev: hosting device for @res
414 * @pgmap: pointer to a struct dev_pagemap
415 *
416 * Notes:
417 * 1/ At a minimum the res and type members of @pgmap must be initialized
418 * by the caller before passing it to this function
419 *
420 * 2/ The altmap field may optionally be initialized, in which case
421 * PGMAP_ALTMAP_VALID must be set in pgmap->flags.
422 *
423 * 3/ The ref field may optionally be provided, in which pgmap->ref must be
424 * 'live' on entry and will be killed and reaped at
425 * devm_memremap_pages_release() time, or if this routine fails.
426 *
427 * 4/ range is expected to be a host memory range that could feasibly be
428 * treated as a "System RAM" range, i.e. not a device mmio range, but
429 * this is not enforced.
430 */
431void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
432{
433 int error;
434 void *ret;
435
436 ret = memremap_pages(pgmap, dev_to_node(dev));
437 if (IS_ERR(ret))
438 return ret;
439
440 error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
441 pgmap);
442 if (error)
443 return ERR_PTR(error);
444 return ret;
445}
446EXPORT_SYMBOL_GPL(devm_memremap_pages);
447
448void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
449{
450 devm_release_action(dev, devm_memremap_pages_release, pgmap);
451}
452EXPORT_SYMBOL_GPL(devm_memunmap_pages);
453
454unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
455{
456 /* number of pfns from base where pfn_to_page() is valid */
457 if (altmap)
458 return altmap->reserve + altmap->free;
459 return 0;
460}
461
462void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
463{
464 altmap->alloc -= nr_pfns;
465}
466
467/**
468 * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
469 * @pfn: page frame number to lookup page_map
470 * @pgmap: optional known pgmap that already has a reference
471 *
472 * If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap
473 * is non-NULL but does not cover @pfn the reference to it will be released.
474 */
475struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
476 struct dev_pagemap *pgmap)
477{
478 resource_size_t phys = PFN_PHYS(pfn);
479
480 /*
481 * In the cached case we're already holding a live reference.
482 */
483 if (pgmap) {
484 if (phys >= pgmap->range.start && phys <= pgmap->range.end)
485 return pgmap;
486 put_dev_pagemap(pgmap);
487 }
488
489 /* fall back to slow path lookup */
490 rcu_read_lock();
491 pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
492 if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
493 pgmap = NULL;
494 rcu_read_unlock();
495
496 return pgmap;
497}
498EXPORT_SYMBOL_GPL(get_dev_pagemap);
499
500#ifdef CONFIG_DEV_PAGEMAP_OPS
501void free_devmap_managed_page(struct page *page)
502{
503 /* notify page idle for dax */
504 if (!is_device_private_page(page)) {
505 wake_up_var(&page->_refcount);
506 return;
507 }
508
509 __ClearPageWaiters(page);
510
511 mem_cgroup_uncharge(page);
512
513 /*
514 * When a device_private page is freed, the page->mapping field
515 * may still contain a (stale) mapping value. For example, the
516 * lower bits of page->mapping may still identify the page as an
517 * anonymous page. Ultimately, this entire field is just stale
518 * and wrong, and it will cause errors if not cleared. One
519 * example is:
520 *
521 * migrate_vma_pages()
522 * migrate_vma_insert_page()
523 * page_add_new_anon_rmap()
524 * __page_set_anon_rmap()
525 * ...checks page->mapping, via PageAnon(page) call,
526 * and incorrectly concludes that the page is an
527 * anonymous page. Therefore, it incorrectly,
528 * silently fails to set up the new anon rmap.
529 *
530 * For other types of ZONE_DEVICE pages, migration is either
531 * handled differently or not done at all, so there is no need
532 * to clear page->mapping.
533 */
534 page->mapping = NULL;
535 page->pgmap->ops->page_free(page);
536}
537#endif /* CONFIG_DEV_PAGEMAP_OPS */