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