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