1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | /* Copyright(c) 2015 Intel Corporation. All rights reserved. */ |
3 | #include <linux/radix-tree.h> |
4 | #include <linux/device.h> |
5 | #include <linux/types.h> |
6 | #include <linux/pfn_t.h> |
7 | #include <linux/io.h> |
8 | #include <linux/kasan.h> |
9 | #include <linux/mm.h> |
10 | #include <linux/memory_hotplug.h> |
11 | #include <linux/swap.h> |
12 | #include <linux/swapops.h> |
13 | #include <linux/wait_bit.h> |
14 | |
15 | static DEFINE_MUTEX(pgmap_lock); |
16 | static RADIX_TREE(pgmap_radix, GFP_KERNEL); |
17 | #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1) |
18 | #define SECTION_SIZE (1UL << PA_SECTION_SHIFT) |
19 | |
20 | static unsigned long order_at(struct resource *res, unsigned long pgoff) |
21 | { |
22 | unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff; |
23 | unsigned long nr_pages, mask; |
24 | |
25 | nr_pages = PHYS_PFN(resource_size(res)); |
26 | if (nr_pages == pgoff) |
27 | return ULONG_MAX; |
28 | |
29 | /* |
30 | * What is the largest aligned power-of-2 range available from |
31 | * this resource pgoff to the end of the resource range, |
32 | * considering the alignment of the current pgoff? |
33 | */ |
34 | mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff); |
35 | if (!mask) |
36 | return ULONG_MAX; |
37 | |
38 | return find_first_bit(&mask, BITS_PER_LONG); |
39 | } |
40 | |
41 | #define foreach_order_pgoff(res, order, pgoff) \ |
42 | for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \ |
43 | pgoff += 1UL << order, order = order_at((res), pgoff)) |
44 | |
45 | #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) |
46 | int device_private_entry_fault(struct vm_area_struct *vma, |
47 | unsigned long addr, |
48 | swp_entry_t entry, |
49 | unsigned int flags, |
50 | pmd_t *pmdp) |
51 | { |
52 | struct page *page = device_private_entry_to_page(entry); |
53 | |
54 | /* |
55 | * The page_fault() callback must migrate page back to system memory |
56 | * so that CPU can access it. This might fail for various reasons |
57 | * (device issue, device was unsafely unplugged, ...). When such |
58 | * error conditions happen, the callback must return VM_FAULT_SIGBUS. |
59 | * |
60 | * Note that because memory cgroup charges are accounted to the device |
61 | * memory, this should never fail because of memory restrictions (but |
62 | * allocation of regular system page might still fail because we are |
63 | * out of memory). |
64 | * |
65 | * There is a more in-depth description of what that callback can and |
66 | * cannot do, in include/linux/memremap.h |
67 | */ |
68 | return page->pgmap->page_fault(vma, addr, page, flags, pmdp); |
69 | } |
70 | EXPORT_SYMBOL(device_private_entry_fault); |
71 | #endif /* CONFIG_DEVICE_PRIVATE */ |
72 | |
73 | static void pgmap_radix_release(struct resource *res, unsigned long end_pgoff) |
74 | { |
75 | unsigned long pgoff, order; |
76 | |
77 | mutex_lock(&pgmap_lock); |
78 | foreach_order_pgoff(res, order, pgoff) { |
79 | if (pgoff >= end_pgoff) |
80 | break; |
81 | radix_tree_delete(&pgmap_radix, PHYS_PFN(res->start) + pgoff); |
82 | } |
83 | mutex_unlock(&pgmap_lock); |
84 | |
85 | synchronize_rcu(); |
86 | } |
87 | |
88 | static unsigned long pfn_first(struct dev_pagemap *pgmap) |
89 | { |
90 | const struct resource *res = &pgmap->res; |
91 | struct vmem_altmap *altmap = &pgmap->altmap; |
92 | unsigned long pfn; |
93 | |
94 | pfn = res->start >> PAGE_SHIFT; |
95 | if (pgmap->altmap_valid) |
96 | pfn += vmem_altmap_offset(altmap); |
97 | return pfn; |
98 | } |
99 | |
100 | static unsigned long pfn_end(struct dev_pagemap *pgmap) |
101 | { |
102 | const struct resource *res = &pgmap->res; |
103 | |
104 | return (res->start + resource_size(res)) >> PAGE_SHIFT; |
105 | } |
106 | |
107 | static unsigned long pfn_next(unsigned long pfn) |
108 | { |
109 | if (pfn % 1024 == 0) |
110 | cond_resched(); |
111 | return pfn + 1; |
112 | } |
113 | |
114 | #define for_each_device_pfn(pfn, map) \ |
115 | for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn)) |
116 | |
117 | static void devm_memremap_pages_release(void *data) |
118 | { |
119 | struct dev_pagemap *pgmap = data; |
120 | struct device *dev = pgmap->dev; |
121 | struct resource *res = &pgmap->res; |
122 | resource_size_t align_start, align_size; |
123 | unsigned long pfn; |
124 | |
125 | for_each_device_pfn(pfn, pgmap) |
126 | put_page(pfn_to_page(pfn)); |
127 | |
128 | if (percpu_ref_tryget_live(pgmap->ref)) { |
129 | dev_WARN(dev, "%s: page mapping is still live!\n" , __func__); |
130 | percpu_ref_put(pgmap->ref); |
131 | } |
132 | |
133 | /* pages are dead and unused, undo the arch mapping */ |
134 | align_start = res->start & ~(SECTION_SIZE - 1); |
135 | align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) |
136 | - align_start; |
137 | |
138 | mem_hotplug_begin(); |
139 | arch_remove_memory(align_start, align_size, pgmap->altmap_valid ? |
140 | &pgmap->altmap : NULL); |
141 | kasan_remove_zero_shadow(__va(align_start), align_size); |
142 | mem_hotplug_done(); |
143 | |
144 | untrack_pfn(NULL, PHYS_PFN(align_start), align_size); |
145 | pgmap_radix_release(res, -1); |
146 | dev_WARN_ONCE(dev, pgmap->altmap.alloc, |
147 | "%s: failed to free all reserved pages\n" , __func__); |
148 | } |
149 | |
150 | /** |
151 | * devm_memremap_pages - remap and provide memmap backing for the given resource |
152 | * @dev: hosting device for @res |
153 | * @pgmap: pointer to a struct dev_pgmap |
154 | * |
155 | * Notes: |
156 | * 1/ At a minimum the res, ref and type members of @pgmap must be initialized |
157 | * by the caller before passing it to this function |
158 | * |
159 | * 2/ The altmap field may optionally be initialized, in which case altmap_valid |
160 | * must be set to true |
161 | * |
162 | * 3/ pgmap.ref must be 'live' on entry and 'dead' before devm_memunmap_pages() |
163 | * time (or devm release event). The expected order of events is that ref has |
164 | * been through percpu_ref_kill() before devm_memremap_pages_release(). The |
165 | * wait for the completion of all references being dropped and |
166 | * percpu_ref_exit() must occur after devm_memremap_pages_release(). |
167 | * |
168 | * 4/ res is expected to be a host memory range that could feasibly be |
169 | * treated as a "System RAM" range, i.e. not a device mmio range, but |
170 | * this is not enforced. |
171 | */ |
172 | void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) |
173 | { |
174 | resource_size_t align_start, align_size, align_end; |
175 | struct vmem_altmap *altmap = pgmap->altmap_valid ? |
176 | &pgmap->altmap : NULL; |
177 | struct resource *res = &pgmap->res; |
178 | unsigned long pfn, pgoff, order; |
179 | pgprot_t pgprot = PAGE_KERNEL; |
180 | int error, nid, is_ram; |
181 | struct dev_pagemap *conflict_pgmap; |
182 | |
183 | align_start = res->start & ~(SECTION_SIZE - 1); |
184 | align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) |
185 | - align_start; |
186 | align_end = align_start + align_size - 1; |
187 | |
188 | conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL); |
189 | if (conflict_pgmap) { |
190 | dev_WARN(dev, "Conflicting mapping in same section\n" ); |
191 | put_dev_pagemap(conflict_pgmap); |
192 | return ERR_PTR(-ENOMEM); |
193 | } |
194 | |
195 | conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); |
196 | if (conflict_pgmap) { |
197 | dev_WARN(dev, "Conflicting mapping in same section\n" ); |
198 | put_dev_pagemap(conflict_pgmap); |
199 | return ERR_PTR(-ENOMEM); |
200 | } |
201 | |
202 | is_ram = region_intersects(align_start, align_size, |
203 | IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); |
204 | |
205 | if (is_ram == REGION_MIXED) { |
206 | WARN_ONCE(1, "%s attempted on mixed region %pr\n" , |
207 | __func__, res); |
208 | return ERR_PTR(-ENXIO); |
209 | } |
210 | |
211 | if (is_ram == REGION_INTERSECTS) |
212 | return __va(res->start); |
213 | |
214 | if (!pgmap->ref) |
215 | return ERR_PTR(-EINVAL); |
216 | |
217 | pgmap->dev = dev; |
218 | |
219 | mutex_lock(&pgmap_lock); |
220 | error = 0; |
221 | |
222 | foreach_order_pgoff(res, order, pgoff) { |
223 | error = __radix_tree_insert(&pgmap_radix, |
224 | PHYS_PFN(res->start) + pgoff, order, pgmap); |
225 | if (error) { |
226 | dev_err(dev, "%s: failed: %d\n" , __func__, error); |
227 | break; |
228 | } |
229 | } |
230 | mutex_unlock(&pgmap_lock); |
231 | if (error) |
232 | goto err_radix; |
233 | |
234 | nid = dev_to_node(dev); |
235 | if (nid < 0) |
236 | nid = numa_mem_id(); |
237 | |
238 | error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(align_start), 0, |
239 | align_size); |
240 | if (error) |
241 | goto err_pfn_remap; |
242 | |
243 | mem_hotplug_begin(); |
244 | error = kasan_add_zero_shadow(__va(align_start), align_size); |
245 | if (error) { |
246 | mem_hotplug_done(); |
247 | goto err_kasan; |
248 | } |
249 | |
250 | error = arch_add_memory(nid, align_start, align_size, altmap, false); |
251 | if (!error) |
252 | move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], |
253 | align_start >> PAGE_SHIFT, |
254 | align_size >> PAGE_SHIFT, altmap); |
255 | mem_hotplug_done(); |
256 | if (error) |
257 | goto err_add_memory; |
258 | |
259 | for_each_device_pfn(pfn, pgmap) { |
260 | struct page *page = pfn_to_page(pfn); |
261 | |
262 | /* |
263 | * ZONE_DEVICE pages union ->lru with a ->pgmap back |
264 | * pointer. It is a bug if a ZONE_DEVICE page is ever |
265 | * freed or placed on a driver-private list. Seed the |
266 | * storage with LIST_POISON* values. |
267 | */ |
268 | list_del(&page->lru); |
269 | page->pgmap = pgmap; |
270 | percpu_ref_get(pgmap->ref); |
271 | } |
272 | |
273 | devm_add_action(dev, devm_memremap_pages_release, pgmap); |
274 | |
275 | return __va(res->start); |
276 | |
277 | err_add_memory: |
278 | kasan_remove_zero_shadow(__va(align_start), align_size); |
279 | err_kasan: |
280 | untrack_pfn(NULL, PHYS_PFN(align_start), align_size); |
281 | err_pfn_remap: |
282 | err_radix: |
283 | pgmap_radix_release(res, pgoff); |
284 | return ERR_PTR(error); |
285 | } |
286 | EXPORT_SYMBOL(devm_memremap_pages); |
287 | |
288 | unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) |
289 | { |
290 | /* number of pfns from base where pfn_to_page() is valid */ |
291 | return altmap->reserve + altmap->free; |
292 | } |
293 | |
294 | void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns) |
295 | { |
296 | altmap->alloc -= nr_pfns; |
297 | } |
298 | |
299 | /** |
300 | * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn |
301 | * @pfn: page frame number to lookup page_map |
302 | * @pgmap: optional known pgmap that already has a reference |
303 | * |
304 | * If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap |
305 | * is non-NULL but does not cover @pfn the reference to it will be released. |
306 | */ |
307 | struct dev_pagemap *get_dev_pagemap(unsigned long pfn, |
308 | struct dev_pagemap *pgmap) |
309 | { |
310 | resource_size_t phys = PFN_PHYS(pfn); |
311 | |
312 | /* |
313 | * In the cached case we're already holding a live reference. |
314 | */ |
315 | if (pgmap) { |
316 | if (phys >= pgmap->res.start && phys <= pgmap->res.end) |
317 | return pgmap; |
318 | put_dev_pagemap(pgmap); |
319 | } |
320 | |
321 | /* fall back to slow path lookup */ |
322 | rcu_read_lock(); |
323 | pgmap = radix_tree_lookup(&pgmap_radix, PHYS_PFN(phys)); |
324 | if (pgmap && !percpu_ref_tryget_live(pgmap->ref)) |
325 | pgmap = NULL; |
326 | rcu_read_unlock(); |
327 | |
328 | return pgmap; |
329 | } |
330 | EXPORT_SYMBOL_GPL(get_dev_pagemap); |
331 | |
332 | #ifdef CONFIG_DEV_PAGEMAP_OPS |
333 | DEFINE_STATIC_KEY_FALSE(devmap_managed_key); |
334 | EXPORT_SYMBOL(devmap_managed_key); |
335 | static atomic_t devmap_enable; |
336 | |
337 | /* |
338 | * Toggle the static key for ->page_free() callbacks when dev_pagemap |
339 | * pages go idle. |
340 | */ |
341 | void dev_pagemap_get_ops(void) |
342 | { |
343 | if (atomic_inc_return(&devmap_enable) == 1) |
344 | static_branch_enable(&devmap_managed_key); |
345 | } |
346 | EXPORT_SYMBOL_GPL(dev_pagemap_get_ops); |
347 | |
348 | void dev_pagemap_put_ops(void) |
349 | { |
350 | if (atomic_dec_and_test(&devmap_enable)) |
351 | static_branch_disable(&devmap_managed_key); |
352 | } |
353 | EXPORT_SYMBOL_GPL(dev_pagemap_put_ops); |
354 | |
355 | void __put_devmap_managed_page(struct page *page) |
356 | { |
357 | int count = page_ref_dec_return(page); |
358 | |
359 | /* |
360 | * If refcount is 1 then page is freed and refcount is stable as nobody |
361 | * holds a reference on the page. |
362 | */ |
363 | if (count == 1) { |
364 | /* Clear Active bit in case of parallel mark_page_accessed */ |
365 | __ClearPageActive(page); |
366 | __ClearPageWaiters(page); |
367 | |
368 | page->mapping = NULL; |
369 | mem_cgroup_uncharge(page); |
370 | |
371 | page->pgmap->page_free(page, page->pgmap->data); |
372 | } else if (!count) |
373 | __put_page(page); |
374 | } |
375 | EXPORT_SYMBOL(__put_devmap_managed_page); |
376 | #endif /* CONFIG_DEV_PAGEMAP_OPS */ |
377 | |