1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_MEMREMAP_H_ |
3 | #define _LINUX_MEMREMAP_H_ |
4 | |
5 | #include <linux/mmzone.h> |
6 | #include <linux/range.h> |
7 | #include <linux/ioport.h> |
8 | #include <linux/percpu-refcount.h> |
9 | |
10 | struct resource; |
11 | struct device; |
12 | |
13 | /** |
14 | * struct vmem_altmap - pre-allocated storage for vmemmap_populate |
15 | * @base_pfn: base of the entire dev_pagemap mapping |
16 | * @reserve: pages mapped, but reserved for driver use (relative to @base) |
17 | * @free: free pages set aside in the mapping for memmap storage |
18 | * @align: pages reserved to meet allocation alignments |
19 | * @alloc: track pages consumed, private to vmemmap_populate() |
20 | */ |
21 | struct vmem_altmap { |
22 | unsigned long base_pfn; |
23 | const unsigned long end_pfn; |
24 | const unsigned long reserve; |
25 | unsigned long free; |
26 | unsigned long align; |
27 | unsigned long alloc; |
28 | }; |
29 | |
30 | /* |
31 | * Specialize ZONE_DEVICE memory into multiple types each has a different |
32 | * usage. |
33 | * |
34 | * MEMORY_DEVICE_PRIVATE: |
35 | * Device memory that is not directly addressable by the CPU: CPU can neither |
36 | * read nor write private memory. In this case, we do still have struct pages |
37 | * backing the device memory. Doing so simplifies the implementation, but it is |
38 | * important to remember that there are certain points at which the struct page |
39 | * must be treated as an opaque object, rather than a "normal" struct page. |
40 | * |
41 | * A more complete discussion of unaddressable memory may be found in |
42 | * include/linux/hmm.h and Documentation/mm/hmm.rst. |
43 | * |
44 | * MEMORY_DEVICE_COHERENT: |
45 | * Device memory that is cache coherent from device and CPU point of view. This |
46 | * is used on platforms that have an advanced system bus (like CAPI or CXL). A |
47 | * driver can hotplug the device memory using ZONE_DEVICE and with that memory |
48 | * type. Any page of a process can be migrated to such memory. However no one |
49 | * should be allowed to pin such memory so that it can always be evicted. |
50 | * |
51 | * MEMORY_DEVICE_FS_DAX: |
52 | * Host memory that has similar access semantics as System RAM i.e. DMA |
53 | * coherent and supports page pinning. In support of coordinating page |
54 | * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a |
55 | * wakeup event whenever a page is unpinned and becomes idle. This |
56 | * wakeup is used to coordinate physical address space management (ex: |
57 | * fs truncate/hole punch) vs pinned pages (ex: device dma). |
58 | * |
59 | * MEMORY_DEVICE_GENERIC: |
60 | * Host memory that has similar access semantics as System RAM i.e. DMA |
61 | * coherent and supports page pinning. This is for example used by DAX devices |
62 | * that expose memory using a character device. |
63 | * |
64 | * MEMORY_DEVICE_PCI_P2PDMA: |
65 | * Device memory residing in a PCI BAR intended for use with Peer-to-Peer |
66 | * transactions. |
67 | */ |
68 | enum memory_type { |
69 | /* 0 is reserved to catch uninitialized type fields */ |
70 | MEMORY_DEVICE_PRIVATE = 1, |
71 | MEMORY_DEVICE_COHERENT, |
72 | MEMORY_DEVICE_FS_DAX, |
73 | MEMORY_DEVICE_GENERIC, |
74 | MEMORY_DEVICE_PCI_P2PDMA, |
75 | }; |
76 | |
77 | struct dev_pagemap_ops { |
78 | /* |
79 | * Called once the page refcount reaches 0. The reference count will be |
80 | * reset to one by the core code after the method is called to prepare |
81 | * for handing out the page again. |
82 | */ |
83 | void (*page_free)(struct page *page); |
84 | |
85 | /* |
86 | * Used for private (un-addressable) device memory only. Must migrate |
87 | * the page back to a CPU accessible page. |
88 | */ |
89 | vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf); |
90 | |
91 | /* |
92 | * Handle the memory failure happens on a range of pfns. Notify the |
93 | * processes who are using these pfns, and try to recover the data on |
94 | * them if necessary. The mf_flags is finally passed to the recover |
95 | * function through the whole notify routine. |
96 | * |
97 | * When this is not implemented, or it returns -EOPNOTSUPP, the caller |
98 | * will fall back to a common handler called mf_generic_kill_procs(). |
99 | */ |
100 | int (*memory_failure)(struct dev_pagemap *pgmap, unsigned long pfn, |
101 | unsigned long nr_pages, int mf_flags); |
102 | }; |
103 | |
104 | #define PGMAP_ALTMAP_VALID (1 << 0) |
105 | |
106 | /** |
107 | * struct dev_pagemap - metadata for ZONE_DEVICE mappings |
108 | * @altmap: pre-allocated/reserved memory for vmemmap allocations |
109 | * @ref: reference count that pins the devm_memremap_pages() mapping |
110 | * @done: completion for @ref |
111 | * @type: memory type: see MEMORY_* in memory_hotplug.h |
112 | * @flags: PGMAP_* flags to specify defailed behavior |
113 | * @vmemmap_shift: structural definition of how the vmemmap page metadata |
114 | * is populated, specifically the metadata page order. |
115 | * A zero value (default) uses base pages as the vmemmap metadata |
116 | * representation. A bigger value will set up compound struct pages |
117 | * of the requested order value. |
118 | * @ops: method table |
119 | * @owner: an opaque pointer identifying the entity that manages this |
120 | * instance. Used by various helpers to make sure that no |
121 | * foreign ZONE_DEVICE memory is accessed. |
122 | * @nr_range: number of ranges to be mapped |
123 | * @range: range to be mapped when nr_range == 1 |
124 | * @ranges: array of ranges to be mapped when nr_range > 1 |
125 | */ |
126 | struct dev_pagemap { |
127 | struct vmem_altmap altmap; |
128 | struct percpu_ref ref; |
129 | struct completion done; |
130 | enum memory_type type; |
131 | unsigned int flags; |
132 | unsigned long vmemmap_shift; |
133 | const struct dev_pagemap_ops *ops; |
134 | void *owner; |
135 | int nr_range; |
136 | union { |
137 | struct range range; |
138 | DECLARE_FLEX_ARRAY(struct range, ranges); |
139 | }; |
140 | }; |
141 | |
142 | static inline bool pgmap_has_memory_failure(struct dev_pagemap *pgmap) |
143 | { |
144 | return pgmap->ops && pgmap->ops->memory_failure; |
145 | } |
146 | |
147 | static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap) |
148 | { |
149 | if (pgmap->flags & PGMAP_ALTMAP_VALID) |
150 | return &pgmap->altmap; |
151 | return NULL; |
152 | } |
153 | |
154 | static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap) |
155 | { |
156 | return 1 << pgmap->vmemmap_shift; |
157 | } |
158 | |
159 | static inline bool is_device_private_page(const struct page *page) |
160 | { |
161 | return IS_ENABLED(CONFIG_DEVICE_PRIVATE) && |
162 | is_zone_device_page(page) && |
163 | page->pgmap->type == MEMORY_DEVICE_PRIVATE; |
164 | } |
165 | |
166 | static inline bool folio_is_device_private(const struct folio *folio) |
167 | { |
168 | return is_device_private_page(page: &folio->page); |
169 | } |
170 | |
171 | static inline bool is_pci_p2pdma_page(const struct page *page) |
172 | { |
173 | return IS_ENABLED(CONFIG_PCI_P2PDMA) && |
174 | is_zone_device_page(page) && |
175 | page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA; |
176 | } |
177 | |
178 | static inline bool is_device_coherent_page(const struct page *page) |
179 | { |
180 | return is_zone_device_page(page) && |
181 | page->pgmap->type == MEMORY_DEVICE_COHERENT; |
182 | } |
183 | |
184 | static inline bool folio_is_device_coherent(const struct folio *folio) |
185 | { |
186 | return is_device_coherent_page(page: &folio->page); |
187 | } |
188 | |
189 | #ifdef CONFIG_ZONE_DEVICE |
190 | void zone_device_page_init(struct page *page); |
191 | void *memremap_pages(struct dev_pagemap *pgmap, int nid); |
192 | void memunmap_pages(struct dev_pagemap *pgmap); |
193 | void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); |
194 | void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); |
195 | struct dev_pagemap *get_dev_pagemap(unsigned long pfn, |
196 | struct dev_pagemap *pgmap); |
197 | bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn); |
198 | |
199 | unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); |
200 | void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); |
201 | unsigned long memremap_compat_align(void); |
202 | #else |
203 | static inline void *devm_memremap_pages(struct device *dev, |
204 | struct dev_pagemap *pgmap) |
205 | { |
206 | /* |
207 | * Fail attempts to call devm_memremap_pages() without |
208 | * ZONE_DEVICE support enabled, this requires callers to fall |
209 | * back to plain devm_memremap() based on config |
210 | */ |
211 | WARN_ON_ONCE(1); |
212 | return ERR_PTR(-ENXIO); |
213 | } |
214 | |
215 | static inline void devm_memunmap_pages(struct device *dev, |
216 | struct dev_pagemap *pgmap) |
217 | { |
218 | } |
219 | |
220 | static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, |
221 | struct dev_pagemap *pgmap) |
222 | { |
223 | return NULL; |
224 | } |
225 | |
226 | static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn) |
227 | { |
228 | return false; |
229 | } |
230 | |
231 | static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) |
232 | { |
233 | return 0; |
234 | } |
235 | |
236 | static inline void vmem_altmap_free(struct vmem_altmap *altmap, |
237 | unsigned long nr_pfns) |
238 | { |
239 | } |
240 | |
241 | /* when memremap_pages() is disabled all archs can remap a single page */ |
242 | static inline unsigned long memremap_compat_align(void) |
243 | { |
244 | return PAGE_SIZE; |
245 | } |
246 | #endif /* CONFIG_ZONE_DEVICE */ |
247 | |
248 | static inline void put_dev_pagemap(struct dev_pagemap *pgmap) |
249 | { |
250 | if (pgmap) |
251 | percpu_ref_put(ref: &pgmap->ref); |
252 | } |
253 | |
254 | #endif /* _LINUX_MEMREMAP_H_ */ |
255 | |