1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MEMREMAP_H_
3 #define _LINUX_MEMREMAP_H_
4 #include <linux/range.h>
5 #include <linux/ioport.h>
6 #include <linux/percpu-refcount.h>
7
8 struct resource;
9 struct device;
10
11 /**
12 * struct vmem_altmap - pre-allocated storage for vmemmap_populate
13 * @base_pfn: base of the entire dev_pagemap mapping
14 * @reserve: pages mapped, but reserved for driver use (relative to @base)
15 * @free: free pages set aside in the mapping for memmap storage
16 * @align: pages reserved to meet allocation alignments
17 * @alloc: track pages consumed, private to vmemmap_populate()
18 */
19 struct vmem_altmap {
20 const unsigned long base_pfn;
21 const unsigned long end_pfn;
22 const unsigned long reserve;
23 unsigned long free;
24 unsigned long align;
25 unsigned long alloc;
26 };
27
28 /*
29 * Specialize ZONE_DEVICE memory into multiple types each having differents
30 * usage.
31 *
32 * MEMORY_DEVICE_PRIVATE:
33 * Device memory that is not directly addressable by the CPU: CPU can neither
34 * read nor write private memory. In this case, we do still have struct pages
35 * backing the device memory. Doing so simplifies the implementation, but it is
36 * important to remember that there are certain points at which the struct page
37 * must be treated as an opaque object, rather than a "normal" struct page.
38 *
39 * A more complete discussion of unaddressable memory may be found in
40 * include/linux/hmm.h and Documentation/vm/hmm.rst.
41 *
42 * MEMORY_DEVICE_FS_DAX:
43 * Host memory that has similar access semantics as System RAM i.e. DMA
44 * coherent and supports page pinning. In support of coordinating page
45 * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
46 * wakeup event whenever a page is unpinned and becomes idle. This
47 * wakeup is used to coordinate physical address space management (ex:
48 * fs truncate/hole punch) vs pinned pages (ex: device dma).
49 *
50 * MEMORY_DEVICE_GENERIC:
51 * Host memory that has similar access semantics as System RAM i.e. DMA
52 * coherent and supports page pinning. This is for example used by DAX devices
53 * that expose memory using a character device.
54 *
55 * MEMORY_DEVICE_PCI_P2PDMA:
56 * Device memory residing in a PCI BAR intended for use with Peer-to-Peer
57 * transactions.
58 */
59 enum memory_type {
60 /* 0 is reserved to catch uninitialized type fields */
61 MEMORY_DEVICE_PRIVATE = 1,
62 MEMORY_DEVICE_FS_DAX,
63 MEMORY_DEVICE_GENERIC,
64 MEMORY_DEVICE_PCI_P2PDMA,
65 };
66
67 struct dev_pagemap_ops {
68 /*
69 * Called once the page refcount reaches 1. (ZONE_DEVICE pages never
70 * reach 0 refcount unless there is a refcount bug. This allows the
71 * device driver to implement its own memory management.)
72 */
73 void (*page_free)(struct page *page);
74
75 /*
76 * Transition the refcount in struct dev_pagemap to the dead state.
77 */
78 void (*kill)(struct dev_pagemap *pgmap);
79
80 /*
81 * Wait for refcount in struct dev_pagemap to be idle and reap it.
82 */
83 void (*cleanup)(struct dev_pagemap *pgmap);
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 #define PGMAP_ALTMAP_VALID (1 << 0)
93
94 /**
95 * struct dev_pagemap - metadata for ZONE_DEVICE mappings
96 * @altmap: pre-allocated/reserved memory for vmemmap allocations
97 * @ref: reference count that pins the devm_memremap_pages() mapping
98 * @internal_ref: internal reference if @ref is not provided by the caller
99 * @done: completion for @internal_ref
100 * @type: memory type: see MEMORY_* in memory_hotplug.h
101 * @flags: PGMAP_* flags to specify defailed behavior
102 * @ops: method table
103 * @owner: an opaque pointer identifying the entity that manages this
104 * instance. Used by various helpers to make sure that no
105 * foreign ZONE_DEVICE memory is accessed.
106 * @nr_range: number of ranges to be mapped
107 * @range: range to be mapped when nr_range == 1
108 * @ranges: array of ranges to be mapped when nr_range > 1
109 */
110 struct dev_pagemap {
111 struct vmem_altmap altmap;
112 struct percpu_ref *ref;
113 struct percpu_ref internal_ref;
114 struct completion done;
115 enum memory_type type;
116 unsigned int flags;
117 const struct dev_pagemap_ops *ops;
118 void *owner;
119 int nr_range;
120 union {
121 struct range range;
122 struct range ranges[0];
123 };
124 };
125
pgmap_altmap(struct dev_pagemap * pgmap)126 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
127 {
128 if (pgmap->flags & PGMAP_ALTMAP_VALID)
129 return &pgmap->altmap;
130 return NULL;
131 }
132
133 #ifdef CONFIG_ZONE_DEVICE
134 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
135 void memunmap_pages(struct dev_pagemap *pgmap);
136 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
137 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
138 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
139 struct dev_pagemap *pgmap);
140
141 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
142 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
143 unsigned long memremap_compat_align(void);
144 #else
devm_memremap_pages(struct device * dev,struct dev_pagemap * pgmap)145 static inline void *devm_memremap_pages(struct device *dev,
146 struct dev_pagemap *pgmap)
147 {
148 /*
149 * Fail attempts to call devm_memremap_pages() without
150 * ZONE_DEVICE support enabled, this requires callers to fall
151 * back to plain devm_memremap() based on config
152 */
153 WARN_ON_ONCE(1);
154 return ERR_PTR(-ENXIO);
155 }
156
devm_memunmap_pages(struct device * dev,struct dev_pagemap * pgmap)157 static inline void devm_memunmap_pages(struct device *dev,
158 struct dev_pagemap *pgmap)
159 {
160 }
161
get_dev_pagemap(unsigned long pfn,struct dev_pagemap * pgmap)162 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
163 struct dev_pagemap *pgmap)
164 {
165 return NULL;
166 }
167
vmem_altmap_offset(struct vmem_altmap * altmap)168 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
169 {
170 return 0;
171 }
172
vmem_altmap_free(struct vmem_altmap * altmap,unsigned long nr_pfns)173 static inline void vmem_altmap_free(struct vmem_altmap *altmap,
174 unsigned long nr_pfns)
175 {
176 }
177
178 /* when memremap_pages() is disabled all archs can remap a single page */
memremap_compat_align(void)179 static inline unsigned long memremap_compat_align(void)
180 {
181 return PAGE_SIZE;
182 }
183 #endif /* CONFIG_ZONE_DEVICE */
184
put_dev_pagemap(struct dev_pagemap * pgmap)185 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
186 {
187 if (pgmap)
188 percpu_ref_put(pgmap->ref);
189 }
190
191 #endif /* _LINUX_MEMREMAP_H_ */
192
