1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MEMREMAP_H_
3 #define _LINUX_MEMREMAP_H_
4 #include <linux/ioport.h>
5 #include <linux/percpu-refcount.h>
6
7 struct resource;
8 struct device;
9
10 /**
11 * struct vmem_altmap - pre-allocated storage for vmemmap_populate
12 * @base_pfn: base of the entire dev_pagemap mapping
13 * @reserve: pages mapped, but reserved for driver use (relative to @base)
14 * @free: free pages set aside in the mapping for memmap storage
15 * @align: pages reserved to meet allocation alignments
16 * @alloc: track pages consumed, private to vmemmap_populate()
17 */
18 struct vmem_altmap {
19 const unsigned long base_pfn;
20 const unsigned long end_pfn;
21 const unsigned long reserve;
22 unsigned long free;
23 unsigned long align;
24 unsigned long alloc;
25 };
26
27 /*
28 * Specialize ZONE_DEVICE memory into multiple types each having differents
29 * usage.
30 *
31 * MEMORY_DEVICE_PRIVATE:
32 * Device memory that is not directly addressable by the CPU: CPU can neither
33 * read nor write private memory. In this case, we do still have struct pages
34 * backing the device memory. Doing so simplifies the implementation, but it is
35 * important to remember that there are certain points at which the struct page
36 * must be treated as an opaque object, rather than a "normal" struct page.
37 *
38 * A more complete discussion of unaddressable memory may be found in
39 * include/linux/hmm.h and Documentation/vm/hmm.rst.
40 *
41 * MEMORY_DEVICE_FS_DAX:
42 * Host memory that has similar access semantics as System RAM i.e. DMA
43 * coherent and supports page pinning. In support of coordinating page
44 * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
45 * wakeup event whenever a page is unpinned and becomes idle. This
46 * wakeup is used to coordinate physical address space management (ex:
47 * fs truncate/hole punch) vs pinned pages (ex: device dma).
48 *
49 * MEMORY_DEVICE_DEVDAX:
50 * Host memory that has similar access semantics as System RAM i.e. DMA
51 * coherent and supports page pinning. In contrast to
52 * MEMORY_DEVICE_FS_DAX, this memory is access via a device-dax
53 * 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_DEVDAX,
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 * @res: physical address range covered by @ref
98 * @ref: reference count that pins the devm_memremap_pages() mapping
99 * @internal_ref: internal reference if @ref is not provided by the caller
100 * @done: completion for @internal_ref
101 * @dev: host device of the mapping for debug
102 * @data: private data pointer for page_free()
103 * @type: memory type: see MEMORY_* in memory_hotplug.h
104 * @flags: PGMAP_* flags to specify defailed behavior
105 * @ops: method table
106 */
107 struct dev_pagemap {
108 struct vmem_altmap altmap;
109 struct resource res;
110 struct percpu_ref *ref;
111 struct percpu_ref internal_ref;
112 struct completion done;
113 enum memory_type type;
114 unsigned int flags;
115 const struct dev_pagemap_ops *ops;
116 };
117
118 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
119 {
120 if (pgmap->flags & PGMAP_ALTMAP_VALID)
121 return &pgmap->altmap;
122 return NULL;
123 }
124
125 #ifdef CONFIG_ZONE_DEVICE
126 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
127 void memunmap_pages(struct dev_pagemap *pgmap);
128 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
129 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
130 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
131 struct dev_pagemap *pgmap);
132
133 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
134 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
135 #else
136 static inline void *devm_memremap_pages(struct device *dev,
137 struct dev_pagemap *pgmap)
138 {
139 /*
140 * Fail attempts to call devm_memremap_pages() without
141 * ZONE_DEVICE support enabled, this requires callers to fall
142 * back to plain devm_memremap() based on config
143 */
144 WARN_ON_ONCE(1);
145 return ERR_PTR(-ENXIO);
146 }
147
148 static inline void devm_memunmap_pages(struct device *dev,
149 struct dev_pagemap *pgmap)
150 {
151 }
152
153 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
154 struct dev_pagemap *pgmap)
155 {
156 return NULL;
157 }
158
159 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
160 {
161 return 0;
162 }
163
164 static inline void vmem_altmap_free(struct vmem_altmap *altmap,
165 unsigned long nr_pfns)
166 {
167 }
168 #endif /* CONFIG_ZONE_DEVICE */
169
170 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
171 {
172 if (pgmap)
173 percpu_ref_put(pgmap->ref);
174 }
175 #endif /* _LINUX_MEMREMAP_H_ */