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>
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()
19 const unsigned long base_pfn;
20 const unsigned long end_pfn;
21 const unsigned long reserve;
28 * Specialize ZONE_DEVICE memory into multiple types each having differents
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.
38 * A more complete discussion of unaddressable memory may be found in
39 * include/linux/hmm.h and Documentation/vm/hmm.rst.
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).
49 * MEMORY_DEVICE_GENERIC:
50 * Host memory that has similar access semantics as System RAM i.e. DMA
51 * coherent and supports page pinning. This is for example used by DAX devices
52 * that expose memory using a character device.
54 * MEMORY_DEVICE_PCI_P2PDMA:
55 * Device memory residing in a PCI BAR intended for use with Peer-to-Peer
59 /* 0 is reserved to catch uninitialized type fields */
60 MEMORY_DEVICE_PRIVATE = 1,
62 MEMORY_DEVICE_GENERIC,
63 MEMORY_DEVICE_PCI_P2PDMA,
66 struct dev_pagemap_ops {
68 * Called once the page refcount reaches 1. (ZONE_DEVICE pages never
69 * reach 0 refcount unless there is a refcount bug. This allows the
70 * device driver to implement its own memory management.)
72 void (*page_free)(struct page *page);
75 * Transition the refcount in struct dev_pagemap to the dead state.
77 void (*kill)(struct dev_pagemap *pgmap);
80 * Wait for refcount in struct dev_pagemap to be idle and reap it.
82 void (*cleanup)(struct dev_pagemap *pgmap);
85 * Used for private (un-addressable) device memory only. Must migrate
86 * the page back to a CPU accessible page.
88 vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
91 #define PGMAP_ALTMAP_VALID (1 << 0)
94 * struct dev_pagemap - metadata for ZONE_DEVICE mappings
95 * @altmap: pre-allocated/reserved memory for vmemmap allocations
96 * @res: physical address range covered by @ref
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
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.
108 struct vmem_altmap altmap;
110 struct percpu_ref *ref;
111 struct percpu_ref internal_ref;
112 struct completion done;
113 enum memory_type type;
115 const struct dev_pagemap_ops *ops;
119 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
121 if (pgmap->flags & PGMAP_ALTMAP_VALID)
122 return &pgmap->altmap;
126 #ifdef CONFIG_ZONE_DEVICE
127 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
128 void memunmap_pages(struct dev_pagemap *pgmap);
129 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
130 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
131 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
132 struct dev_pagemap *pgmap);
134 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
135 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
136 unsigned long memremap_compat_align(void);
138 static inline void *devm_memremap_pages(struct device *dev,
139 struct dev_pagemap *pgmap)
142 * Fail attempts to call devm_memremap_pages() without
143 * ZONE_DEVICE support enabled, this requires callers to fall
144 * back to plain devm_memremap() based on config
147 return ERR_PTR(-ENXIO);
150 static inline void devm_memunmap_pages(struct device *dev,
151 struct dev_pagemap *pgmap)
155 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
156 struct dev_pagemap *pgmap)
161 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
166 static inline void vmem_altmap_free(struct vmem_altmap *altmap,
167 unsigned long nr_pfns)
171 /* when memremap_pages() is disabled all archs can remap a single page */
172 static inline unsigned long memremap_compat_align(void)
176 #endif /* CONFIG_ZONE_DEVICE */
178 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
181 percpu_ref_put(pgmap->ref);
184 #endif /* _LINUX_MEMREMAP_H_ */