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>
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()
20 unsigned long base_pfn;
21 const unsigned long end_pfn;
22 const unsigned long reserve;
29 * Specialize ZONE_DEVICE memory into multiple types each has a different
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.
39 * A more complete discussion of unaddressable memory may be found in
40 * include/linux/hmm.h and Documentation/vm/hmm.rst.
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).
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.
55 * MEMORY_DEVICE_PCI_P2PDMA:
56 * Device memory residing in a PCI BAR intended for use with Peer-to-Peer
60 /* 0 is reserved to catch uninitialized type fields */
61 MEMORY_DEVICE_PRIVATE = 1,
63 MEMORY_DEVICE_GENERIC,
64 MEMORY_DEVICE_PCI_P2PDMA,
67 struct dev_pagemap_ops {
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.)
73 void (*page_free)(struct page *page);
76 * Used for private (un-addressable) device memory only. Must migrate
77 * the page back to a CPU accessible page.
79 vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
82 #define PGMAP_ALTMAP_VALID (1 << 0)
85 * struct dev_pagemap - metadata for ZONE_DEVICE mappings
86 * @altmap: pre-allocated/reserved memory for vmemmap allocations
87 * @ref: reference count that pins the devm_memremap_pages() mapping
88 * @done: completion for @ref
89 * @type: memory type: see MEMORY_* in memory_hotplug.h
90 * @flags: PGMAP_* flags to specify defailed behavior
91 * @vmemmap_shift: structural definition of how the vmemmap page metadata
92 * is populated, specifically the metadata page order.
93 * A zero value (default) uses base pages as the vmemmap metadata
94 * representation. A bigger value will set up compound struct pages
95 * of the requested order value.
97 * @owner: an opaque pointer identifying the entity that manages this
98 * instance. Used by various helpers to make sure that no
99 * foreign ZONE_DEVICE memory is accessed.
100 * @nr_range: number of ranges to be mapped
101 * @range: range to be mapped when nr_range == 1
102 * @ranges: array of ranges to be mapped when nr_range > 1
105 struct vmem_altmap altmap;
106 struct percpu_ref ref;
107 struct completion done;
108 enum memory_type type;
110 unsigned long vmemmap_shift;
111 const struct dev_pagemap_ops *ops;
116 struct range ranges[0];
120 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
122 if (pgmap->flags & PGMAP_ALTMAP_VALID)
123 return &pgmap->altmap;
127 static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap)
129 return 1 << pgmap->vmemmap_shift;
132 #ifdef CONFIG_ZONE_DEVICE
133 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
134 void memunmap_pages(struct dev_pagemap *pgmap);
135 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
136 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
137 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
138 struct dev_pagemap *pgmap);
139 bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
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);
145 static inline void *devm_memremap_pages(struct device *dev,
146 struct dev_pagemap *pgmap)
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
154 return ERR_PTR(-ENXIO);
157 static inline void devm_memunmap_pages(struct device *dev,
158 struct dev_pagemap *pgmap)
162 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
163 struct dev_pagemap *pgmap)
168 static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
173 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
178 static inline void vmem_altmap_free(struct vmem_altmap *altmap,
179 unsigned long nr_pfns)
183 /* when memremap_pages() is disabled all archs can remap a single page */
184 static inline unsigned long memremap_compat_align(void)
188 #endif /* CONFIG_ZONE_DEVICE */
190 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
193 percpu_ref_put(&pgmap->ref);
196 #endif /* _LINUX_MEMREMAP_H_ */