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 reserve;
27 * Specialize ZONE_DEVICE memory into multiple types each having differents
30 * MEMORY_DEVICE_PRIVATE:
31 * Device memory that is not directly addressable by the CPU: CPU can neither
32 * read nor write private memory. In this case, we do still have struct pages
33 * backing the device memory. Doing so simplifies the implementation, but it is
34 * important to remember that there are certain points at which the struct page
35 * must be treated as an opaque object, rather than a "normal" struct page.
37 * A more complete discussion of unaddressable memory may be found in
38 * include/linux/hmm.h and Documentation/vm/hmm.rst.
40 * MEMORY_DEVICE_FS_DAX:
41 * Host memory that has similar access semantics as System RAM i.e. DMA
42 * coherent and supports page pinning. In support of coordinating page
43 * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
44 * wakeup event whenever a page is unpinned and becomes idle. This
45 * wakeup is used to coordinate physical address space management (ex:
46 * fs truncate/hole punch) vs pinned pages (ex: device dma).
48 * MEMORY_DEVICE_DEVDAX:
49 * Host memory that has similar access semantics as System RAM i.e. DMA
50 * coherent and supports page pinning. In contrast to
51 * MEMORY_DEVICE_FS_DAX, this memory is access via a device-dax
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,
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 * @dev: host device of the mapping for debug
101 * @data: private data pointer for page_free()
102 * @type: memory type: see MEMORY_* in memory_hotplug.h
103 * @flags: PGMAP_* flags to specify defailed behavior
107 struct vmem_altmap altmap;
109 struct percpu_ref *ref;
110 struct percpu_ref internal_ref;
111 struct completion done;
113 enum memory_type type;
115 u64 pci_p2pdma_bus_offset;
116 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 *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
128 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
129 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
130 struct dev_pagemap *pgmap);
132 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
133 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
135 static inline void *devm_memremap_pages(struct device *dev,
136 struct dev_pagemap *pgmap)
139 * Fail attempts to call devm_memremap_pages() without
140 * ZONE_DEVICE support enabled, this requires callers to fall
141 * back to plain devm_memremap() based on config
144 return ERR_PTR(-ENXIO);
147 static inline void devm_memunmap_pages(struct device *dev,
148 struct dev_pagemap *pgmap)
152 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
153 struct dev_pagemap *pgmap)
158 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
163 static inline void vmem_altmap_free(struct vmem_altmap *altmap,
164 unsigned long nr_pfns)
167 #endif /* CONFIG_ZONE_DEVICE */
169 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
172 percpu_ref_put(pgmap->ref);
174 #endif /* _LINUX_MEMREMAP_H_ */