1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_MEMREMAP_H_
3#define _LINUX_MEMREMAP_H_
4
5#include <linux/mmzone.h>
6#include <linux/range.h>
7#include <linux/ioport.h>
8#include <linux/percpu-refcount.h>
9
10struct resource;
11struct device;
12
13/**
14 * struct vmem_altmap - pre-allocated storage for vmemmap_populate
15 * @base_pfn: base of the entire dev_pagemap mapping
16 * @reserve: pages mapped, but reserved for driver use (relative to @base)
17 * @free: free pages set aside in the mapping for memmap storage
18 * @align: pages reserved to meet allocation alignments
19 * @alloc: track pages consumed, private to vmemmap_populate()
20 */
21struct vmem_altmap {
22	unsigned long base_pfn;
23	const unsigned long end_pfn;
24	const unsigned long reserve;
25	unsigned long free;
26	unsigned long align;
27	unsigned long alloc;
28	bool inaccessible;
29};
30
31/*
32 * Specialize ZONE_DEVICE memory into multiple types each has a different
33 * usage.
34 *
35 * MEMORY_DEVICE_PRIVATE:
36 * Device memory that is not directly addressable by the CPU: CPU can neither
37 * read nor write private memory. In this case, we do still have struct pages
38 * backing the device memory. Doing so simplifies the implementation, but it is
39 * important to remember that there are certain points at which the struct page
40 * must be treated as an opaque object, rather than a "normal" struct page.
41 *
42 * A more complete discussion of unaddressable memory may be found in
43 * include/linux/hmm.h and Documentation/mm/hmm.rst.
44 *
45 * MEMORY_DEVICE_COHERENT:
46 * Device memory that is cache coherent from device and CPU point of view. This
47 * is used on platforms that have an advanced system bus (like CAPI or CXL). A
48 * driver can hotplug the device memory using ZONE_DEVICE and with that memory
49 * type. Any page of a process can be migrated to such memory. However no one
50 * should be allowed to pin such memory so that it can always be evicted.
51 *
52 * MEMORY_DEVICE_FS_DAX:
53 * Host memory that has similar access semantics as System RAM i.e. DMA
54 * coherent and supports page pinning. In support of coordinating page
55 * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
56 * wakeup event whenever a page is unpinned and becomes idle. This
57 * wakeup is used to coordinate physical address space management (ex:
58 * fs truncate/hole punch) vs pinned pages (ex: device dma).
59 *
60 * MEMORY_DEVICE_GENERIC:
61 * Host memory that has similar access semantics as System RAM i.e. DMA
62 * coherent and supports page pinning. This is for example used by DAX devices
63 * that expose memory using a character device.
64 *
65 * MEMORY_DEVICE_PCI_P2PDMA:
66 * Device memory residing in a PCI BAR intended for use with Peer-to-Peer
67 * transactions.
68 */
69enum memory_type {
70	/* 0 is reserved to catch uninitialized type fields */
71	MEMORY_DEVICE_PRIVATE = 1,
72	MEMORY_DEVICE_COHERENT,
73	MEMORY_DEVICE_FS_DAX,
74	MEMORY_DEVICE_GENERIC,
75	MEMORY_DEVICE_PCI_P2PDMA,
76};
77
78struct dev_pagemap_ops {
79	/*
80	 * Called once the page refcount reaches 0.  The reference count will be
81	 * reset to one by the core code after the method is called to prepare
82	 * for handing out the page again.
83	 */
84	void (*page_free)(struct page *page);
85
86	/*
87	 * Used for private (un-addressable) device memory only.  Must migrate
88	 * the page back to a CPU accessible page.
89	 */
90	vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
91
92	/*
93	 * Handle the memory failure happens on a range of pfns.  Notify the
94	 * processes who are using these pfns, and try to recover the data on
95	 * them if necessary.  The mf_flags is finally passed to the recover
96	 * function through the whole notify routine.
97	 *
98	 * When this is not implemented, or it returns -EOPNOTSUPP, the caller
99	 * will fall back to a common handler called mf_generic_kill_procs().
100	 */
101	int (*memory_failure)(struct dev_pagemap *pgmap, unsigned long pfn,
102			      unsigned long nr_pages, int mf_flags);
103};
104
105#define PGMAP_ALTMAP_VALID	(1 << 0)
106
107/**
108 * struct dev_pagemap - metadata for ZONE_DEVICE mappings
109 * @altmap: pre-allocated/reserved memory for vmemmap allocations
110 * @ref: reference count that pins the devm_memremap_pages() mapping
111 * @done: completion for @ref
112 * @type: memory type: see MEMORY_* above in memremap.h
113 * @flags: PGMAP_* flags to specify defailed behavior
114 * @vmemmap_shift: structural definition of how the vmemmap page metadata
115 *      is populated, specifically the metadata page order.
116 *	A zero value (default) uses base pages as the vmemmap metadata
117 *	representation. A bigger value will set up compound struct pages
118 *	of the requested order value.
119 * @ops: method table
120 * @owner: an opaque pointer identifying the entity that manages this
121 *	instance.  Used by various helpers to make sure that no
122 *	foreign ZONE_DEVICE memory is accessed.
123 * @nr_range: number of ranges to be mapped
124 * @range: range to be mapped when nr_range == 1
125 * @ranges: array of ranges to be mapped when nr_range > 1
126 */
127struct dev_pagemap {
128	struct vmem_altmap altmap;
129	struct percpu_ref ref;
130	struct completion done;
131	enum memory_type type;
132	unsigned int flags;
133	unsigned long vmemmap_shift;
134	const struct dev_pagemap_ops *ops;
135	void *owner;
136	int nr_range;
137	union {
138		struct range range;
139		DECLARE_FLEX_ARRAY(struct range, ranges);
140	};
141};
142
143static inline bool pgmap_has_memory_failure(struct dev_pagemap *pgmap)
144{
145	return pgmap->ops && pgmap->ops->memory_failure;
146}
147
148static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
149{
150	if (pgmap->flags & PGMAP_ALTMAP_VALID)
151		return &pgmap->altmap;
152	return NULL;
153}
154
155static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap)
156{
157	return 1 << pgmap->vmemmap_shift;
158}
159
160static inline bool is_device_private_page(const struct page *page)
161{
162	return IS_ENABLED(CONFIG_DEVICE_PRIVATE) &&
163		is_zone_device_page(page) &&
164		page->pgmap->type == MEMORY_DEVICE_PRIVATE;
165}
166
167static inline bool folio_is_device_private(const struct folio *folio)
168{
169	return is_device_private_page(&folio->page);
170}
171
172static inline bool is_pci_p2pdma_page(const struct page *page)
173{
174	return IS_ENABLED(CONFIG_PCI_P2PDMA) &&
175		is_zone_device_page(page) &&
176		page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA;
177}
178
179static inline bool is_device_coherent_page(const struct page *page)
180{
181	return is_zone_device_page(page) &&
182		page->pgmap->type == MEMORY_DEVICE_COHERENT;
183}
184
185static inline bool folio_is_device_coherent(const struct folio *folio)
186{
187	return is_device_coherent_page(&folio->page);
188}
189
190#ifdef CONFIG_ZONE_DEVICE
191void zone_device_page_init(struct page *page);
192void *memremap_pages(struct dev_pagemap *pgmap, int nid);
193void memunmap_pages(struct dev_pagemap *pgmap);
194void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
195void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
196struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
197		struct dev_pagemap *pgmap);
198bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
199
200unsigned long memremap_compat_align(void);
201#else
202static inline void *devm_memremap_pages(struct device *dev,
203		struct dev_pagemap *pgmap)
204{
205	/*
206	 * Fail attempts to call devm_memremap_pages() without
207	 * ZONE_DEVICE support enabled, this requires callers to fall
208	 * back to plain devm_memremap() based on config
209	 */
210	WARN_ON_ONCE(1);
211	return ERR_PTR(-ENXIO);
212}
213
214static inline void devm_memunmap_pages(struct device *dev,
215		struct dev_pagemap *pgmap)
216{
217}
218
219static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
220		struct dev_pagemap *pgmap)
221{
222	return NULL;
223}
224
225static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
226{
227	return false;
228}
229
230/* when memremap_pages() is disabled all archs can remap a single page */
231static inline unsigned long memremap_compat_align(void)
232{
233	return PAGE_SIZE;
234}
235#endif /* CONFIG_ZONE_DEVICE */
236
237static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
238{
239	if (pgmap)
240		percpu_ref_put(&pgmap->ref);
241}
242
243#endif /* _LINUX_MEMREMAP_H_ */
244