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> 7 8struct resource; 9struct device; 10 11/** 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() 18 */ 19struct vmem_altmap { 20 unsigned long base_pfn; 21 const unsigned long end_pfn; 22 const unsigned long reserve; 23 unsigned long free; 24 unsigned long align; 25 unsigned long alloc; 26}; 27 28/* 29 * Specialize ZONE_DEVICE memory into multiple types each has a different 30 * usage. 31 * 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. 38 * 39 * A more complete discussion of unaddressable memory may be found in 40 * include/linux/hmm.h and Documentation/vm/hmm.rst. 41 * 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). 49 * 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. 54 * 55 * MEMORY_DEVICE_PCI_P2PDMA: 56 * Device memory residing in a PCI BAR intended for use with Peer-to-Peer 57 * transactions. 58 */ 59enum memory_type { 60 /* 0 is reserved to catch uninitialized type fields */ 61 MEMORY_DEVICE_PRIVATE = 1, 62 MEMORY_DEVICE_FS_DAX, 63 MEMORY_DEVICE_GENERIC, 64 MEMORY_DEVICE_PCI_P2PDMA, 65}; 66 67struct 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 * @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 102 * @ops: method table 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. 106 * @nr_range: number of ranges to be mapped 107 * @range: range to be mapped when nr_range == 1 108 * @ranges: array of ranges to be mapped when nr_range > 1 109 */ 110struct dev_pagemap { 111 struct vmem_altmap altmap; 112 struct percpu_ref *ref; 113 struct percpu_ref internal_ref; 114 struct completion done; 115 enum memory_type type; 116 unsigned int flags; 117 const struct dev_pagemap_ops *ops; 118 void *owner; 119 int nr_range; 120 union { 121 struct range range; 122 struct range ranges[0]; 123 }; 124}; 125 126static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap) 127{ 128 if (pgmap->flags & PGMAP_ALTMAP_VALID) 129 return &pgmap->altmap; 130 return NULL; 131} 132 133#ifdef CONFIG_ZONE_DEVICE 134void *memremap_pages(struct dev_pagemap *pgmap, int nid); 135void memunmap_pages(struct dev_pagemap *pgmap); 136void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 137void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 138struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 139 struct dev_pagemap *pgmap); 140bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn); 141 142unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 143void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 144unsigned long memremap_compat_align(void); 145#else 146static inline void *devm_memremap_pages(struct device *dev, 147 struct dev_pagemap *pgmap) 148{ 149 /* 150 * Fail attempts to call devm_memremap_pages() without 151 * ZONE_DEVICE support enabled, this requires callers to fall 152 * back to plain devm_memremap() based on config 153 */ 154 WARN_ON_ONCE(1); 155 return ERR_PTR(-ENXIO); 156} 157 158static inline void devm_memunmap_pages(struct device *dev, 159 struct dev_pagemap *pgmap) 160{ 161} 162 163static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 164 struct dev_pagemap *pgmap) 165{ 166 return NULL; 167} 168 169static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn) 170{ 171 return false; 172} 173 174static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 175{ 176 return 0; 177} 178 179static inline void vmem_altmap_free(struct vmem_altmap *altmap, 180 unsigned long nr_pfns) 181{ 182} 183 184/* when memremap_pages() is disabled all archs can remap a single page */ 185static inline unsigned long memremap_compat_align(void) 186{ 187 return PAGE_SIZE; 188} 189#endif /* CONFIG_ZONE_DEVICE */ 190 191static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 192{ 193 if (pgmap) 194 percpu_ref_put(pgmap->ref); 195} 196 197#endif /* _LINUX_MEMREMAP_H_ */ 198