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> 6 7 struct resource; 8 struct device; 9 10 /** 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() 17 */ 18 struct vmem_altmap { 19 const unsigned long base_pfn; 20 const unsigned long end_pfn; 21 const unsigned long reserve; 22 unsigned long free; 23 unsigned long align; 24 unsigned long alloc; 25 }; 26 27 /* 28 * Specialize ZONE_DEVICE memory into multiple types each having differents 29 * usage. 30 * 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. 37 * 38 * A more complete discussion of unaddressable memory may be found in 39 * include/linux/hmm.h and Documentation/vm/hmm.rst. 40 * 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). 48 * 49 * MEMORY_DEVICE_DEVDAX: 50 * Host memory that has similar access semantics as System RAM i.e. DMA 51 * coherent and supports page pinning. In contrast to 52 * MEMORY_DEVICE_FS_DAX, this memory is access via a device-dax 53 * 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 */ 59 enum memory_type { 60 /* 0 is reserved to catch uninitialized type fields */ 61 MEMORY_DEVICE_PRIVATE = 1, 62 MEMORY_DEVICE_FS_DAX, 63 MEMORY_DEVICE_DEVDAX, 64 MEMORY_DEVICE_PCI_P2PDMA, 65 }; 66 67 struct 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 * @res: physical address range covered by @ref 98 * @ref: reference count that pins the devm_memremap_pages() mapping 99 * @internal_ref: internal reference if @ref is not provided by the caller 100 * @done: completion for @internal_ref 101 * @dev: host device of the mapping for debug 102 * @data: private data pointer for page_free() 103 * @type: memory type: see MEMORY_* in memory_hotplug.h 104 * @flags: PGMAP_* flags to specify defailed behavior 105 * @ops: method table 106 * @owner: an opaque pointer identifying the entity that manages this 107 * instance. Used by various helpers to make sure that no 108 * foreign ZONE_DEVICE memory is accessed. 109 */ 110 struct dev_pagemap { 111 struct vmem_altmap altmap; 112 struct resource res; 113 struct percpu_ref *ref; 114 struct percpu_ref internal_ref; 115 struct completion done; 116 enum memory_type type; 117 unsigned int flags; 118 const struct dev_pagemap_ops *ops; 119 void *owner; 120 }; 121 122 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap) 123 { 124 if (pgmap->flags & PGMAP_ALTMAP_VALID) 125 return &pgmap->altmap; 126 return NULL; 127 } 128 129 #ifdef CONFIG_ZONE_DEVICE 130 void *memremap_pages(struct dev_pagemap *pgmap, int nid); 131 void memunmap_pages(struct dev_pagemap *pgmap); 132 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 133 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 134 struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 135 struct dev_pagemap *pgmap); 136 137 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 138 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 139 #else 140 static inline void *devm_memremap_pages(struct device *dev, 141 struct dev_pagemap *pgmap) 142 { 143 /* 144 * Fail attempts to call devm_memremap_pages() without 145 * ZONE_DEVICE support enabled, this requires callers to fall 146 * back to plain devm_memremap() based on config 147 */ 148 WARN_ON_ONCE(1); 149 return ERR_PTR(-ENXIO); 150 } 151 152 static inline void devm_memunmap_pages(struct device *dev, 153 struct dev_pagemap *pgmap) 154 { 155 } 156 157 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 158 struct dev_pagemap *pgmap) 159 { 160 return NULL; 161 } 162 163 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 164 { 165 return 0; 166 } 167 168 static inline void vmem_altmap_free(struct vmem_altmap *altmap, 169 unsigned long nr_pfns) 170 { 171 } 172 #endif /* CONFIG_ZONE_DEVICE */ 173 174 static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 175 { 176 if (pgmap) 177 percpu_ref_put(pgmap->ref); 178 } 179 #endif /* _LINUX_MEMREMAP_H_ */ 180