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 * @type: memory type: see MEMORY_* in memory_hotplug.h 102 * @flags: PGMAP_* flags to specify defailed behavior 103 * @ops: method table 104 * @owner: an opaque pointer identifying the entity that manages this 105 * instance. Used by various helpers to make sure that no 106 * foreign ZONE_DEVICE memory is accessed. 107 */ 108 struct dev_pagemap { 109 struct vmem_altmap altmap; 110 struct resource res; 111 struct percpu_ref *ref; 112 struct percpu_ref internal_ref; 113 struct completion done; 114 enum memory_type type; 115 unsigned int flags; 116 const struct dev_pagemap_ops *ops; 117 void *owner; 118 }; 119 120 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap) 121 { 122 if (pgmap->flags & PGMAP_ALTMAP_VALID) 123 return &pgmap->altmap; 124 return NULL; 125 } 126 127 #ifdef CONFIG_ZONE_DEVICE 128 void *memremap_pages(struct dev_pagemap *pgmap, int nid); 129 void memunmap_pages(struct dev_pagemap *pgmap); 130 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 131 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 132 struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 133 struct dev_pagemap *pgmap); 134 135 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 136 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 137 unsigned long memremap_compat_align(void); 138 #else 139 static inline void *devm_memremap_pages(struct device *dev, 140 struct dev_pagemap *pgmap) 141 { 142 /* 143 * Fail attempts to call devm_memremap_pages() without 144 * ZONE_DEVICE support enabled, this requires callers to fall 145 * back to plain devm_memremap() based on config 146 */ 147 WARN_ON_ONCE(1); 148 return ERR_PTR(-ENXIO); 149 } 150 151 static inline void devm_memunmap_pages(struct device *dev, 152 struct dev_pagemap *pgmap) 153 { 154 } 155 156 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 157 struct dev_pagemap *pgmap) 158 { 159 return NULL; 160 } 161 162 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 163 { 164 return 0; 165 } 166 167 static inline void vmem_altmap_free(struct vmem_altmap *altmap, 168 unsigned long nr_pfns) 169 { 170 } 171 172 /* when memremap_pages() is disabled all archs can remap a single page */ 173 static inline unsigned long memremap_compat_align(void) 174 { 175 return PAGE_SIZE; 176 } 177 #endif /* CONFIG_ZONE_DEVICE */ 178 179 static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 180 { 181 if (pgmap) 182 percpu_ref_put(pgmap->ref); 183 } 184 185 #endif /* _LINUX_MEMREMAP_H_ */ 186