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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 : 10 : struct resource; 11 : struct 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 : */ 21 : struct 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 : }; 29 : 30 : /* 31 : * Specialize ZONE_DEVICE memory into multiple types each has a different 32 : * usage. 33 : * 34 : * MEMORY_DEVICE_PRIVATE: 35 : * Device memory that is not directly addressable by the CPU: CPU can neither 36 : * read nor write private memory. In this case, we do still have struct pages 37 : * backing the device memory. Doing so simplifies the implementation, but it is 38 : * important to remember that there are certain points at which the struct page 39 : * must be treated as an opaque object, rather than a "normal" struct page. 40 : * 41 : * A more complete discussion of unaddressable memory may be found in 42 : * include/linux/hmm.h and Documentation/mm/hmm.rst. 43 : * 44 : * MEMORY_DEVICE_COHERENT: 45 : * Device memory that is cache coherent from device and CPU point of view. This 46 : * is used on platforms that have an advanced system bus (like CAPI or CXL). A 47 : * driver can hotplug the device memory using ZONE_DEVICE and with that memory 48 : * type. Any page of a process can be migrated to such memory. However no one 49 : * should be allowed to pin such memory so that it can always be evicted. 50 : * 51 : * MEMORY_DEVICE_FS_DAX: 52 : * Host memory that has similar access semantics as System RAM i.e. DMA 53 : * coherent and supports page pinning. In support of coordinating page 54 : * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a 55 : * wakeup event whenever a page is unpinned and becomes idle. This 56 : * wakeup is used to coordinate physical address space management (ex: 57 : * fs truncate/hole punch) vs pinned pages (ex: device dma). 58 : * 59 : * MEMORY_DEVICE_GENERIC: 60 : * Host memory that has similar access semantics as System RAM i.e. DMA 61 : * coherent and supports page pinning. This is for example used by DAX devices 62 : * that expose memory using a character device. 63 : * 64 : * MEMORY_DEVICE_PCI_P2PDMA: 65 : * Device memory residing in a PCI BAR intended for use with Peer-to-Peer 66 : * transactions. 67 : */ 68 : enum memory_type { 69 : /* 0 is reserved to catch uninitialized type fields */ 70 : MEMORY_DEVICE_PRIVATE = 1, 71 : MEMORY_DEVICE_COHERENT, 72 : MEMORY_DEVICE_FS_DAX, 73 : MEMORY_DEVICE_GENERIC, 74 : MEMORY_DEVICE_PCI_P2PDMA, 75 : }; 76 : 77 : struct dev_pagemap_ops { 78 : /* 79 : * Called once the page refcount reaches 0. The reference count will be 80 : * reset to one by the core code after the method is called to prepare 81 : * for handing out the page again. 82 : */ 83 : void (*page_free)(struct page *page); 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 : * Handle the memory failure happens on a range of pfns. Notify the 93 : * processes who are using these pfns, and try to recover the data on 94 : * them if necessary. The mf_flags is finally passed to the recover 95 : * function through the whole notify routine. 96 : * 97 : * When this is not implemented, or it returns -EOPNOTSUPP, the caller 98 : * will fall back to a common handler called mf_generic_kill_procs(). 99 : */ 100 : int (*memory_failure)(struct dev_pagemap *pgmap, unsigned long pfn, 101 : unsigned long nr_pages, int mf_flags); 102 : }; 103 : 104 : #define PGMAP_ALTMAP_VALID (1 << 0) 105 : 106 : /** 107 : * struct dev_pagemap - metadata for ZONE_DEVICE mappings 108 : * @altmap: pre-allocated/reserved memory for vmemmap allocations 109 : * @ref: reference count that pins the devm_memremap_pages() mapping 110 : * @done: completion for @ref 111 : * @type: memory type: see MEMORY_* in memory_hotplug.h 112 : * @flags: PGMAP_* flags to specify defailed behavior 113 : * @vmemmap_shift: structural definition of how the vmemmap page metadata 114 : * is populated, specifically the metadata page order. 115 : * A zero value (default) uses base pages as the vmemmap metadata 116 : * representation. A bigger value will set up compound struct pages 117 : * of the requested order value. 118 : * @ops: method table 119 : * @owner: an opaque pointer identifying the entity that manages this 120 : * instance. Used by various helpers to make sure that no 121 : * foreign ZONE_DEVICE memory is accessed. 122 : * @nr_range: number of ranges to be mapped 123 : * @range: range to be mapped when nr_range == 1 124 : * @ranges: array of ranges to be mapped when nr_range > 1 125 : */ 126 : struct dev_pagemap { 127 : struct vmem_altmap altmap; 128 : struct percpu_ref ref; 129 : struct completion done; 130 : enum memory_type type; 131 : unsigned int flags; 132 : unsigned long vmemmap_shift; 133 : const struct dev_pagemap_ops *ops; 134 : void *owner; 135 : int nr_range; 136 : union { 137 : struct range range; 138 : DECLARE_FLEX_ARRAY(struct range, ranges); 139 : }; 140 : }; 141 : 142 : static inline bool pgmap_has_memory_failure(struct dev_pagemap *pgmap) 143 : { 144 : return pgmap->ops && pgmap->ops->memory_failure; 145 : } 146 : 147 : static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap) 148 : { 149 : if (pgmap->flags & PGMAP_ALTMAP_VALID) 150 : return &pgmap->altmap; 151 : return NULL; 152 : } 153 : 154 : static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap) 155 : { 156 : return 1 << pgmap->vmemmap_shift; 157 : } 158 : 159 : static inline bool is_device_private_page(const struct page *page) 160 : { 161 : return IS_ENABLED(CONFIG_DEVICE_PRIVATE) && 162 : is_zone_device_page(page) && 163 : page->pgmap->type == MEMORY_DEVICE_PRIVATE; 164 : } 165 : 166 : static inline bool folio_is_device_private(const struct folio *folio) 167 : { 168 0 : return is_device_private_page(&folio->page); 169 : } 170 : 171 : static inline bool is_pci_p2pdma_page(const struct page *page) 172 : { 173 : return IS_ENABLED(CONFIG_PCI_P2PDMA) && 174 : is_zone_device_page(page) && 175 : page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA; 176 : } 177 : 178 : static inline bool is_device_coherent_page(const struct page *page) 179 : { 180 0 : return is_zone_device_page(page) && 181 : page->pgmap->type == MEMORY_DEVICE_COHERENT; 182 : } 183 : 184 : static inline bool folio_is_device_coherent(const struct folio *folio) 185 : { 186 0 : return is_device_coherent_page(&folio->page); 187 : } 188 : 189 : #ifdef CONFIG_ZONE_DEVICE 190 : void zone_device_page_init(struct page *page); 191 : void *memremap_pages(struct dev_pagemap *pgmap, int nid); 192 : void memunmap_pages(struct dev_pagemap *pgmap); 193 : void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 194 : void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 195 : struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 196 : struct dev_pagemap *pgmap); 197 : bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn); 198 : 199 : unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 200 : void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 201 : unsigned long memremap_compat_align(void); 202 : #else 203 : static inline void *devm_memremap_pages(struct device *dev, 204 : struct dev_pagemap *pgmap) 205 : { 206 : /* 207 : * Fail attempts to call devm_memremap_pages() without 208 : * ZONE_DEVICE support enabled, this requires callers to fall 209 : * back to plain devm_memremap() based on config 210 : */ 211 : WARN_ON_ONCE(1); 212 : return ERR_PTR(-ENXIO); 213 : } 214 : 215 : static inline void devm_memunmap_pages(struct device *dev, 216 : struct dev_pagemap *pgmap) 217 : { 218 : } 219 : 220 : static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 221 : struct dev_pagemap *pgmap) 222 : { 223 : return NULL; 224 : } 225 : 226 : static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn) 227 : { 228 : return false; 229 : } 230 : 231 : static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 232 : { 233 : return 0; 234 : } 235 : 236 : static inline void vmem_altmap_free(struct vmem_altmap *altmap, 237 : unsigned long nr_pfns) 238 : { 239 : } 240 : 241 : /* when memremap_pages() is disabled all archs can remap a single page */ 242 : static inline unsigned long memremap_compat_align(void) 243 : { 244 : return PAGE_SIZE; 245 : } 246 : #endif /* CONFIG_ZONE_DEVICE */ 247 : 248 : static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 249 : { 250 : if (pgmap) 251 : percpu_ref_put(&pgmap->ref); 252 : } 253 : 254 : #endif /* _LINUX_MEMREMAP_H_ */
