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 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 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 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 memremap_compat_align(void); 200 #else 201 static inline void *devm_memremap_pages(struct device *dev, 202 struct dev_pagemap *pgmap) 203 { 204 /* 205 * Fail attempts to call devm_memremap_pages() without 206 * ZONE_DEVICE support enabled, this requires callers to fall 207 * back to plain devm_memremap() based on config 208 */ 209 WARN_ON_ONCE(1); 210 return ERR_PTR(-ENXIO); 211 } 212 213 static inline void devm_memunmap_pages(struct device *dev, 214 struct dev_pagemap *pgmap) 215 { 216 } 217 218 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 219 struct dev_pagemap *pgmap) 220 { 221 return NULL; 222 } 223 224 static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn) 225 { 226 return false; 227 } 228 229 /* when memremap_pages() is disabled all archs can remap a single page */ 230 static inline unsigned long memremap_compat_align(void) 231 { 232 return PAGE_SIZE; 233 } 234 #endif /* CONFIG_ZONE_DEVICE */ 235 236 static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 237 { 238 if (pgmap) 239 percpu_ref_put(&pgmap->ref); 240 } 241 242 #endif /* _LINUX_MEMREMAP_H_ */ 243