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 8 struct resource; 9 struct 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 */ 19 struct 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 */ 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_GENERIC, 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 * Used for private (un-addressable) device memory only. Must migrate 77 * the page back to a CPU accessible page. 78 */ 79 vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf); 80 }; 81 82 #define PGMAP_ALTMAP_VALID (1 << 0) 83 84 /** 85 * struct dev_pagemap - metadata for ZONE_DEVICE mappings 86 * @altmap: pre-allocated/reserved memory for vmemmap allocations 87 * @ref: reference count that pins the devm_memremap_pages() mapping 88 * @done: completion for @ref 89 * @type: memory type: see MEMORY_* in memory_hotplug.h 90 * @flags: PGMAP_* flags to specify defailed behavior 91 * @vmemmap_shift: structural definition of how the vmemmap page metadata 92 * is populated, specifically the metadata page order. 93 * A zero value (default) uses base pages as the vmemmap metadata 94 * representation. A bigger value will set up compound struct pages 95 * of the requested order value. 96 * @ops: method table 97 * @owner: an opaque pointer identifying the entity that manages this 98 * instance. Used by various helpers to make sure that no 99 * foreign ZONE_DEVICE memory is accessed. 100 * @nr_range: number of ranges to be mapped 101 * @range: range to be mapped when nr_range == 1 102 * @ranges: array of ranges to be mapped when nr_range > 1 103 */ 104 struct dev_pagemap { 105 struct vmem_altmap altmap; 106 struct percpu_ref ref; 107 struct completion done; 108 enum memory_type type; 109 unsigned int flags; 110 unsigned long vmemmap_shift; 111 const struct dev_pagemap_ops *ops; 112 void *owner; 113 int nr_range; 114 union { 115 struct range range; 116 struct range ranges[0]; 117 }; 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 static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap) 128 { 129 return 1 << pgmap->vmemmap_shift; 130 } 131 132 #ifdef CONFIG_ZONE_DEVICE 133 void *memremap_pages(struct dev_pagemap *pgmap, int nid); 134 void memunmap_pages(struct dev_pagemap *pgmap); 135 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 136 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 137 struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 138 struct dev_pagemap *pgmap); 139 bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn); 140 141 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 142 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 143 unsigned long memremap_compat_align(void); 144 #else 145 static inline void *devm_memremap_pages(struct device *dev, 146 struct dev_pagemap *pgmap) 147 { 148 /* 149 * Fail attempts to call devm_memremap_pages() without 150 * ZONE_DEVICE support enabled, this requires callers to fall 151 * back to plain devm_memremap() based on config 152 */ 153 WARN_ON_ONCE(1); 154 return ERR_PTR(-ENXIO); 155 } 156 157 static inline void devm_memunmap_pages(struct device *dev, 158 struct dev_pagemap *pgmap) 159 { 160 } 161 162 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 163 struct dev_pagemap *pgmap) 164 { 165 return NULL; 166 } 167 168 static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn) 169 { 170 return false; 171 } 172 173 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 174 { 175 return 0; 176 } 177 178 static inline void vmem_altmap_free(struct vmem_altmap *altmap, 179 unsigned long nr_pfns) 180 { 181 } 182 183 /* when memremap_pages() is disabled all archs can remap a single page */ 184 static inline unsigned long memremap_compat_align(void) 185 { 186 return PAGE_SIZE; 187 } 188 #endif /* CONFIG_ZONE_DEVICE */ 189 190 static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 191 { 192 if (pgmap) 193 percpu_ref_put(&pgmap->ref); 194 } 195 196 #endif /* _LINUX_MEMREMAP_H_ */ 197