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 reserve; 21 unsigned long free; 22 unsigned long align; 23 unsigned long alloc; 24 }; 25 26 /* 27 * Specialize ZONE_DEVICE memory into multiple types each having differents 28 * usage. 29 * 30 * MEMORY_DEVICE_PRIVATE: 31 * Device memory that is not directly addressable by the CPU: CPU can neither 32 * read nor write private memory. In this case, we do still have struct pages 33 * backing the device memory. Doing so simplifies the implementation, but it is 34 * important to remember that there are certain points at which the struct page 35 * must be treated as an opaque object, rather than a "normal" struct page. 36 * 37 * A more complete discussion of unaddressable memory may be found in 38 * include/linux/hmm.h and Documentation/vm/hmm.rst. 39 * 40 * MEMORY_DEVICE_FS_DAX: 41 * Host memory that has similar access semantics as System RAM i.e. DMA 42 * coherent and supports page pinning. In support of coordinating page 43 * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a 44 * wakeup event whenever a page is unpinned and becomes idle. This 45 * wakeup is used to coordinate physical address space management (ex: 46 * fs truncate/hole punch) vs pinned pages (ex: device dma). 47 * 48 * MEMORY_DEVICE_DEVDAX: 49 * Host memory that has similar access semantics as System RAM i.e. DMA 50 * coherent and supports page pinning. In contrast to 51 * MEMORY_DEVICE_FS_DAX, this memory is access via a device-dax 52 * character device. 53 * 54 * MEMORY_DEVICE_PCI_P2PDMA: 55 * Device memory residing in a PCI BAR intended for use with Peer-to-Peer 56 * transactions. 57 */ 58 enum memory_type { 59 /* 0 is reserved to catch uninitialized type fields */ 60 MEMORY_DEVICE_PRIVATE = 1, 61 MEMORY_DEVICE_FS_DAX, 62 MEMORY_DEVICE_DEVDAX, 63 MEMORY_DEVICE_PCI_P2PDMA, 64 }; 65 66 struct dev_pagemap_ops { 67 /* 68 * Called once the page refcount reaches 1. (ZONE_DEVICE pages never 69 * reach 0 refcount unless there is a refcount bug. This allows the 70 * device driver to implement its own memory management.) 71 */ 72 void (*page_free)(struct page *page); 73 74 /* 75 * Transition the refcount in struct dev_pagemap to the dead state. 76 */ 77 void (*kill)(struct dev_pagemap *pgmap); 78 79 /* 80 * Wait for refcount in struct dev_pagemap to be idle and reap it. 81 */ 82 void (*cleanup)(struct dev_pagemap *pgmap); 83 84 /* 85 * Used for private (un-addressable) device memory only. Must migrate 86 * the page back to a CPU accessible page. 87 */ 88 vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf); 89 }; 90 91 #define PGMAP_ALTMAP_VALID (1 << 0) 92 93 /** 94 * struct dev_pagemap - metadata for ZONE_DEVICE mappings 95 * @altmap: pre-allocated/reserved memory for vmemmap allocations 96 * @res: physical address range covered by @ref 97 * @ref: reference count that pins the devm_memremap_pages() mapping 98 * @internal_ref: internal reference if @ref is not provided by the caller 99 * @done: completion for @internal_ref 100 * @dev: host device of the mapping for debug 101 * @data: private data pointer for page_free() 102 * @type: memory type: see MEMORY_* in memory_hotplug.h 103 * @flags: PGMAP_* flags to specify defailed behavior 104 * @ops: method table 105 */ 106 struct dev_pagemap { 107 struct vmem_altmap altmap; 108 struct resource res; 109 struct percpu_ref *ref; 110 struct percpu_ref internal_ref; 111 struct completion done; 112 struct device *dev; 113 enum memory_type type; 114 unsigned int flags; 115 u64 pci_p2pdma_bus_offset; 116 const struct dev_pagemap_ops *ops; 117 }; 118 119 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap) 120 { 121 if (pgmap->flags & PGMAP_ALTMAP_VALID) 122 return &pgmap->altmap; 123 return NULL; 124 } 125 126 #ifdef CONFIG_ZONE_DEVICE 127 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 128 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 129 struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 130 struct dev_pagemap *pgmap); 131 132 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 133 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 134 #else 135 static inline void *devm_memremap_pages(struct device *dev, 136 struct dev_pagemap *pgmap) 137 { 138 /* 139 * Fail attempts to call devm_memremap_pages() without 140 * ZONE_DEVICE support enabled, this requires callers to fall 141 * back to plain devm_memremap() based on config 142 */ 143 WARN_ON_ONCE(1); 144 return ERR_PTR(-ENXIO); 145 } 146 147 static inline void devm_memunmap_pages(struct device *dev, 148 struct dev_pagemap *pgmap) 149 { 150 } 151 152 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 153 struct dev_pagemap *pgmap) 154 { 155 return NULL; 156 } 157 158 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 159 { 160 return 0; 161 } 162 163 static inline void vmem_altmap_free(struct vmem_altmap *altmap, 164 unsigned long nr_pfns) 165 { 166 } 167 #endif /* CONFIG_ZONE_DEVICE */ 168 169 static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 170 { 171 if (pgmap) 172 percpu_ref_put(pgmap->ref); 173 } 174 #endif /* _LINUX_MEMREMAP_H_ */ 175