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_PUBLIC: 41 * Device memory that is cache coherent from device and CPU point of view. This 42 * is use on platform that have an advance system bus (like CAPI or CCIX). A 43 * driver can hotplug the device memory using ZONE_DEVICE and with that memory 44 * type. Any page of a process can be migrated to such memory. However no one 45 * should be allow to pin such memory so that it can always be evicted. 46 * 47 * MEMORY_DEVICE_FS_DAX: 48 * Host memory that has similar access semantics as System RAM i.e. DMA 49 * coherent and supports page pinning. In support of coordinating page 50 * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a 51 * wakeup event whenever a page is unpinned and becomes idle. This 52 * wakeup is used to coordinate physical address space management (ex: 53 * fs truncate/hole punch) vs pinned pages (ex: device dma). 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 MEMORY_DEVICE_PRIVATE = 1, 61 MEMORY_DEVICE_PUBLIC, 62 MEMORY_DEVICE_FS_DAX, 63 MEMORY_DEVICE_PCI_P2PDMA, 64 }; 65 66 /* 67 * Additional notes about MEMORY_DEVICE_PRIVATE may be found in 68 * include/linux/hmm.h and Documentation/vm/hmm.rst. There is also a brief 69 * explanation in include/linux/memory_hotplug.h. 70 * 71 * The page_free() callback is called once the page refcount reaches 1 72 * (ZONE_DEVICE pages never reach 0 refcount unless there is a refcount bug. 73 * This allows the device driver to implement its own memory management.) 74 */ 75 typedef void (*dev_page_free_t)(struct page *page, void *data); 76 77 /** 78 * struct dev_pagemap - metadata for ZONE_DEVICE mappings 79 * @page_free: free page callback when page refcount reaches 1 80 * @altmap: pre-allocated/reserved memory for vmemmap allocations 81 * @res: physical address range covered by @ref 82 * @ref: reference count that pins the devm_memremap_pages() mapping 83 * @kill: callback to transition @ref to the dead state 84 * @cleanup: callback to wait for @ref to be idle and reap it 85 * @dev: host device of the mapping for debug 86 * @data: private data pointer for page_free() 87 * @type: memory type: see MEMORY_* in memory_hotplug.h 88 */ 89 struct dev_pagemap { 90 dev_page_free_t page_free; 91 struct vmem_altmap altmap; 92 bool altmap_valid; 93 struct resource res; 94 struct percpu_ref *ref; 95 void (*kill)(struct percpu_ref *ref); 96 void (*cleanup)(struct percpu_ref *ref); 97 struct device *dev; 98 void *data; 99 enum memory_type type; 100 u64 pci_p2pdma_bus_offset; 101 }; 102 103 #ifdef CONFIG_ZONE_DEVICE 104 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); 105 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap); 106 struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 107 struct dev_pagemap *pgmap); 108 109 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); 110 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); 111 #else 112 static inline void *devm_memremap_pages(struct device *dev, 113 struct dev_pagemap *pgmap) 114 { 115 /* 116 * Fail attempts to call devm_memremap_pages() without 117 * ZONE_DEVICE support enabled, this requires callers to fall 118 * back to plain devm_memremap() based on config 119 */ 120 WARN_ON_ONCE(1); 121 return ERR_PTR(-ENXIO); 122 } 123 124 static inline void devm_memunmap_pages(struct device *dev, 125 struct dev_pagemap *pgmap) 126 { 127 } 128 129 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn, 130 struct dev_pagemap *pgmap) 131 { 132 return NULL; 133 } 134 135 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) 136 { 137 return 0; 138 } 139 140 static inline void vmem_altmap_free(struct vmem_altmap *altmap, 141 unsigned long nr_pfns) 142 { 143 } 144 #endif /* CONFIG_ZONE_DEVICE */ 145 146 static inline void put_dev_pagemap(struct dev_pagemap *pgmap) 147 { 148 if (pgmap) 149 percpu_ref_put(pgmap->ref); 150 } 151 #endif /* _LINUX_MEMREMAP_H_ */ 152