include/linux/memremap.h

   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         bool inaccessible;
  29 };
  30
  31 /*
  32  * Specialize ZONE_DEVICE memory into multiple types each has a different
  33  * usage.
  34  *
  35  * MEMORY_DEVICE_PRIVATE:
  36  * Device memory that is not directly addressable by the CPU: CPU can neither
  37  * read nor write private memory. In this case, we do still have struct pages
  38  * backing the device memory. Doing so simplifies the implementation, but it is
  39  * important to remember that there are certain points at which the struct page
  40  * must be treated as an opaque object, rather than a "normal" struct page.
  41  *
  42  * A more complete discussion of unaddressable memory may be found in
  43  * include/linux/hmm.h and Documentation/mm/hmm.rst.
  44  *
  45  * MEMORY_DEVICE_COHERENT:
  46  * Device memory that is cache coherent from device and CPU point of view. This
  47  * is used on platforms that have an advanced system bus (like CAPI or CXL). A
  48  * driver can hotplug the device memory using ZONE_DEVICE and with that memory
  49  * type. Any page of a process can be migrated to such memory. However no one
  50  * should be allowed to pin such memory so that it can always be evicted.
  51  *
  52  * MEMORY_DEVICE_FS_DAX:
  53  * Host memory that has similar access semantics as System RAM i.e. DMA
  54  * coherent and supports page pinning. In support of coordinating page
  55  * pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
  56  * wakeup event whenever a page is unpinned and becomes idle. This
  57  * wakeup is used to coordinate physical address space management (ex:
  58  * fs truncate/hole punch) vs pinned pages (ex: device dma).
  59  *
  60  * MEMORY_DEVICE_GENERIC:
  61  * Host memory that has similar access semantics as System RAM i.e. DMA
  62  * coherent and supports page pinning. This is for example used by DAX devices
  63  * that expose memory using a character device.
  64  *
  65  * MEMORY_DEVICE_PCI_P2PDMA:
  66  * Device memory residing in a PCI BAR intended for use with Peer-to-Peer
  67  * transactions.
  68  */
  69 enum memory_type {
  70         /* 0 is reserved to catch uninitialized type fields */
  71         MEMORY_DEVICE_PRIVATE = 1,
  72         MEMORY_DEVICE_COHERENT,
  73         MEMORY_DEVICE_FS_DAX,
  74         MEMORY_DEVICE_GENERIC,
  75         MEMORY_DEVICE_PCI_P2PDMA,
  76 };
  77
  78 struct dev_pagemap_ops {
  79         /*
  80          * Called once the page refcount reaches 0.  The reference count will be
  81          * reset to one by the core code after the method is called to prepare
  82          * for handing out the page again.
  83          */
  84         void (*page_free)(struct page *page);
  85
  86         /*
  87          * Used for private (un-addressable) device memory only.  Must migrate
  88          * the page back to a CPU accessible page.
  89          */
  90         vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
  91
  92         /*
  93          * Handle the memory failure happens on a range of pfns.  Notify the
  94          * processes who are using these pfns, and try to recover the data on
  95          * them if necessary.  The mf_flags is finally passed to the recover
  96          * function through the whole notify routine.
  97          *
  98          * When this is not implemented, or it returns -EOPNOTSUPP, the caller
  99          * will fall back to a common handler called mf_generic_kill_procs().
 100          */
 101         int (*memory_failure)(struct dev_pagemap *pgmap, unsigned long pfn,
 102                               unsigned long nr_pages, int mf_flags);
 103 };
 104
 105 #define PGMAP_ALTMAP_VALID      (1 << 0)
 106
 107 /**
 108  * struct dev_pagemap - metadata for ZONE_DEVICE mappings
 109  * @altmap: pre-allocated/reserved memory for vmemmap allocations
 110  * @ref: reference count that pins the devm_memremap_pages() mapping
 111  * @done: completion for @ref
 112  * @type: memory type: see MEMORY_* above in memremap.h
 113  * @flags: PGMAP_* flags to specify defailed behavior
 114  * @vmemmap_shift: structural definition of how the vmemmap page metadata
 115  *      is populated, specifically the metadata page order.
 116  *      A zero value (default) uses base pages as the vmemmap metadata
 117  *      representation. A bigger value will set up compound struct pages
 118  *      of the requested order value.
 119  * @ops: method table
 120  * @owner: an opaque pointer identifying the entity that manages this
 121  *      instance.  Used by various helpers to make sure that no
 122  *      foreign ZONE_DEVICE memory is accessed.
 123  * @nr_range: number of ranges to be mapped
 124  * @range: range to be mapped when nr_range == 1
 125  * @ranges: array of ranges to be mapped when nr_range > 1
 126  */
 127 struct dev_pagemap {
 128         struct vmem_altmap altmap;
 129         struct percpu_ref ref;
 130         struct completion done;
 131         enum memory_type type;
 132         unsigned int flags;
 133         unsigned long vmemmap_shift;
 134         const struct dev_pagemap_ops *ops;
 135         void *owner;
 136         int nr_range;
 137         union {
 138                 struct range range;
 139                 DECLARE_FLEX_ARRAY(struct range, ranges);
 140         };
 141 };
 142
 143 static inline bool pgmap_has_memory_failure(struct dev_pagemap *pgmap)
 144 {
 145         return pgmap->ops && pgmap->ops->memory_failure;
 146 }
 147
 148 static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
 149 {
 150         if (pgmap->flags & PGMAP_ALTMAP_VALID)
 151                 return &pgmap->altmap;
 152         return NULL;
 153 }
 154
 155 static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap)
 156 {
 157         return 1 << pgmap->vmemmap_shift;
 158 }
 159
 160 static inline bool is_device_private_page(const struct page *page)
 161 {
 162         return IS_ENABLED(CONFIG_DEVICE_PRIVATE) &&
 163                 is_zone_device_page(page) &&
 164                 page->pgmap->type == MEMORY_DEVICE_PRIVATE;
 165 }
 166
 167 static inline bool folio_is_device_private(const struct folio *folio)
 168 {
 169         return is_device_private_page(&folio->page);
 170 }
 171
 172 static inline bool is_pci_p2pdma_page(const struct page *page)
 173 {
 174         return IS_ENABLED(CONFIG_PCI_P2PDMA) &&
 175                 is_zone_device_page(page) &&
 176                 page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA;
 177 }
 178
 179 static inline bool is_device_coherent_page(const struct page *page)
 180 {
 181         return is_zone_device_page(page) &&
 182                 page->pgmap->type == MEMORY_DEVICE_COHERENT;
 183 }
 184
 185 static inline bool folio_is_device_coherent(const struct folio *folio)
 186 {
 187         return is_device_coherent_page(&folio->page);
 188 }
 189
 190 #ifdef CONFIG_ZONE_DEVICE
 191 void zone_device_page_init(struct page *page);
 192 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
 193 void memunmap_pages(struct dev_pagemap *pgmap);
 194 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
 195 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
 196 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 197                 struct dev_pagemap *pgmap);
 198 bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
 199
 200 unsigned long memremap_compat_align(void);
 201 #else
 202 static inline void *devm_memremap_pages(struct device *dev,
 203                 struct dev_pagemap *pgmap)
 204 {
 205         /*
 206          * Fail attempts to call devm_memremap_pages() without
 207          * ZONE_DEVICE support enabled, this requires callers to fall
 208          * back to plain devm_memremap() based on config
 209          */
 210         WARN_ON_ONCE(1);
 211         return ERR_PTR(-ENXIO);
 212 }
 213
 214 static inline void devm_memunmap_pages(struct device *dev,
 215                 struct dev_pagemap *pgmap)
 216 {
 217 }
 218
 219 static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 220                 struct dev_pagemap *pgmap)
 221 {
 222         return NULL;
 223 }
 224
 225 static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
 226 {
 227         return false;
 228 }
 229
 230 /* when memremap_pages() is disabled all archs can remap a single page */
 231 static inline unsigned long memremap_compat_align(void)
 232 {
 233         return PAGE_SIZE;
 234 }
 235 #endif /* CONFIG_ZONE_DEVICE */
 236
 237 static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
 238 {
 239         if (pgmap)
 240                 percpu_ref_put(&pgmap->ref);
 241 }
 242
 243 #endif /* _LINUX_MEMREMAP_H_ */