Line data    Source code

       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             :         const 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 having differents
      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             :          * Transition the refcount in struct dev_pagemap to the dead state.
      77             :          */
      78             :         void (*kill)(struct dev_pagemap *pgmap);
      79             : 
      80             :         /*
      81             :          * Wait for refcount in struct dev_pagemap to be idle and reap it.
      82             :          */
      83             :         void (*cleanup)(struct dev_pagemap *pgmap);
      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             : #define PGMAP_ALTMAP_VALID      (1 << 0)
      93             : 
      94             : /**
      95             :  * struct dev_pagemap - metadata for ZONE_DEVICE mappings
      96             :  * @altmap: pre-allocated/reserved memory for vmemmap allocations
      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             :  * @type: memory type: see MEMORY_* in memory_hotplug.h
     101             :  * @flags: PGMAP_* flags to specify defailed behavior
     102             :  * @ops: method table
     103             :  * @owner: an opaque pointer identifying the entity that manages this
     104             :  *      instance.  Used by various helpers to make sure that no
     105             :  *      foreign ZONE_DEVICE memory is accessed.
     106             :  * @nr_range: number of ranges to be mapped
     107             :  * @range: range to be mapped when nr_range == 1
     108             :  * @ranges: array of ranges to be mapped when nr_range > 1
     109             :  */
     110             : struct dev_pagemap {
     111             :         struct vmem_altmap altmap;
     112             :         struct percpu_ref *ref;
     113             :         struct percpu_ref internal_ref;
     114             :         struct completion done;
     115             :         enum memory_type type;
     116             :         unsigned int flags;
     117             :         const struct dev_pagemap_ops *ops;
     118             :         void *owner;
     119             :         int nr_range;
     120             :         union {
     121             :                 struct range range;
     122             :                 struct range ranges[0];
     123             :         };
     124             : };
     125             : 
     126             : static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
     127             : {
     128             :         if (pgmap->flags & PGMAP_ALTMAP_VALID)
     129             :                 return &pgmap->altmap;
     130             :         return NULL;
     131             : }
     132             : 
     133             : #ifdef CONFIG_ZONE_DEVICE
     134             : void *memremap_pages(struct dev_pagemap *pgmap, int nid);
     135             : void memunmap_pages(struct dev_pagemap *pgmap);
     136             : void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
     137             : void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
     138             : struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
     139             :                 struct dev_pagemap *pgmap);
     140             : bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
     141             : 
     142             : unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
     143             : void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
     144             : unsigned long memremap_compat_align(void);
     145             : #else
     146             : static inline void *devm_memremap_pages(struct device *dev,
     147             :                 struct dev_pagemap *pgmap)
     148             : {
     149             :         /*
     150             :          * Fail attempts to call devm_memremap_pages() without
     151             :          * ZONE_DEVICE support enabled, this requires callers to fall
     152             :          * back to plain devm_memremap() based on config
     153             :          */
     154             :         WARN_ON_ONCE(1);
     155             :         return ERR_PTR(-ENXIO);
     156             : }
     157             : 
     158             : static inline void devm_memunmap_pages(struct device *dev,
     159             :                 struct dev_pagemap *pgmap)
     160             : {
     161             : }
     162             : 
     163           0 : static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
     164             :                 struct dev_pagemap *pgmap)
     165             : {
     166           0 :         return NULL;
     167             : }
     168             : 
     169             : static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
     170             : {
     171             :         return false;
     172             : }
     173             : 
     174             : static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
     175             : {
     176             :         return 0;
     177             : }
     178             : 
     179             : static inline void vmem_altmap_free(struct vmem_altmap *altmap,
     180             :                 unsigned long nr_pfns)
     181             : {
     182             : }
     183             : 
     184             : /* when memremap_pages() is disabled all archs can remap a single page */
     185             : static inline unsigned long memremap_compat_align(void)
     186             : {
     187             :         return PAGE_SIZE;
     188             : }
     189             : #endif /* CONFIG_ZONE_DEVICE */
     190             : 
     191           0 : static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
     192             : {
     193           0 :         if (pgmap)
     194           0 :                 percpu_ref_put(pgmap->ref);
     195           0 : }
     196             : 
     197             : #endif /* _LINUX_MEMREMAP_H_ */