include/migration/page_cache.h

   1 /*
   2  * Page cache for QEMU
   3  * The cache is base on a hash of the page address
   4  *
   5  * Copyright 2012 Red Hat, Inc. and/or its affiliates
   6  *
   7  * Authors:
   8  *  Orit Wasserman  <owasserm@redhat.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  11  * See the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #ifndef PAGE_CACHE_H
  16 #define PAGE_CACHE_H
  17
  18 /* Page cache for storing guest pages */
  19 typedef struct PageCache PageCache;
  20
  21 /**
  22  * cache_init: Initialize the page cache
  23  *
  24  *
  25  * Returns new allocated cache or NULL on error
  26  *
  27  * @cache pointer to the PageCache struct
  28  * @num_pages: cache maximal number of cached pages
  29  * @page_size: cache page size
  30  */
  31 PageCache *cache_init(int64_t num_pages, unsigned int page_size);
  32
  33 /**
  34  * cache_fini: free all cache resources
  35  * @cache pointer to the PageCache struct
  36  */
  37 void cache_fini(PageCache *cache);
  38
  39 /**
  40  * cache_is_cached: Checks to see if the page is cached
  41  *
  42  * Returns %true if page is cached
  43  *
  44  * @cache pointer to the PageCache struct
  45  * @addr: page addr
  46  */
  47 bool cache_is_cached(const PageCache *cache, uint64_t addr);
  48
  49 /**
  50  * get_cached_data: Get the data cached for an addr
  51  *
  52  * Returns pointer to the data cached or NULL if not cached
  53  *
  54  * @cache pointer to the PageCache struct
  55  * @addr: page addr
  56  */
  57 uint8_t *get_cached_data(const PageCache *cache, uint64_t addr);
  58
  59 /**
  60  * cache_insert: insert the page into the cache. the page cache
  61  * will dup the data on insert. the previous value will be overwritten
  62  *
  63  * Returns -1 on error
  64  *
  65  * @cache pointer to the PageCache struct
  66  * @addr: page address
  67  * @pdata: pointer to the page
  68  */
  69 int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata);
  70
  71 /**
  72  * cache_resize: resize the page cache. In case of size reduction the extra
  73  * pages will be freed
  74  *
  75  * Returns -1 on error new cache size on success
  76  *
  77  * @cache pointer to the PageCache struct
  78  * @num_pages: new page cache size (in pages)
  79  */
  80 int64_t cache_resize(PageCache *cache, int64_t num_pages);
  81
  82 #endif