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  * @current_age: current bitmap generation
  47  */
  48 bool cache_is_cached(const PageCache *cache, uint64_t addr,
  49                      uint64_t current_age);
  50
  51 /**
  52  * get_cached_data: Get the data cached for an addr
  53  *
  54  * Returns pointer to the data cached or NULL if not cached
  55  *
  56  * @cache pointer to the PageCache struct
  57  * @addr: page addr
  58  */
  59 uint8_t *get_cached_data(const PageCache *cache, uint64_t addr);
  60
  61 /**
  62  * cache_insert: insert the page into the cache. the page cache
  63  * will dup the data on insert. the previous value will be overwritten
  64  *
  65  * Returns -1 when the page isn't inserted into cache
  66  *
  67  * @cache pointer to the PageCache struct
  68  * @addr: page address
  69  * @pdata: pointer to the page
  70  * @current_age: current bitmap generation
  71  */
  72 int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata,
  73                  uint64_t current_age);
  74
  75 /**
  76  * cache_resize: resize the page cache. In case of size reduction the extra
  77  * pages will be freed
  78  *
  79  * Returns -1 on error new cache size on success
  80  *
  81  * @cache pointer to the PageCache struct
  82  * @num_pages: new page cache size (in pages)
  83  */
  84 int64_t cache_resize(PageCache *cache, int64_t num_pages);
  85
  86 #endif