xref: /openbmc/qemu/migration/page_cache.h (revision f4ceebde)
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_size: cache size in bytes
28  * @page_size: cache page size
29  * @errp: set *errp if the check failed, with reason
30  */
31 PageCache *cache_init(uint64_t cache_size, size_t page_size, Error **errp);
32 /**
33  * cache_fini: free all cache resources
34  * @cache pointer to the PageCache struct
35  */
36 void cache_fini(PageCache *cache);
37 
38 /**
39  * cache_is_cached: Checks to see if the page is cached
40  *
41  * Returns %true if page is cached
42  *
43  * @cache pointer to the PageCache struct
44  * @addr: page addr
45  * @current_age: current bitmap generation
46  */
47 bool cache_is_cached(const PageCache *cache, uint64_t addr,
48                      uint64_t current_age);
49 
50 /**
51  * get_cached_data: Get the data cached for an addr
52  *
53  * Returns pointer to the data cached or NULL if not cached
54  *
55  * @cache pointer to the PageCache struct
56  * @addr: page addr
57  */
58 uint8_t *get_cached_data(const PageCache *cache, uint64_t addr);
59 
60 /**
61  * cache_insert: insert the page into the cache. the page cache
62  * will dup the data on insert. the previous value will be overwritten
63  *
64  * Returns -1 when the page isn't inserted into cache
65  *
66  * @cache pointer to the PageCache struct
67  * @addr: page address
68  * @pdata: pointer to the page
69  * @current_age: current bitmap generation
70  */
71 int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata,
72                  uint64_t current_age);
73 
74 #endif
75