s390x/pci: use a PCI Function structure
[qemu.git] / migration / page_cache.c
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 #include "qemu/osdep.h"
16
17 #include "qapi/qmp/qerror.h"
18 #include "qapi/error.h"
19 #include "qemu/host-utils.h"
20 #include "page_cache.h"
21 #include "trace.h"
22
23 /* the page in cache will not be replaced in two cycles */
24 #define CACHED_PAGE_LIFETIME 2
25
26 typedef struct CacheItem CacheItem;
27
28 struct CacheItem {
29 uint64_t it_addr;
30 uint64_t it_age;
31 uint8_t *it_data;
32 };
33
34 struct PageCache {
35 CacheItem *page_cache;
36 size_t page_size;
37 size_t max_num_items;
38 size_t num_items;
39 };
40
41 PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp)
42 {
43 int64_t i;
44 size_t num_pages = new_size / page_size;
45 PageCache *cache;
46
47 if (new_size < page_size) {
48 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
49 "is smaller than one target page size");
50 return NULL;
51 }
52
53 /* round down to the nearest power of 2 */
54 if (!is_power_of_2(num_pages)) {
55 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
56 "is not a power of two number of pages");
57 return NULL;
58 }
59
60 /* We prefer not to abort if there is no memory */
61 cache = g_try_malloc(sizeof(*cache));
62 if (!cache) {
63 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
64 "Failed to allocate cache");
65 return NULL;
66 }
67 cache->page_size = page_size;
68 cache->num_items = 0;
69 cache->max_num_items = num_pages;
70
71 trace_migration_pagecache_init(cache->max_num_items);
72
73 /* We prefer not to abort if there is no memory */
74 cache->page_cache = g_try_malloc((cache->max_num_items) *
75 sizeof(*cache->page_cache));
76 if (!cache->page_cache) {
77 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
78 "Failed to allocate page cache");
79 g_free(cache);
80 return NULL;
81 }
82
83 for (i = 0; i < cache->max_num_items; i++) {
84 cache->page_cache[i].it_data = NULL;
85 cache->page_cache[i].it_age = 0;
86 cache->page_cache[i].it_addr = -1;
87 }
88
89 return cache;
90 }
91
92 void cache_fini(PageCache *cache)
93 {
94 int64_t i;
95
96 g_assert(cache);
97 g_assert(cache->page_cache);
98
99 for (i = 0; i < cache->max_num_items; i++) {
100 g_free(cache->page_cache[i].it_data);
101 }
102
103 g_free(cache->page_cache);
104 cache->page_cache = NULL;
105 g_free(cache);
106 }
107
108 static size_t cache_get_cache_pos(const PageCache *cache,
109 uint64_t address)
110 {
111 g_assert(cache->max_num_items);
112 return (address / cache->page_size) & (cache->max_num_items - 1);
113 }
114
115 static CacheItem *cache_get_by_addr(const PageCache *cache, uint64_t addr)
116 {
117 size_t pos;
118
119 g_assert(cache);
120 g_assert(cache->page_cache);
121
122 pos = cache_get_cache_pos(cache, addr);
123
124 return &cache->page_cache[pos];
125 }
126
127 uint8_t *get_cached_data(const PageCache *cache, uint64_t addr)
128 {
129 return cache_get_by_addr(cache, addr)->it_data;
130 }
131
132 bool cache_is_cached(const PageCache *cache, uint64_t addr,
133 uint64_t current_age)
134 {
135 CacheItem *it;
136
137 it = cache_get_by_addr(cache, addr);
138
139 if (it->it_addr == addr) {
140 /* update the it_age when the cache hit */
141 it->it_age = current_age;
142 return true;
143 }
144 return false;
145 }
146
147 int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata,
148 uint64_t current_age)
149 {
150
151 CacheItem *it;
152
153 /* actual update of entry */
154 it = cache_get_by_addr(cache, addr);
155
156 if (it->it_data && it->it_addr != addr &&
157 it->it_age + CACHED_PAGE_LIFETIME > current_age) {
158 /* the cache page is fresh, don't replace it */
159 return -1;
160 }
161 /* allocate page */
162 if (!it->it_data) {
163 it->it_data = g_try_malloc(cache->page_size);
164 if (!it->it_data) {
165 trace_migration_pagecache_insert();
166 return -1;
167 }
168 cache->num_items++;
169 }
170
171 memcpy(it->it_data, pdata, cache->page_size);
172
173 it->it_age = current_age;
174 it->it_addr = addr;
175
176 return 0;
177 }