2  * Page cache for QEMU
3  * The cache is base on a hash of the page address
11  * See the COPYING file in the top-level directory.
19 #include "qemu/host-utils.h"
23 /* the page in cache will not be replaced in two cycles */
45     PageCache *cache;  in cache_init()  local
48         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",  in cache_init()
55         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",  in cache_init()
61     cache = g_try_malloc(sizeof(*cache));  in cache_init()
62     if (!cache) {  in cache_init()
63         error_setg(errp, "Failed to allocate cache");  in cache_init()
66     cache->page_size = page_size;  in cache_init()
67     cache->num_items = 0;  in cache_init()
68     cache->max_num_items = num_pages;  in cache_init()
70     trace_migration_pagecache_init(cache->max_num_items);  in cache_init()
73     cache->page_cache = g_try_malloc((cache->max_num_items) *  in cache_init()
74                                      sizeof(*cache->page_cache));  in cache_init()
75     if (!cache->page_cache) {  in cache_init()
76         error_setg(errp, "Failed to allocate page cache");  in cache_init()
77         g_free(cache);  in cache_init()
81     for (i = 0; i < cache->max_num_items; i++) {  in cache_init()
82         cache->page_cache[i].it_data = NULL;  in cache_init()
83         cache->page_cache[i].it_age = 0;  in cache_init()
84         cache->page_cache[i].it_addr = -1;  in cache_init()
87     return cache;  in cache_init()
90 void cache_fini(PageCache *cache)  in cache_fini()  argument
94     g_assert(cache);  in cache_fini()
95     g_assert(cache->page_cache);  in cache_fini()
97     for (i = 0; i < cache->max_num_items; i++) {  in cache_fini()
98         g_free(cache->page_cache[i].it_data);  in cache_fini()
101     g_free(cache->page_cache);  in cache_fini()
102     cache->page_cache = NULL;  in cache_fini()
103     g_free(cache);  in cache_fini()
106 static size_t cache_get_cache_pos(const PageCache *cache,  in cache_get_cache_pos()  argument
109     g_assert(cache->max_num_items);  in cache_get_cache_pos()
110     return (address / cache->page_size) & (cache->max_num_items - 1);  in cache_get_cache_pos()
113 static CacheItem *cache_get_by_addr(const PageCache *cache, uint64_t addr)  in cache_get_by_addr()  argument
117     g_assert(cache);  in cache_get_by_addr()
118     g_assert(cache->page_cache);  in cache_get_by_addr()
120     pos = cache_get_cache_pos(cache, addr);  in cache_get_by_addr()
122     return &cache->page_cache[pos];  in cache_get_by_addr()
125 uint8_t *get_cached_data(const PageCache *cache, uint64_t addr)  in get_cached_data()  argument
127     return cache_get_by_addr(cache, addr)->it_data;  in get_cached_data()
130 bool cache_is_cached(const PageCache *cache, uint64_t addr,  in cache_is_cached()  argument
135     it = cache_get_by_addr(cache, addr);  in cache_is_cached()
137     if (it->it_addr == addr) {  in cache_is_cached()
138         /* update the it_age when the cache hit */  in cache_is_cached()
139         it->it_age = current_age;  in cache_is_cached()
145 int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata,  in cache_insert()  argument
152     it = cache_get_by_addr(cache, addr);  in cache_insert()
154     if (it->it_data && it->it_addr != addr &&  in cache_insert()
155         it->it_age + CACHED_PAGE_LIFETIME > current_age) {  in cache_insert()
156         /* the cache page is fresh, don't replace it */  in cache_insert()
157         return -1;  in cache_insert()
160     if (!it->it_data) {  in cache_insert()
161         it->it_data = g_try_malloc(cache->page_size);  in cache_insert()
162         if (!it->it_data) {  in cache_insert()
164             return -1;  in cache_insert()
166         cache->num_items++;  in cache_insert()
169     memcpy(it->it_data, pdata, cache->page_size);  in cache_insert()
171     it->it_age = current_age;  in cache_insert()
172     it->it_addr = addr;  in cache_insert()