qemu/migration/page_cache.c
Markus Armbruster 7bfc47936e migration: Fix cache_init()'s "Failed to allocate" error messages
cache_init() attempts to handle allocation failure.  The two error
messages are garbage, as untested error messages commonly are:

    Parameter 'cache size' expects Failed to allocate cache
    Parameter 'cache size' expects Failed to allocate page cache

Fix them to just

    Failed to allocate cache
    Failed to allocate page cache

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210202141734.2488076-4-armbru@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-02-08 11:19:51 +00:00

176 lines
4.2 KiB
C

/*
* Page cache for QEMU
* The cache is base on a hash of the page address
*
* Copyright 2012 Red Hat, Inc. and/or its affiliates
*
* Authors:
* Orit Wasserman <owasserm@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qapi/qmp/qerror.h"
#include "qapi/error.h"
#include "qemu/host-utils.h"
#include "page_cache.h"
#include "trace.h"
/* the page in cache will not be replaced in two cycles */
#define CACHED_PAGE_LIFETIME 2
typedef struct CacheItem CacheItem;
struct CacheItem {
uint64_t it_addr;
uint64_t it_age;
uint8_t *it_data;
};
struct PageCache {
CacheItem *page_cache;
size_t page_size;
size_t max_num_items;
size_t num_items;
};
PageCache *cache_init(uint64_t new_size, size_t page_size, Error **errp)
{
int64_t i;
size_t num_pages = new_size / page_size;
PageCache *cache;
if (new_size < page_size) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"is smaller than one target page size");
return NULL;
}
/* round down to the nearest power of 2 */
if (!is_power_of_2(num_pages)) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"is not a power of two number of pages");
return NULL;
}
/* We prefer not to abort if there is no memory */
cache = g_try_malloc(sizeof(*cache));
if (!cache) {
error_setg(errp, "Failed to allocate cache");
return NULL;
}
cache->page_size = page_size;
cache->num_items = 0;
cache->max_num_items = num_pages;
trace_migration_pagecache_init(cache->max_num_items);
/* We prefer not to abort if there is no memory */
cache->page_cache = g_try_malloc((cache->max_num_items) *
sizeof(*cache->page_cache));
if (!cache->page_cache) {
error_setg(errp, "Failed to allocate page cache");
g_free(cache);
return NULL;
}
for (i = 0; i < cache->max_num_items; i++) {
cache->page_cache[i].it_data = NULL;
cache->page_cache[i].it_age = 0;
cache->page_cache[i].it_addr = -1;
}
return cache;
}
void cache_fini(PageCache *cache)
{
int64_t i;
g_assert(cache);
g_assert(cache->page_cache);
for (i = 0; i < cache->max_num_items; i++) {
g_free(cache->page_cache[i].it_data);
}
g_free(cache->page_cache);
cache->page_cache = NULL;
g_free(cache);
}
static size_t cache_get_cache_pos(const PageCache *cache,
uint64_t address)
{
g_assert(cache->max_num_items);
return (address / cache->page_size) & (cache->max_num_items - 1);
}
static CacheItem *cache_get_by_addr(const PageCache *cache, uint64_t addr)
{
size_t pos;
g_assert(cache);
g_assert(cache->page_cache);
pos = cache_get_cache_pos(cache, addr);
return &cache->page_cache[pos];
}
uint8_t *get_cached_data(const PageCache *cache, uint64_t addr)
{
return cache_get_by_addr(cache, addr)->it_data;
}
bool cache_is_cached(const PageCache *cache, uint64_t addr,
uint64_t current_age)
{
CacheItem *it;
it = cache_get_by_addr(cache, addr);
if (it->it_addr == addr) {
/* update the it_age when the cache hit */
it->it_age = current_age;
return true;
}
return false;
}
int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata,
uint64_t current_age)
{
CacheItem *it;
/* actual update of entry */
it = cache_get_by_addr(cache, addr);
if (it->it_data && it->it_addr != addr &&
it->it_age + CACHED_PAGE_LIFETIME > current_age) {
/* the cache page is fresh, don't replace it */
return -1;
}
/* allocate page */
if (!it->it_data) {
it->it_data = g_try_malloc(cache->page_size);
if (!it->it_data) {
trace_migration_pagecache_insert();
return -1;
}
cache->num_items++;
}
memcpy(it->it_data, pdata, cache->page_size);
it->it_age = current_age;
it->it_addr = addr;
return 0;
}