static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data, ram_addr_t current_addr, RAMBlock *block, ram_addr_t offset, int cont, bool last_stage) { int encoded_len = 0, bytes_sent = -1; uint8_t *prev_cached_page; if (!cache_is_cached(XBZRLE.cache, current_addr)) { acct_info.xbzrle_cache_miss++; if (!last_stage) { if (cache_insert(XBZRLE.cache, current_addr, *current_data) == -1) { return -1; } else { /* update *current_data when the page has been inserted into cache */ *current_data = get_cached_data(XBZRLE.cache, current_addr); } } return -1; } prev_cached_page = get_cached_data(XBZRLE.cache, current_addr); /* save current buffer into memory */ memcpy(XBZRLE.current_buf, *current_data, TARGET_PAGE_SIZE); /* XBZRLE encoding (if there is no overflow) */ encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE, XBZRLE.encoded_buf, TARGET_PAGE_SIZE); if (encoded_len == 0) { DPRINTF("Skipping unmodified page\n"); return 0; } else if (encoded_len == -1) { DPRINTF("Overflow\n"); acct_info.xbzrle_overflows++; /* update data in the cache */ if (!last_stage) { memcpy(prev_cached_page, *current_data, TARGET_PAGE_SIZE); *current_data = prev_cached_page; } return -1; } /* we need to update the data in the cache, in order to get the same data */ if (!last_stage) { memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE); } /* Send XBZRLE based compressed page */ bytes_sent = save_block_hdr(f, block, offset, cont, RAM_SAVE_FLAG_XBZRLE); qemu_put_byte(f, ENCODING_FLAG_XBZRLE); qemu_put_be16(f, encoded_len); qemu_put_buffer(f, XBZRLE.encoded_buf, encoded_len); bytes_sent += encoded_len + 1 + 2; acct_info.xbzrle_pages++; acct_info.xbzrle_bytes += bytes_sent; return bytes_sent; }