/*
* Multifd zlib compression implementation
*
* Copyright (c) 2020 Red Hat Inc
*
* Authors:
* Juan Quintela <quintela@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 <zlib.h>
#include "qemu/rcu.h"
#include "exec/ramblock.h"
#include "exec/target_page.h"
#include "qapi/error.h"
#include "migration.h"
#include "trace.h"
#include "multifd.h"
struct zlib_data {
/* stream for compression */
z_stream zs;
/* compressed buffer */
uint8_t *zbuff;
/* size of compressed buffer */
uint32_t zbuff_len;
/* uncompressed buffer of size qemu_target_page_size() */
uint8_t *buf;
};
/* Multifd zlib compression */
/**
* zlib_send_setup: setup send side
*
* Setup each channel with zlib compression.
*
* Returns 0 for success or -1 for error
*
* @p: Params for the channel that we are using
* @errp: pointer to an error
*/
static int zlib_send_setup(MultiFDSendParams *p, Error **errp)
{
struct zlib_data *z = g_new0(struct zlib_data, 1);
z_stream *zs = &z->zs;
const char *err_msg;
zs->zalloc = Z_NULL;
zs->zfree = Z_NULL;
zs->opaque = Z_NULL;
if (deflateInit(zs, migrate_multifd_zlib_level()) != Z_OK) {
err_msg = "deflate init failed";
goto err_free_z;
}
/* This is the maxium size of the compressed buffer */
z->zbuff_len = compressBound(MULTIFD_PACKET_SIZE);
z->zbuff = g_try_malloc(z->zbuff_len);
if (!z->zbuff) {
err_msg = "out of memory for zbuff";
goto err_deflate_end;
}
z->buf = g_try_malloc(qemu_target_page_size());
if (!z->buf) {
err_msg = "out of memory for buf";
goto err_free_zbuff;
}
p->data = z;
return 0;
err_free_zbuff:
g_free(z->zbuff);
err_deflate_end:
deflateEnd(&z->zs);
err_free_z:
g_free(z);
error_setg(errp, "multifd %u: %s", p->id, err_msg);
return -1;
}
/**
* zlib_send_cleanup: cleanup send side
*
* Close the channel and return memory.
*
* @p: Params for the channel that we are using
* @errp: pointer to an error
*/
static void zlib_send_cleanup(MultiFDSendParams *p, Error **errp)
{
struct zlib_data *z = p->data;
deflateEnd(&z->zs);
g_free(z->zbuff);
z->zbuff = NULL;
g_free(z->buf);
z->buf = NULL;
g_free(p->data);
p->data = NULL;
}
/**
* zlib_send_prepare: prepare date to be able to send
*
* Create a compressed buffer with all the pages that we are going to
* send.
*
* Returns 0 for success or -1 for error
*
* @p: Params for the channel that we are using
* @errp: pointer to an error
*/
static int zlib_send_prepare(MultiFDSendParams *p, Error **errp)
{
struct zlib_data *z = p->data;
size_t page_size = qemu_target_page_size();
z_stream *zs = &z->zs;
uint32_t out_size = 0;
int ret;
uint32_t i;
for (i = 0; i < p->normal_num; i++) {
uint32_t available = z->zbuff_len - out_size;
int flush = Z_NO_FLUSH;
if (i == p->normal_num - 1) {
flush = Z_SYNC_FLUSH;
}
/*
* Since the VM might be running, the page may be changing concurrently
* with compression. zlib does not guarantee that this is safe,
* therefore copy the page before calling deflate().
*/
memcpy(z->buf, p->pages->block->host + p->normal[i], page_size);
zs->avail_in = page_size;
zs->next_in = z->buf;
zs->avail_out = available;
zs->next_out = z->zbuff + out_size;
/*
* Welcome to deflate semantics
*
* We need to loop while:
* - return is Z_OK
* - there are stuff to be compressed
* - there are output space free
*/
do {
ret = deflate(zs, flush);
} while (ret == Z_OK && zs->avail_in && zs->avail_out);
if (ret == Z_OK && zs->avail_in) {
error_setg(errp, "multifd %u: deflate failed to compress all input",
p->id);
return -1;
}
if (ret != Z_OK) {
error_setg(errp, "multifd %u: deflate returned %d instead of Z_OK",
p->id, ret);
return -1;
}
out_size += available - zs->avail_out;
}
p->iov[p->iovs_num].iov_base = z->zbuff;
p->iov[p->iovs_num].iov_len = out_size;
p->iovs_num++;
p->next_packet_size = out_size;
p->flags |= MULTIFD_FLAG_ZLIB;
return 0;
}
/**
* zlib_recv_setup: setup receive side
*
* Create the compressed channel and buffer.
*
* Returns 0 for success or -1 for error
*
* @p: Params for the channel that we are using
* @errp: pointer to an error
*/
static int zlib_recv_setup(MultiFDRecvParams *p, Error **errp)
{
struct zlib_data *z = g_new0(struct zlib_data, 1);
z_stream *zs = &z->zs;
p->data = z;
zs->zalloc = Z_NULL;
zs->zfree = Z_NULL;
zs->opaque = Z_NULL;
zs->avail_in = 0;
zs->next_in = Z_NULL;
if (inflateInit(zs) != Z_OK) {
error_setg(errp, "multifd %u: inflate init failed", p->id);
return -1;
}
/* To be safe, we reserve twice the size of the packet */
z->zbuff_len = MULTIFD_PACKET_SIZE * 2;
z->zbuff = g_try_malloc(z->zbuff_len);
if (!z->zbuff) {
inflateEnd(zs);
error_setg(errp, "multifd %u: out of memory for zbuff", p->id);
return -1;
}
return 0;
}
/**
* zlib_recv_cleanup: setup receive side
*
* For no compression this function does nothing.
*
* @p: Params for the channel that we are using
*/
static void zlib_recv_cleanup(MultiFDRecvParams *p)
{
struct zlib_data *z = p->data;
inflateEnd(&z->zs);
g_free(z->zbuff);
z->zbuff = NULL;
g_free(p->data);
p->data = NULL;
}
/**
* zlib_recv_pages: read the data from the channel into actual pages
*
* Read the compressed buffer, and uncompress it into the actual
* pages.
*
* Returns 0 for success or -1 for error
*
* @p: Params for the channel that we are using
* @errp: pointer to an error
*/
static int zlib_recv_pages(MultiFDRecvParams *p, Error **errp)
{
struct zlib_data *z = p->data;
size_t page_size = qemu_target_page_size();
z_stream *zs = &z->zs;
uint32_t in_size = p->next_packet_size;
/* we measure the change of total_out */
uint32_t out_size = zs->total_out;
uint32_t expected_size = p->normal_num * page_size;
uint32_t flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
int ret;
int i;
if (flags != MULTIFD_FLAG_ZLIB) {
error_setg(errp, "multifd %u: flags received %x flags expected %x",
p->id, flags, MULTIFD_FLAG_ZLIB);
return -1;
}
ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp);
if (ret != 0) {
return ret;
}
zs->avail_in = in_size;
zs->next_in = z->zbuff;
for (i = 0; i < p->normal_num; i++) {
int flush = Z_NO_FLUSH;
unsigned long start = zs->total_out;
if (i == p->normal_num - 1) {
flush = Z_SYNC_FLUSH;
}
zs->avail_out = page_size;
zs->next_out = p->host + p->normal[i];
/*
* Welcome to inflate semantics
*
* We need to loop while:
* - return is Z_OK
* - there are input available
* - we haven't completed a full page
*/
do {
ret = inflate(zs, flush);
} while (ret == Z_OK && zs->avail_in
&& (zs->total_out - start) < page_size);
if (ret == Z_OK && (zs->total_out - start) < page_size) {
error_setg(errp, "multifd %u: inflate generated too few output",
p->id);
return -1;
}
if (ret != Z_OK) {
error_setg(errp, "multifd %u: inflate returned %d instead of Z_OK",
p->id, ret);
return -1;
}
}
out_size = zs->total_out - out_size;
if (out_size != expected_size) {
error_setg(errp, "multifd %u: packet size received %u size expected %u",
p->id, out_size, expected_size);
return -1;
}
return 0;
}
static MultiFDMethods multifd_zlib_ops = {
.send_setup = zlib_send_setup,
.send_cleanup = zlib_send_cleanup,
.send_prepare = zlib_send_prepare,
.recv_setup = zlib_recv_setup,
.recv_cleanup = zlib_recv_cleanup,
.recv_pages = zlib_recv_pages
};
static void multifd_zlib_register(void)
{
multifd_register_ops(MULTIFD_COMPRESSION_ZLIB, &multifd_zlib_ops);
}
migration_init(multifd_zlib_register);
