qemu-e2k/migration/socket.c
Leonardo Bras 5b1d9bab2d multifd: Implement zero copy write in multifd migration (multifd-zero-copy)
Implement zero copy send on nocomp_send_write(), by making use of QIOChannel
writev + flags & flush interface.

Change multifd_send_sync_main() so flush_zero_copy() can be called
after each iteration in order to make sure all dirty pages are sent before
a new iteration is started. It will also flush at the beginning and at the
end of migration.

Also make it return -1 if flush_zero_copy() fails, in order to cancel
the migration process, and avoid resuming the guest in the target host
without receiving all current RAM.

This will work fine on RAM migration because the RAM pages are not usually freed,
and there is no problem on changing the pages content between writev_zero_copy() and
the actual sending of the buffer, because this change will dirty the page and
cause it to be re-sent on a next iteration anyway.

A lot of locked memory may be needed in order to use multifd migration
with zero-copy enabled, so disabling the feature should be necessary for
low-privileged users trying to perform multifd migrations.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220513062836.965425-9-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-05-16 13:56:24 +01:00

205 lines
5.8 KiB
C

/*
* QEMU live migration via socket
*
* Copyright Red Hat, Inc. 2009-2016
*
* Authors:
* Chris Lalancette <clalance@redhat.com>
* Daniel P. Berrange <berrange@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "qemu/osdep.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "channel.h"
#include "socket.h"
#include "migration.h"
#include "qemu-file.h"
#include "io/channel-socket.h"
#include "io/net-listener.h"
#include "trace.h"
struct SocketOutgoingArgs {
SocketAddress *saddr;
} outgoing_args;
void socket_send_channel_create(QIOTaskFunc f, void *data)
{
QIOChannelSocket *sioc = qio_channel_socket_new();
qio_channel_socket_connect_async(sioc, outgoing_args.saddr,
f, data, NULL, NULL);
}
int socket_send_channel_destroy(QIOChannel *send)
{
/* Remove channel */
object_unref(OBJECT(send));
if (outgoing_args.saddr) {
qapi_free_SocketAddress(outgoing_args.saddr);
outgoing_args.saddr = NULL;
}
return 0;
}
struct SocketConnectData {
MigrationState *s;
char *hostname;
};
static void socket_connect_data_free(void *opaque)
{
struct SocketConnectData *data = opaque;
if (!data) {
return;
}
g_free(data->hostname);
g_free(data);
}
static void socket_outgoing_migration(QIOTask *task,
gpointer opaque)
{
struct SocketConnectData *data = opaque;
QIOChannel *sioc = QIO_CHANNEL(qio_task_get_source(task));
Error *err = NULL;
if (qio_task_propagate_error(task, &err)) {
trace_migration_socket_outgoing_error(error_get_pretty(err));
goto out;
}
trace_migration_socket_outgoing_connected(data->hostname);
if (migrate_use_zero_copy_send() &&
!qio_channel_has_feature(sioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
error_setg(&err, "Zero copy send feature not detected in host kernel");
}
out:
migration_channel_connect(data->s, sioc, data->hostname, err);
object_unref(OBJECT(sioc));
}
static void
socket_start_outgoing_migration_internal(MigrationState *s,
SocketAddress *saddr,
Error **errp)
{
QIOChannelSocket *sioc = qio_channel_socket_new();
struct SocketConnectData *data = g_new0(struct SocketConnectData, 1);
data->s = s;
/* in case previous migration leaked it */
qapi_free_SocketAddress(outgoing_args.saddr);
outgoing_args.saddr = saddr;
if (saddr->type == SOCKET_ADDRESS_TYPE_INET) {
data->hostname = g_strdup(saddr->u.inet.host);
}
qio_channel_set_name(QIO_CHANNEL(sioc), "migration-socket-outgoing");
qio_channel_socket_connect_async(sioc,
saddr,
socket_outgoing_migration,
data,
socket_connect_data_free,
NULL);
}
void socket_start_outgoing_migration(MigrationState *s,
const char *str,
Error **errp)
{
Error *err = NULL;
SocketAddress *saddr = socket_parse(str, &err);
if (!err) {
socket_start_outgoing_migration_internal(s, saddr, &err);
}
error_propagate(errp, err);
}
static void socket_accept_incoming_migration(QIONetListener *listener,
QIOChannelSocket *cioc,
gpointer opaque)
{
trace_migration_socket_incoming_accepted();
if (migration_has_all_channels()) {
error_report("%s: Extra incoming migration connection; ignoring",
__func__);
return;
}
qio_channel_set_name(QIO_CHANNEL(cioc), "migration-socket-incoming");
migration_channel_process_incoming(QIO_CHANNEL(cioc));
}
static void
socket_incoming_migration_end(void *opaque)
{
QIONetListener *listener = opaque;
qio_net_listener_disconnect(listener);
object_unref(OBJECT(listener));
}
static void
socket_start_incoming_migration_internal(SocketAddress *saddr,
Error **errp)
{
QIONetListener *listener = qio_net_listener_new();
MigrationIncomingState *mis = migration_incoming_get_current();
size_t i;
int num = 1;
qio_net_listener_set_name(listener, "migration-socket-listener");
if (migrate_use_multifd()) {
num = migrate_multifd_channels();
}
if (qio_net_listener_open_sync(listener, saddr, num, errp) < 0) {
object_unref(OBJECT(listener));
return;
}
mis->transport_data = listener;
mis->transport_cleanup = socket_incoming_migration_end;
qio_net_listener_set_client_func_full(listener,
socket_accept_incoming_migration,
NULL, NULL,
g_main_context_get_thread_default());
for (i = 0; i < listener->nsioc; i++) {
SocketAddress *address =
qio_channel_socket_get_local_address(listener->sioc[i], errp);
if (!address) {
return;
}
migrate_add_address(address);
qapi_free_SocketAddress(address);
}
}
void socket_start_incoming_migration(const char *str, Error **errp)
{
Error *err = NULL;
SocketAddress *saddr = socket_parse(str, &err);
if (!err) {
socket_start_incoming_migration_internal(saddr, &err);
}
qapi_free_SocketAddress(saddr);
error_propagate(errp, err);
}