qemu-iotests: add 203 savevm with IOThreads test

#!/usr/bin/env python

#

# Copyright (C) 2017 Red Hat, Inc.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

#

# Creator/Owner: Stefan Hajnoczi <stefanha@redhat.com>

#

# Check that QMP 'migrate' with multiple drives on a single IOThread completes

# successfully.  This particular command triggered a hang in the source QEMU

# process due to recursive AioContext locking in bdrv_invalidate_all() and

# BDRV_POLL_WHILE().

import iotests

iotests.verify_image_format(supported_fmts=['qcow2'])

iotests.verify_platform(['linux'])

with iotests.FilePath('disk0.img') as disk0_img_path, \

     iotests.FilePath('disk1.img') as disk1_img_path, \

     iotests.VM() as vm:

    img_size = '10M'

    iotests.qemu_img_pipe('create', '-f', iotests.imgfmt, disk0_img_path, img_size)

    iotests.qemu_img_pipe('create', '-f', iotests.imgfmt, disk1_img_path, img_size)

    iotests.log('Launching VM...')

    (vm.add_object('iothread,id=iothread0')

       .add_drive(disk0_img_path, 'node-name=drive0-node', interface='none')

       .add_drive(disk1_img_path, 'node-name=drive1-node', interface='none')

       .launch())

    iotests.log('Setting IOThreads...')

    iotests.log(vm.qmp('x-blockdev-set-iothread',

                       node_name='drive0-node', iothread='iothread0',

                       force=True))

    iotests.log(vm.qmp('x-blockdev-set-iothread',

                       node_name='drive1-node', iothread='iothread0',

                       force=True))

    iotests.log('Starting migration...')

    iotests.log(vm.qmp('migrate', uri='exec:cat >/dev/null'))

    while True:

        vm.get_qmp_event(wait=60.0)

        result = vm.qmp('query-migrate')

        status = result.get('return', {}).get('status', None)

        if status == 'completed':

            break

Launching VM...

Setting IOThreads...

{u'return': {}}

{u'return': {}}

Starting migration...

{u'return': {}}

198 rw auto

200 rw auto

202 rw auto quick

203 rw auto