python/qemu: Kill QEMU process if 'quit' doesn't work

qemu with hax to log dma reads & writes jcs.org/2018/11/12/vfio

With a QEMU bug, it can happen that the QEMU process doesn't react to a
'quit' QMP command. If we got an exception during previous QMP
communication (e.g. iotests Timeout expiring), we could also be in an
inconsistent state where after sending 'quit' we immediately read an old
response and close the socket even though the 'quit' command wasn't
processed yet. Both cases would lead to a hanging test.

Fix this by waiting for the QEMU process to exit after sending 'quit'
with a timeout, and if it doesn't happen within three seconds, send
SIGKILL.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200313083617.8326-3-kwolf@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

authored by

Kevin Wolf and committed by

Peter Maydell 6 years ago cd87f5e3 aa1cbeb8

1 changed file

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python

qemu

machine.py

python/qemu/machine.py

··· 359 359 if not has_quit: 360 360 self._qmp.cmd('quit') 361 361 self._qmp.close() 362 + self._popen.wait(timeout=3) 362 363 except: 363 364 self._popen.kill() 364 365 self._popen.wait()