mirror_qemu/monitor
Stefan Hajnoczi 8ec90598e9 monitor: only run coroutine commands in qemu_aio_context
monitor_qmp_dispatcher_co() runs in the iohandler AioContext that is not
polled during nested event loops. The coroutine currently reschedules
itself in the main loop's qemu_aio_context AioContext, which is polled
during nested event loops. One known problem is that QMP device-add
calls drain_call_rcu(), which temporarily drops the BQL, leading to all
sorts of havoc like other vCPU threads re-entering device emulation code
while another vCPU thread is waiting in device emulation code with
aio_poll().

Paolo Bonzini suggested running non-coroutine QMP handlers in the
iohandler AioContext. This avoids trouble with nested event loops. His
original idea was to move coroutine rescheduling to
monitor_qmp_dispatch(), but I resorted to moving it to qmp_dispatch()
because we don't know if the QMP handler needs to run in coroutine
context in monitor_qmp_dispatch(). monitor_qmp_dispatch() would have
been nicer since it's associated with the monitor implementation and not
as general as qmp_dispatch(), which is also used by qemu-ga.

A number of qemu-iotests need updated .out files because the order of
QMP events vs QMP responses has changed.

Solves Issue #1933.

Cc: qemu-stable@nongnu.org
Fixes: 7bed89958b ("device_core: use drain_call_rcu in in qmp_device_add")
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2215192
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2214985
Buglink: https://issues.redhat.com/browse/RHEL-17369
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240118144823.1497953-4-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Tested-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit effd60c878)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: omit changes to tests missing in 7.2)
2024-01-26 19:40:19 +03:00
..
hmp-cmds.c qemu-sockets: move and rename SocketAddress_to_str() 2022-10-28 13:28:52 +08:00
hmp.c monitor: expose monitor_puts to rest of code 2022-10-06 11:53:40 +01:00
meson.build meson: add spice_headers dependency. 2020-10-15 11:14:40 +02:00
misc.c qmp/hmp, device_tree.c: introduce dumpdtb 2022-10-17 16:15:10 -03:00
monitor-internal.h monitor: expose monitor_puts to rest of code 2022-10-06 11:53:40 +01:00
monitor.c Move error_printf_unless_qmp() with monitor unit 2022-04-21 17:09:09 +04:00
qmp-cmds-control.c qapi: Implement deprecated-output=hide for QMP introspection 2021-03-19 16:05:11 +01:00
qmp-cmds.c jobs: group together API calls under the same job lock 2022-10-07 12:11:41 +02:00
qmp.c monitor: only run coroutine commands in qemu_aio_context 2024-01-26 19:40:19 +03:00
trace-events docs: fix references to docs/devel/tracing.rst 2021-06-02 06:51:09 +02:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00