qemu/monitor
Stefan Hajnoczi effd60c878 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>
2024-01-26 11:16:58 +01:00
..
fds.c monitor: restrict command getfd to POSIX hosts 2023-03-13 15:46:09 +04:00
hmp-cmds-target.c accel/tcg: Replace CPUState.env_ptr with cpu_env() 2023-10-04 11:03:54 -07:00
hmp-cmds.c hmp: Improve sync-profile error message 2023-11-17 10:07:52 +01:00
hmp-target.c monitor: Rename misc.c to hmp-target.c 2023-02-04 07:56:54 +01:00
hmp.c monitor: do not use mb_read/mb_set for suspend_cnt 2023-05-25 10:18:33 +02:00
meson.build meson: Replace softmmu_ss -> system_ss 2023-06-20 10:01:30 +02:00
monitor-internal.h monitor: introduce qmp_dispatcher_co_wake 2023-05-25 10:18:33 +02:00
monitor.c qapi: Add HV_BALLOON_STATUS_REPORT event and its QMP query command 2023-11-06 14:08:10 +01:00
qmp-cmds-control.c monitor: Drop unnecessary includes 2023-02-04 07:56:52 +01:00
qmp-cmds.c qmp: 'add_client' actually expects sockets 2023-03-13 15:40:41 +04:00
qmp.c monitor: only run coroutine commands in qemu_aio_context 2024-01-26 11:16:58 +01:00
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