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 reschedule

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: 7bed89958bfbf40df9ca681cefbdca63abdde39d ("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 effd60c878176bcaf97fa7ce2b12d04bb8ead6f7)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

show more ...

Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- virtio-blk: Multiqueue fixes and cleanups
- blklogwrites: Fixes for write_zeroes and superblock update r

Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- virtio-blk: Multiqueue fixes and cleanups
- blklogwrites: Fixes for write_zeroes and superblock update races
- commit/stream: Allow users to request only format driver names in
backing file format
- monitor: only run coroutine commands in qemu_aio_context
- Some iotest fixes

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# -----END PGP SIGNATURE-----
# gpg: Signature made Fri 26 Jan 2024 12:26:20 GMT
# gpg: using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
# gpg: issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6

* tag 'for-upstream' of https://repo.or.cz/qemu/kevin:
iotests/277: Use iotests.sock_dir for socket creation
iotests/iothreads-stream: Use the right TimeoutError
tests/unit: Bump test-replication timeout to 60 seconds
iotests/264: Use iotests.sock_dir for socket creation
block/blklogwrites: Protect mutable driver state with a mutex.
virtio-blk: always set ioeventfd during startup
virtio-blk: tolerate failure to set BlockBackend AioContext
virtio-blk: restart s->rq reqs in vq AioContexts
virtio-blk: rename dataplane to ioeventfd
virtio-blk: rename dataplane create/destroy functions
virtio-blk: move dataplane code into virtio-blk.c
monitor: only run coroutine commands in qemu_aio_context
iotests: port 141 to Python for reliable QMP testing
iotests: add filter_qmp_generated_node_ids()
stream: Allow users to request only format driver names in backing file format
commit: Allow users to request only format driver names in backing file format
string-output-visitor: Fix (pseudo) struct handling
block/blklogwrites: Fix a bug when logging "write zeroes" operations.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

show more ...

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 reschedule

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: 7bed89958bfbf40df9ca681cefbdca63abdde39d ("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>

show more ...

Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches:

- mirror: Fix early return from drain (could cause deadlocks)
- vmdk: Fixed probing for version 3 im

Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches:

- mirror: Fix early return from drain (could cause deadlocks)
- vmdk: Fixed probing for version 3 images
- vl: Fix to create migration object before block backends again (fixes
segfault for block drivers that set migration blockers)
- Several minor fixes, documentation and test case improvements

# gpg: Signature made Tue 19 Mar 2019 14:59:17 GMT
# gpg: using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
qemu-iotests: Treat custom TEST_DIR in 051
blockdev: Check @replaces in blockdev_mirror_common
block: Make bdrv_{copy_on_read,crypto_luks,replication} static
blockjob: fix user pause in block_job_error_action
qemu-iotests: Fix 232 for non-qcow2
vl: Fix to create migration object before block backends again
iotests: 153: Wait for an answer to QMP commands
block: Silence Coverity in bdrv_drop_intermediate()
vmdk: Support version=3 in VMDK descriptor files
qapi: fix block-latency-histogram-set description and examples
qcow2: Fix data file error condition in qcow2_co_create()
mirror: Confirm we're quiesced only if the job is paused or cancelled

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

show more ...

qemu-iotests: Fix 232 for non-qcow2

232 is marked as generic, but commit 12efe428c9e added code that assumes
qcow2. What the new test really needs is backing files and support for
updating the backi

qemu-iotests: Fix 232 for non-qcow2

232 is marked as generic, but commit 12efe428c9e added code that assumes
qcow2. What the new test really needs is backing files and support for
updating the backing file link (.bdrv_change_backing_file).

Split the non-generic code into a new test case 247 and make it work
with qed, too.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...