virtio_ccw: fix synchronize_cbs() after interrupt fallback

virtio_ccw_synchronize_cbs() assumes the device uses adapter interrupts
when vcdev->airq_info is not NULL. If registering adapter indicators
fails, virtio_ccw_find_vqs() falls back to classic interrupts but can
leave airq_info set.

With VIRTIO_HARDEN_NOTIFICATION enabled,
virtio_ccw_int_handler() invokes callbacks under vcdev->irq_lock.
synchronize_cbs() instead takes the indicator area lock, so it does
not synchronize with those callbacks.

Use vcdev->is_thinint, which the fallback clears, to select the lock.
Keep the airq_info check because is_thinint can be set before the
first find_vqs() call, when airq_info is still NULL.

Fixes: 3a232277c1ac ("virtio-ccw: implement synchronize_cbs()")
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260908053817.26065-2-kmehltretter@gmail.com>

0 files changed, 0 insertions, 0 deletions