Am 22.01.2024 um 18:26 hat Stefan Hajnoczi geschrieben:
> Requests that complete in an IOThread use irqfd to notify the guest
> while requests that complete in the main loop thread use the traditional
> qdev irq code path. The reason for this conditional is that the irq code
> path requires the BQL:
>
> if (s->ioeventfd_started && !s->ioeventfd_disabled) {
> virtio_notify_irqfd(vdev, req->vq);
> } else {
> virtio_notify(vdev, req->vq);
> }
>
> There is a corner case where the conditional invokes the irq code path
> instead of the irqfd code path:
>
> static void virtio_blk_stop_ioeventfd(VirtIODevice *vdev)
> {
> ...
> /*
> * Set ->ioeventfd_started to false before draining so that host
> notifiers
> * are not detached/attached anymore.
> */
> s->ioeventfd_started = false;
>
> /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
> blk_drain(s->conf.conf.blk);
>
> During blk_drain() the conditional produces the wrong result because
> ioeventfd_started is false.
>
> Use qemu_in_iothread() instead of checking the ioeventfd state.
>
> Buglink: https://issues.redhat.com/browse/RHEL-15394
> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
Thanks, applied to the block branch.
Kevin
