Re: [PULL v4 29/83] virtio: introduce virtio_queue_enable()

[Jason Wang]

On Wed, Nov 9, 2022 at 3:43 AM Stefan Hajnoczi <stefanha@gmail.com> wrote:
>
> On Mon, 7 Nov 2022 at 18:10, Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > From: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> >
> > Introduce the interface queue_enable() in VirtioDeviceClass and the
> > fucntion virtio_queue_enable() in virtio, it can be called when
> > VIRTIO_PCI_COMMON_Q_ENABLE is written and related virtqueue can be
> > started. It only supports the devices of virtio 1 or later. The
> > not-supported devices can only start the virtqueue when DRIVER_OK.
> >
> > Signed-off-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > Acked-by: Jason Wang <jasowang@redhat.com>
> > Message-Id: <20221017092558.111082-4-xuanzhuo@linux.alibaba.com>
> > Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  include/hw/virtio/virtio.h |  2 ++
> >  hw/virtio/virtio.c         | 14 ++++++++++++++
> >  2 files changed, 16 insertions(+)
> >
> > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> > index 74d76c1dbc..b00b3fcf31 100644
> > --- a/include/hw/virtio/virtio.h
> > +++ b/include/hw/virtio/virtio.h
> > @@ -149,6 +149,7 @@ struct VirtioDeviceClass {
> >      void (*reset)(VirtIODevice *vdev);
> >      void (*set_status)(VirtIODevice *vdev, uint8_t val);
> >      void (*queue_reset)(VirtIODevice *vdev, uint32_t queue_index);
> > +    void (*queue_enable)(VirtIODevice *vdev, uint32_t queue_index);
> >      /* For transitional devices, this is a bitmap of features
> >       * that are only exposed on the legacy interface but not
> >       * the modern one.
> > @@ -288,6 +289,7 @@ int virtio_queue_set_host_notifier_mr(VirtIODevice 
> > *vdev, int n,
> >  int virtio_set_status(VirtIODevice *vdev, uint8_t val);
> >  void virtio_reset(void *opaque);
> >  void virtio_queue_reset(VirtIODevice *vdev, uint32_t queue_index);
> > +void virtio_queue_enable(VirtIODevice *vdev, uint32_t queue_index);
> >  void virtio_update_irq(VirtIODevice *vdev);
> >  int virtio_set_features(VirtIODevice *vdev, uint64_t val);
> >
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index cf5f9ca387..9683b2e158 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -2495,6 +2495,20 @@ void virtio_queue_reset(VirtIODevice *vdev, uint32_t 
> > queue_index)
> >      __virtio_queue_reset(vdev, queue_index);
> >  }
> >
> > +void virtio_queue_enable(VirtIODevice *vdev, uint32_t queue_index)
> > +{
> > +    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
> > +
> > +    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> > +        error_report("queue_enable is only suppported in devices of virtio 
> > "
> > +                     "1.0 or later.");
>
> Why is this triggering here? Maybe virtio_queue_enable() is called too
> early. I have verified that the Linux guest driver sets VERSION_1. I
> didn't check what SeaBIOS does.

Looks like a bug, we should check device features here at least and it
should be guest errors instead of error_report() here.

Thanks

>
> $ build/qemu-system-x86_64 -M accel=kvm -m 1G -cpu host -blockdev
> file,node-name=drive0,filename=test.img -device
> virtio-blk-pci,drive=drive0
> qemu: queue_enable is only suppported in devices of virtio 1.0 or later.
>
> Stefan
>