Re: [PATCH] virtio-pci: fix queue_enable write

[Jason Wang]

On 2020/6/9 下午11:43, Michael S. Tsirkin wrote:
> On Fri, May 29, 2020 at 11:07:28AM +0800, Jason Wang wrote:
> > Spec said: The driver uses this to selectively prevent the device from
> > executing requests from this virtqueue. 1 - enabled; 0 - disabled.
> >
> > Though write 0 to queue_enable is forbidden by the sepc, we should not
> spec?


Chapter 4.1.4.3.2 said:

"

The driver MUST NOT write a 0 to queue_enable.

"


> > assume that the value is 1.
> >
> > Fix this by ignoring the write value other than 1.
> >
> > Cc: Michael S. Tsirkin <mst@redhat.com>
> > Cc: Stefan Hajnoczi <stefanha@redhat.com>
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
>
> Do we want to call virtio_error here so we can figure out something's wrong?


That looks better. Will do.

Thanks


> > ---
> >   hw/virtio/virtio-pci.c | 10 ++++++----
> >   1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index d028c17c24..b3558eeaee 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -1273,16 +1273,18 @@ static void virtio_pci_common_write(void *opaque, 
> > hwaddr addr,
> >           virtio_queue_set_vector(vdev, vdev->queue_sel, val);
> >           break;
> >       case VIRTIO_PCI_COMMON_Q_ENABLE:
> > -        virtio_queue_set_num(vdev, vdev->queue_sel,
> > -                             proxy->vqs[vdev->queue_sel].num);
> > -        virtio_queue_set_rings(vdev, vdev->queue_sel,
> > +        if (val == 1) {
> > +            virtio_queue_set_num(vdev, vdev->queue_sel,
> > +                                 proxy->vqs[vdev->queue_sel].num);
> > +            virtio_queue_set_rings(vdev, vdev->queue_sel,
> >                          ((uint64_t)proxy->vqs[vdev->queue_sel].desc[1]) << 32 |
> >                          proxy->vqs[vdev->queue_sel].desc[0],
> >                          ((uint64_t)proxy->vqs[vdev->queue_sel].avail[1]) << 32 
> > |
> >                          proxy->vqs[vdev->queue_sel].avail[0],
> >                          ((uint64_t)proxy->vqs[vdev->queue_sel].used[1]) << 32 |
> >                          proxy->vqs[vdev->queue_sel].used[0]);
> > -        proxy->vqs[vdev->queue_sel].enabled = 1;
> > +            proxy->vqs[vdev->queue_sel].enabled = 1;
> > +        }
> >           break;
> >       case VIRTIO_PCI_COMMON_Q_DESCLO:
> >           proxy->vqs[vdev->queue_sel].desc[0] = val;
> > --
> > 2.20.1