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

["Michael S. Tsirkin" <mst@redhat.com>]

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?

> 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?



> ---
>  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