Re: [PATCH V2] virtio-pci: fix queue_enable write

[Stefano Garzarella]

On Wed, Jun 10, 2020 at 01:43:51PM +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 spec, we should not
> assume that the value is 1.
> 
> Fix this by ignore the write value other than 1.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> Changes from V1:
> - fix typo
> - warn wrong value through virtio_error
> ---
>  hw/virtio/virtio-pci.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index d028c17c24..7bc8c1c056 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1273,16 +1273,20 @@ 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) {

Does it have to be 1 or can it be any value other than 0?

Thanks,
Stefano

> +            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;
> +        } else {
> +            virtio_error(vdev, "wrong value for queue_enable %"PRIx64, val);
> +        }
>          break;
>      case VIRTIO_PCI_COMMON_Q_DESCLO:
>          proxy->vqs[vdev->queue_sel].desc[0] = val;
> -- 
> 2.20.1
> 
>