Re: [Qemu-devel] [PATCH 3/8] virtio: Add support for guest setting of queue size

[Peter Maydell]

On 8 July 2013 20:39, Anthony Liguori <address@hidden> wrote:
> Peter Maydell <address@hidden> writes:
>> +void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>> +{
>> +    vdev->vq[n].vring.num = num;
>> +    virtqueue_init(&vdev->vq[n]);
>
> I think some level of checking is probably needed on num since we do a
> tremendous amount of math on it.  I doubt it's exploitable since it's
> always treated as a PA, but better to be safe than sorry.

So at the moment we do that in the transport:

+        if (value <= VIRTQUEUE_MAX_SIZE) {
+            DPRINTF("calling virtio_queue_set_num\n");
+            virtio_queue_set_num(vdev, vdev->queue_sel, value);
+        }

but I agree it would be better done here in the generic code.

-- PMM