On Mon, Dec 23, 2019 at 04:18:20PM +0300, Denis Plotnikov wrote: > 1. virtqueue_size is a power of 2 > 2. virtqueue_size > 2, since seg_max is virtqueue_size - 2 > > Signed-off-by: Denis Plotnikov <[email protected]> > --- > hw/virtio/virtio.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 04716b5f6c..e3ab69061e 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -2166,7 +2166,8 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, > int num) > */ > if (!!num != !!vdev->vq[n].vring.num || > num > VIRTQUEUE_MAX_SIZE || > - num < 0) { > + num < 2 ||
This is generic VIRTIO code so it's not possible to make assumptions
about seg_max, which is a virtio-blk/scsi concept. Other VIRTIO devices
may tolerate num < 2 just fine. Please drop this.
> + !is_power_of_2(num)) {
This constraint only applies to the Split Virtqueue layout. Please see
VIRTIO 1.1 "2.7.10.1 Structure Size and Alignment" for the Packed
Virtqueue layout:
The Queue Size value does not have to be a power of 2.
The condition should be:
!(virtio_has_features(vdev, VIRTIO_F_RING_PACKED) || is_power_of_2(num))
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