virtio_ring: Allow non power of 2 sizes for packed virtqueue

virtio_ring: Allow non power of 2 sizes for packed virtqueue

According to the Virtio Specification, the Queue Size parameter of a
virtqueue corresponds to the maximum number of descriptors in that
queue, and it does not have to be a power of 2 for packed virtqueues.
However, the virtio_pci_modern driver enforced a power of 2 check for
virtqueue sizes, which is unnecessary and restrictive for packed
virtuqueue.

Split virtqueue still needs to check the virtqueue size is power_of_2
which has been done in vring_alloc_queue_split of the virtio_ring layer.

To validate this change, we tested various virtqueue sizes for packed
rings, including 128, 256, 512, 100, 200, 500, and 1000, with
CONFIG_PAGE_POISONING enabled, and all tests passed successfully.

Signed-off-by: Feng Liu <feliu@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Message-Id: <20230315185458.11638-2-feliu@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>