Separate the logic of initializing vring, and subsequent patches will call it separately. This function completes the variable initialization of packed vring. It together with the logic of atatch constitutes the initialization of vring. Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Acked-by: Jason Wang <jasowang@redhat.com> Message-Id: <20220801063902.129329-21-xuanzhuo@linux.alibaba.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>