virtio: hand virtio ring alignment as argument to vring_new_virtqueue

This allows each virtio user to hand in the alignment appropriate to
their virtio_ring structures.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index f28643f..7462a51 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -249,8 +249,8 @@
 		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 
 	/* create the vring */
-	vq = vring_new_virtqueue(info->num, vdev, info->queue,
-				 vp_notify, callback);
+	vq = vring_new_virtqueue(info->num, VIRTIO_PCI_VRING_ALIGN,
+				 vdev, info->queue, vp_notify, callback);
 	if (!vq) {
 		err = -ENOMEM;
 		goto out_activate_queue;
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 6eb5303..5777196 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -274,6 +274,7 @@
 };
 
 struct virtqueue *vring_new_virtqueue(unsigned int num,
+				      unsigned int vring_align,
 				      struct virtio_device *vdev,
 				      void *pages,
 				      void (*notify)(struct virtqueue *),
@@ -292,7 +293,7 @@
 	if (!vq)
 		return NULL;
 
-	vring_init(&vq->vring, num, pages, PAGE_SIZE);
+	vring_init(&vq->vring, num, pages, vring_align);
 	vq->vq.callback = callback;
 	vq->vq.vdev = vdev;
 	vq->vq.vq_ops = &vring_vq_ops;