[PATCH v8 11/50] virtio: allow transports to get avail/used addresses

From: Michael S. Tsirkin
Date: Mon Dec 01 2014 - 11:04:09 EST

From: Cornelia Huck <cornelia.huck@xxxxxxxxxx>

For virtio-1, we can theoretically have a more complex virtqueue
layout with avail and used buffers not on a contiguous memory area
with the descriptor table. For now, it's fine for a transport driver
to stay with the old layout: It needs, however, a way to access
the locations of the avail/used rings so it can register them with
the host.

Reviewed-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
include/linux/virtio.h | 3 +++
drivers/virtio/virtio_ring.c | 16 ++++++++++++++++
2 files changed, 19 insertions(+)

diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 149284e..d6359a5 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -75,6 +75,9 @@ unsigned int virtqueue_get_vring_size(struct virtqueue *vq);

bool virtqueue_is_broken(struct virtqueue *vq);

+void *virtqueue_get_avail(struct virtqueue *vq);
+void *virtqueue_get_used(struct virtqueue *vq);
* virtio_device - representation of a device using virtio
* @index: unique position on the virtio bus
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 0d3c737..55532a4 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -827,4 +827,20 @@ void virtio_break_device(struct virtio_device *dev)

+void *virtqueue_get_avail(struct virtqueue *_vq)
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ return vq->vring.avail;
+void *virtqueue_get_used(struct virtqueue *_vq)
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ return vq->vring.used;

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