[dpdk-dev] [RFC 1/2] vhost: add packed ring support to vring base requests

[Maxime Coquelin <maxime.coquelin@redhat.com>]

For consistency with Vhost kernel backend, save the wrap
counter value into bit 31 of num's vring state field.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost_user.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index a2d4c9ffc..31cfdf163 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -648,10 +648,15 @@ static int
 vhost_user_set_vring_base(struct virtio_net *dev,
 			  VhostUserMsg *msg)
 {
-	dev->virtqueue[msg->payload.state.index]->last_used_idx  =
-			msg->payload.state.num;
-	dev->virtqueue[msg->payload.state.index]->last_avail_idx =
-			msg->payload.state.num;
+	struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];
+	if (dev->features & (1ULL << VIRTIO_F_RING_PACKED)) {
+		vq->avail_wrap_counter = msg->payload.state.num >> 31;
+		vq->used_wrap_counter = vq->avail_wrap_counter;
+		msg->payload.state.num &= ~(1 << 31);
+	}
+
+	vq->last_used_idx = msg->payload.state.num;
+	vq->last_avail_idx = msg->payload.state.num;
 
 	return 0;
 }
@@ -1083,6 +1088,9 @@ vhost_user_get_vring_base(struct virtio_net *dev,
 	/* Here we are safe to get the last avail index */
 	msg->payload.state.num = vq->last_avail_idx;
 
+	if (dev->features & (1ULL << VIRTIO_F_RING_PACKED))
+		msg->payload.state.num |= vq->avail_wrap_counter << 31;
+
 	RTE_LOG(INFO, VHOST_CONFIG,
 		"vring base idx:%d file:%d\n", msg->payload.state.index,
 		msg->payload.state.num);
-- 
2.17.1