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

[Jens Freimann]

On Wed, Aug 08, 2018 at 05:23:22PM +0200, Maxime Coquelin wrote:
>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 at 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;

Maybe I don't understand when this is called, but the wrap counters
could have different values, no?

Apart from that:

Reviewed-by: Jens Freimann <jfreimann at redhat.com> 

regards,
Jens