net/enic: initialize RQ fetch index before enabling RQ

The fetch index must be initialized only when RQ is
disabled. Otherwise, it may lead to stale entries in IG descriptor
cache on the VIC.

Fixes: a74629cfa3 ("net/enic: enable RQ first and then post Rx buffers")
Cc: stable@dpdk.org

Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>
Reviewed-by: John Daley <johndale@cisco.com>

drivers/net/enic/enic_main.c

@@ -320,6 +320,8 @@ enic_alloc_rx_queue_mbufs(struct enic *enic, struct vnic_rq *rq)
 	 * enic_start_rq().
 	 */
 	rq->need_initial_post = true;
+	/* Initialize fetch index while RQ is disabled */
+	iowrite32(0, &rq->ctrl->fetch_index);
 	return 0;
 }
 
@@ -345,7 +347,6 @@ enic_initial_post_rx(struct enic *enic, struct vnic_rq *rq)
 	dev_debug(enic, "port=%u, qidx=%u, Write %u posted idx, %u sw held\n",
 		enic->port_id, rq->index, rq->posted_index, rq->rx_nb_hold);
 	iowrite32(rq->posted_index, &rq->ctrl->posted_index);
-	iowrite32(0, &rq->ctrl->fetch_index);
 	rte_rmb();
 	rq->need_initial_post = false;
 }