RDMA/rxe: Lookup kernel AH from ah index in UD WQEs

Add code to rxe_get_av in rxe_av.c to use the AH index in UD send WQEs to
lookup the kernel AH. For old user providers continue to use the AV passed
in WQEs. Move setting pkt->rxe to before the call to rxe_get_av() to get
access to the AH pool.

Link: https://lore.kernel.org/r/20211007204051.10086-6-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/sw/rxe/rxe_av.c

@@ -101,11 +101,29 @@ void rxe_av_fill_ip_info(struct rxe_av *av, struct rdma_ah_attr *attr)
 
 struct rxe_av *rxe_get_av(struct rxe_pkt_info *pkt)
 {
+	struct rxe_ah *ah;
+	u32 ah_num;
+
 	if (!pkt || !pkt->qp)
 		return NULL;
 
 	if (qp_type(pkt->qp) == IB_QPT_RC || qp_type(pkt->qp) == IB_QPT_UC)
 		return &pkt->qp->pri_av;
 
-	return (pkt->wqe) ? &pkt->wqe->wr.wr.ud.av : NULL;
+	if (!pkt->wqe)
+		return NULL;
+
+	ah_num = pkt->wqe->wr.wr.ud.ah_num;
+	if (ah_num) {
+		/* only new user provider or kernel client */
+		ah = rxe_pool_get_index(&pkt->rxe->ah_pool, ah_num);
+		if (!ah || ah->ah_num != ah_num || rxe_ah_pd(ah) != pkt->qp->pd) {
+			pr_warn("Unable to find AH matching ah_num\n");
+			return NULL;
+		}
+		return &ah->av;
+	}
+
+	/* only old user provider for UD sends*/
+	return &pkt->wqe->wr.wr.ud.av;
 }

drivers/infiniband/sw/rxe/rxe_req.c

@@ -379,9 +379,8 @@ static struct sk_buff *init_req_packet(struct rxe_qp *qp,
 	/* length from start of bth to end of icrc */
 	paylen = rxe_opcode[opcode].length + payload + pad + RXE_ICRC_SIZE;
 
-	/* pkt->hdr, rxe, port_num and mask are initialized in ifc
-	 * layer
-	 */
+	/* pkt->hdr, port_num and mask are initialized in ifc layer */
+	pkt->rxe	= rxe;
 	pkt->opcode	= opcode;
 	pkt->qp		= qp;
 	pkt->psn	= qp->req.psn;
@@ -391,6 +390,9 @@ static struct sk_buff *init_req_packet(struct rxe_qp *qp,
 
 	/* init skb */
 	av = rxe_get_av(pkt);
+	if (!av)
+		return NULL;
+
 	skb = rxe_init_packet(rxe, av, paylen, pkt);
 	if (unlikely(!skb))
 		return NULL;