[PATCH for-next v2 2/6] RDMA/rxe: Handle loopback of mcast packets

[Bob Pearson <rpearsonhpe@gmail.com>]

Currently the rdma_rxe driver does not send mcast packets correctly.
It does not loop mcast packets back to local qp's which belong to
the same mcast group. It also uses the wrong qp number for the
packets.

Add code to rxe_xmit_packet() to correctly handle mcast packets
which must be sent on the wire and also duplicated to any local qp's
which may belong the mcast group, but not including the sender.

Add a mask bit to indicate that a multicast packet has been locally
sent and use to set the correct qpn for multicast packets and
identify mcast packets when sending.

Fixes: 8700e3e7c485 ("Soft RoCE driver")
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
---
 drivers/infiniband/sw/rxe/rxe_av.c     |  7 +++++++
 drivers/infiniband/sw/rxe/rxe_loc.h    |  1 +
 drivers/infiniband/sw/rxe/rxe_net.c    | 26 +++++++++++++++++++++++++-
 drivers/infiniband/sw/rxe/rxe_opcode.h |  2 +-
 drivers/infiniband/sw/rxe/rxe_recv.c   |  4 ++++
 drivers/infiniband/sw/rxe/rxe_req.c    | 11 +++++++++--
 6 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_av.c b/drivers/infiniband/sw/rxe/rxe_av.c
index 4ac17b8def28..022173eb5d75 100644
--- a/drivers/infiniband/sw/rxe/rxe_av.c
+++ b/drivers/infiniband/sw/rxe/rxe_av.c
@@ -7,6 +7,13 @@
 #include "rxe.h"
 #include "rxe_loc.h"
 
+bool rxe_is_mcast_av(struct rxe_av *av)
+{
+	struct in6_addr *daddr = (struct in6_addr *)av->grh.dgid.raw;
+
+	return rdma_is_multicast_addr(daddr);
+}
+
 void rxe_init_av(struct rdma_ah_attr *attr, struct rxe_av *av)
 {
 	rxe_av_from_attr(rdma_ah_get_port_num(attr), av, attr);
diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
index 3d2504a0ae56..62b2b25903fc 100644
--- a/drivers/infiniband/sw/rxe/rxe_loc.h
+++ b/drivers/infiniband/sw/rxe/rxe_loc.h
@@ -8,6 +8,7 @@
 #define RXE_LOC_H
 
 /* rxe_av.c */
+bool rxe_is_mcast_av(struct rxe_av *av);
 void rxe_init_av(struct rdma_ah_attr *attr, struct rxe_av *av);
 int rxe_chk_ah_attr(struct rxe_dev *rxe, struct rdma_ah_attr *attr);
 void rxe_av_from_attr(u8 port_num, struct rxe_av *av,
diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
index cd59666158b1..b72f3397ff6b 100644
--- a/drivers/infiniband/sw/rxe/rxe_net.c
+++ b/drivers/infiniband/sw/rxe/rxe_net.c
@@ -412,6 +412,28 @@ static int rxe_loopback(struct sk_buff *skb, struct rxe_pkt_info *pkt)
 	return 0;
 }
 
+/*
+ * For a multicast packet, must send remotely and looback to any local qps
+ * that may belong to the mcast group.
+ */
+static int rxe_loop_and_send(struct sk_buff *skb, struct rxe_pkt_info *pkt)
+{
+	struct sk_buff *cskb;
+	int err, loc_err = 0;
+
+	if (atomic_read(&pkt->rxe->mcg_num)) {
+		loc_err = -ENOMEM;
+		cskb = skb_clone(skb, GFP_KERNEL);
+		if (cskb)
+			loc_err = rxe_loopback(cskb, pkt);
+	}
+
+	err = rxe_send(skb, pkt);
+	if (loc_err)
+		err = loc_err;
+	return err;
+}
+
 int rxe_xmit_packet(struct rxe_qp *qp, struct rxe_pkt_info *pkt,
 		    struct sk_buff *skb)
 {
@@ -431,7 +453,9 @@ int rxe_xmit_packet(struct rxe_qp *qp, struct rxe_pkt_info *pkt,
 
 	rxe_icrc_generate(skb, pkt);
 
-	if (pkt->mask & RXE_LOOPBACK_MASK)
+	if (pkt->mask & RXE_MCAST_MASK)
+		err = rxe_loop_and_send(skb, pkt);
+	else if (pkt->mask & RXE_LOOPBACK_MASK)
 		err = rxe_loopback(skb, pkt);
 	else
 		err = rxe_send(skb, pkt);
diff --git a/drivers/infiniband/sw/rxe/rxe_opcode.h b/drivers/infiniband/sw/rxe/rxe_opcode.h
index 5686b691d6b8..c4cf672ea26d 100644
--- a/drivers/infiniband/sw/rxe/rxe_opcode.h
+++ b/drivers/infiniband/sw/rxe/rxe_opcode.h
@@ -85,7 +85,7 @@ enum rxe_hdr_mask {
 	RXE_END_MASK		= BIT(NUM_HDR_TYPES + 11),
 
 	RXE_LOOPBACK_MASK	= BIT(NUM_HDR_TYPES + 12),
-
+	RXE_MCAST_MASK		= BIT(NUM_HDR_TYPES + 13),
 	RXE_ATOMIC_WRITE_MASK   = BIT(NUM_HDR_TYPES + 14),
 
 	RXE_READ_OR_ATOMIC_MASK	= (RXE_READ_MASK | RXE_ATOMIC_MASK),
diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index 5861e4244049..7153de0799fc 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -217,6 +217,10 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
 	list_for_each_entry(mca, &mcg->qp_list, qp_list) {
 		qp = mca->qp;
 
+		/* don't reply packet to sender if locally sent */
+		if (pkt->mask & RXE_MCAST_MASK && qp_num(qp) == deth_sqp(pkt))
+			continue;
+
 		/* validate qp for incoming packet */
 		err = check_type_state(rxe, pkt, qp);
 		if (err)
diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c
index d8c41fd626a9..599bec88cb54 100644
--- a/drivers/infiniband/sw/rxe/rxe_req.c
+++ b/drivers/infiniband/sw/rxe/rxe_req.c
@@ -442,8 +442,12 @@ static struct sk_buff *init_req_packet(struct rxe_qp *qp,
 			(pkt->mask & (RXE_WRITE_MASK | RXE_IMMDT_MASK)) ==
 			(RXE_WRITE_MASK | RXE_IMMDT_MASK));
 
-	qp_num = (pkt->mask & RXE_DETH_MASK) ? ibwr->wr.ud.remote_qpn :
-					 qp->attr.dest_qp_num;
+	if (pkt->mask & RXE_MCAST_MASK)
+		qp_num = IB_MULTICAST_QPN;
+	else if (pkt->mask & RXE_DETH_MASK)
+		qp_num = ibwr->wr.ud.remote_qpn;
+	else
+		qp_num = qp->attr.dest_qp_num;
 
 	ack_req = ((pkt->mask & RXE_END_MASK) ||
 		(qp->req.noack_pkts++ > RXE_MAX_PKT_PER_ACK));
@@ -809,6 +813,9 @@ int rxe_requester(struct rxe_qp *qp)
 		goto err;
 	}
 
+	if (rxe_is_mcast_av(av))
+		pkt.mask |= RXE_MCAST_MASK;
+
 	skb = init_req_packet(qp, av, wqe, opcode, payload, &pkt);
 	if (unlikely(!skb)) {
 		rxe_dbg_qp(qp, "Failed allocating skb\n");
-- 
2.40.1