RDMA/cxgb3: Support peer-2-peer connection setup

Open MPI, Intel MPI and other applications don't respect the iWARP
requirement that the client (active) side of the connection send the
first RDMA message.  This class of application connection setup is
called peer-to-peer.  Typically once the connection is setup, _both_
sides want to send data.

This patch enables supporting peer-to-peer over the chelsio RNIC by
enforcing this iWARP requirement in the driver itself as part of RDMA
connection setup.

Connection setup is extended, when the peer2peer module option is 1,
such that the MPA initiator will send a 0B Read (the RTR) just after
connection setup.  The MPA responder will suspend SQ processing until
the RTR message is received and reply-to.

In the longer term, this will be handled in a standardized way by
enhancing the MPA negotiation so peers can indicate whether they
want/need the RTR and what type of RTR (0B read, 0B write, or 0B send)
should be sent.  This will be done by standardizing a few bits of the
private data in order to negotiate all this.  However this patch
enables peer-to-peer applications now and allows most of the required
firmware and driver changes to be done and tested now.

Design:

 - Add a module option, peer2peer, to enable this mode.

 - New firmware support for peer-to-peer mode:

	- a new bit in the rdma_init WR to tell it to do peer-2-peer
	  and what form of RTR message to send or expect.

	- process _all_ preposted recvs before moving the connection
	  into rdma mode.

	- passive side: defer completing the rdma_init WR until all
	  pre-posted recvs are processed.  Suspend SQ processing until
	  the RTR is received.

	- active side: expect and process the 0B read WR on offload TX
	  queue. Defer completing the rdma_init WR until all
	  pre-posted recvs are processed.  Suspend SQ processing until
	  the 0B read WR is processed from the offload TX queue.

 - If peer2peer is set, driver posts 0B read request on offload TX
   queue just after posting the rdma_init WR to the offload TX queue.

 - Add CQ poll logic to ignore unsolicitied read responses.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 49 insertions, 18 deletions

diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index 0b515d899f6..d44a6df9ad8 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_cm.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_cm.c
@@ -63,6 +63,10 @@ static char *states[] = {
 	NULL,
 };
 
+int peer2peer = 0;
+module_param(peer2peer, int, 0644);
+MODULE_PARM_DESC(peer2peer, "Support peer2peer ULPs (default=0)");
+
 static int ep_timeout_secs = 10;
 module_param(ep_timeout_secs, int, 0644);
 MODULE_PARM_DESC(ep_timeout_secs, "CM Endpoint operation timeout "
@@ -514,7 +518,7 @@ static void send_mpa_req(struct iwch_ep *ep, struct sk_buff *skb)
 	skb_reset_transport_header(skb);
 	len = skb->len;
 	req = (struct tx_data_wr *) skb_push(skb, sizeof(*req));
-	req->wr_hi = htonl(V_WR_OP(FW_WROPCODE_OFLD_TX_DATA));
+	req->wr_hi = htonl(V_WR_OP(FW_WROPCODE_OFLD_TX_DATA)|F_WR_COMPL);
 	req->wr_lo = htonl(V_WR_TID(ep->hwtid));
 	req->len = htonl(len);
 	req->param = htonl(V_TX_PORT(ep->l2t->smt_idx) |
@@ -565,7 +569,7 @@ static int send_mpa_reject(struct iwch_ep *ep, const void *pdata, u8 plen)
 	set_arp_failure_handler(skb, arp_failure_discard);
 	skb_reset_transport_header(skb);
 	req = (struct tx_data_wr *) skb_push(skb, sizeof(*req));
-	req->wr_hi = htonl(V_WR_OP(FW_WROPCODE_OFLD_TX_DATA));
+	req->wr_hi = htonl(V_WR_OP(FW_WROPCODE_OFLD_TX_DATA)|F_WR_COMPL);
 	req->wr_lo = htonl(V_WR_TID(ep->hwtid));
 	req->len = htonl(mpalen);
 	req->param = htonl(V_TX_PORT(ep->l2t->smt_idx) |
@@ -617,7 +621,7 @@ static int send_mpa_reply(struct iwch_ep *ep, const void *pdata, u8 plen)
 	skb_reset_transport_header(skb);
 	len = skb->len;
 	req = (struct tx_data_wr *) skb_push(skb, sizeof(*req));
-	req->wr_hi = htonl(V_WR_OP(FW_WROPCODE_OFLD_TX_DATA));
+	req->wr_hi = htonl(V_WR_OP(FW_WROPCODE_OFLD_TX_DATA)|F_WR_COMPL);
 	req->wr_lo = htonl(V_WR_TID(ep->hwtid));
 	req->len = htonl(len);
 	req->param = htonl(V_TX_PORT(ep->l2t->smt_idx) |
@@ -885,6 +889,7 @@ static void process_mpa_reply(struct iwch_ep *ep, struct sk_buff *skb)
 	 * the MPA header is valid.
 	 */
 	state_set(&ep->com, FPDU_MODE);
+	ep->mpa_attr.initiator = 1;
 	ep->mpa_attr.crc_enabled = (mpa->flags & MPA_CRC) | crc_enabled ? 1 : 0;
 	ep->mpa_attr.recv_marker_enabled = markers_enabled;
 	ep->mpa_attr.xmit_marker_enabled = mpa->flags & MPA_MARKERS ? 1 : 0;
@@ -907,8 +912,14 @@ static void process_mpa_reply(struct iwch_ep *ep, struct sk_buff *skb)
 	/* bind QP and TID with INIT_WR */
 	err = iwch_modify_qp(ep->com.qp->rhp,
 			     ep->com.qp, mask, &attrs, 1);
-	if (!err)
-		goto out;
+	if (err)
+		goto err;
+
+	if (peer2peer && iwch_rqes_posted(ep->com.qp) == 0) {
+		iwch_post_zb_read(ep->com.qp);
+	}
+
+	goto out;
 err:
 	abort_connection(ep, skb, GFP_KERNEL);
 out:
@@ -1001,6 +1012,7 @@ static void process_mpa_request(struct iwch_ep *ep, struct sk_buff *skb)
 	 * If we get here we have accumulated the entire mpa
 	 * start reply message including private data.
 	 */
+	ep->mpa_attr.initiator = 0;
 	ep->mpa_attr.crc_enabled = (mpa->flags & MPA_CRC) | crc_enabled ? 1 : 0;
 	ep->mpa_attr.recv_marker_enabled = markers_enabled;
 	ep->mpa_attr.xmit_marker_enabled = mpa->flags & MPA_MARKERS ? 1 : 0;
@@ -1071,17 +1083,33 @@ static int tx_ack(struct t3cdev *tdev, struct sk_buff *skb, void *ctx)
 
 	PDBG("%s ep %p credits %u\n", __func__, ep, credits);
 
-	if (credits == 0)
+	if (credits == 0) {
+		PDBG(KERN_ERR "%s 0 credit ack  ep %p state %u\n",
+			__func__, ep, state_read(&ep->com));
 		return CPL_RET_BUF_DONE;
+	}
+
 	BUG_ON(credits != 1);
-	BUG_ON(ep->mpa_skb == NULL);
-	kfree_skb(ep->mpa_skb);
-	ep->mpa_skb = NULL;
 	dst_confirm(ep->dst);
-	if (state_read(&ep->com) == MPA_REP_SENT) {
-		ep->com.rpl_done = 1;
-		PDBG("waking up ep %p\n", ep);
-		wake_up(&ep->com.waitq);
+	if (!ep->mpa_skb) {
+		PDBG("%s rdma_init wr_ack ep %p state %u\n",
+			__func__, ep, state_read(&ep->com));
+		if (ep->mpa_attr.initiator) {
+			PDBG("%s initiator ep %p state %u\n",
+				__func__, ep, state_read(&ep->com));
+			if (peer2peer)
+				iwch_post_zb_read(ep->com.qp);
+		} else {
+			PDBG("%s responder ep %p state %u\n",
+				__func__, ep, state_read(&ep->com));
+			ep->com.rpl_done = 1;
+			wake_up(&ep->com.waitq);
+		}
+	} else {
+		PDBG("%s lsm ack ep %p state %u freeing skb\n",
+			__func__, ep, state_read(&ep->com));
+		kfree_skb(ep->mpa_skb);
+		ep->mpa_skb = NULL;
 	}
 	return CPL_RET_BUF_DONE;
 }
@@ -1795,16 +1823,19 @@ int iwch_accept_cr(struct iw_cm_id *cm_id, struct iw_cm_conn_param *conn_param)
 	if (err)
 		goto err;
 
+	/* if needed, wait for wr_ack */
+	if (iwch_rqes_posted(qp)) {
+		wait_event(ep->com.waitq, ep->com.rpl_done);
+		err = ep->com.rpl_err;
+		if (err)
+			goto err;
+	}
+
 	err = send_mpa_reply(ep, conn_param->private_data,
 			     conn_param->private_data_len);
 	if (err)
 		goto err;
 
-	/* wait for wr_ack */
-	wait_event(ep->com.waitq, ep->com.rpl_done);
-	err = ep->com.rpl_err;
-	if (err)
-		goto err;
 
 	state_set(&ep->com, FPDU_MODE);
 	established_upcall(ep);