IB/hfi1: Add functions to receive TID RDMA WRITE request

This patch adds the functions to receive TID RDMA WRITE request. The
request will be stored in the QP's s_ack_queue. This patch also adds
code to handle duplicate TID RDMA WRITE request and a function to
allocate TID resources for data receiving on the responder side.
Signed-off-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/init.c

@@ -1512,6 +1512,7 @@ static int __init hfi1_mod_init(void)
 		goto bail_dev;
 	}
 
+	hfi1_compute_tid_rdma_flow_wt();
 	/*
 	 * These must be called before the driver is registered with
 	 * the PCI subsystem.

drivers/infiniband/hw/hfi1/rc.c

@@ -2411,6 +2411,7 @@ void hfi1_rc_rcv(struct hfi1_packet *packet)
 	void *data = packet->payload;
 	u32 tlen = packet->tlen;
 	struct rvt_qp *qp = packet->qp;
+	struct hfi1_qp_priv *qpriv = qp->priv;
 	struct hfi1_ibport *ibp = rcd_to_iport(rcd);
 	struct ib_other_headers *ohdr = packet->ohdr;
 	u32 opcode = packet->opcode;
@@ -2716,6 +2717,7 @@ void hfi1_rc_rcv(struct hfi1_packet *packet)
 		qp->r_state = opcode;
 		qp->r_nak_state = 0;
 		qp->r_head_ack_queue = next;
+		qpriv->r_tid_alloc = qp->r_head_ack_queue;
 
 		/* Schedule the send engine. */
 		qp->s_flags |= RVT_S_RESP_PENDING;
@@ -2789,6 +2791,7 @@ void hfi1_rc_rcv(struct hfi1_packet *packet)
 		qp->r_state = opcode;
 		qp->r_nak_state = 0;
 		qp->r_head_ack_queue = next;
+		qpriv->r_tid_alloc = qp->r_head_ack_queue;
 
 		/* Schedule the send engine. */
 		qp->s_flags |= RVT_S_RESP_PENDING;

drivers/infiniband/hw/hfi1/tid_rdma.c

@@ -109,12 +109,15 @@ static u32 mask_generation(u32 a)
  * C - Capcode
  */
 
+static u32 tid_rdma_flow_wt;
+
 static void tid_rdma_trigger_resume(struct work_struct *work);
 static void hfi1_kern_exp_rcv_free_flows(struct tid_rdma_request *req);
 static int hfi1_kern_exp_rcv_alloc_flows(struct tid_rdma_request *req,
 					 gfp_t gfp);
 static void hfi1_init_trdma_req(struct rvt_qp *qp,
 				struct tid_rdma_request *req);
+static void hfi1_tid_write_alloc_resources(struct rvt_qp *qp, bool intr_ctx);
 
 static u64 tid_rdma_opfn_encode(struct tid_rdma_params *p)
 {
@@ -313,6 +316,11 @@ int hfi1_qp_priv_init(struct rvt_dev_info *rdi, struct rvt_qp *qp,
 	qpriv->flow_state.index = RXE_NUM_TID_FLOWS;
 	qpriv->flow_state.last_index = RXE_NUM_TID_FLOWS;
 	qpriv->flow_state.generation = KERN_GENERATION_RESERVED;
+	qpriv->rnr_nak_state = TID_RNR_NAK_INIT;
+	qpriv->r_tid_head = HFI1_QP_WQE_INVALID;
+	qpriv->r_tid_tail = HFI1_QP_WQE_INVALID;
+	qpriv->r_tid_ack = HFI1_QP_WQE_INVALID;
+	qpriv->r_tid_alloc = HFI1_QP_WQE_INVALID;
 	INIT_LIST_HEAD(&qpriv->tid_wait);
 
 	if (init_attr->qp_type == IB_QPT_RC && HFI1_CAP_IS_KSET(TID_RDMA)) {
@@ -1959,6 +1967,8 @@ static int tid_rdma_rcv_error(struct hfi1_packet *packet,
 {
 	struct hfi1_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
 	struct hfi1_ctxtdata *rcd = ((struct hfi1_qp_priv *)qp->priv)->rcd;
+	struct hfi1_ibdev *dev = to_idev(qp->ibqp.device);
+	struct hfi1_qp_priv *qpriv = qp->priv;
 	struct rvt_ack_entry *e;
 	struct tid_rdma_request *req;
 	unsigned long flags;
@@ -1982,7 +1992,8 @@ static int tid_rdma_rcv_error(struct hfi1_packet *packet,
 
 	spin_lock_irqsave(&qp->s_lock, flags);
 	e = find_prev_entry(qp, psn, &prev, NULL, &old_req);
-	if (!e || e->opcode != TID_OP(READ_REQ))
+	if (!e || (e->opcode != TID_OP(READ_REQ) &&
+		   e->opcode != TID_OP(WRITE_REQ)))
 		goto unlock;
 
 	req = ack_to_tid_req(e);
@@ -2042,6 +2053,114 @@ static int tid_rdma_rcv_error(struct hfi1_packet *packet,
 		 */
 		if (old_req)
 			goto unlock;
+	} else {
+		struct flow_state *fstate;
+		bool schedule = false;
+		u8 i;
+
+		if (req->state == TID_REQUEST_RESEND) {
+			req->state = TID_REQUEST_RESEND_ACTIVE;
+		} else if (req->state == TID_REQUEST_INIT_RESEND) {
+			req->state = TID_REQUEST_INIT;
+			schedule = true;
+		}
+
+		/*
+		 * True if the request is already scheduled (between
+		 * qp->s_tail_ack_queue and qp->r_head_ack_queue).
+		 * Also, don't change requests, which are at the SYNC
+		 * point and haven't generated any responses yet.
+		 * There is nothing to retransmit for them yet.
+		 */
+		if (old_req || req->state == TID_REQUEST_INIT ||
+		    (req->state == TID_REQUEST_SYNC && !req->cur_seg)) {
+			for (i = prev + 1; ; i++) {
+				if (i > rvt_size_atomic(&dev->rdi))
+					i = 0;
+				if (i == qp->r_head_ack_queue)
+					break;
+				e = &qp->s_ack_queue[i];
+				req = ack_to_tid_req(e);
+				if (e->opcode == TID_OP(WRITE_REQ) &&
+				    req->state == TID_REQUEST_INIT)
+					req->state = TID_REQUEST_INIT_RESEND;
+			}
+			/*
+			 * If the state of the request has been changed,
+			 * the first leg needs to get scheduled in order to
+			 * pick up the change. Otherwise, normal response
+			 * processing should take care of it.
+			 */
+			if (!schedule)
+				goto unlock;
+		}
+
+		/*
+		 * If there is no more allocated segment, just schedule the qp
+		 * without changing any state.
+		 */
+		if (req->clear_tail == req->setup_head)
+			goto schedule;
+		/*
+		 * If this request has sent responses for segments, which have
+		 * not received data yet (flow_idx != clear_tail), the flow_idx
+		 * pointer needs to be adjusted so the same responses can be
+		 * re-sent.
+		 */
+		if (CIRC_CNT(req->flow_idx, req->clear_tail, MAX_FLOWS)) {
+			fstate = &req->flows[req->clear_tail].flow_state;
+			qpriv->pending_tid_w_segs -=
+				CIRC_CNT(req->flow_idx, req->clear_tail,
+					 MAX_FLOWS);
+			req->flow_idx =
+				CIRC_ADD(req->clear_tail,
+					 delta_psn(psn, fstate->resp_ib_psn),
+					 MAX_FLOWS);
+			qpriv->pending_tid_w_segs +=
+				delta_psn(psn, fstate->resp_ib_psn);
+			/*
+			 * When flow_idx == setup_head, we've gotten a duplicate
+			 * request for a segment, which has not been allocated
+			 * yet. In that case, don't adjust this request.
+			 * However, we still want to go through the loop below
+			 * to adjust all subsequent requests.
+			 */
+			if (CIRC_CNT(req->setup_head, req->flow_idx,
+				     MAX_FLOWS)) {
+				req->cur_seg = delta_psn(psn, e->psn);
+				req->state = TID_REQUEST_RESEND_ACTIVE;
+			}
+		}
+
+		for (i = prev + 1; ; i++) {
+			/*
+			 * Look at everything up to and including
+			 * s_tail_ack_queue
+			 */
+			if (i > rvt_size_atomic(&dev->rdi))
+				i = 0;
+			if (i == qp->r_head_ack_queue)
+				break;
+			e = &qp->s_ack_queue[i];
+			req = ack_to_tid_req(e);
+			trace_hfi1_tid_req_rcv_err(qp, 0, e->opcode, e->psn,
+						   e->lpsn, req);
+			if (e->opcode != TID_OP(WRITE_REQ) ||
+			    req->cur_seg == req->comp_seg ||
+			    req->state == TID_REQUEST_INIT ||
+			    req->state == TID_REQUEST_INIT_RESEND) {
+				if (req->state == TID_REQUEST_INIT)
+					req->state = TID_REQUEST_INIT_RESEND;
+				continue;
+			}
+			qpriv->pending_tid_w_segs -=
+				CIRC_CNT(req->flow_idx,
+					 req->clear_tail,
+					 MAX_FLOWS);
+			req->flow_idx = req->clear_tail;
+			req->state = TID_REQUEST_RESEND;
+			req->cur_seg = req->comp_seg;
+		}
 	}
 	/* Re-process old requests.*/
 	if (qp->s_acked_ack_queue == qp->s_tail_ack_queue)
@@ -2054,6 +2173,18 @@ static int tid_rdma_rcv_error(struct hfi1_packet *packet,
 	 * wrong memory region.
 	 */
 	qp->s_ack_state = OP(ACKNOWLEDGE);
+schedule:
+	/*
+	 * It's possible to receive a retry psn that is earlier than an RNRNAK
+	 * psn. In this case, the rnrnak state should be cleared.
+	 */
+	if (qpriv->rnr_nak_state) {
+		qp->s_nak_state = 0;
+		qpriv->rnr_nak_state = TID_RNR_NAK_INIT;
+		qp->r_psn = e->lpsn + 1;
+		hfi1_tid_write_alloc_resources(qp, true);
+	}
+
 	qp->r_state = e->opcode;
 	qp->r_nak_state = 0;
 	qp->s_flags |= RVT_S_RESP_PENDING;
@@ -2164,6 +2295,14 @@ void hfi1_rc_rcv_tid_rdma_read_req(struct hfi1_packet *packet)
 
 	qp->r_head_ack_queue = next;
 
+	/*
+	 * For all requests other than TID WRITE which are added to the ack
+	 * queue, qpriv->r_tid_alloc follows qp->r_head_ack_queue. It is ok to
+	 * do this because of interlocks between these and TID WRITE
+	 * requests. The same change has also been made in hfi1_rc_rcv().
+	 */
+	qpriv->r_tid_alloc = qp->r_head_ack_queue;
+
 	/* Schedule the send tasklet. */
 	qp->s_flags |= RVT_S_RESP_PENDING;
 	hfi1_schedule_send(qp);
@@ -3015,3 +3154,432 @@ u32 hfi1_build_tid_rdma_write_req(struct rvt_qp *qp, struct rvt_swqe *wqe,
 	rcu_read_unlock();
 	return sizeof(ohdr->u.tid_rdma.w_req) / sizeof(u32);
 }
+
+void hfi1_compute_tid_rdma_flow_wt(void)
+{
+	/*
+	 * Heuristic for computing the RNR timeout when waiting on the flow
+	 * queue. Rather than a computationaly expensive exact estimate of when
+	 * a flow will be available, we assume that if a QP is at position N in
+	 * the flow queue it has to wait approximately (N + 1) * (number of
+	 * segments between two sync points), assuming PMTU of 4K. The rationale
+	 * for this is that flows are released and recycled at each sync point.
+	 */
+	tid_rdma_flow_wt = MAX_TID_FLOW_PSN * enum_to_mtu(OPA_MTU_4096) /
+		TID_RDMA_MAX_SEGMENT_SIZE;
+}
+
+static u32 position_in_queue(struct hfi1_qp_priv *qpriv,
+			     struct tid_queue *queue)
+{
+	return qpriv->tid_enqueue - queue->dequeue;
+}
+
+/*
+ * @qp: points to rvt_qp context.
+ * @to_seg: desired RNR timeout in segments.
+ * Return: index of the next highest timeout in the ib_hfi1_rnr_table[]
+ */
+static u32 hfi1_compute_tid_rnr_timeout(struct rvt_qp *qp, u32 to_seg)
+{
+	struct hfi1_qp_priv *qpriv = qp->priv;
+	u64 timeout;
+	u32 bytes_per_us;
+	u8 i;
+
+	bytes_per_us = active_egress_rate(qpriv->rcd->ppd) / 8;
+	timeout = (to_seg * TID_RDMA_MAX_SEGMENT_SIZE) / bytes_per_us;
+	/*
+	 * Find the next highest value in the RNR table to the required
+	 * timeout. This gives the responder some padding.
+	 */
+	for (i = 1; i <= IB_AETH_CREDIT_MASK; i++)
+		if (rvt_rnr_tbl_to_usec(i) >= timeout)
+			return i;
+	return 0;
+}
+
+/**
+ * Central place for resource allocation at TID write responder,
+ * is called from write_req and write_data interrupt handlers as
+ * well as the send thread when a queued QP is scheduled for
+ * resource allocation.
+ *
+ * Iterates over (a) segments of a request and then (b) queued requests
+ * themselves to allocate resources for up to local->max_write
+ * segments across multiple requests. Stop allocating when we
+ * hit a sync point, resume allocating after data packets at
+ * sync point have been received.
+ *
+ * Resource allocation and sending of responses is decoupled. The
+ * request/segment which are being allocated and sent are as follows.
+ * Resources are allocated for:
+ *     [request: qpriv->r_tid_alloc, segment: req->alloc_seg]
+ * The send thread sends:
+ *     [request: qp->s_tail_ack_queue, segment:req->cur_seg]
+ */
+static void hfi1_tid_write_alloc_resources(struct rvt_qp *qp, bool intr_ctx)
+{
+	struct tid_rdma_request *req;
+	struct hfi1_qp_priv *qpriv = qp->priv;
+	struct hfi1_ctxtdata *rcd = qpriv->rcd;
+	struct tid_rdma_params *local = &qpriv->tid_rdma.local;
+	struct rvt_ack_entry *e;
+	u32 npkts, to_seg;
+	bool last;
+	int ret = 0;
+
+	lockdep_assert_held(&qp->s_lock);
+
+	while (1) {
+		/*
+		 * Don't allocate more segments if a RNR NAK has already been
+		 * scheduled to avoid messing up qp->r_psn: the RNR NAK will
+		 * be sent only when all allocated segments have been sent.
+		 * However, if more segments are allocated before that, TID RDMA
+		 * WRITE RESP packets will be sent out for these new segments
+		 * before the RNR NAK packet. When the requester receives the
+		 * RNR NAK packet, it will restart with qp->s_last_psn + 1,
+		 * which does not match qp->r_psn and will be dropped.
+		 * Consequently, the requester will exhaust its retries and
+		 * put the qp into error state.
+		 */
+		if (qpriv->rnr_nak_state == TID_RNR_NAK_SEND)
+			break;
+
+		/* No requests left to process */
+		if (qpriv->r_tid_alloc == qpriv->r_tid_head) {
+			/* If all data has been received, clear the flow */
+			if (qpriv->flow_state.index < RXE_NUM_TID_FLOWS &&
+			    !qpriv->alloc_w_segs)
+				hfi1_kern_clear_hw_flow(rcd, qp);
+			break;
+		}
+
+		e = &qp->s_ack_queue[qpriv->r_tid_alloc];
+		if (e->opcode != TID_OP(WRITE_REQ))
+			goto next_req;
+		req = ack_to_tid_req(e);
+		/* Finished allocating for all segments of this request */
+		if (req->alloc_seg >= req->total_segs)
+			goto next_req;
+
+		/* Can allocate only a maximum of local->max_write for a QP */
+		if (qpriv->alloc_w_segs >= local->max_write)
+			break;
+
+		/* Don't allocate at a sync point with data packets pending */
+		if (qpriv->sync_pt && qpriv->alloc_w_segs)
+			break;
+
+		/* All data received at the sync point, continue */
+		if (qpriv->sync_pt && !qpriv->alloc_w_segs) {
+			hfi1_kern_clear_hw_flow(rcd, qp);
+			qpriv->sync_pt = false;
+			if (qpriv->s_flags & HFI1_R_TID_SW_PSN)
+				qpriv->s_flags &= ~HFI1_R_TID_SW_PSN;
+		}
+
+		/* Allocate flow if we don't have one */
+		if (qpriv->flow_state.index >= RXE_NUM_TID_FLOWS) {
+			ret = hfi1_kern_setup_hw_flow(qpriv->rcd, qp);
+			if (ret) {
+				to_seg = tid_rdma_flow_wt *
+					position_in_queue(qpriv,
+							  &rcd->flow_queue);
+				break;
+			}
+		}
+
+		npkts = rvt_div_round_up_mtu(qp, req->seg_len);
+
+		/*
+		 * We are at a sync point if we run out of KDETH PSN space.
+		 * Last PSN of every generation is reserved for RESYNC.
+		 */
+		if (qpriv->flow_state.psn + npkts > MAX_TID_FLOW_PSN - 1) {
+			qpriv->sync_pt = true;
+			break;
+		}
+
+		/*
+		 * If overtaking req->acked_tail, send an RNR NAK. Because the
+		 * QP is not queued in this case, and the issue can only be
+		 * caused due a delay in scheduling the second leg which we
+		 * cannot estimate, we use a rather arbitrary RNR timeout of
+		 * (MAX_FLOWS / 2) segments
+		 */
+		if (!CIRC_SPACE(req->setup_head, req->acked_tail,
+				MAX_FLOWS)) {
+			ret = -EAGAIN;
+			to_seg = MAX_FLOWS >> 1;
+			qpriv->s_flags |= RVT_S_ACK_PENDING;
+			break;
+		}
+
+		/* Try to allocate rcv array / TID entries */
+		ret = hfi1_kern_exp_rcv_setup(req, &req->ss, &last);
+		if (ret == -EAGAIN)
+			to_seg = position_in_queue(qpriv, &rcd->rarr_queue);
+		if (ret)
+			break;
+
+		qpriv->alloc_w_segs++;
+		req->alloc_seg++;
+		continue;
+next_req:
+		/* Begin processing the next request */
+		if (++qpriv->r_tid_alloc >
+		    rvt_size_atomic(ib_to_rvt(qp->ibqp.device)))
+			qpriv->r_tid_alloc = 0;
+	}
+
+	/*
+	 * Schedule an RNR NAK to be sent if (a) flow or rcv array allocation
+	 * has failed (b) we are called from the rcv handler interrupt context
+	 * (c) an RNR NAK has not already been scheduled
+	 */
+	if (ret == -EAGAIN && intr_ctx && !qp->r_nak_state)
+		goto send_rnr_nak;
+
+	return;
+
+send_rnr_nak:
+	lockdep_assert_held(&qp->r_lock);
+
+	/* Set r_nak_state to prevent unrelated events from generating NAK's */
+	qp->r_nak_state = hfi1_compute_tid_rnr_timeout(qp, to_seg) | IB_RNR_NAK;
+
+	/* Pull back r_psn to the segment being RNR NAK'd */
+	qp->r_psn = e->psn + req->alloc_seg;
+	qp->r_ack_psn = qp->r_psn;
+	/*
+	 * Pull back r_head_ack_queue to the ack entry following the request
+	 * being RNR NAK'd. This allows resources to be allocated to the request
+	 * if the queued QP is scheduled.
+	 */
+	qp->r_head_ack_queue = qpriv->r_tid_alloc + 1;
+	if (qp->r_head_ack_queue > rvt_size_atomic(ib_to_rvt(qp->ibqp.device)))
+		qp->r_head_ack_queue = 0;
+	qpriv->r_tid_head = qp->r_head_ack_queue;
+	/*
+	 * These send side fields are used in make_rc_ack(). They are set in
+	 * hfi1_send_rc_ack() but must be set here before dropping qp->s_lock
+	 * for consistency
+	 */
+	qp->s_nak_state = qp->r_nak_state;
+	qp->s_ack_psn = qp->r_ack_psn;
+	/*
+	 * Clear the ACK PENDING flag to prevent unwanted ACK because we
+	 * have modified qp->s_ack_psn here.
+	 */
+	qp->s_flags &= ~(RVT_S_ACK_PENDING);
+
+	/*
+	 * qpriv->rnr_nak_state is used to determine when the scheduled RNR NAK
+	 * has actually been sent. qp->s_flags RVT_S_ACK_PENDING bit cannot be
+	 * used for this because qp->s_lock is dropped before calling
+	 * hfi1_send_rc_ack() leading to inconsistency between the receive
+	 * interrupt handlers and the send thread in make_rc_ack()
+	 */
+	qpriv->rnr_nak_state = TID_RNR_NAK_SEND;
+
+	/*
+	 * Schedule RNR NAK to be sent. RNR NAK's are scheduled from the receive
+	 * interrupt handlers but will be sent from the send engine behind any
+	 * previous responses that may have been scheduled
+	 */
+	rc_defered_ack(rcd, qp);
+}
+
+void hfi1_rc_rcv_tid_rdma_write_req(struct hfi1_packet *packet)
+{
+	/* HANDLER FOR TID RDMA WRITE REQUEST packet (Responder side)*/
+
+	/*
+	 * 1. Verify TID RDMA WRITE REQ as per IB_OPCODE_RC_RDMA_WRITE_FIRST
+	 *    (see hfi1_rc_rcv())
+	 *     - Don't allow 0-length requests.
+	 * 2. Put TID RDMA WRITE REQ into the response queueu (s_ack_queue)
+	 *     - Setup struct tid_rdma_req with request info
+	 *     - Prepare struct tid_rdma_flow array?
+	 * 3. Set the qp->s_ack_state as state diagram in design doc.
+	 * 4. Set RVT_S_RESP_PENDING in s_flags.
+	 * 5. Kick the send engine (hfi1_schedule_send())
+	 */
+	struct hfi1_ctxtdata *rcd = packet->rcd;
+	struct rvt_qp *qp = packet->qp;
+	struct hfi1_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
+	struct ib_other_headers *ohdr = packet->ohdr;
+	struct rvt_ack_entry *e;
+	unsigned long flags;
+	struct ib_reth *reth;
+	struct hfi1_qp_priv *qpriv = qp->priv;
+	struct tid_rdma_request *req;
+	u32 bth0, psn, len, rkey, num_segs;
+	bool is_fecn;
+	u8 next;
+	u64 vaddr;
+	int diff;
+
+	bth0 = be32_to_cpu(ohdr->bth[0]);
+	if (hfi1_ruc_check_hdr(ibp, packet))
+		return;
+
+	is_fecn = process_ecn(qp, packet);
+	psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
+
+	if (qp->state == IB_QPS_RTR && !(qp->r_flags & RVT_R_COMM_EST))
+		rvt_comm_est(qp);
+
+	if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
+		goto nack_inv;
+
+	reth = &ohdr->u.tid_rdma.w_req.reth;
+	vaddr = be64_to_cpu(reth->vaddr);
+	len = be32_to_cpu(reth->length);
+
+	num_segs = DIV_ROUND_UP(len, qpriv->tid_rdma.local.max_len);
+	diff = delta_psn(psn, qp->r_psn);
+	if (unlikely(diff)) {
+		if (tid_rdma_rcv_error(packet, ohdr, qp, psn, diff))
+			return;
+		goto send_ack;
+	}
+
+	/*
+	 * The resent request which was previously RNR NAK'd is inserted at the
+	 * location of the original request, which is one entry behind
+	 * r_head_ack_queue
+	 */
+	if (qpriv->rnr_nak_state)
+		qp->r_head_ack_queue = qp->r_head_ack_queue ?
+			qp->r_head_ack_queue - 1 :
+			rvt_size_atomic(ib_to_rvt(qp->ibqp.device));
+
+	/* We've verified the request, insert it into the ack queue. */
+	next = qp->r_head_ack_queue + 1;
+	if (next > rvt_size_atomic(ib_to_rvt(qp->ibqp.device)))
+		next = 0;
+	spin_lock_irqsave(&qp->s_lock, flags);
+	if (unlikely(next == qp->s_acked_ack_queue)) {
+		if (!qp->s_ack_queue[next].sent)
+			goto nack_inv_unlock;
+		update_ack_queue(qp, next);
+	}
+	e = &qp->s_ack_queue[qp->r_head_ack_queue];
+	req = ack_to_tid_req(e);
+
+	/* Bring previously RNR NAK'd request back to life */
+	if (qpriv->rnr_nak_state) {
+		qp->r_nak_state = 0;
+		qp->s_nak_state = 0;
+		qpriv->rnr_nak_state = TID_RNR_NAK_INIT;
+		qp->r_psn = e->lpsn + 1;
+		req->state = TID_REQUEST_INIT;
+		goto update_head;
+	}
+
+	if (e->rdma_sge.mr) {
+		rvt_put_mr(e->rdma_sge.mr);
+		e->rdma_sge.mr = NULL;
+	}
+
+	/* The length needs to be in multiples of PAGE_SIZE */
+	if (!len || len & ~PAGE_MASK)
+		goto nack_inv_unlock;
+
+	rkey = be32_to_cpu(reth->rkey);
+	qp->r_len = len;
+
+	if (e->opcode == TID_OP(WRITE_REQ) &&
+	    (req->setup_head != req->clear_tail ||
+	     req->clear_tail != req->acked_tail))
+		goto nack_inv_unlock;
+
+	if (unlikely(!rvt_rkey_ok(qp, &e->rdma_sge, qp->r_len, vaddr,
+				  rkey, IB_ACCESS_REMOTE_WRITE)))
+		goto nack_acc;
+
+	qp->r_psn += num_segs - 1;
+
+	e->opcode = (bth0 >> 24) & 0xff;
+	e->psn = psn;
+	e->lpsn = qp->r_psn;
+	e->sent = 0;
+
+	req->n_flows = min_t(u16, num_segs, qpriv->tid_rdma.local.max_write);
+	req->state = TID_REQUEST_INIT;
+	req->cur_seg = 0;
+	req->comp_seg = 0;
+	req->ack_seg = 0;
+	req->alloc_seg = 0;
+	req->isge = 0;
+	req->seg_len = qpriv->tid_rdma.local.max_len;
+	req->total_len = len;
+	req->total_segs = num_segs;
+	req->r_flow_psn = e->psn;
+	req->ss.sge = e->rdma_sge;
+	req->ss.num_sge = 1;
+
+	req->flow_idx = req->setup_head;
+	req->clear_tail = req->setup_head;
+	req->acked_tail = req->setup_head;
+
+	qp->r_state = e->opcode;
+	qp->r_nak_state = 0;
+	/*
+	 * We need to increment the MSN here instead of when we
+	 * finish sending the result since a duplicate request would
+	 * increment it more than once.
+	 */
+	qp->r_msn++;
+	qp->r_psn++;
+
+	if (qpriv->r_tid_tail == HFI1_QP_WQE_INVALID) {
+		qpriv->r_tid_tail = qp->r_head_ack_queue;
+	} else if (qpriv->r_tid_tail == qpriv->r_tid_head) {
+		struct tid_rdma_request *ptr;
+
+		e = &qp->s_ack_queue[qpriv->r_tid_tail];
+		ptr = ack_to_tid_req(e);
+
+		if (e->opcode != TID_OP(WRITE_REQ) ||
+		    ptr->comp_seg == ptr->total_segs) {
+			if (qpriv->r_tid_tail == qpriv->r_tid_ack)
+				qpriv->r_tid_ack = qp->r_head_ack_queue;
+			qpriv->r_tid_tail = qp->r_head_ack_queue;
+		}
+	}
+update_head:
+	qp->r_head_ack_queue = next;
+	qpriv->r_tid_head = qp->r_head_ack_queue;
+
+	hfi1_tid_write_alloc_resources(qp, true);
+
+	/* Schedule the send tasklet. */
+	qp->s_flags |= RVT_S_RESP_PENDING;
+	hfi1_schedule_send(qp);
+
+	spin_unlock_irqrestore(&qp->s_lock, flags);
+	if (is_fecn)
+		goto send_ack;
+	return;
+
+nack_inv_unlock:
+	spin_unlock_irqrestore(&qp->s_lock, flags);
+nack_inv:
+	rvt_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
+	qp->r_nak_state = IB_NAK_INVALID_REQUEST;
+	qp->r_ack_psn = qp->r_psn;
+	/* Queue NAK for later */
+	rc_defered_ack(rcd, qp);
+	return;
+nack_acc:
+	spin_unlock_irqrestore(&qp->s_lock, flags);
+	rvt_rc_error(qp, IB_WC_LOC_PROT_ERR);
+	qp->r_nak_state = IB_NAK_REMOTE_ACCESS_ERROR;
+	qp->r_ack_psn = qp->r_psn;
+send_ack:
+	hfi1_send_rc_ack(packet, is_fecn);
+}

drivers/infiniband/hw/hfi1/tid_rdma.h

@@ -26,7 +26,9 @@
  *
  * HFI1_S_TID_WAIT_INTERLCK - QP is waiting for requester interlock
  */
+/* BIT(4) reserved for RVT_S_ACK_PENDING. */
 #define HFI1_S_TID_WAIT_INTERLCK  BIT(5)
+#define HFI1_R_TID_SW_PSN         BIT(19)
 
 /*
  * Unlike regular IB RDMA VERBS, which do not require an entry
@@ -89,10 +91,12 @@ struct tid_rdma_request {
 	} e;
 
 	struct tid_rdma_flow *flows;	/* array of tid flows */
+	struct rvt_sge_state ss; /* SGE state for TID RDMA requests */
 	u16 n_flows;		/* size of the flow buffer window */
 	u16 setup_head;		/* flow index we are setting up */
 	u16 clear_tail;		/* flow index we are clearing */
 	u16 flow_idx;		/* flow index most recently set up */
+	u16 acked_tail;
 
 	u32 seg_len;
 	u32 total_len;
@@ -103,6 +107,7 @@ struct tid_rdma_request {
 	u32 cur_seg;		/* index of current segment */
 	u32 comp_seg;           /* index of last completed segment */
 	u32 ack_seg;            /* index of last ack'ed segment */
+	u32 alloc_seg;          /* index of next segment to be allocated */
 	u32 isge;		/* index of "current" sge */
 	u32 ack_pending;        /* num acks pending for this request */
 
@@ -174,6 +179,12 @@ struct tid_rdma_flow {
 	u32 tid_entry[TID_RDMA_MAX_PAGES];
 };
 
+enum tid_rnr_nak_state {
+	TID_RNR_NAK_INIT = 0,
+	TID_RNR_NAK_SEND,
+	TID_RNR_NAK_SENT,
+};
+
 bool tid_rdma_conn_req(struct rvt_qp *qp, u64 *data);
 bool tid_rdma_conn_reply(struct rvt_qp *qp, u64 data);
 bool tid_rdma_conn_resp(struct rvt_qp *qp, u64 *data);
@@ -247,4 +258,9 @@ static inline void hfi1_setup_tid_rdma_wqe(struct rvt_qp *qp,
 u32 hfi1_build_tid_rdma_write_req(struct rvt_qp *qp, struct rvt_swqe *wqe,
 				  struct ib_other_headers *ohdr,
 				  u32 *bth1, u32 *bth2, u32 *len);
+
+void hfi1_compute_tid_rdma_flow_wt(void);
+
+void hfi1_rc_rcv_tid_rdma_write_req(struct hfi1_packet *packet);
+
 #endif /* HFI1_TID_RDMA_H */

drivers/infiniband/hw/hfi1/verbs.h

@@ -172,7 +172,15 @@ struct hfi1_qp_priv {
 	unsigned long tid_timer_timeout_jiffies;
 
 	/* variables for the TID RDMA SE state machine */
+	u8 rnr_nak_state;       /* RNR NAK state */
 	u32 s_flags;
+	u32 r_tid_head;     /* Most recently added TID RDMA request */
+	u32 r_tid_tail;     /* the last completed TID RDMA request */
+	u32 r_tid_ack;      /* the TID RDMA request to be ACK'ed */
+	u32 r_tid_alloc;    /* Request for which we are allocating resources */
+	u32 pending_tid_w_segs; /* Num of pending tid write segments */
+	u32 alloc_w_segs;       /* Number of segments for which write */
+			       /* resources have been allocated for this QP */
 
 	/* For TID RDMA READ */
 	u32 tid_r_reqs;         /* Num of tid reads requested */
@@ -180,8 +188,12 @@ struct hfi1_qp_priv {
 	u32 pending_tid_r_segs; /* Num of pending tid read segments */
 	u16 pkts_ps;            /* packets per segment */
 	u8 timeout_shift;       /* account for number of packets per segment */
+
+	u8 sync_pt;           /* Set when QP reaches sync point */
 };
 
+#define HFI1_QP_WQE_INVALID   ((u32)-1)
+
 struct hfi1_swqe_priv {
 	struct tid_rdma_request tid_req;
 	struct rvt_sge_state ss;  /* Used for TID RDMA READ Request */