IB/hfi1: Add functions to build TID RDMA READ request

This patch adds the helper functions to build the TID RDMA READ request
on the requester side. The key is to allocate TID resources (TID flow
and TID entries) and send the resource information to the responder side
along with the read request. Since the TID resources are limited, each
TID RDMA READ request has to be split into segments with a default
segment size of 256K. A software flow is allocated to track the data
transaction for each segment. The work request opcode, packet opcode, and
packet formats for TID RDMA READ protocol are also defined in this patch.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@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>

1 files changed, 200 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/hfi1/tid_rdma.c b/drivers/infiniband/hw/hfi1/tid_rdma.c
index 506b5a59ded5..56c8c10b5a85 100644
--- a/drivers/infiniband/hw/hfi1/tid_rdma.c
+++ b/drivers/infiniband/hw/hfi1/tid_rdma.c
@@ -6,11 +6,27 @@
 
 #include "hfi.h"
 #include "qp.h"
+#include "rc.h"
 #include "verbs.h"
 #include "tid_rdma.h"
 #include "exp_rcv.h"
 #include "trace.h"
 
+/**
+ * DOC: TID RDMA READ protocol
+ *
+ * This is an end-to-end protocol at the hfi1 level between two nodes that
+ * improves performance by avoiding data copy on the requester side. It
+ * converts a qualified RDMA READ request into a TID RDMA READ request on
+ * the requester side and thereafter handles the request and response
+ * differently. To be qualified, the RDMA READ request should meet the
+ * following:
+ * -- The total data length should be greater than 256K;
+ * -- The total data length should be a multiple of 4K page size;
+ * -- Each local scatter-gather entry should be 4K page aligned;
+ * -- Each local scatter-gather entry should be a multiple of 4K page size;
+ */
+
 #define RCV_TID_FLOW_TABLE_CTRL_FLOW_VALID_SMASK BIT_ULL(32)
 #define RCV_TID_FLOW_TABLE_CTRL_HDR_SUPP_EN_SMASK BIT_ULL(33)
 #define RCV_TID_FLOW_TABLE_CTRL_KEEP_AFTER_SEQ_ERR_SMASK BIT_ULL(34)
@@ -18,6 +34,9 @@
 #define RCV_TID_FLOW_TABLE_STATUS_SEQ_MISMATCH_SMASK BIT_ULL(37)
 #define RCV_TID_FLOW_TABLE_STATUS_GEN_MISMATCH_SMASK BIT_ULL(38)
 
+/* Maximum number of packets within a flow generation. */
+#define MAX_TID_FLOW_PSN BIT(HFI1_KDETH_BTH_SEQ_SHIFT)
+
 #define GENERATION_MASK 0xFFFFF
 
 static u32 mask_generation(u32 a)
@@ -45,6 +64,9 @@ static u32 mask_generation(u32 a)
 
 #define MAX_EXPECTED_PAGES     (MAX_EXPECTED_BUFFER / PAGE_SIZE)
 
+#define TID_RDMA_DESTQP_FLOW_SHIFT      11
+#define TID_RDMA_DESTQP_FLOW_MASK       0x1f
+
 #define TID_OPFN_QP_CTXT_MASK 0xff
 #define TID_OPFN_QP_CTXT_SHIFT 56
 #define TID_OPFN_QP_KDETH_MASK 0xff
@@ -1597,3 +1619,181 @@ u64 hfi1_access_sw_tid_wait(const struct cntr_entry *entry,
 
 	return dd->verbs_dev.n_tidwait;
 }
+
+/* TID RDMA READ functions */
+u32 hfi1_build_tid_rdma_read_packet(struct rvt_swqe *wqe,
+				    struct ib_other_headers *ohdr, u32 *bth1,
+				    u32 *bth2, u32 *len)
+{
+	struct tid_rdma_request *req = wqe_to_tid_req(wqe);
+	struct tid_rdma_flow *flow = &req->flows[req->flow_idx];
+	struct rvt_qp *qp = req->qp;
+	struct hfi1_qp_priv *qpriv = qp->priv;
+	struct hfi1_swqe_priv *wpriv = wqe->priv;
+	struct tid_rdma_read_req *rreq = &ohdr->u.tid_rdma.r_req;
+	struct tid_rdma_params *remote;
+	u32 req_len = 0;
+	void *req_addr = NULL;
+
+	/* This is the IB psn used to send the request */
+	*bth2 = mask_psn(flow->flow_state.ib_spsn + flow->pkt);
+
+	/* TID Entries for TID RDMA READ payload */
+	req_addr = &flow->tid_entry[flow->tid_idx];
+	req_len = sizeof(*flow->tid_entry) *
+			(flow->tidcnt - flow->tid_idx);
+
+	memset(&ohdr->u.tid_rdma.r_req, 0, sizeof(ohdr->u.tid_rdma.r_req));
+	wpriv->ss.sge.vaddr = req_addr;
+	wpriv->ss.sge.sge_length = req_len;
+	wpriv->ss.sge.length = wpriv->ss.sge.sge_length;
+	/*
+	 * We can safely zero these out. Since the first SGE covers the
+	 * entire packet, nothing else should even look at the MR.
+	 */
+	wpriv->ss.sge.mr = NULL;
+	wpriv->ss.sge.m = 0;
+	wpriv->ss.sge.n = 0;
+
+	wpriv->ss.sg_list = NULL;
+	wpriv->ss.total_len = wpriv->ss.sge.sge_length;
+	wpriv->ss.num_sge = 1;
+
+	/* Construct the TID RDMA READ REQ packet header */
+	rcu_read_lock();
+	remote = rcu_dereference(qpriv->tid_rdma.remote);
+
+	KDETH_RESET(rreq->kdeth0, KVER, 0x1);
+	KDETH_RESET(rreq->kdeth1, JKEY, remote->jkey);
+	rreq->reth.vaddr = cpu_to_be64(wqe->rdma_wr.remote_addr +
+			   req->cur_seg * req->seg_len + flow->sent);
+	rreq->reth.rkey = cpu_to_be32(wqe->rdma_wr.rkey);
+	rreq->reth.length = cpu_to_be32(*len);
+	rreq->tid_flow_psn =
+		cpu_to_be32((flow->flow_state.generation <<
+			     HFI1_KDETH_BTH_SEQ_SHIFT) |
+			    ((flow->flow_state.spsn + flow->pkt) &
+			     HFI1_KDETH_BTH_SEQ_MASK));
+	rreq->tid_flow_qp =
+		cpu_to_be32(qpriv->tid_rdma.local.qp |
+			    ((flow->idx & TID_RDMA_DESTQP_FLOW_MASK) <<
+			     TID_RDMA_DESTQP_FLOW_SHIFT) |
+			    qpriv->rcd->ctxt);
+	rreq->verbs_qp = cpu_to_be32(qp->remote_qpn);
+	*bth1 &= ~RVT_QPN_MASK;
+	*bth1 |= remote->qp;
+	*bth2 |= IB_BTH_REQ_ACK;
+	rcu_read_unlock();
+
+	/* We are done with this segment */
+	flow->sent += *len;
+	req->cur_seg++;
+	qp->s_state = TID_OP(READ_REQ);
+	req->ack_pending++;
+	req->flow_idx = (req->flow_idx + 1) & (MAX_FLOWS - 1);
+	qpriv->pending_tid_r_segs++;
+	qp->s_num_rd_atomic++;
+
+	/* Set the TID RDMA READ request payload size */
+	*len = req_len;
+
+	return sizeof(ohdr->u.tid_rdma.r_req) / sizeof(u32);
+}
+
+/*
+ * @len: contains the data length to read upon entry and the read request
+ *       payload length upon exit.
+ */
+u32 hfi1_build_tid_rdma_read_req(struct rvt_qp *qp, struct rvt_swqe *wqe,
+				 struct ib_other_headers *ohdr, u32 *bth1,
+				 u32 *bth2, u32 *len)
+	__must_hold(&qp->s_lock)
+{
+	struct hfi1_qp_priv *qpriv = qp->priv;
+	struct tid_rdma_request *req = wqe_to_tid_req(wqe);
+	struct tid_rdma_flow *flow = NULL;
+	u32 hdwords = 0;
+	bool last;
+	bool retry = true;
+	u32 npkts = rvt_div_round_up_mtu(qp, *len);
+
+	/*
+	 * Check sync conditions. Make sure that there are no pending
+	 * segments before freeing the flow.
+	 */
+sync_check:
+	if (req->state == TID_REQUEST_SYNC) {
+		if (qpriv->pending_tid_r_segs)
+			goto done;
+
+		hfi1_kern_clear_hw_flow(req->rcd, qp);
+		req->state = TID_REQUEST_ACTIVE;
+	}
+
+	/*
+	 * If the request for this segment is resent, the tid resources should
+	 * have been allocated before. In this case, req->flow_idx should
+	 * fall behind req->setup_head.
+	 */
+	if (req->flow_idx == req->setup_head) {
+		retry = false;
+		if (req->state == TID_REQUEST_RESEND) {
+			/*
+			 * This is the first new segment for a request whose
+			 * earlier segments have been re-sent. We need to
+			 * set up the sge pointer correctly.
+			 */
+			restart_sge(&qp->s_sge, wqe, req->s_next_psn,
+				    qp->pmtu);
+			req->isge = 0;
+			req->state = TID_REQUEST_ACTIVE;
+		}
+
+		/*
+		 * Check sync. The last PSN of each generation is reserved for
+		 * RESYNC.
+		 */
+		if ((qpriv->flow_state.psn + npkts) > MAX_TID_FLOW_PSN - 1) {
+			req->state = TID_REQUEST_SYNC;
+			goto sync_check;
+		}
+
+		/* Allocate the flow if not yet */
+		if (hfi1_kern_setup_hw_flow(qpriv->rcd, qp))
+			goto done;
+
+		/*
+		 * The following call will advance req->setup_head after
+		 * allocating the tid entries.
+		 */
+		if (hfi1_kern_exp_rcv_setup(req, &qp->s_sge, &last)) {
+			req->state = TID_REQUEST_QUEUED;
+
+			/*
+			 * We don't have resources for this segment. The QP has
+			 * already been queued.
+			 */
+			goto done;
+		}
+	}
+
+	/* req->flow_idx should only be one slot behind req->setup_head */
+	flow = &req->flows[req->flow_idx];
+	flow->pkt = 0;
+	flow->tid_idx = 0;
+	flow->sent = 0;
+	if (!retry) {
+		/* Set the first and last IB PSN for the flow in use.*/
+		flow->flow_state.ib_spsn = req->s_next_psn;
+		flow->flow_state.ib_lpsn =
+			flow->flow_state.ib_spsn + flow->npkts - 1;
+	}
+
+	/* Calculate the next segment start psn.*/
+	req->s_next_psn += flow->npkts;
+
+	/* Build the packet header */
+	hdwords = hfi1_build_tid_rdma_read_packet(wqe, ohdr, bth1, bth2, len);
+done:
+	return hdwords;
+}