Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma

[mirror_ubuntu-bionic-kernel.git] / drivers / infiniband / hw / hfi1 / ruc.c

/*
 * Copyright(c) 2015 - 2017 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/spinlock.h>

#include "hfi.h"
#include "mad.h"
#include "qp.h"
#include "verbs_txreq.h"
#include "trace.h"

/*
 * Validate a RWQE and fill in the SGE state.
 * Return 1 if OK.
 */
static int init_sge(struct rvt_qp *qp, struct rvt_rwqe *wqe)
{
        int i, j, ret;
        struct ib_wc wc;
        struct rvt_lkey_table *rkt;
        struct rvt_pd *pd;
        struct rvt_sge_state *ss;

        rkt = &to_idev(qp->ibqp.device)->rdi.lkey_table;
        pd = ibpd_to_rvtpd(qp->ibqp.srq ? qp->ibqp.srq->pd : qp->ibqp.pd);
        ss = &qp->r_sge;
        ss->sg_list = qp->r_sg_list;
        qp->r_len = 0;
        for (i = j = 0; i < wqe->num_sge; i++) {
                if (wqe->sg_list[i].length == 0)
                        continue;
                /* Check LKEY */
                ret = rvt_lkey_ok(rkt, pd, j ? &ss->sg_list[j - 1] : &ss->sge,
                                  NULL, &wqe->sg_list[i],
                                  IB_ACCESS_LOCAL_WRITE);
                if (unlikely(ret <= 0))
                        goto bad_lkey;
                qp->r_len += wqe->sg_list[i].length;
                j++;
        }
        ss->num_sge = j;
        ss->total_len = qp->r_len;
        ret = 1;
        goto bail;

bad_lkey:
        while (j) {
                struct rvt_sge *sge = --j ? &ss->sg_list[j - 1] : &ss->sge;

                rvt_put_mr(sge->mr);
        }
        ss->num_sge = 0;
        memset(&wc, 0, sizeof(wc));
        wc.wr_id = wqe->wr_id;
        wc.status = IB_WC_LOC_PROT_ERR;
        wc.opcode = IB_WC_RECV;
        wc.qp = &qp->ibqp;
        /* Signal solicited completion event. */
        rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc, 1);
        ret = 0;
bail:
        return ret;
}

/**
 * hfi1_rvt_get_rwqe - copy the next RWQE into the QP's RWQE
 * @qp: the QP
 * @wr_id_only: update qp->r_wr_id only, not qp->r_sge
 *
 * Return -1 if there is a local error, 0 if no RWQE is available,
 * otherwise return 1.
 *
 * Can be called from interrupt level.
 */
int hfi1_rvt_get_rwqe(struct rvt_qp *qp, int wr_id_only)
{
        unsigned long flags;
        struct rvt_rq *rq;
        struct rvt_rwq *wq;
        struct rvt_srq *srq;
        struct rvt_rwqe *wqe;
        void (*handler)(struct ib_event *, void *);
        u32 tail;
        int ret;

        if (qp->ibqp.srq) {
                srq = ibsrq_to_rvtsrq(qp->ibqp.srq);
                handler = srq->ibsrq.event_handler;
                rq = &srq->rq;
        } else {
                srq = NULL;
                handler = NULL;
                rq = &qp->r_rq;
        }

        spin_lock_irqsave(&rq->lock, flags);
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)) {
                ret = 0;
                goto unlock;
        }

        wq = rq->wq;
        tail = wq->tail;
        /* Validate tail before using it since it is user writable. */
        if (tail >= rq->size)
                tail = 0;
        if (unlikely(tail == wq->head)) {
                ret = 0;
                goto unlock;
        }
        /* Make sure entry is read after head index is read. */
        smp_rmb();
        wqe = rvt_get_rwqe_ptr(rq, tail);
        /*
         * Even though we update the tail index in memory, the verbs
         * consumer is not supposed to post more entries until a
         * completion is generated.
         */
        if (++tail >= rq->size)
                tail = 0;
        wq->tail = tail;
        if (!wr_id_only && !init_sge(qp, wqe)) {
                ret = -1;
                goto unlock;
        }
        qp->r_wr_id = wqe->wr_id;

        ret = 1;
        set_bit(RVT_R_WRID_VALID, &qp->r_aflags);
        if (handler) {
                u32 n;

                /*
                 * Validate head pointer value and compute
                 * the number of remaining WQEs.
                 */
                n = wq->head;
                if (n >= rq->size)
                        n = 0;
                if (n < tail)
                        n += rq->size - tail;
                else
                        n -= tail;
                if (n < srq->limit) {
                        struct ib_event ev;

                        srq->limit = 0;
                        spin_unlock_irqrestore(&rq->lock, flags);
                        ev.device = qp->ibqp.device;
                        ev.element.srq = qp->ibqp.srq;
                        ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
                        handler(&ev, srq->ibsrq.srq_context);
                        goto bail;
                }
        }
unlock:
        spin_unlock_irqrestore(&rq->lock, flags);
bail:
        return ret;
}

static int gid_ok(union ib_gid *gid, __be64 gid_prefix, __be64 id)
{
        return (gid->global.interface_id == id &&
                (gid->global.subnet_prefix == gid_prefix ||
                 gid->global.subnet_prefix == IB_DEFAULT_GID_PREFIX));
}

/*
 *
 * This should be called with the QP r_lock held.
 *
 * The s_lock will be acquired around the hfi1_migrate_qp() call.
 */
int hfi1_ruc_check_hdr(struct hfi1_ibport *ibp, struct hfi1_packet *packet)
{
        __be64 guid;
        unsigned long flags;
        struct rvt_qp *qp = packet->qp;
        u8 sc5 = ibp->sl_to_sc[rdma_ah_get_sl(&qp->remote_ah_attr)];
        u32 dlid = packet->dlid;
        u32 slid = packet->slid;
        u32 sl = packet->sl;
        int migrated;
        u32 bth0, bth1;
        u16 pkey;

        bth0 = be32_to_cpu(packet->ohdr->bth[0]);
        bth1 = be32_to_cpu(packet->ohdr->bth[1]);
        if (packet->etype == RHF_RCV_TYPE_BYPASS) {
                pkey = hfi1_16B_get_pkey(packet->hdr);
                migrated = bth1 & OPA_BTH_MIG_REQ;
        } else {
                pkey = ib_bth_get_pkey(packet->ohdr);
                migrated = bth0 & IB_BTH_MIG_REQ;
        }

        if (qp->s_mig_state == IB_MIG_ARMED && migrated) {
                if (!packet->grh) {
                        if ((rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
                             IB_AH_GRH) &&
                            (packet->etype != RHF_RCV_TYPE_BYPASS))
                                return 1;
                } else {
                        const struct ib_global_route *grh;

                        if (!(rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
                              IB_AH_GRH))
                                return 1;
                        grh = rdma_ah_read_grh(&qp->alt_ah_attr);
                        guid = get_sguid(ibp, grh->sgid_index);
                        if (!gid_ok(&packet->grh->dgid, ibp->rvp.gid_prefix,
                                    guid))
                                return 1;
                        if (!gid_ok(
                                &packet->grh->sgid,
                                grh->dgid.global.subnet_prefix,
                                grh->dgid.global.interface_id))
                                return 1;
                }
                if (unlikely(rcv_pkey_check(ppd_from_ibp(ibp), pkey,
                                            sc5, slid))) {
                        hfi1_bad_pkey(ibp, pkey, sl, 0, qp->ibqp.qp_num,
                                      slid, dlid);
                        return 1;
                }
                /* Validate the SLID. See Ch. 9.6.1.5 and 17.2.8 */
                if (slid != rdma_ah_get_dlid(&qp->alt_ah_attr) ||
                    ppd_from_ibp(ibp)->port !=
                        rdma_ah_get_port_num(&qp->alt_ah_attr))
                        return 1;
                spin_lock_irqsave(&qp->s_lock, flags);
                hfi1_migrate_qp(qp);
                spin_unlock_irqrestore(&qp->s_lock, flags);
        } else {
                if (!packet->grh) {
                        if ((rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
                             IB_AH_GRH) &&
                            (packet->etype != RHF_RCV_TYPE_BYPASS))
                                return 1;
                } else {
                        const struct ib_global_route *grh;

                        if (!(rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
                                                   IB_AH_GRH))
                                return 1;
                        grh = rdma_ah_read_grh(&qp->remote_ah_attr);
                        guid = get_sguid(ibp, grh->sgid_index);
                        if (!gid_ok(&packet->grh->dgid, ibp->rvp.gid_prefix,
                                    guid))
                                return 1;
                        if (!gid_ok(
                             &packet->grh->sgid,
                             grh->dgid.global.subnet_prefix,
                             grh->dgid.global.interface_id))
                                return 1;
                }
                if (unlikely(rcv_pkey_check(ppd_from_ibp(ibp), pkey,
                                            sc5, slid))) {
                        hfi1_bad_pkey(ibp, pkey, sl, 0, qp->ibqp.qp_num,
                                      slid, dlid);
                        return 1;
                }
                /* Validate the SLID. See Ch. 9.6.1.5 */
                if ((slid != rdma_ah_get_dlid(&qp->remote_ah_attr)) ||
                    ppd_from_ibp(ibp)->port != qp->port_num)
                        return 1;
                if (qp->s_mig_state == IB_MIG_REARM && !migrated)
                        qp->s_mig_state = IB_MIG_ARMED;
        }

        return 0;
}

/**
 * ruc_loopback - handle UC and RC loopback requests
 * @sqp: the sending QP
 *
 * This is called from hfi1_do_send() to
 * forward a WQE addressed to the same HFI.
 * Note that although we are single threaded due to the send engine, we still
 * have to protect against post_send().  We don't have to worry about
 * receive interrupts since this is a connected protocol and all packets
 * will pass through here.
 */
static void ruc_loopback(struct rvt_qp *sqp)
{
        struct hfi1_ibport *ibp = to_iport(sqp->ibqp.device, sqp->port_num);
        struct rvt_qp *qp;
        struct rvt_swqe *wqe;
        struct rvt_sge *sge;
        unsigned long flags;
        struct ib_wc wc;
        u64 sdata;
        atomic64_t *maddr;
        enum ib_wc_status send_status;
        bool release;
        int ret;
        bool copy_last = false;
        int local_ops = 0;

        rcu_read_lock();

        /*
         * Note that we check the responder QP state after
         * checking the requester's state.
         */
        qp = rvt_lookup_qpn(ib_to_rvt(sqp->ibqp.device), &ibp->rvp,
                            sqp->remote_qpn);

        spin_lock_irqsave(&sqp->s_lock, flags);

        /* Return if we are already busy processing a work request. */
        if ((sqp->s_flags & (RVT_S_BUSY | RVT_S_ANY_WAIT)) ||
            !(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_OR_FLUSH_SEND))
                goto unlock;

        sqp->s_flags |= RVT_S_BUSY;

again:
        smp_read_barrier_depends(); /* see post_one_send() */
        if (sqp->s_last == READ_ONCE(sqp->s_head))
                goto clr_busy;
        wqe = rvt_get_swqe_ptr(sqp, sqp->s_last);

        /* Return if it is not OK to start a new work request. */
        if (!(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_NEXT_SEND_OK)) {
                if (!(ib_rvt_state_ops[sqp->state] & RVT_FLUSH_SEND))
                        goto clr_busy;
                /* We are in the error state, flush the work request. */
                send_status = IB_WC_WR_FLUSH_ERR;
                goto flush_send;
        }

        /*
         * We can rely on the entry not changing without the s_lock
         * being held until we update s_last.
         * We increment s_cur to indicate s_last is in progress.
         */
        if (sqp->s_last == sqp->s_cur) {
                if (++sqp->s_cur >= sqp->s_size)
                        sqp->s_cur = 0;
        }
        spin_unlock_irqrestore(&sqp->s_lock, flags);

        if (!qp || !(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) ||
            qp->ibqp.qp_type != sqp->ibqp.qp_type) {
                ibp->rvp.n_pkt_drops++;
                /*
                 * For RC, the requester would timeout and retry so
                 * shortcut the timeouts and just signal too many retries.
                 */
                if (sqp->ibqp.qp_type == IB_QPT_RC)
                        send_status = IB_WC_RETRY_EXC_ERR;
                else
                        send_status = IB_WC_SUCCESS;
                goto serr;
        }

        memset(&wc, 0, sizeof(wc));
        send_status = IB_WC_SUCCESS;

        release = true;
        sqp->s_sge.sge = wqe->sg_list[0];
        sqp->s_sge.sg_list = wqe->sg_list + 1;
        sqp->s_sge.num_sge = wqe->wr.num_sge;
        sqp->s_len = wqe->length;
        switch (wqe->wr.opcode) {
        case IB_WR_REG_MR:
                goto send_comp;

        case IB_WR_LOCAL_INV:
                if (!(wqe->wr.send_flags & RVT_SEND_COMPLETION_ONLY)) {
                        if (rvt_invalidate_rkey(sqp,
                                                wqe->wr.ex.invalidate_rkey))
                                send_status = IB_WC_LOC_PROT_ERR;
                        local_ops = 1;
                }
                goto send_comp;

        case IB_WR_SEND_WITH_INV:
                if (!rvt_invalidate_rkey(qp, wqe->wr.ex.invalidate_rkey)) {
                        wc.wc_flags = IB_WC_WITH_INVALIDATE;
                        wc.ex.invalidate_rkey = wqe->wr.ex.invalidate_rkey;
                }
                goto send;

        case IB_WR_SEND_WITH_IMM:
                wc.wc_flags = IB_WC_WITH_IMM;
                wc.ex.imm_data = wqe->wr.ex.imm_data;
                /* FALLTHROUGH */
        case IB_WR_SEND:
send:
                ret = hfi1_rvt_get_rwqe(qp, 0);
                if (ret < 0)
                        goto op_err;
                if (!ret)
                        goto rnr_nak;
                break;

        case IB_WR_RDMA_WRITE_WITH_IMM:
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
                        goto inv_err;
                wc.wc_flags = IB_WC_WITH_IMM;
                wc.ex.imm_data = wqe->wr.ex.imm_data;
                ret = hfi1_rvt_get_rwqe(qp, 1);
                if (ret < 0)
                        goto op_err;
                if (!ret)
                        goto rnr_nak;
                /* skip copy_last set and qp_access_flags recheck */
                goto do_write;
        case IB_WR_RDMA_WRITE:
                copy_last = rvt_is_user_qp(qp);
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
                        goto inv_err;
do_write:
                if (wqe->length == 0)
                        break;
                if (unlikely(!rvt_rkey_ok(qp, &qp->r_sge.sge, wqe->length,
                                          wqe->rdma_wr.remote_addr,
                                          wqe->rdma_wr.rkey,
                                          IB_ACCESS_REMOTE_WRITE)))
                        goto acc_err;
                qp->r_sge.sg_list = NULL;
                qp->r_sge.num_sge = 1;
                qp->r_sge.total_len = wqe->length;
                break;

        case IB_WR_RDMA_READ:
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_READ)))
                        goto inv_err;
                if (unlikely(!rvt_rkey_ok(qp, &sqp->s_sge.sge, wqe->length,
                                          wqe->rdma_wr.remote_addr,
                                          wqe->rdma_wr.rkey,
                                          IB_ACCESS_REMOTE_READ)))
                        goto acc_err;
                release = false;
                sqp->s_sge.sg_list = NULL;
                sqp->s_sge.num_sge = 1;
                qp->r_sge.sge = wqe->sg_list[0];
                qp->r_sge.sg_list = wqe->sg_list + 1;
                qp->r_sge.num_sge = wqe->wr.num_sge;
                qp->r_sge.total_len = wqe->length;
                break;

        case IB_WR_ATOMIC_CMP_AND_SWP:
        case IB_WR_ATOMIC_FETCH_AND_ADD:
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_ATOMIC)))
                        goto inv_err;
                if (unlikely(!rvt_rkey_ok(qp, &qp->r_sge.sge, sizeof(u64),
                                          wqe->atomic_wr.remote_addr,
                                          wqe->atomic_wr.rkey,
                                          IB_ACCESS_REMOTE_ATOMIC)))
                        goto acc_err;
                /* Perform atomic OP and save result. */
                maddr = (atomic64_t *)qp->r_sge.sge.vaddr;
                sdata = wqe->atomic_wr.compare_add;
                *(u64 *)sqp->s_sge.sge.vaddr =
                        (wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) ?
                        (u64)atomic64_add_return(sdata, maddr) - sdata :
                        (u64)cmpxchg((u64 *)qp->r_sge.sge.vaddr,
                                      sdata, wqe->atomic_wr.swap);
                rvt_put_mr(qp->r_sge.sge.mr);
                qp->r_sge.num_sge = 0;
                goto send_comp;

        default:
                send_status = IB_WC_LOC_QP_OP_ERR;
                goto serr;
        }

        sge = &sqp->s_sge.sge;
        while (sqp->s_len) {
                u32 len = sqp->s_len;

                if (len > sge->length)
                        len = sge->length;
                if (len > sge->sge_length)
                        len = sge->sge_length;
                WARN_ON_ONCE(len == 0);
                hfi1_copy_sge(&qp->r_sge, sge->vaddr, len, release, copy_last);
                sge->vaddr += len;
                sge->length -= len;
                sge->sge_length -= len;
                if (sge->sge_length == 0) {
                        if (!release)
                                rvt_put_mr(sge->mr);
                        if (--sqp->s_sge.num_sge)
                                *sge = *sqp->s_sge.sg_list++;
                } else if (sge->length == 0 && sge->mr->lkey) {
                        if (++sge->n >= RVT_SEGSZ) {
                                if (++sge->m >= sge->mr->mapsz)
                                        break;
                                sge->n = 0;
                        }
                        sge->vaddr =
                                sge->mr->map[sge->m]->segs[sge->n].vaddr;
                        sge->length =
                                sge->mr->map[sge->m]->segs[sge->n].length;
                }
                sqp->s_len -= len;
        }
        if (release)
                rvt_put_ss(&qp->r_sge);

        if (!test_and_clear_bit(RVT_R_WRID_VALID, &qp->r_aflags))
                goto send_comp;

        if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM)
                wc.opcode = IB_WC_RECV_RDMA_WITH_IMM;
        else
                wc.opcode = IB_WC_RECV;
        wc.wr_id = qp->r_wr_id;
        wc.status = IB_WC_SUCCESS;
        wc.byte_len = wqe->length;
        wc.qp = &qp->ibqp;
        wc.src_qp = qp->remote_qpn;
        wc.slid = rdma_ah_get_dlid(&qp->remote_ah_attr) & U16_MAX;
        wc.sl = rdma_ah_get_sl(&qp->remote_ah_attr);
        wc.port_num = 1;
        /* Signal completion event if the solicited bit is set. */
        rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc,
                     wqe->wr.send_flags & IB_SEND_SOLICITED);

send_comp:
        spin_lock_irqsave(&sqp->s_lock, flags);
        ibp->rvp.n_loop_pkts++;
flush_send:
        sqp->s_rnr_retry = sqp->s_rnr_retry_cnt;
        hfi1_send_complete(sqp, wqe, send_status);
        if (local_ops) {
                atomic_dec(&sqp->local_ops_pending);
                local_ops = 0;
        }
        goto again;

rnr_nak:
        /* Handle RNR NAK */
        if (qp->ibqp.qp_type == IB_QPT_UC)
                goto send_comp;
        ibp->rvp.n_rnr_naks++;
        /*
         * Note: we don't need the s_lock held since the BUSY flag
         * makes this single threaded.
         */
        if (sqp->s_rnr_retry == 0) {
                send_status = IB_WC_RNR_RETRY_EXC_ERR;
                goto serr;
        }
        if (sqp->s_rnr_retry_cnt < 7)
                sqp->s_rnr_retry--;
        spin_lock_irqsave(&sqp->s_lock, flags);
        if (!(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_RECV_OK))
                goto clr_busy;
        rvt_add_rnr_timer(sqp, qp->r_min_rnr_timer <<
                                IB_AETH_CREDIT_SHIFT);
        goto clr_busy;

op_err:
        send_status = IB_WC_REM_OP_ERR;
        wc.status = IB_WC_LOC_QP_OP_ERR;
        goto err;

inv_err:
        send_status = IB_WC_REM_INV_REQ_ERR;
        wc.status = IB_WC_LOC_QP_OP_ERR;
        goto err;

acc_err:
        send_status = IB_WC_REM_ACCESS_ERR;
        wc.status = IB_WC_LOC_PROT_ERR;
err:
        /* responder goes to error state */
        rvt_rc_error(qp, wc.status);

serr:
        spin_lock_irqsave(&sqp->s_lock, flags);
        hfi1_send_complete(sqp, wqe, send_status);
        if (sqp->ibqp.qp_type == IB_QPT_RC) {
                int lastwqe = rvt_error_qp(sqp, IB_WC_WR_FLUSH_ERR);

                sqp->s_flags &= ~RVT_S_BUSY;
                spin_unlock_irqrestore(&sqp->s_lock, flags);
                if (lastwqe) {
                        struct ib_event ev;

                        ev.device = sqp->ibqp.device;
                        ev.element.qp = &sqp->ibqp;
                        ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
                        sqp->ibqp.event_handler(&ev, sqp->ibqp.qp_context);
                }
                goto done;
        }
clr_busy:
        sqp->s_flags &= ~RVT_S_BUSY;
unlock:
        spin_unlock_irqrestore(&sqp->s_lock, flags);
done:
        rcu_read_unlock();
}

/**
 * hfi1_make_grh - construct a GRH header
 * @ibp: a pointer to the IB port
 * @hdr: a pointer to the GRH header being constructed
 * @grh: the global route address to send to
 * @hwords: size of header after grh being sent in dwords
 * @nwords: the number of 32 bit words of data being sent
 *
 * Return the size of the header in 32 bit words.
 */
u32 hfi1_make_grh(struct hfi1_ibport *ibp, struct ib_grh *hdr,
                  const struct ib_global_route *grh, u32 hwords, u32 nwords)
{
        hdr->version_tclass_flow =
                cpu_to_be32((IB_GRH_VERSION << IB_GRH_VERSION_SHIFT) |
                            (grh->traffic_class << IB_GRH_TCLASS_SHIFT) |
                            (grh->flow_label << IB_GRH_FLOW_SHIFT));
        hdr->paylen = cpu_to_be16((hwords + nwords) << 2);
        /* next_hdr is defined by C8-7 in ch. 8.4.1 */
        hdr->next_hdr = IB_GRH_NEXT_HDR;
        hdr->hop_limit = grh->hop_limit;
        /* The SGID is 32-bit aligned. */
        hdr->sgid.global.subnet_prefix = ibp->rvp.gid_prefix;
        hdr->sgid.global.interface_id =
                grh->sgid_index < HFI1_GUIDS_PER_PORT ?
                get_sguid(ibp, grh->sgid_index) :
                get_sguid(ibp, HFI1_PORT_GUID_INDEX);
        hdr->dgid = grh->dgid;

        /* GRH header size in 32-bit words. */
        return sizeof(struct ib_grh) / sizeof(u32);
}

#define BTH2_OFFSET (offsetof(struct hfi1_sdma_header, \
                              hdr.ibh.u.oth.bth[2]) / 4)

/**
 * build_ahg - create ahg in s_ahg
 * @qp: a pointer to QP
 * @npsn: the next PSN for the request/response
 *
 * This routine handles the AHG by allocating an ahg entry and causing the
 * copy of the first middle.
 *
 * Subsequent middles use the copied entry, editing the
 * PSN with 1 or 2 edits.
 */
static inline void build_ahg(struct rvt_qp *qp, u32 npsn)
{
        struct hfi1_qp_priv *priv = qp->priv;

        if (unlikely(qp->s_flags & RVT_S_AHG_CLEAR))
                clear_ahg(qp);
        if (!(qp->s_flags & RVT_S_AHG_VALID)) {
                /* first middle that needs copy  */
                if (qp->s_ahgidx < 0)
                        qp->s_ahgidx = sdma_ahg_alloc(priv->s_sde);
                if (qp->s_ahgidx >= 0) {
                        qp->s_ahgpsn = npsn;
                        priv->s_ahg->tx_flags |= SDMA_TXREQ_F_AHG_COPY;
                        /* save to protect a change in another thread */
                        priv->s_ahg->ahgidx = qp->s_ahgidx;
                        qp->s_flags |= RVT_S_AHG_VALID;
                }
        } else {
                /* subsequent middle after valid */
                if (qp->s_ahgidx >= 0) {
                        priv->s_ahg->tx_flags |= SDMA_TXREQ_F_USE_AHG;
                        priv->s_ahg->ahgidx = qp->s_ahgidx;
                        priv->s_ahg->ahgcount++;
                        priv->s_ahg->ahgdesc[0] =
                                sdma_build_ahg_descriptor(
                                        (__force u16)cpu_to_be16((u16)npsn),
                                        BTH2_OFFSET,
                                        16,
                                        16);
                        if ((npsn & 0xffff0000) !=
                                        (qp->s_ahgpsn & 0xffff0000)) {
                                priv->s_ahg->ahgcount++;
                                priv->s_ahg->ahgdesc[1] =
                                        sdma_build_ahg_descriptor(
                                                (__force u16)cpu_to_be16(
                                                        (u16)(npsn >> 16)),
                                                BTH2_OFFSET,
                                                0,
                                                16);
                        }
                }
        }
}

static inline void hfi1_make_ruc_bth(struct rvt_qp *qp,
                                     struct ib_other_headers *ohdr,
                                     u32 bth0, u32 bth1, u32 bth2)
{
        bth1 |= qp->remote_qpn;
        ohdr->bth[0] = cpu_to_be32(bth0);
        ohdr->bth[1] = cpu_to_be32(bth1);
        ohdr->bth[2] = cpu_to_be32(bth2);
}

static inline void hfi1_make_ruc_header_16B(struct rvt_qp *qp,
                                            struct ib_other_headers *ohdr,
                                            u32 bth0, u32 bth2, int middle,
                                            struct hfi1_pkt_state *ps)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ibport *ibp = ps->ibp;
        struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
        u32 bth1 = 0;
        u32 slid;
        u16 pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);
        u8 l4 = OPA_16B_L4_IB_LOCAL;
        u8 extra_bytes = hfi1_get_16b_padding((qp->s_hdrwords << 2),
                                   ps->s_txreq->s_cur_size);
        u32 nwords = SIZE_OF_CRC + ((ps->s_txreq->s_cur_size +
                                 extra_bytes + SIZE_OF_LT) >> 2);
        u8 becn = 0;

        if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH) &&
            hfi1_check_mcast(rdma_ah_get_dlid(&qp->remote_ah_attr))) {
                struct ib_grh *grh;
                struct ib_global_route *grd =
                        rdma_ah_retrieve_grh(&qp->remote_ah_attr);
                int hdrwords;

                /*
                 * Ensure OPA GIDs are transformed to IB gids
                 * before creating the GRH.
                 */
                if (grd->sgid_index == OPA_GID_INDEX)
                        grd->sgid_index = 0;
                grh = &ps->s_txreq->phdr.hdr.opah.u.l.grh;
                l4 = OPA_16B_L4_IB_GLOBAL;
                hdrwords = qp->s_hdrwords - 4;
                qp->s_hdrwords += hfi1_make_grh(ibp, grh, grd,
                                                hdrwords, nwords);
                middle = 0;
        }

        if (qp->s_mig_state == IB_MIG_MIGRATED)
                bth1 |= OPA_BTH_MIG_REQ;
        else
                middle = 0;

        if (middle)
                build_ahg(qp, bth2);
        else
                qp->s_flags &= ~RVT_S_AHG_VALID;

        bth0 |= pkey;
        bth0 |= extra_bytes << 20;
        if (qp->s_flags & RVT_S_ECN) {
                qp->s_flags &= ~RVT_S_ECN;
                /* we recently received a FECN, so return a BECN */
                becn = 1;
        }
        hfi1_make_ruc_bth(qp, ohdr, bth0, bth1, bth2);

        if (!ppd->lid)
                slid = be32_to_cpu(OPA_LID_PERMISSIVE);
        else
                slid = ppd->lid |
                        (rdma_ah_get_path_bits(&qp->remote_ah_attr) &
                        ((1 << ppd->lmc) - 1));

        hfi1_make_16b_hdr(&ps->s_txreq->phdr.hdr.opah,
                          slid,
                          opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr),
                                      16B),
                          (qp->s_hdrwords + nwords) >> 1,
                          pkey, becn, 0, l4, priv->s_sc);
}

static inline void hfi1_make_ruc_header_9B(struct rvt_qp *qp,
                                           struct ib_other_headers *ohdr,
                                           u32 bth0, u32 bth2, int middle,
                                           struct hfi1_pkt_state *ps)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ibport *ibp = ps->ibp;
        u32 bth1 = 0;
        u16 pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);
        u16 lrh0 = HFI1_LRH_BTH;
        u8 extra_bytes = -ps->s_txreq->s_cur_size & 3;
        u32 nwords = SIZE_OF_CRC + ((ps->s_txreq->s_cur_size +
                                         extra_bytes) >> 2);

        if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH)) {
                struct ib_grh *grh = &ps->s_txreq->phdr.hdr.ibh.u.l.grh;
                int hdrwords = qp->s_hdrwords - 2;

                lrh0 = HFI1_LRH_GRH;
                qp->s_hdrwords +=
                        hfi1_make_grh(ibp, grh,
                                      rdma_ah_read_grh(&qp->remote_ah_attr),
                                      hdrwords, nwords);
                middle = 0;
        }
        lrh0 |= (priv->s_sc & 0xf) << 12 |
                (rdma_ah_get_sl(&qp->remote_ah_attr) & 0xf) << 4;

        if (qp->s_mig_state == IB_MIG_MIGRATED)
                bth0 |= IB_BTH_MIG_REQ;
        else
                middle = 0;

        if (middle)
                build_ahg(qp, bth2);
        else
                qp->s_flags &= ~RVT_S_AHG_VALID;

        bth0 |= pkey;
        bth0 |= extra_bytes << 20;
        if (qp->s_flags & RVT_S_ECN) {
                qp->s_flags &= ~RVT_S_ECN;
                /* we recently received a FECN, so return a BECN */
                bth1 |= (IB_BECN_MASK << IB_BECN_SHIFT);
        }
        hfi1_make_ruc_bth(qp, ohdr, bth0, bth1, bth2);
        hfi1_make_ib_hdr(&ps->s_txreq->phdr.hdr.ibh,
                         lrh0,
                         qp->s_hdrwords + nwords,
                         opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr), 9B),
                         ppd_from_ibp(ibp)->lid |
                                rdma_ah_get_path_bits(&qp->remote_ah_attr));
}

typedef void (*hfi1_make_ruc_hdr)(struct rvt_qp *qp,
                                  struct ib_other_headers *ohdr,
                                  u32 bth0, u32 bth2, int middle,
                                  struct hfi1_pkt_state *ps);

/* We support only two types - 9B and 16B for now */
static const hfi1_make_ruc_hdr hfi1_ruc_header_tbl[2] = {
        [HFI1_PKT_TYPE_9B] = &hfi1_make_ruc_header_9B,
        [HFI1_PKT_TYPE_16B] = &hfi1_make_ruc_header_16B
};

void hfi1_make_ruc_header(struct rvt_qp *qp, struct ib_other_headers *ohdr,
                          u32 bth0, u32 bth2, int middle,
                          struct hfi1_pkt_state *ps)
{
        struct hfi1_qp_priv *priv = qp->priv;

        /*
         * reset s_ahg/AHG fields
         *
         * This insures that the ahgentry/ahgcount
         * are at a non-AHG default to protect
         * build_verbs_tx_desc() from using
         * an include ahgidx.
         *
         * build_ahg() will modify as appropriate
         * to use the AHG feature.
         */
        priv->s_ahg->tx_flags = 0;
        priv->s_ahg->ahgcount = 0;
        priv->s_ahg->ahgidx = 0;

        /* Make the appropriate header */
        hfi1_ruc_header_tbl[priv->hdr_type](qp, ohdr, bth0, bth2, middle, ps);
}

/* when sending, force a reschedule every one of these periods */
#define SEND_RESCHED_TIMEOUT (5 * HZ)  /* 5s in jiffies */

/**
 * schedule_send_yield - test for a yield required for QP send engine
 * @timeout: Final time for timeout slice for jiffies
 * @qp: a pointer to QP
 * @ps: a pointer to a structure with commonly lookup values for
 *      the the send engine progress
 *
 * This routine checks if the time slice for the QP has expired
 * for RC QPs, if so an additional work entry is queued. At this
 * point, other QPs have an opportunity to be scheduled. It
 * returns true if a yield is required, otherwise, false
 * is returned.
 */
static bool schedule_send_yield(struct rvt_qp *qp,
                                struct hfi1_pkt_state *ps)
{
        ps->pkts_sent = true;

        if (unlikely(time_after(jiffies, ps->timeout))) {
                if (!ps->in_thread ||
                    workqueue_congested(ps->cpu, ps->ppd->hfi1_wq)) {
                        spin_lock_irqsave(&qp->s_lock, ps->flags);
                        qp->s_flags &= ~RVT_S_BUSY;
                        hfi1_schedule_send(qp);
                        spin_unlock_irqrestore(&qp->s_lock, ps->flags);
                        this_cpu_inc(*ps->ppd->dd->send_schedule);
                        trace_hfi1_rc_expired_time_slice(qp, true);
                        return true;
                }

                cond_resched();
                this_cpu_inc(*ps->ppd->dd->send_schedule);
                ps->timeout = jiffies + ps->timeout_int;
        }

        trace_hfi1_rc_expired_time_slice(qp, false);
        return false;
}

void hfi1_do_send_from_rvt(struct rvt_qp *qp)
{
        hfi1_do_send(qp, false);
}

void _hfi1_do_send(struct work_struct *work)
{
        struct iowait *wait = container_of(work, struct iowait, iowork);
        struct rvt_qp *qp = iowait_to_qp(wait);

        hfi1_do_send(qp, true);
}

/**
 * hfi1_do_send - perform a send on a QP
 * @work: contains a pointer to the QP
 * @in_thread: true if in a workqueue thread
 *
 * Process entries in the send work queue until credit or queue is
 * exhausted.  Only allow one CPU to send a packet per QP.
 * Otherwise, two threads could send packets out of order.
 */
void hfi1_do_send(struct rvt_qp *qp, bool in_thread)
{
        struct hfi1_pkt_state ps;
        struct hfi1_qp_priv *priv = qp->priv;
        int (*make_req)(struct rvt_qp *qp, struct hfi1_pkt_state *ps);

        ps.dev = to_idev(qp->ibqp.device);
        ps.ibp = to_iport(qp->ibqp.device, qp->port_num);
        ps.ppd = ppd_from_ibp(ps.ibp);
        ps.in_thread = in_thread;

        trace_hfi1_rc_do_send(qp, in_thread);

        switch (qp->ibqp.qp_type) {
        case IB_QPT_RC:
                if (!loopback && ((rdma_ah_get_dlid(&qp->remote_ah_attr) &
                                   ~((1 << ps.ppd->lmc) - 1)) ==
                                  ps.ppd->lid)) {
                        ruc_loopback(qp);
                        return;
                }
                make_req = hfi1_make_rc_req;
                ps.timeout_int = qp->timeout_jiffies;
                break;
        case IB_QPT_UC:
                if (!loopback && ((rdma_ah_get_dlid(&qp->remote_ah_attr) &
                                   ~((1 << ps.ppd->lmc) - 1)) ==
                                  ps.ppd->lid)) {
                        ruc_loopback(qp);
                        return;
                }
                make_req = hfi1_make_uc_req;
                ps.timeout_int = SEND_RESCHED_TIMEOUT;
                break;
        default:
                make_req = hfi1_make_ud_req;
                ps.timeout_int = SEND_RESCHED_TIMEOUT;
        }

        spin_lock_irqsave(&qp->s_lock, ps.flags);

        /* Return if we are already busy processing a work request. */
        if (!hfi1_send_ok(qp)) {
                spin_unlock_irqrestore(&qp->s_lock, ps.flags);
                return;
        }

        qp->s_flags |= RVT_S_BUSY;

        ps.timeout_int = ps.timeout_int / 8;
        ps.timeout = jiffies + ps.timeout_int;
        ps.cpu = priv->s_sde ? priv->s_sde->cpu :
                        cpumask_first(cpumask_of_node(ps.ppd->dd->node));
        ps.pkts_sent = false;

        /* insure a pre-built packet is handled  */
        ps.s_txreq = get_waiting_verbs_txreq(qp);
        do {
                /* Check for a constructed packet to be sent. */
                if (qp->s_hdrwords != 0) {
                        spin_unlock_irqrestore(&qp->s_lock, ps.flags);
                        /*
                         * If the packet cannot be sent now, return and
                         * the send engine will be woken up later.
                         */
                        if (hfi1_verbs_send(qp, &ps))
                                return;
                        /* Record that s_ahg is empty. */
                        qp->s_hdrwords = 0;
                        /* allow other tasks to run */
                        if (schedule_send_yield(qp, &ps))
                                return;

                        spin_lock_irqsave(&qp->s_lock, ps.flags);
                }
        } while (make_req(qp, &ps));
        iowait_starve_clear(ps.pkts_sent, &priv->s_iowait);
        spin_unlock_irqrestore(&qp->s_lock, ps.flags);
}

/*
 * This should be called with s_lock held.
 */
void hfi1_send_complete(struct rvt_qp *qp, struct rvt_swqe *wqe,
                        enum ib_wc_status status)
{
        u32 old_last, last;

        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_OR_FLUSH_SEND))
                return;

        last = qp->s_last;
        old_last = last;
        trace_hfi1_qp_send_completion(qp, wqe, last);
        if (++last >= qp->s_size)
                last = 0;
        trace_hfi1_qp_send_completion(qp, wqe, last);
        qp->s_last = last;
        /* See post_send() */
        barrier();
        rvt_put_swqe(wqe);
        if (qp->ibqp.qp_type == IB_QPT_UD ||
            qp->ibqp.qp_type == IB_QPT_SMI ||
            qp->ibqp.qp_type == IB_QPT_GSI)
                atomic_dec(&ibah_to_rvtah(wqe->ud_wr.ah)->refcount);

        rvt_qp_swqe_complete(qp,
                             wqe,
                             ib_hfi1_wc_opcode[wqe->wr.opcode],
                             status);

        if (qp->s_acked == old_last)
                qp->s_acked = last;
        if (qp->s_cur == old_last)
                qp->s_cur = last;
        if (qp->s_tail == old_last)
                qp->s_tail = last;
        if (qp->state == IB_QPS_SQD && last == qp->s_cur)
                qp->s_draining = 0;
}