/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 Chelsio Communications, Inc.
 * All rights reserved.
 * Written by: Navdeep Parhar <np@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 <sys/cdefs.h>
#include "opt_inet.h"

#include <sys/param.h>
#include <sys/aio.h>
#include <sys/bio.h>
#include <sys/file.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/module.h>
#include <sys/protosw.h>
#include <sys/proc.h>
#include <sys/domain.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/taskqueue.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/ip.h>
#include <netinet/tcp_var.h>
#define TCPSTATES
#include <netinet/tcp_fsm.h>
#include <netinet/toecore.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_object.h>

#include <cam/scsi/scsi_all.h>
#include <cam/ctl/ctl_io.h>

#ifdef TCP_OFFLOAD
#include "common/common.h"
#include "common/t4_msg.h"
#include "common/t4_regs.h"
#include "common/t4_tcb.h"
#include "tom/t4_tom.h"

/*
 * Use the 'backend3' field in AIO jobs to store the amount of data
 * received by the AIO job so far.
 */
#define aio_received    backend3

static void aio_ddp_requeue_task(void *context, int pending);
static void ddp_complete_all(struct toepcb *toep, int error);
static void t4_aio_cancel_active(struct kaiocb *job);
static void t4_aio_cancel_queued(struct kaiocb *job);
static int t4_alloc_page_pods_for_rcvbuf(struct ppod_region *pr,
    struct ddp_rcv_buffer *drb);
static int t4_write_page_pods_for_rcvbuf(struct adapter *sc,
    struct sge_wrq *wrq, int tid, struct ddp_rcv_buffer *drb);

static TAILQ_HEAD(, pageset) ddp_orphan_pagesets;
static struct mtx ddp_orphan_pagesets_lock;
static struct task ddp_orphan_task;

#define MAX_DDP_BUFFER_SIZE             (M_TCB_RX_DDP_BUF0_LEN)

/*
 * A page set holds information about a user buffer used for AIO DDP.
 * The page set holds resources such as the VM pages backing the
 * buffer (either held or wired) and the page pods associated with the
 * buffer.  Recently used page sets are cached to allow for efficient
 * reuse of buffers (avoiding the need to re-fault in pages, hold
 * them, etc.).  Note that cached page sets keep the backing pages
 * wired.  The number of wired pages is capped by only allowing for
 * two wired pagesets per connection.  This is not a perfect cap, but
 * is a trade-off for performance.
 *
 * If an application ping-pongs two buffers for a connection via
 * aio_read(2) then those buffers should remain wired and expensive VM
 * fault lookups should be avoided after each buffer has been used
 * once.  If an application uses more than two buffers then this will
 * fall back to doing expensive VM fault lookups for each operation.
 */
static void
free_pageset(struct tom_data *td, struct pageset *ps)
{
        vm_page_t p;
        int i;

        if (ps->prsv.prsv_nppods > 0)
                t4_free_page_pods(&ps->prsv);

        for (i = 0; i < ps->npages; i++) {
                p = ps->pages[i];
                vm_page_unwire(p, PQ_INACTIVE);
        }
        mtx_lock(&ddp_orphan_pagesets_lock);
        TAILQ_INSERT_TAIL(&ddp_orphan_pagesets, ps, link);
        taskqueue_enqueue(taskqueue_thread, &ddp_orphan_task);
        mtx_unlock(&ddp_orphan_pagesets_lock);
}

static void
ddp_free_orphan_pagesets(void *context, int pending)
{
        struct pageset *ps;

        mtx_lock(&ddp_orphan_pagesets_lock);
        while (!TAILQ_EMPTY(&ddp_orphan_pagesets)) {
                ps = TAILQ_FIRST(&ddp_orphan_pagesets);
                TAILQ_REMOVE(&ddp_orphan_pagesets, ps, link);
                mtx_unlock(&ddp_orphan_pagesets_lock);
                if (ps->vm)
                        vmspace_free(ps->vm);
                free(ps, M_CXGBE);
                mtx_lock(&ddp_orphan_pagesets_lock);
        }
        mtx_unlock(&ddp_orphan_pagesets_lock);
}

static void
recycle_pageset(struct toepcb *toep, struct pageset *ps)
{

        DDP_ASSERT_LOCKED(toep);
        if (!(toep->ddp.flags & DDP_DEAD)) {
                KASSERT(toep->ddp.cached_count + toep->ddp.active_count <
                    nitems(toep->ddp.db), ("too many wired pagesets"));
                TAILQ_INSERT_HEAD(&toep->ddp.cached_pagesets, ps, link);
                toep->ddp.cached_count++;
        } else
                free_pageset(toep->td, ps);
}

static void
ddp_complete_one(struct kaiocb *job, int error)
{
        long copied;

        /*
         * If this job had copied data out of the socket buffer before
         * it was cancelled, report it as a short read rather than an
         * error.
         */
        copied = job->aio_received;
        if (copied != 0 || error == 0)
                aio_complete(job, copied, 0);
        else
                aio_complete(job, -1, error);
}

static void
free_ddp_rcv_buffer(struct toepcb *toep, struct ddp_rcv_buffer *drb)
{
        t4_free_page_pods(&drb->prsv);
        free(drb->buf, M_CXGBE);
        free(drb, M_CXGBE);
        counter_u64_add(toep->ofld_rxq->ddp_buffer_free, 1);
        free_toepcb(toep);
}

static void
recycle_ddp_rcv_buffer(struct toepcb *toep, struct ddp_rcv_buffer *drb)
{
        DDP_CACHE_LOCK(toep);
        if (!(toep->ddp.flags & DDP_DEAD) &&
            toep->ddp.cached_count < t4_ddp_rcvbuf_cache) {
                TAILQ_INSERT_HEAD(&toep->ddp.cached_buffers, drb, link);
                toep->ddp.cached_count++;
                DDP_CACHE_UNLOCK(toep);
        } else {
                DDP_CACHE_UNLOCK(toep);
                free_ddp_rcv_buffer(toep, drb);
        }
}

static struct ddp_rcv_buffer *
alloc_cached_ddp_rcv_buffer(struct toepcb *toep)
{
        struct ddp_rcv_buffer *drb;

        DDP_CACHE_LOCK(toep);
        if (!TAILQ_EMPTY(&toep->ddp.cached_buffers)) {
                drb = TAILQ_FIRST(&toep->ddp.cached_buffers);
                TAILQ_REMOVE(&toep->ddp.cached_buffers, drb, link);
                toep->ddp.cached_count--;
                counter_u64_add(toep->ofld_rxq->ddp_buffer_reuse, 1);
        } else
                drb = NULL;
        DDP_CACHE_UNLOCK(toep);
        return (drb);
}

static struct ddp_rcv_buffer *
alloc_ddp_rcv_buffer(struct toepcb *toep, int how)
{
        struct tom_data *td = toep->td;
        struct adapter *sc = td_adapter(td);
        struct ddp_rcv_buffer *drb;
        int error;

        drb = malloc(sizeof(*drb), M_CXGBE, how | M_ZERO);
        if (drb == NULL)
                return (NULL);

        drb->buf = contigmalloc(t4_ddp_rcvbuf_len, M_CXGBE, how, 0, ~0,
            t4_ddp_rcvbuf_len, 0);
        if (drb->buf == NULL) {
                free(drb, M_CXGBE);
                return (NULL);
        }
        drb->len = t4_ddp_rcvbuf_len;
        drb->refs = 1;

        error = t4_alloc_page_pods_for_rcvbuf(&td->pr, drb);
        if (error != 0) {
                free(drb->buf, M_CXGBE);
                free(drb, M_CXGBE);
                return (NULL);
        }

        error = t4_write_page_pods_for_rcvbuf(sc, toep->ctrlq, toep->tid, drb);
        if (error != 0) {
                t4_free_page_pods(&drb->prsv);
                free(drb->buf, M_CXGBE);
                free(drb, M_CXGBE);
                return (NULL);
        }

        hold_toepcb(toep);
        counter_u64_add(toep->ofld_rxq->ddp_buffer_alloc, 1);
        return (drb);
}

static void
free_ddp_buffer(struct toepcb *toep, struct ddp_buffer *db)
{
        if ((toep->ddp.flags & DDP_RCVBUF) != 0) {
                if (db->drb != NULL)
                        free_ddp_rcv_buffer(toep, db->drb);
#ifdef INVARIANTS
                db->drb = NULL;
#endif
                return;
        }

        if (db->job) {
                /*
                 * XXX: If we are un-offloading the socket then we
                 * should requeue these on the socket somehow.  If we
                 * got a FIN from the remote end, then this completes
                 * any remaining requests with an EOF read.
                 */
                if (!aio_clear_cancel_function(db->job))
                        ddp_complete_one(db->job, 0);
#ifdef INVARIANTS
                db->job = NULL;
#endif
        }

        if (db->ps) {
                free_pageset(toep->td, db->ps);
#ifdef INVARIANTS
                db->ps = NULL;
#endif
        }
}

static void
ddp_init_toep(struct toepcb *toep)
{

        toep->ddp.flags = DDP_OK;
        toep->ddp.active_id = -1;
        mtx_init(&toep->ddp.lock, "t4 ddp", NULL, MTX_DEF);
        mtx_init(&toep->ddp.cache_lock, "t4 ddp cache", NULL, MTX_DEF);
}

void
ddp_uninit_toep(struct toepcb *toep)
{

        mtx_destroy(&toep->ddp.lock);
        mtx_destroy(&toep->ddp.cache_lock);
}

void
release_ddp_resources(struct toepcb *toep)
{
        struct ddp_rcv_buffer *drb;
        struct pageset *ps;
        int i;

        DDP_LOCK(toep);
        DDP_CACHE_LOCK(toep);
        toep->ddp.flags |= DDP_DEAD;
        DDP_CACHE_UNLOCK(toep);
        for (i = 0; i < nitems(toep->ddp.db); i++) {
                free_ddp_buffer(toep, &toep->ddp.db[i]);
        }
        if ((toep->ddp.flags & DDP_AIO) != 0) {
                while ((ps = TAILQ_FIRST(&toep->ddp.cached_pagesets)) != NULL) {
                        TAILQ_REMOVE(&toep->ddp.cached_pagesets, ps, link);
                        free_pageset(toep->td, ps);
                }
                ddp_complete_all(toep, 0);
        }
        if ((toep->ddp.flags & DDP_RCVBUF) != 0) {
                DDP_CACHE_LOCK(toep);
                while ((drb = TAILQ_FIRST(&toep->ddp.cached_buffers)) != NULL) {
                        TAILQ_REMOVE(&toep->ddp.cached_buffers, drb, link);
                        free_ddp_rcv_buffer(toep, drb);
                }
                DDP_CACHE_UNLOCK(toep);
        }
        DDP_UNLOCK(toep);
}

#ifdef INVARIANTS
void
ddp_assert_empty(struct toepcb *toep)
{
        int i;

        MPASS((toep->ddp.flags & (DDP_TASK_ACTIVE | DDP_DEAD)) != DDP_TASK_ACTIVE);
        for (i = 0; i < nitems(toep->ddp.db); i++) {
                if ((toep->ddp.flags & DDP_AIO) != 0) {
                        MPASS(toep->ddp.db[i].job == NULL);
                        MPASS(toep->ddp.db[i].ps == NULL);
                } else
                        MPASS(toep->ddp.db[i].drb == NULL);
        }
        if ((toep->ddp.flags & DDP_AIO) != 0) {
                MPASS(TAILQ_EMPTY(&toep->ddp.cached_pagesets));
                MPASS(TAILQ_EMPTY(&toep->ddp.aiojobq));
        }
        if ((toep->ddp.flags & DDP_RCVBUF) != 0)
                MPASS(TAILQ_EMPTY(&toep->ddp.cached_buffers));
}
#endif

static void
complete_ddp_buffer(struct toepcb *toep, struct ddp_buffer *db,
    unsigned int db_idx)
{
        struct ddp_rcv_buffer *drb;
        unsigned int db_flag;

        toep->ddp.active_count--;
        if (toep->ddp.active_id == db_idx) {
                if (toep->ddp.active_count == 0) {
                        if ((toep->ddp.flags & DDP_AIO) != 0)
                                KASSERT(toep->ddp.db[db_idx ^ 1].job == NULL,
                                    ("%s: active_count mismatch", __func__));
                        else
                                KASSERT(toep->ddp.db[db_idx ^ 1].drb == NULL,
                                    ("%s: active_count mismatch", __func__));
                        toep->ddp.active_id = -1;
                } else
                        toep->ddp.active_id ^= 1;
#ifdef VERBOSE_TRACES
                CTR3(KTR_CXGBE, "%s: tid %u, ddp_active_id = %d", __func__,
                    toep->tid, toep->ddp.active_id);
#endif
        } else {
                KASSERT(toep->ddp.active_count != 0 &&
                    toep->ddp.active_id != -1,
                    ("%s: active count mismatch", __func__));
        }

        if ((toep->ddp.flags & DDP_AIO) != 0) {
                db->cancel_pending = 0;
                db->job = NULL;
                recycle_pageset(toep, db->ps);
                db->ps = NULL;
        } else {
                drb = db->drb;
                if (atomic_fetchadd_int(&drb->refs, -1) == 1)
                        recycle_ddp_rcv_buffer(toep, drb);
                db->drb = NULL;
                db->placed = 0;
        }

        db_flag = db_idx == 1 ? DDP_BUF1_ACTIVE : DDP_BUF0_ACTIVE;
        KASSERT(toep->ddp.flags & db_flag,
            ("%s: DDP buffer not active. toep %p, ddp_flags 0x%x",
            __func__, toep, toep->ddp.flags));
        toep->ddp.flags &= ~db_flag;
}

/* Called when m_free drops the last reference. */
static void
ddp_rcv_mbuf_done(struct mbuf *m)
{
        struct toepcb *toep = m->m_ext.ext_arg1;
        struct ddp_rcv_buffer *drb = m->m_ext.ext_arg2;

        recycle_ddp_rcv_buffer(toep, drb);
}

static void
queue_ddp_rcvbuf_mbuf(struct toepcb *toep, u_int db_idx, u_int len)
{
        struct inpcb *inp = toep->inp;
        struct sockbuf *sb;
        struct ddp_buffer *db;
        struct ddp_rcv_buffer *drb;
        struct mbuf *m;

        m = m_gethdr(M_NOWAIT, MT_DATA);
        if (m == NULL) {
                printf("%s: failed to allocate mbuf", __func__);
                return;
        }
        m->m_pkthdr.rcvif = toep->vi->ifp;

        db = &toep->ddp.db[db_idx];
        drb = db->drb;
        m_extaddref(m, (char *)drb->buf + db->placed, len, &drb->refs,
            ddp_rcv_mbuf_done, toep, drb);
        m->m_pkthdr.len = len;
        m->m_len = len;

        sb = &inp->inp_socket->so_rcv;
        SOCKBUF_LOCK_ASSERT(sb);
        sbappendstream_locked(sb, m, 0);

        db->placed += len;
        toep->ofld_rxq->rx_toe_ddp_octets += len;
}

/* XXX: handle_ddp_data code duplication */
void
insert_ddp_data(struct toepcb *toep, uint32_t n)
{
        struct inpcb *inp = toep->inp;
        struct tcpcb *tp = intotcpcb(inp);
        struct ddp_buffer *db;
        struct kaiocb *job;
        size_t placed;
        long copied;
        unsigned int db_idx;
#ifdef INVARIANTS
        unsigned int db_flag;
#endif
        bool ddp_rcvbuf;

        INP_WLOCK_ASSERT(inp);
        DDP_ASSERT_LOCKED(toep);

        ddp_rcvbuf = (toep->ddp.flags & DDP_RCVBUF) != 0;
        tp->rcv_nxt += n;
#ifndef USE_DDP_RX_FLOW_CONTROL
        KASSERT(tp->rcv_wnd >= n, ("%s: negative window size", __func__));
        tp->rcv_wnd -= n;
#endif
        CTR2(KTR_CXGBE, "%s: placed %u bytes before falling out of DDP",
            __func__, n);
        while (toep->ddp.active_count > 0) {
                MPASS(toep->ddp.active_id != -1);
                db_idx = toep->ddp.active_id;
#ifdef INVARIANTS
                db_flag = db_idx == 1 ? DDP_BUF1_ACTIVE : DDP_BUF0_ACTIVE;
#endif
                MPASS((toep->ddp.flags & db_flag) != 0);
                db = &toep->ddp.db[db_idx];
                if (ddp_rcvbuf) {
                        placed = n;
                        if (placed > db->drb->len - db->placed)
                                placed = db->drb->len - db->placed;
                        if (placed != 0)
                                queue_ddp_rcvbuf_mbuf(toep, db_idx, placed);
                        complete_ddp_buffer(toep, db, db_idx);
                        n -= placed;
                        continue;
                }
                job = db->job;
                copied = job->aio_received;
                placed = n;
                if (placed > job->uaiocb.aio_nbytes - copied)
                        placed = job->uaiocb.aio_nbytes - copied;
                if (placed > 0) {
                        job->msgrcv = 1;
                        toep->ofld_rxq->rx_aio_ddp_jobs++;
                }
                toep->ofld_rxq->rx_aio_ddp_octets += placed;
                if (!aio_clear_cancel_function(job)) {
                        /*
                         * Update the copied length for when
                         * t4_aio_cancel_active() completes this
                         * request.
                         */
                        job->aio_received += placed;
                } else if (copied + placed != 0) {
                        CTR4(KTR_CXGBE,
                            "%s: completing %p (copied %ld, placed %lu)",
                            __func__, job, copied, placed);
                        /* XXX: This always completes if there is some data. */
                        aio_complete(job, copied + placed, 0);
                } else if (aio_set_cancel_function(job, t4_aio_cancel_queued)) {
                        TAILQ_INSERT_HEAD(&toep->ddp.aiojobq, job, list);
                        toep->ddp.waiting_count++;
                } else
                        aio_cancel(job);
                n -= placed;
                complete_ddp_buffer(toep, db, db_idx);
        }

        MPASS(n == 0);
}

/* SET_TCB_FIELD sent as a ULP command looks like this */
#define LEN__SET_TCB_FIELD_ULP (sizeof(struct ulp_txpkt) + \
    sizeof(struct ulptx_idata) + sizeof(struct cpl_set_tcb_field_core))

/* RX_DATA_ACK sent as a ULP command looks like this */
#define LEN__RX_DATA_ACK_ULP (sizeof(struct ulp_txpkt) + \
    sizeof(struct ulptx_idata) + sizeof(struct cpl_rx_data_ack_core))

static inline void *
mk_rx_data_ack_ulp(struct ulp_txpkt *ulpmc, struct toepcb *toep)
{
        struct ulptx_idata *ulpsc;
        struct cpl_rx_data_ack_core *req;

        ulpmc->cmd_dest = htonl(V_ULPTX_CMD(ULP_TX_PKT) | V_ULP_TXPKT_DEST(0));
        ulpmc->len = htobe32(howmany(LEN__RX_DATA_ACK_ULP, 16));

        ulpsc = (struct ulptx_idata *)(ulpmc + 1);
        ulpsc->cmd_more = htobe32(V_ULPTX_CMD(ULP_TX_SC_IMM));
        ulpsc->len = htobe32(sizeof(*req));

        req = (struct cpl_rx_data_ack_core *)(ulpsc + 1);
        OPCODE_TID(req) = htobe32(MK_OPCODE_TID(CPL_RX_DATA_ACK, toep->tid));
        req->credit_dack = htobe32(F_RX_MODULATE_RX);

        ulpsc = (struct ulptx_idata *)(req + 1);
        if (LEN__RX_DATA_ACK_ULP % 16) {
                ulpsc->cmd_more = htobe32(V_ULPTX_CMD(ULP_TX_SC_NOOP));
                ulpsc->len = htobe32(0);
                return (ulpsc + 1);
        }
        return (ulpsc);
}

static struct wrqe *
mk_update_tcb_for_ddp(struct adapter *sc, struct toepcb *toep, int db_idx,
    struct ppod_reservation *prsv, int offset, uint32_t len,
    uint64_t ddp_flags, uint64_t ddp_flags_mask)
{
        struct wrqe *wr;
        struct work_request_hdr *wrh;
        struct ulp_txpkt *ulpmc;
        int wrlen;

        KASSERT(db_idx == 0 || db_idx == 1,
            ("%s: bad DDP buffer index %d", __func__, db_idx));

        /*
         * We'll send a compound work request that has 3 SET_TCB_FIELDs and an
         * RX_DATA_ACK (with RX_MODULATE to speed up delivery).
         *
         * The work request header is 16B and always ends at a 16B boundary.
         * The ULPTX master commands that follow must all end at 16B boundaries
         * too so we round up the size to 16.
         */
        wrlen = sizeof(*wrh) + 3 * roundup2(LEN__SET_TCB_FIELD_ULP, 16) +
            roundup2(LEN__RX_DATA_ACK_ULP, 16);

        wr = alloc_wrqe(wrlen, toep->ctrlq);
        if (wr == NULL)
                return (NULL);
        wrh = wrtod(wr);
        INIT_ULPTX_WRH(wrh, wrlen, 1, 0);       /* atomic */
        ulpmc = (struct ulp_txpkt *)(wrh + 1);

        /* Write the buffer's tag */
        ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid,
            W_TCB_RX_DDP_BUF0_TAG + db_idx,
            V_TCB_RX_DDP_BUF0_TAG(M_TCB_RX_DDP_BUF0_TAG),
            V_TCB_RX_DDP_BUF0_TAG(prsv->prsv_tag));

        /* Update the current offset in the DDP buffer and its total length */
        if (db_idx == 0)
                ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid,
                    W_TCB_RX_DDP_BUF0_OFFSET,
                    V_TCB_RX_DDP_BUF0_OFFSET(M_TCB_RX_DDP_BUF0_OFFSET) |
                    V_TCB_RX_DDP_BUF0_LEN(M_TCB_RX_DDP_BUF0_LEN),
                    V_TCB_RX_DDP_BUF0_OFFSET(offset) |
                    V_TCB_RX_DDP_BUF0_LEN(len));
        else
                ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid,
                    W_TCB_RX_DDP_BUF1_OFFSET,
                    V_TCB_RX_DDP_BUF1_OFFSET(M_TCB_RX_DDP_BUF1_OFFSET) |
                    V_TCB_RX_DDP_BUF1_LEN((u64)M_TCB_RX_DDP_BUF1_LEN << 32),
                    V_TCB_RX_DDP_BUF1_OFFSET(offset) |
                    V_TCB_RX_DDP_BUF1_LEN((u64)len << 32));

        /* Update DDP flags */
        ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid, W_TCB_RX_DDP_FLAGS,
            ddp_flags_mask, ddp_flags);

        /* Gratuitous RX_DATA_ACK with RX_MODULATE set to speed up delivery. */
        ulpmc = mk_rx_data_ack_ulp(ulpmc, toep);

        return (wr);
}

static int
handle_ddp_data_aio(struct toepcb *toep, __be32 ddp_report, __be32 rcv_nxt,
    int len)
{
        uint32_t report = be32toh(ddp_report);
        unsigned int db_idx;
        struct inpcb *inp = toep->inp;
        struct tcpcb *tp = intotcpcb(inp);
        struct ddp_buffer *db;
        struct socket *so;
        struct sockbuf *sb;
        struct kaiocb *job;
        long copied;

        db_idx = report & F_DDP_BUF_IDX ? 1 : 0;

        if (__predict_false(!(report & F_DDP_INV)))
                CXGBE_UNIMPLEMENTED("DDP buffer still valid");

        INP_WLOCK(inp);
        so = inp_inpcbtosocket(inp);
        sb = &so->so_rcv;
        DDP_LOCK(toep);

        KASSERT(toep->ddp.active_id == db_idx,
            ("completed DDP buffer (%d) != active_id (%d) for tid %d", db_idx,
            toep->ddp.active_id, toep->tid));
        db = &toep->ddp.db[db_idx];
        job = db->job;

        if (__predict_false(tp->t_flags & TF_DISCONNECTED)) {
                /*
                 * This can happen due to an administrative tcpdrop(8).
                 * Just fail the request with ECONNRESET.
                 */
                CTR5(KTR_CXGBE, "%s: tid %u, seq 0x%x, len %d, t_flags 0x%x",
                    __func__, toep->tid, be32toh(rcv_nxt), len, tp->t_flags);
                if (aio_clear_cancel_function(job))
                        ddp_complete_one(job, ECONNRESET);
                goto completed;
        }

        tp = intotcpcb(inp);

        /*
         * For RX_DDP_COMPLETE, len will be zero and rcv_nxt is the
         * sequence number of the next byte to receive.  The length of
         * the data received for this message must be computed by
         * comparing the new and old values of rcv_nxt.
         *
         * For RX_DATA_DDP, len might be non-zero, but it is only the
         * length of the most recent DMA.  It does not include the
         * total length of the data received since the previous update
         * for this DDP buffer.  rcv_nxt is the sequence number of the
         * first received byte from the most recent DMA.
         */
        len += be32toh(rcv_nxt) - tp->rcv_nxt;
        tp->rcv_nxt += len;
        tp->t_rcvtime = ticks;
#ifndef USE_DDP_RX_FLOW_CONTROL
        KASSERT(tp->rcv_wnd >= len, ("%s: negative window size", __func__));
        tp->rcv_wnd -= len;
#endif
#ifdef VERBOSE_TRACES
        CTR5(KTR_CXGBE, "%s: tid %u, DDP[%d] placed %d bytes (%#x)", __func__,
            toep->tid, db_idx, len, report);
#endif

        /* receive buffer autosize */
        MPASS(toep->vnet == so->so_vnet);
        CURVNET_SET(toep->vnet);
        SOCKBUF_LOCK(sb);
        if (sb->sb_flags & SB_AUTOSIZE &&
            V_tcp_do_autorcvbuf &&
            sb->sb_hiwat < V_tcp_autorcvbuf_max &&
            len > (sbspace(sb) / 8 * 7)) {
                struct adapter *sc = td_adapter(toep->td);
                unsigned int hiwat = sb->sb_hiwat;
                unsigned int newsize = min(hiwat + sc->tt.autorcvbuf_inc,
                    V_tcp_autorcvbuf_max);

                if (!sbreserve_locked(so, SO_RCV, newsize, NULL))
                        sb->sb_flags &= ~SB_AUTOSIZE;
        }
        SOCKBUF_UNLOCK(sb);
        CURVNET_RESTORE();

        job->msgrcv = 1;
        toep->ofld_rxq->rx_aio_ddp_jobs++;
        toep->ofld_rxq->rx_aio_ddp_octets += len;
        if (db->cancel_pending) {
                /*
                 * Update the job's length but defer completion to the
                 * TCB_RPL callback.
                 */
                job->aio_received += len;
                goto out;
        } else if (!aio_clear_cancel_function(job)) {
                /*
                 * Update the copied length for when
                 * t4_aio_cancel_active() completes this request.
                 */
                job->aio_received += len;
        } else {
                copied = job->aio_received;
#ifdef VERBOSE_TRACES
                CTR5(KTR_CXGBE,
                    "%s: tid %u, completing %p (copied %ld, placed %d)",
                    __func__, toep->tid, job, copied, len);
#endif
                aio_complete(job, copied + len, 0);
                t4_rcvd(&toep->td->tod, tp);
        }

completed:
        complete_ddp_buffer(toep, db, db_idx);
        if (toep->ddp.waiting_count > 0)
                ddp_queue_toep(toep);
out:
        DDP_UNLOCK(toep);
        INP_WUNLOCK(inp);

        return (0);
}

static bool
queue_ddp_rcvbuf(struct toepcb *toep, struct ddp_rcv_buffer *drb)
{
        struct adapter *sc = td_adapter(toep->td);
        struct ddp_buffer *db;
        struct wrqe *wr;
        uint64_t ddp_flags, ddp_flags_mask;
        int buf_flag, db_idx;

        DDP_ASSERT_LOCKED(toep);

        KASSERT((toep->ddp.flags & DDP_DEAD) == 0, ("%s: DDP_DEAD", __func__));
        KASSERT(toep->ddp.active_count < nitems(toep->ddp.db),
            ("%s: no empty DDP buffer slot", __func__));

        /* Determine which DDP buffer to use. */
        if (toep->ddp.db[0].drb == NULL) {
                db_idx = 0;
        } else {
                MPASS(toep->ddp.db[1].drb == NULL);
                db_idx = 1;
        }

        /*
         * Permit PSH to trigger a partial completion without
         * invalidating the rest of the buffer, but disable the PUSH
         * timer.
         */
        ddp_flags = 0;
        ddp_flags_mask = 0;
        if (db_idx == 0) {
                ddp_flags |= V_TF_DDP_PSH_NO_INVALIDATE0(1) |
                    V_TF_DDP_PUSH_DISABLE_0(0) | V_TF_DDP_PSHF_ENABLE_0(1) |
                    V_TF_DDP_BUF0_VALID(1);
                ddp_flags_mask |= V_TF_DDP_PSH_NO_INVALIDATE0(1) |
                    V_TF_DDP_PUSH_DISABLE_0(1) | V_TF_DDP_PSHF_ENABLE_0(1) |
                    V_TF_DDP_BUF0_FLUSH(1) | V_TF_DDP_BUF0_VALID(1);
                buf_flag = DDP_BUF0_ACTIVE;
        } else {
                ddp_flags |= V_TF_DDP_PSH_NO_INVALIDATE1(1) |
                    V_TF_DDP_PUSH_DISABLE_1(0) | V_TF_DDP_PSHF_ENABLE_1(1) |
                    V_TF_DDP_BUF1_VALID(1);
                ddp_flags_mask |= V_TF_DDP_PSH_NO_INVALIDATE1(1) |
                    V_TF_DDP_PUSH_DISABLE_1(1) | V_TF_DDP_PSHF_ENABLE_1(1) |
                    V_TF_DDP_BUF1_FLUSH(1) | V_TF_DDP_BUF1_VALID(1);
                buf_flag = DDP_BUF1_ACTIVE;
        }
        MPASS((toep->ddp.flags & buf_flag) == 0);
        if ((toep->ddp.flags & (DDP_BUF0_ACTIVE | DDP_BUF1_ACTIVE)) == 0) {
                MPASS(db_idx == 0);
                MPASS(toep->ddp.active_id == -1);
                MPASS(toep->ddp.active_count == 0);
                ddp_flags_mask |= V_TF_DDP_ACTIVE_BUF(1);
        }

        /*
         * The TID for this connection should still be valid.  If
         * DDP_DEAD is set, SBS_CANTRCVMORE should be set, so we
         * shouldn't be this far anyway.
         */
        wr = mk_update_tcb_for_ddp(sc, toep, db_idx, &drb->prsv, 0, drb->len,
            ddp_flags, ddp_flags_mask);
        if (wr == NULL) {
                recycle_ddp_rcv_buffer(toep, drb);
                printf("%s: mk_update_tcb_for_ddp failed\n", __func__);
                return (false);
        }

#ifdef VERBOSE_TRACES
        CTR(KTR_CXGBE,
            "%s: tid %u, scheduling DDP[%d] (flags %#lx/%#lx)", __func__,
            toep->tid, db_idx, ddp_flags, ddp_flags_mask);
#endif
        /*
         * Hold a reference on scheduled buffers that is dropped in
         * complete_ddp_buffer.
         */
        drb->refs = 1;

        /* Give the chip the go-ahead. */
        t4_wrq_tx(sc, wr);
        db = &toep->ddp.db[db_idx];
        db->drb = drb;
        toep->ddp.flags |= buf_flag;
        toep->ddp.active_count++;
        if (toep->ddp.active_count == 1) {
                MPASS(toep->ddp.active_id == -1);
                toep->ddp.active_id = db_idx;
                CTR2(KTR_CXGBE, "%s: ddp_active_id = %d", __func__,
                    toep->ddp.active_id);
        }
        return (true);
}

static int
handle_ddp_data_rcvbuf(struct toepcb *toep, __be32 ddp_report, __be32 rcv_nxt,
    int len)
{
        uint32_t report = be32toh(ddp_report);
        struct inpcb *inp = toep->inp;
        struct tcpcb *tp = intotcpcb(inp);
        struct socket *so;
        struct sockbuf *sb;
        struct ddp_buffer *db;
        struct ddp_rcv_buffer *drb;
        unsigned int db_idx;
        bool invalidated;

        db_idx = report & F_DDP_BUF_IDX ? 1 : 0;

        invalidated = (report & F_DDP_INV) != 0;

        INP_WLOCK(inp);
        so = inp_inpcbtosocket(inp);
        sb = &so->so_rcv;
        DDP_LOCK(toep);

        KASSERT(toep->ddp.active_id == db_idx,
            ("completed DDP buffer (%d) != active_id (%d) for tid %d", db_idx,
            toep->ddp.active_id, toep->tid));
        db = &toep->ddp.db[db_idx];

        if (__predict_false(tp->t_flags & TF_DISCONNECTED)) {
                /*
                 * This can happen due to an administrative tcpdrop(8).
                 * Just ignore the received data.
                 */
                CTR5(KTR_CXGBE, "%s: tid %u, seq 0x%x, len %d, t_flags 0x%x",
                    __func__, toep->tid, be32toh(rcv_nxt), len, tp->t_flags);
                if (invalidated)
                        complete_ddp_buffer(toep, db, db_idx);
                goto out;
        }

        /*
         * For RX_DDP_COMPLETE, len will be zero and rcv_nxt is the
         * sequence number of the next byte to receive.  The length of
         * the data received for this message must be computed by
         * comparing the new and old values of rcv_nxt.
         *
         * For RX_DATA_DDP, len might be non-zero, but it is only the
         * length of the most recent DMA.  It does not include the
         * total length of the data received since the previous update
         * for this DDP buffer.  rcv_nxt is the sequence number of the
         * first received byte from the most recent DMA.
         */
        len += be32toh(rcv_nxt) - tp->rcv_nxt;
        tp->rcv_nxt += len;
        tp->t_rcvtime = ticks;
#ifndef USE_DDP_RX_FLOW_CONTROL
        KASSERT(tp->rcv_wnd >= len, ("%s: negative window size", __func__));
        tp->rcv_wnd -= len;
#endif
#ifdef VERBOSE_TRACES
        CTR5(KTR_CXGBE, "%s: tid %u, DDP[%d] placed %d bytes (%#x)", __func__,
            toep->tid, db_idx, len, report);
#endif

        /* receive buffer autosize */
        MPASS(toep->vnet == so->so_vnet);
        CURVNET_SET(toep->vnet);
        SOCKBUF_LOCK(sb);
        if (sb->sb_flags & SB_AUTOSIZE &&
            V_tcp_do_autorcvbuf &&
            sb->sb_hiwat < V_tcp_autorcvbuf_max &&
            len > (sbspace(sb) / 8 * 7)) {
                struct adapter *sc = td_adapter(toep->td);
                unsigned int hiwat = sb->sb_hiwat;
                unsigned int newsize = min(hiwat + sc->tt.autorcvbuf_inc,
                    V_tcp_autorcvbuf_max);

                if (!sbreserve_locked(so, SO_RCV, newsize, NULL))
                        sb->sb_flags &= ~SB_AUTOSIZE;
        }

        if (len > 0) {
                queue_ddp_rcvbuf_mbuf(toep, db_idx, len);
                t4_rcvd_locked(&toep->td->tod, tp);
        }
        sorwakeup_locked(so);
        SOCKBUF_UNLOCK_ASSERT(sb);
        CURVNET_RESTORE();

        if (invalidated)
                complete_ddp_buffer(toep, db, db_idx);
        else
                KASSERT(db->placed < db->drb->len,
                    ("%s: full DDP buffer not invalidated", __func__));

        if (toep->ddp.active_count != nitems(toep->ddp.db)) {
                drb = alloc_cached_ddp_rcv_buffer(toep);
                if (drb == NULL)
                        drb = alloc_ddp_rcv_buffer(toep, M_NOWAIT);
                if (drb == NULL)
                        ddp_queue_toep(toep);
                else {
                        if (!queue_ddp_rcvbuf(toep, drb)) {
                                ddp_queue_toep(toep);
                        }
                }
        }
out:
        DDP_UNLOCK(toep);
        INP_WUNLOCK(inp);

        return (0);
}

static int
handle_ddp_data(struct toepcb *toep, __be32 ddp_report, __be32 rcv_nxt, int len)
{
        if ((toep->ddp.flags & DDP_RCVBUF) != 0)
                return (handle_ddp_data_rcvbuf(toep, ddp_report, rcv_nxt, len));
        else
                return (handle_ddp_data_aio(toep, ddp_report, rcv_nxt, len));
}

void
handle_ddp_indicate(struct toepcb *toep)
{

        DDP_ASSERT_LOCKED(toep);
        if ((toep->ddp.flags & DDP_RCVBUF) != 0) {
                /*
                 * Indicates are not meaningful for RCVBUF since
                 * buffers are activated when the socket option is
                 * set.
                 */
                return;
        }

        MPASS(toep->ddp.active_count == 0);
        MPASS((toep->ddp.flags & (DDP_BUF0_ACTIVE | DDP_BUF1_ACTIVE)) == 0);
        if (toep->ddp.waiting_count == 0) {
                /*
                 * The pending requests that triggered the request for an
                 * an indicate were cancelled.  Those cancels should have
                 * already disabled DDP.  Just ignore this as the data is
                 * going into the socket buffer anyway.
                 */
                return;
        }
        CTR3(KTR_CXGBE, "%s: tid %d indicated (%d waiting)", __func__,
            toep->tid, toep->ddp.waiting_count);
        ddp_queue_toep(toep);
}

CTASSERT(CPL_COOKIE_DDP0 + 1 == CPL_COOKIE_DDP1);

static int
do_ddp_tcb_rpl(struct sge_iq *iq, const struct rss_header *rss, struct mbuf *m)
{
        struct adapter *sc = iq->adapter;
        const struct cpl_set_tcb_rpl *cpl = (const void *)(rss + 1);
        unsigned int tid = GET_TID(cpl);
        unsigned int db_idx;
        struct toepcb *toep;
        struct inpcb *inp;
        struct ddp_buffer *db;
        struct kaiocb *job;
        long copied;

        if (cpl->status != CPL_ERR_NONE)
                panic("XXX: tcp_rpl failed: %d", cpl->status);

        toep = lookup_tid(sc, tid);
        inp = toep->inp;
        switch (cpl->cookie) {
        case V_WORD(W_TCB_RX_DDP_FLAGS) | V_COOKIE(CPL_COOKIE_DDP0):
        case V_WORD(W_TCB_RX_DDP_FLAGS) | V_COOKIE(CPL_COOKIE_DDP1):
                /*
                 * XXX: This duplicates a lot of code with handle_ddp_data().
                 */
                KASSERT((toep->ddp.flags & DDP_AIO) != 0,
                    ("%s: DDP_RCVBUF", __func__));
                db_idx = G_COOKIE(cpl->cookie) - CPL_COOKIE_DDP0;
                MPASS(db_idx < nitems(toep->ddp.db));
                INP_WLOCK(inp);
                DDP_LOCK(toep);
                db = &toep->ddp.db[db_idx];

                /*
                 * handle_ddp_data() should leave the job around until
                 * this callback runs once a cancel is pending.
                 */
                MPASS(db != NULL);
                MPASS(db->job != NULL);
                MPASS(db->cancel_pending);

                /*
                 * XXX: It's not clear what happens if there is data
                 * placed when the buffer is invalidated.  I suspect we
                 * need to read the TCB to see how much data was placed.
                 *
                 * For now this just pretends like nothing was placed.
                 *
                 * XXX: Note that if we did check the PCB we would need to
                 * also take care of updating the tp, etc.
                 */
                job = db->job;
                copied = job->aio_received;
                if (copied == 0) {
                        CTR2(KTR_CXGBE, "%s: cancelling %p", __func__, job);
                        aio_cancel(job);
                } else {
                        CTR3(KTR_CXGBE, "%s: completing %p (copied %ld)",
                            __func__, job, copied);
                        aio_complete(job, copied, 0);
                        t4_rcvd(&toep->td->tod, intotcpcb(inp));
                }

                complete_ddp_buffer(toep, db, db_idx);
                if (toep->ddp.waiting_count > 0)
                        ddp_queue_toep(toep);
                DDP_UNLOCK(toep);
                INP_WUNLOCK(inp);
                break;
        default:
                panic("XXX: unknown tcb_rpl offset %#x, cookie %#x",
                    G_WORD(cpl->cookie), G_COOKIE(cpl->cookie));
        }

        return (0);
}

void
handle_ddp_close(struct toepcb *toep, struct tcpcb *tp, __be32 rcv_nxt)
{
        struct socket *so = toep->inp->inp_socket;
        struct sockbuf *sb = &so->so_rcv;
        struct ddp_buffer *db;
        struct kaiocb *job;
        long copied;
        unsigned int db_idx;
#ifdef INVARIANTS
        unsigned int db_flag;
#endif
        int len, placed;
        bool ddp_rcvbuf;

        INP_WLOCK_ASSERT(toep->inp);
        DDP_ASSERT_LOCKED(toep);

        ddp_rcvbuf = (toep->ddp.flags & DDP_RCVBUF) != 0;

        /* - 1 is to ignore the byte for FIN */
        len = be32toh(rcv_nxt) - tp->rcv_nxt - 1;
        tp->rcv_nxt += len;

        CTR(KTR_CXGBE, "%s: tid %d placed %u bytes before FIN", __func__,
            toep->tid, len);
        while (toep->ddp.active_count > 0) {
                MPASS(toep->ddp.active_id != -1);
                db_idx = toep->ddp.active_id;
#ifdef INVARIANTS
                db_flag = db_idx == 1 ? DDP_BUF1_ACTIVE : DDP_BUF0_ACTIVE;
#endif
                MPASS((toep->ddp.flags & db_flag) != 0);
                db = &toep->ddp.db[db_idx];
                if (ddp_rcvbuf) {
                        placed = len;
                        if (placed > db->drb->len - db->placed)
                                placed = db->drb->len - db->placed;
                        if (placed != 0) {
                                SOCKBUF_LOCK(sb);
                                queue_ddp_rcvbuf_mbuf(toep, db_idx, placed);
                                sorwakeup_locked(so);
                                SOCKBUF_UNLOCK_ASSERT(sb);
                        }
                        complete_ddp_buffer(toep, db, db_idx);
                        len -= placed;
                        continue;
                }
                job = db->job;
                copied = job->aio_received;
                placed = len;
                if (placed > job->uaiocb.aio_nbytes - copied)
                        placed = job->uaiocb.aio_nbytes - copied;
                if (placed > 0) {
                        job->msgrcv = 1;
                        toep->ofld_rxq->rx_aio_ddp_jobs++;
                }
                toep->ofld_rxq->rx_aio_ddp_octets += placed;
                if (!aio_clear_cancel_function(job)) {
                        /*
                         * Update the copied length for when
                         * t4_aio_cancel_active() completes this
                         * request.
                         */
                        job->aio_received += placed;
                } else {
                        CTR4(KTR_CXGBE, "%s: tid %d completed buf %d len %d",
                            __func__, toep->tid, db_idx, placed);
                        aio_complete(job, copied + placed, 0);
                }
                len -= placed;
                complete_ddp_buffer(toep, db, db_idx);
        }

        MPASS(len == 0);
        if ((toep->ddp.flags & DDP_AIO) != 0)
                ddp_complete_all(toep, 0);
}

#define DDP_ERR (F_DDP_PPOD_MISMATCH | F_DDP_LLIMIT_ERR | F_DDP_ULIMIT_ERR |\
         F_DDP_PPOD_PARITY_ERR | F_DDP_PADDING_ERR | F_DDP_OFFSET_ERR |\
         F_DDP_INVALID_TAG | F_DDP_COLOR_ERR | F_DDP_TID_MISMATCH |\
         F_DDP_INVALID_PPOD | F_DDP_HDRCRC_ERR | F_DDP_DATACRC_ERR)

extern cpl_handler_t t4_cpl_handler[];

static int
do_rx_data_ddp(struct sge_iq *iq, const struct rss_header *rss, struct mbuf *m)
{
        struct adapter *sc = iq->adapter;
        const struct cpl_rx_data_ddp *cpl = (const void *)(rss + 1);
        unsigned int tid = GET_TID(cpl);
        uint32_t vld;
        struct toepcb *toep = lookup_tid(sc, tid);

        KASSERT(m == NULL, ("%s: wasn't expecting payload", __func__));
        KASSERT(toep->tid == tid, ("%s: toep tid/atid mismatch", __func__));
        KASSERT(!(toep->flags & TPF_SYNQE),
            ("%s: toep %p claims to be a synq entry", __func__, toep));

        vld = be32toh(cpl->ddpvld);
        if (__predict_false(vld & DDP_ERR)) {
                panic("%s: DDP error 0x%x (tid %d, toep %p)",
                    __func__, vld, tid, toep);
        }

        if (ulp_mode(toep) == ULP_MODE_ISCSI) {
                t4_cpl_handler[CPL_RX_ISCSI_DDP](iq, rss, m);
                return (0);
        }

        handle_ddp_data(toep, cpl->u.ddp_report, cpl->seq, be16toh(cpl->len));

        return (0);
}

static int
do_rx_ddp_complete(struct sge_iq *iq, const struct rss_header *rss,
    struct mbuf *m)
{
        struct adapter *sc = iq->adapter;
        const struct cpl_rx_ddp_complete *cpl = (const void *)(rss + 1);
        unsigned int tid = GET_TID(cpl);
        struct toepcb *toep = lookup_tid(sc, tid);

        KASSERT(m == NULL, ("%s: wasn't expecting payload", __func__));
        KASSERT(toep->tid == tid, ("%s: toep tid/atid mismatch", __func__));
        KASSERT(!(toep->flags & TPF_SYNQE),
            ("%s: toep %p claims to be a synq entry", __func__, toep));

        handle_ddp_data(toep, cpl->ddp_report, cpl->rcv_nxt, 0);

        return (0);
}

static bool
set_ddp_ulp_mode(struct toepcb *toep)
{
        struct adapter *sc = toep->vi->adapter;
        struct wrqe *wr;
        struct work_request_hdr *wrh;
        struct ulp_txpkt *ulpmc;
        int fields, len;

        if (!sc->tt.ddp)
                return (false);

        fields = 0;

        /* Overlay region including W_TCB_RX_DDP_FLAGS */
        fields += 3;

        /* W_TCB_ULP_TYPE */
        fields++;

#ifdef USE_DDP_RX_FLOW_CONTROL
        /* W_TCB_T_FLAGS */
        fields++;
#endif

        len = sizeof(*wrh) + fields * roundup2(LEN__SET_TCB_FIELD_ULP, 16);
        KASSERT(len <= SGE_MAX_WR_LEN,
            ("%s: WR with %d TCB field updates too large", __func__, fields));

        wr = alloc_wrqe(len, toep->ctrlq);
        if (wr == NULL)
                return (false);

        CTR(KTR_CXGBE, "%s: tid %u", __func__, toep->tid);

        wrh = wrtod(wr);
        INIT_ULPTX_WRH(wrh, len, 1, 0); /* atomic */
        ulpmc = (struct ulp_txpkt *)(wrh + 1);

        /*
         * Words 26/27 are zero except for the DDP_OFF flag in
         * W_TCB_RX_DDP_FLAGS (27).
         */
        ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid, 26,
            0xffffffffffffffff, (uint64_t)V_TF_DDP_OFF(1) << 32);

        /* Words 28/29 are zero. */
        ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid, 28,
            0xffffffffffffffff, 0);

        /* Words 30/31 are zero. */
        ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid, 30,
            0xffffffffffffffff, 0);

        /* Set the ULP mode to ULP_MODE_TCPDDP. */
        toep->params.ulp_mode = ULP_MODE_TCPDDP;
        ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid, W_TCB_ULP_TYPE,
            V_TCB_ULP_TYPE(M_TCB_ULP_TYPE), V_TCB_ULP_TYPE(ULP_MODE_TCPDDP));

#ifdef USE_DDP_RX_FLOW_CONTROL
        /* Set TF_RX_FLOW_CONTROL_DDP. */
        ulpmc = mk_set_tcb_field_ulp(sc, ulpmc, toep->tid, W_TCB_T_FLAGS,
            V_TF_RX_FLOW_CONTROL_DDP(1), V_TF_RX_FLOW_CONTROL_DDP(1));
#endif

        ddp_init_toep(toep);

        t4_wrq_tx(sc, wr);
        return (true);
}

static void
enable_ddp(struct adapter *sc, struct toepcb *toep)
{
        uint64_t ddp_flags;

        KASSERT((toep->ddp.flags & (DDP_ON | DDP_OK | DDP_SC_REQ)) == DDP_OK,
            ("%s: toep %p has bad ddp_flags 0x%x",
            __func__, toep, toep->ddp.flags));

        CTR3(KTR_CXGBE, "%s: tid %u (time %u)",
            __func__, toep->tid, time_uptime);

        ddp_flags = 0;
        if ((toep->ddp.flags & DDP_AIO) != 0)
                ddp_flags |= V_TF_DDP_BUF0_INDICATE(1) |
                    V_TF_DDP_BUF1_INDICATE(1);
        DDP_ASSERT_LOCKED(toep);
        toep->ddp.flags |= DDP_SC_REQ;
        t4_set_tcb_field(sc, toep->ctrlq, toep, W_TCB_RX_DDP_FLAGS,
            V_TF_DDP_OFF(1) | V_TF_DDP_INDICATE_OUT(1) |
            V_TF_DDP_BUF0_INDICATE(1) | V_TF_DDP_BUF1_INDICATE(1) |
            V_TF_DDP_BUF0_VALID(1) | V_TF_DDP_BUF1_VALID(1), ddp_flags, 0, 0);
        t4_set_tcb_field(sc, toep->ctrlq, toep, W_TCB_T_FLAGS,
            V_TF_RCV_COALESCE_ENABLE(1), 0, 0, 0);
}

static int
calculate_hcf(int n1, int n2)
{
        int a, b, t;

        if (n1 <= n2) {
                a = n1;
                b = n2;
        } else {
                a = n2;
                b = n1;
        }

        while (a != 0) {
                t = a;
                a = b % a;
                b = t;
        }

        return (b);
}

static inline int
pages_to_nppods(int npages, int ddp_page_shift)
{

        MPASS(ddp_page_shift >= PAGE_SHIFT);

        return (howmany(npages >> (ddp_page_shift - PAGE_SHIFT), PPOD_PAGES));
}

static int
alloc_page_pods(struct ppod_region *pr, u_int nppods, u_int pgsz_idx,
    struct ppod_reservation *prsv)
{
        vmem_addr_t addr;       /* relative to start of region */

        if (vmem_alloc(pr->pr_arena, PPOD_SZ(nppods), M_NOWAIT | M_FIRSTFIT,
            &addr) != 0)
                return (ENOMEM);

#ifdef VERBOSE_TRACES
        CTR5(KTR_CXGBE, "%-17s arena %p, addr 0x%08x, nppods %d, pgsz %d",
            __func__, pr->pr_arena, (uint32_t)addr & pr->pr_tag_mask,
            nppods, 1 << pr->pr_page_shift[pgsz_idx]);
#endif

        /*
         * The hardware tagmask includes an extra invalid bit but the arena was
         * seeded with valid values only.  An allocation out of this arena will
         * fit inside the tagmask but won't have the invalid bit set.
         */
        MPASS((addr & pr->pr_tag_mask) == addr);
        MPASS((addr & pr->pr_invalid_bit) == 0);

        prsv->prsv_pr = pr;
        prsv->prsv_tag = V_PPOD_PGSZ(pgsz_idx) | addr;
        prsv->prsv_nppods = nppods;

        return (0);
}

static int
t4_alloc_page_pods_for_vmpages(struct ppod_region *pr, vm_page_t *pages,
    int npages, struct ppod_reservation *prsv)
{
        int i, hcf, seglen, idx, nppods;

        /*
         * The DDP page size is unrelated to the VM page size.  We combine
         * contiguous physical pages into larger segments to get the best DDP
         * page size possible.  This is the largest of the four sizes in
         * A_ULP_RX_TDDP_PSZ that evenly divides the HCF of the segment sizes in
         * the page list.
         */
        hcf = 0;
        for (i = 0; i < npages; i++) {
                seglen = PAGE_SIZE;
                while (i < npages - 1 &&
                    VM_PAGE_TO_PHYS(pages[i]) + PAGE_SIZE ==
                    VM_PAGE_TO_PHYS(pages[i + 1])) {
                        seglen += PAGE_SIZE;
                        i++;
                }

                hcf = calculate_hcf(hcf, seglen);
                if (hcf < (1 << pr->pr_page_shift[1])) {
                        idx = 0;
                        goto have_pgsz; /* give up, short circuit */
                }
        }

#define PR_PAGE_MASK(x) ((1 << pr->pr_page_shift[(x)]) - 1)
        MPASS((hcf & PR_PAGE_MASK(0)) == 0); /* PAGE_SIZE is >= 4K everywhere */
        for (idx = nitems(pr->pr_page_shift) - 1; idx > 0; idx--) {
                if ((hcf & PR_PAGE_MASK(idx)) == 0)
                        break;
        }
#undef PR_PAGE_MASK

have_pgsz:
        MPASS(idx <= M_PPOD_PGSZ);

        nppods = pages_to_nppods(npages, pr->pr_page_shift[idx]);
        if (alloc_page_pods(pr, nppods, idx, prsv) != 0)
                return (ENOMEM);
        MPASS(prsv->prsv_nppods > 0);

        return (0);
}

int
t4_alloc_page_pods_for_ps(struct ppod_region *pr, struct pageset *ps)
{
        struct ppod_reservation *prsv = &ps->prsv;

        KASSERT(prsv->prsv_nppods == 0,
            ("%s: page pods already allocated", __func__));

        return (t4_alloc_page_pods_for_vmpages(pr, ps->pages, ps->npages,
            prsv));
}

int
t4_alloc_page_pods_for_bio(struct ppod_region *pr, struct bio *bp,
    struct ppod_reservation *prsv)
{

        MPASS(bp->bio_flags & BIO_UNMAPPED);

        return (t4_alloc_page_pods_for_vmpages(pr, bp->bio_ma, bp->bio_ma_n,
            prsv));
}

int
t4_alloc_page_pods_for_buf(struct ppod_region *pr, vm_offset_t buf, int len,
    struct ppod_reservation *prsv)
{
        int hcf, seglen, idx, npages, nppods;
        uintptr_t start_pva, end_pva, pva, p1;

        MPASS(buf > 0);
        MPASS(len > 0);

        /*
         * The DDP page size is unrelated to the VM page size.  We combine
         * contiguous physical pages into larger segments to get the best DDP
         * page size possible.  This is the largest of the four sizes in
         * A_ULP_RX_ISCSI_PSZ that evenly divides the HCF of the segment sizes
         * in the page list.
         */
        hcf = 0;
        start_pva = trunc_page(buf);
        end_pva = trunc_page(buf + len - 1);
        pva = start_pva;
        while (pva <= end_pva) {
                seglen = PAGE_SIZE;
                p1 = pmap_kextract(pva);
                pva += PAGE_SIZE;
                while (pva <= end_pva && p1 + seglen == pmap_kextract(pva)) {
                        seglen += PAGE_SIZE;
                        pva += PAGE_SIZE;
                }

                hcf = calculate_hcf(hcf, seglen);
                if (hcf < (1 << pr->pr_page_shift[1])) {
                        idx = 0;
                        goto have_pgsz; /* give up, short circuit */
                }
        }

#define PR_PAGE_MASK(x) ((1 << pr->pr_page_shift[(x)]) - 1)
        MPASS((hcf & PR_PAGE_MASK(0)) == 0); /* PAGE_SIZE is >= 4K everywhere */
        for (idx = nitems(pr->pr_page_shift) - 1; idx > 0; idx--) {
                if ((hcf & PR_PAGE_MASK(idx)) == 0)
                        break;
        }
#undef PR_PAGE_MASK

have_pgsz:
        MPASS(idx <= M_PPOD_PGSZ);

        npages = 1;
        npages += (end_pva - start_pva) >> pr->pr_page_shift[idx];
        nppods = howmany(npages, PPOD_PAGES);
        if (alloc_page_pods(pr, nppods, idx, prsv) != 0)
                return (ENOMEM);
        MPASS(prsv->prsv_nppods > 0);

        return (0);
}

static int
t4_alloc_page_pods_for_rcvbuf(struct ppod_region *pr,
    struct ddp_rcv_buffer *drb)
{
        struct ppod_reservation *prsv = &drb->prsv;

        KASSERT(prsv->prsv_nppods == 0,
            ("%s: page pods already allocated", __func__));

        return (t4_alloc_page_pods_for_buf(pr, (vm_offset_t)drb->buf, drb->len,
            prsv));
}

int
t4_alloc_page_pods_for_sgl(struct ppod_region *pr, struct ctl_sg_entry *sgl,
    int entries, struct ppod_reservation *prsv)
{
        int hcf, seglen, idx = 0, npages, nppods, i, len;
        uintptr_t start_pva, end_pva, pva, p1 ;
        vm_offset_t buf;
        struct ctl_sg_entry *sge;

        MPASS(entries > 0);
        MPASS(sgl);

        /*
         * The DDP page size is unrelated to the VM page size.  We combine
         * contiguous physical pages into larger segments to get the best DDP
         * page size possible.  This is the largest of the four sizes in
         * A_ULP_RX_ISCSI_PSZ that evenly divides the HCF of the segment sizes
         * in the page list.
         */
        hcf = 0;
        for (i = entries - 1; i >= 0; i--) {
                sge = sgl + i;
                buf = (vm_offset_t)sge->addr;
                len = sge->len;
                start_pva = trunc_page(buf);
                end_pva = trunc_page(buf + len - 1);
                pva = start_pva;
                while (pva <= end_pva) {
                        seglen = PAGE_SIZE;
                        p1 = pmap_kextract(pva);
                        pva += PAGE_SIZE;
                        while (pva <= end_pva && p1 + seglen ==
                            pmap_kextract(pva)) {
                                seglen += PAGE_SIZE;
                                pva += PAGE_SIZE;
                        }

                        hcf = calculate_hcf(hcf, seglen);
                        if (hcf < (1 << pr->pr_page_shift[1])) {
                                idx = 0;
                                goto have_pgsz; /* give up, short circuit */
                        }
                }
        }
#define PR_PAGE_MASK(x) ((1 << pr->pr_page_shift[(x)]) - 1)
        MPASS((hcf & PR_PAGE_MASK(0)) == 0); /* PAGE_SIZE is >= 4K everywhere */
        for (idx = nitems(pr->pr_page_shift) - 1; idx > 0; idx--) {
                if ((hcf & PR_PAGE_MASK(idx)) == 0)
                        break;
        }
#undef PR_PAGE_MASK

have_pgsz:
        MPASS(idx <= M_PPOD_PGSZ);

        npages = 0;
        while (entries--) {
                npages++;
                start_pva = trunc_page((vm_offset_t)sgl->addr);
                end_pva = trunc_page((vm_offset_t)sgl->addr + sgl->len - 1);
                npages += (end_pva - start_pva) >> pr->pr_page_shift[idx];
                sgl = sgl + 1;
        }
        nppods = howmany(npages, PPOD_PAGES);
        if (alloc_page_pods(pr, nppods, idx, prsv) != 0)
                return (ENOMEM);
        MPASS(prsv->prsv_nppods > 0);
        return (0);
}

void
t4_free_page_pods(struct ppod_reservation *prsv)
{
        struct ppod_region *pr = prsv->prsv_pr;
        vmem_addr_t addr;

        MPASS(prsv != NULL);
        MPASS(prsv->prsv_nppods != 0);

        addr = prsv->prsv_tag & pr->pr_tag_mask;
        MPASS((addr & pr->pr_invalid_bit) == 0);

#ifdef VERBOSE_TRACES
        CTR4(KTR_CXGBE, "%-17s arena %p, addr 0x%08x, nppods %d", __func__,
            pr->pr_arena, addr, prsv->prsv_nppods);
#endif

        vmem_free(pr->pr_arena, addr, PPOD_SZ(prsv->prsv_nppods));
        prsv->prsv_nppods = 0;
}

#define NUM_ULP_TX_SC_IMM_PPODS (256 / PPOD_SIZE)

int
t4_write_page_pods_for_ps(struct adapter *sc, struct sge_wrq *wrq, int tid,
    struct pageset *ps)
{
        struct wrqe *wr;
        struct ulp_mem_io *ulpmc;
        struct ulptx_idata *ulpsc;
        struct pagepod *ppod;
        int i, j, k, n, chunk, len, ddp_pgsz, idx;
        u_int ppod_addr;
        uint32_t cmd;
        struct ppod_reservation *prsv = &ps->prsv;
        struct ppod_region *pr = prsv->prsv_pr;
        vm_paddr_t pa;

        KASSERT(!(ps->flags & PS_PPODS_WRITTEN),
            ("%s: page pods already written", __func__));
        MPASS(prsv->prsv_nppods > 0);

        cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE));
        if (is_t4(sc))
                cmd |= htobe32(F_ULP_MEMIO_ORDER);
        else
                cmd |= htobe32(F_T5_ULP_MEMIO_IMM);
        ddp_pgsz = 1 << pr->pr_page_shift[G_PPOD_PGSZ(prsv->prsv_tag)];
        ppod_addr = pr->pr_start + (prsv->prsv_tag & pr->pr_tag_mask);
        for (i = 0; i < prsv->prsv_nppods; ppod_addr += chunk) {
                /* How many page pods are we writing in this cycle */
                n = min(prsv->prsv_nppods - i, NUM_ULP_TX_SC_IMM_PPODS);
                chunk = PPOD_SZ(n);
                len = roundup2(sizeof(*ulpmc) + sizeof(*ulpsc) + chunk, 16);

                wr = alloc_wrqe(len, wrq);
                if (wr == NULL)
                        return (ENOMEM);        /* ok to just bail out */
                ulpmc = wrtod(wr);

                INIT_ULPTX_WR(ulpmc, len, 0, 0);
                ulpmc->cmd = cmd;
                if (chip_id(sc) >= CHELSIO_T7)
                        ulpmc->dlen = htobe32(V_T7_ULP_MEMIO_DATA_LEN(chunk >> 5));
                else
                        ulpmc->dlen = htobe32(V_ULP_MEMIO_DATA_LEN(chunk >> 5));
                ulpmc->len16 = htobe32(howmany(len - sizeof(ulpmc->wr), 16));
                ulpmc->lock_addr = htobe32(V_ULP_MEMIO_ADDR(ppod_addr >> 5));

                ulpsc = (struct ulptx_idata *)(ulpmc + 1);
                ulpsc->cmd_more = htobe32(V_ULPTX_CMD(ULP_TX_SC_IMM));
                ulpsc->len = htobe32(chunk);

                ppod = (struct pagepod *)(ulpsc + 1);
                for (j = 0; j < n; i++, j++, ppod++) {
                        ppod->vld_tid_pgsz_tag_color = htobe64(F_PPOD_VALID |
                            V_PPOD_TID(tid) | prsv->prsv_tag);
                        ppod->len_offset = htobe64(V_PPOD_LEN(ps->len) |
                            V_PPOD_OFST(ps->offset));
                        ppod->rsvd = 0;
                        idx = i * PPOD_PAGES * (ddp_pgsz / PAGE_SIZE);
                        for (k = 0; k < nitems(ppod->addr); k++) {
                                if (idx < ps->npages) {
                                        pa = VM_PAGE_TO_PHYS(ps->pages[idx]);
                                        ppod->addr[k] = htobe64(pa);
                                        idx += ddp_pgsz / PAGE_SIZE;
                                } else
                                        ppod->addr[k] = 0;
#if 0
                                CTR5(KTR_CXGBE,
                                    "%s: tid %d ppod[%d]->addr[%d] = %p",
                                    __func__, tid, i, k,
                                    be64toh(ppod->addr[k]));
#endif
                        }

                }

                t4_wrq_tx(sc, wr);
        }
        ps->flags |= PS_PPODS_WRITTEN;

        return (0);
}

static int
t4_write_page_pods_for_rcvbuf(struct adapter *sc, struct sge_wrq *wrq, int tid,
    struct ddp_rcv_buffer *drb)
{
        struct wrqe *wr;
        struct ulp_mem_io *ulpmc;
        struct ulptx_idata *ulpsc;
        struct pagepod *ppod;
        int i, j, k, n, chunk, len, ddp_pgsz;
        u_int ppod_addr, offset;
        uint32_t cmd;
        struct ppod_reservation *prsv = &drb->prsv;
        struct ppod_region *pr = prsv->prsv_pr;
        uintptr_t end_pva, pva;
        vm_paddr_t pa;

        MPASS(prsv->prsv_nppods > 0);

        cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE));
        if (is_t4(sc))
                cmd |= htobe32(F_ULP_MEMIO_ORDER);
        else
                cmd |= htobe32(F_T5_ULP_MEMIO_IMM);
        ddp_pgsz = 1 << pr->pr_page_shift[G_PPOD_PGSZ(prsv->prsv_tag)];
        offset = (uintptr_t)drb->buf & PAGE_MASK;
        ppod_addr = pr->pr_start + (prsv->prsv_tag & pr->pr_tag_mask);
        pva = trunc_page((uintptr_t)drb->buf);
        end_pva = trunc_page((uintptr_t)drb->buf + drb->len - 1);
        for (i = 0; i < prsv->prsv_nppods; ppod_addr += chunk) {
                /* How many page pods are we writing in this cycle */
                n = min(prsv->prsv_nppods - i, NUM_ULP_TX_SC_IMM_PPODS);
                MPASS(n > 0);
                chunk = PPOD_SZ(n);
                len = roundup2(sizeof(*ulpmc) + sizeof(*ulpsc) + chunk, 16);

                wr = alloc_wrqe(len, wrq);
                if (wr == NULL)
                        return (ENOMEM);        /* ok to just bail out */
                ulpmc = wrtod(wr);

                INIT_ULPTX_WR(ulpmc, len, 0, 0);
                ulpmc->cmd = cmd;
                ulpmc->dlen = htobe32(V_ULP_MEMIO_DATA_LEN(chunk / 32));
                ulpmc->len16 = htobe32(howmany(len - sizeof(ulpmc->wr), 16));
                ulpmc->lock_addr = htobe32(V_ULP_MEMIO_ADDR(ppod_addr >> 5));

                ulpsc = (struct ulptx_idata *)(ulpmc + 1);
                ulpsc->cmd_more = htobe32(V_ULPTX_CMD(ULP_TX_SC_IMM));
                ulpsc->len = htobe32(chunk);

                ppod = (struct pagepod *)(ulpsc + 1);
                for (j = 0; j < n; i++, j++, ppod++) {
                        ppod->vld_tid_pgsz_tag_color = htobe64(F_PPOD_VALID |
                            V_PPOD_TID(tid) | prsv->prsv_tag);
                        ppod->len_offset = htobe64(V_PPOD_LEN(drb->len) |
                            V_PPOD_OFST(offset));
                        ppod->rsvd = 0;

                        for (k = 0; k < nitems(ppod->addr); k++) {
                                if (pva > end_pva)
                                        ppod->addr[k] = 0;
                                else {
                                        pa = pmap_kextract(pva);
                                        ppod->addr[k] = htobe64(pa);
                                        pva += ddp_pgsz;
                                }
#if 0
                                CTR5(KTR_CXGBE,
                                    "%s: tid %d ppod[%d]->addr[%d] = %p",
                                    __func__, tid, i, k,
                                    be64toh(ppod->addr[k]));
#endif
                        }

                        /*
                         * Walk back 1 segment so that the first address in the
                         * next pod is the same as the last one in the current
                         * pod.
                         */
                        pva -= ddp_pgsz;
                }

                t4_wrq_tx(sc, wr);
        }

        MPASS(pva <= end_pva);

        return (0);
}

struct mbuf *
alloc_raw_wr_mbuf(int len)
{
        struct mbuf *m;

        if (len <= MHLEN)
                m = m_gethdr(M_NOWAIT, MT_DATA);
        else if (len <= MCLBYTES)
                m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
        else
                m = NULL;
        if (m == NULL)
                return (NULL);
        m->m_pkthdr.len = len;
        m->m_len = len;
        set_mbuf_raw_wr(m, true);
        return (m);
}

int
t4_write_page_pods_for_bio(struct adapter *sc, struct toepcb *toep,
    struct ppod_reservation *prsv, struct bio *bp, struct mbufq *wrq)
{
        struct ulp_mem_io *ulpmc;
        struct ulptx_idata *ulpsc;
        struct pagepod *ppod;
        int i, j, k, n, chunk, len, ddp_pgsz, idx;
        u_int ppod_addr;
        uint32_t cmd;
        struct ppod_region *pr = prsv->prsv_pr;
        vm_paddr_t pa;
        struct mbuf *m;

        MPASS(bp->bio_flags & BIO_UNMAPPED);

        cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE));
        if (is_t4(sc))
                cmd |= htobe32(F_ULP_MEMIO_ORDER);
        else
                cmd |= htobe32(F_T5_ULP_MEMIO_IMM);
        ddp_pgsz = 1 << pr->pr_page_shift[G_PPOD_PGSZ(prsv->prsv_tag)];
        ppod_addr = pr->pr_start + (prsv->prsv_tag & pr->pr_tag_mask);
        for (i = 0; i < prsv->prsv_nppods; ppod_addr += chunk) {

                /* How many page pods are we writing in this cycle */
                n = min(prsv->prsv_nppods - i, NUM_ULP_TX_SC_IMM_PPODS);
                MPASS(n > 0);
                chunk = PPOD_SZ(n);
                len = roundup2(sizeof(*ulpmc) + sizeof(*ulpsc) + chunk, 16);

                m = alloc_raw_wr_mbuf(len);
                if (m == NULL)
                        return (ENOMEM);

                ulpmc = mtod(m, struct ulp_mem_io *);
                INIT_ULPTX_WR(ulpmc, len, 0, toep->tid);
                ulpmc->cmd = cmd;
                if (chip_id(sc) >= CHELSIO_T7)
                        ulpmc->dlen = htobe32(V_T7_ULP_MEMIO_DATA_LEN(chunk >> 5));
                else
                        ulpmc->dlen = htobe32(V_ULP_MEMIO_DATA_LEN(chunk >> 5));
                ulpmc->len16 = htobe32(howmany(len - sizeof(ulpmc->wr), 16));
                ulpmc->lock_addr = htobe32(V_ULP_MEMIO_ADDR(ppod_addr >> 5));

                ulpsc = (struct ulptx_idata *)(ulpmc + 1);
                ulpsc->cmd_more = htobe32(V_ULPTX_CMD(ULP_TX_SC_IMM));
                ulpsc->len = htobe32(chunk);

                ppod = (struct pagepod *)(ulpsc + 1);
                for (j = 0; j < n; i++, j++, ppod++) {
                        ppod->vld_tid_pgsz_tag_color = htobe64(F_PPOD_VALID |
                            V_PPOD_TID(toep->tid) |
                            (prsv->prsv_tag & ~V_PPOD_PGSZ(M_PPOD_PGSZ)));
                        ppod->len_offset = htobe64(V_PPOD_LEN(bp->bio_bcount) |
                            V_PPOD_OFST(bp->bio_ma_offset));
                        ppod->rsvd = 0;
                        idx = i * PPOD_PAGES * (ddp_pgsz / PAGE_SIZE);
                        for (k = 0; k < nitems(ppod->addr); k++) {
                                if (idx < bp->bio_ma_n) {
                                        pa = VM_PAGE_TO_PHYS(bp->bio_ma[idx]);
                                        ppod->addr[k] = htobe64(pa);
                                        idx += ddp_pgsz / PAGE_SIZE;
                                } else
                                        ppod->addr[k] = 0;
#if 0
                                CTR5(KTR_CXGBE,
                                    "%s: tid %d ppod[%d]->addr[%d] = %p",
                                    __func__, toep->tid, i, k,
                                    be64toh(ppod->addr[k]));
#endif
                        }
                }

                mbufq_enqueue(wrq, m);
        }

        return (0);
}

int
t4_write_page_pods_for_buf(struct adapter *sc, struct toepcb *toep,
    struct ppod_reservation *prsv, vm_offset_t buf, int buflen,
    struct mbufq *wrq)
{
        struct ulp_mem_io *ulpmc;
        struct ulptx_idata *ulpsc;
        struct pagepod *ppod;
        int i, j, k, n, chunk, len, ddp_pgsz;
        u_int ppod_addr, offset;
        uint32_t cmd;
        struct ppod_region *pr = prsv->prsv_pr;
        uintptr_t end_pva, pva;
        vm_paddr_t pa;
        struct mbuf *m;

        cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE));
        if (is_t4(sc))
                cmd |= htobe32(F_ULP_MEMIO_ORDER);
        else
                cmd |= htobe32(F_T5_ULP_MEMIO_IMM);
        ddp_pgsz = 1 << pr->pr_page_shift[G_PPOD_PGSZ(prsv->prsv_tag)];
        offset = buf & PAGE_MASK;
        ppod_addr = pr->pr_start + (prsv->prsv_tag & pr->pr_tag_mask);
        pva = trunc_page(buf);
        end_pva = trunc_page(buf + buflen - 1);
        for (i = 0; i < prsv->prsv_nppods; ppod_addr += chunk) {

                /* How many page pods are we writing in this cycle */
                n = min(prsv->prsv_nppods - i, NUM_ULP_TX_SC_IMM_PPODS);
                MPASS(n > 0);
                chunk = PPOD_SZ(n);
                len = roundup2(sizeof(*ulpmc) + sizeof(*ulpsc) + chunk, 16);

                m = alloc_raw_wr_mbuf(len);
                if (m == NULL)
                        return (ENOMEM);
                ulpmc = mtod(m, struct ulp_mem_io *);

                INIT_ULPTX_WR(ulpmc, len, 0, toep->tid);
                ulpmc->cmd = cmd;
                if (chip_id(sc) >= CHELSIO_T7)
                        ulpmc->dlen = htobe32(V_T7_ULP_MEMIO_DATA_LEN(chunk >> 5));
                else
                        ulpmc->dlen = htobe32(V_ULP_MEMIO_DATA_LEN(chunk >> 5));
                ulpmc->len16 = htobe32(howmany(len - sizeof(ulpmc->wr), 16));
                ulpmc->lock_addr = htobe32(V_ULP_MEMIO_ADDR(ppod_addr >> 5));

                ulpsc = (struct ulptx_idata *)(ulpmc + 1);
                ulpsc->cmd_more = htobe32(V_ULPTX_CMD(ULP_TX_SC_IMM));
                ulpsc->len = htobe32(chunk);

                ppod = (struct pagepod *)(ulpsc + 1);
                for (j = 0; j < n; i++, j++, ppod++) {
                        ppod->vld_tid_pgsz_tag_color = htobe64(F_PPOD_VALID |
                            V_PPOD_TID(toep->tid) |
                            (prsv->prsv_tag & ~V_PPOD_PGSZ(M_PPOD_PGSZ)));
                        ppod->len_offset = htobe64(V_PPOD_LEN(buflen) |
                            V_PPOD_OFST(offset));
                        ppod->rsvd = 0;

                        for (k = 0; k < nitems(ppod->addr); k++) {
                                if (pva > end_pva)
                                        ppod->addr[k] = 0;
                                else {
                                        pa = pmap_kextract(pva);
                                        ppod->addr[k] = htobe64(pa);
                                        pva += ddp_pgsz;
                                }
#if 0
                                CTR5(KTR_CXGBE,
                                    "%s: tid %d ppod[%d]->addr[%d] = %p",
                                    __func__, toep->tid, i, k,
                                    be64toh(ppod->addr[k]));
#endif
                        }

                        /*
                         * Walk back 1 segment so that the first address in the
                         * next pod is the same as the last one in the current
                         * pod.
                         */
                        pva -= ddp_pgsz;
                }

                mbufq_enqueue(wrq, m);
        }

        MPASS(pva <= end_pva);

        return (0);
}

int
t4_write_page_pods_for_sgl(struct adapter *sc, struct toepcb *toep,
    struct ppod_reservation *prsv, struct ctl_sg_entry *sgl, int entries,
    int xferlen, struct mbufq *wrq)
{
        struct ulp_mem_io *ulpmc;
        struct ulptx_idata *ulpsc;
        struct pagepod *ppod;
        int i, j, k, n, chunk, len, ddp_pgsz;
        u_int ppod_addr, offset, sg_offset = 0;
        uint32_t cmd;
        struct ppod_region *pr = prsv->prsv_pr;
        uintptr_t pva;
        vm_paddr_t pa;
        struct mbuf *m;

        MPASS(sgl != NULL);
        MPASS(entries > 0);
        cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE));
        if (is_t4(sc))
                cmd |= htobe32(F_ULP_MEMIO_ORDER);
        else
                cmd |= htobe32(F_T5_ULP_MEMIO_IMM);
        ddp_pgsz = 1 << pr->pr_page_shift[G_PPOD_PGSZ(prsv->prsv_tag)];
        offset = (vm_offset_t)sgl->addr & PAGE_MASK;
        ppod_addr = pr->pr_start + (prsv->prsv_tag & pr->pr_tag_mask);
        pva = trunc_page((vm_offset_t)sgl->addr);
        for (i = 0; i < prsv->prsv_nppods; ppod_addr += chunk) {

                /* How many page pods are we writing in this cycle */
                n = min(prsv->prsv_nppods - i, NUM_ULP_TX_SC_IMM_PPODS);
                MPASS(n > 0);
                chunk = PPOD_SZ(n);
                len = roundup2(sizeof(*ulpmc) + sizeof(*ulpsc) + chunk, 16);

                m = alloc_raw_wr_mbuf(len);
                if (m == NULL)
                        return (ENOMEM);
                ulpmc = mtod(m, struct ulp_mem_io *);

                INIT_ULPTX_WR(ulpmc, len, 0, toep->tid);
                ulpmc->cmd = cmd;
                if (chip_id(sc) >= CHELSIO_T7)
                        ulpmc->dlen = htobe32(V_T7_ULP_MEMIO_DATA_LEN(chunk >> 5));
                else
                        ulpmc->dlen = htobe32(V_ULP_MEMIO_DATA_LEN(chunk >> 5));
                ulpmc->len16 = htobe32(howmany(len - sizeof(ulpmc->wr), 16));
                ulpmc->lock_addr = htobe32(V_ULP_MEMIO_ADDR(ppod_addr >> 5));

                ulpsc = (struct ulptx_idata *)(ulpmc + 1);
                ulpsc->cmd_more = htobe32(V_ULPTX_CMD(ULP_TX_SC_IMM));
                ulpsc->len = htobe32(chunk);

                ppod = (struct pagepod *)(ulpsc + 1);
                for (j = 0; j < n; i++, j++, ppod++) {
                        ppod->vld_tid_pgsz_tag_color = htobe64(F_PPOD_VALID |
                            V_PPOD_TID(toep->tid) |
                            (prsv->prsv_tag & ~V_PPOD_PGSZ(M_PPOD_PGSZ)));
                        ppod->len_offset = htobe64(V_PPOD_LEN(xferlen) |
                            V_PPOD_OFST(offset));
                        ppod->rsvd = 0;

                        for (k = 0; k < nitems(ppod->addr); k++) {
                                if (entries != 0) {
                                        pa = pmap_kextract(pva + sg_offset);
                                        ppod->addr[k] = htobe64(pa);
                                } else
                                        ppod->addr[k] = 0;

#if 0
                                CTR5(KTR_CXGBE,
                                    "%s: tid %d ppod[%d]->addr[%d] = %p",
                                    __func__, toep->tid, i, k,
                                    be64toh(ppod->addr[k]));
#endif

                                /*
                                 * If this is the last entry in a pod,
                                 * reuse the same entry for first address
                                 * in the next pod.
                                 */
                                if (k + 1 == nitems(ppod->addr))
                                        break;

                                /*
                                 * Don't move to the next DDP page if the
                                 * sgl is already finished.
                                 */
                                if (entries == 0)
                                        continue;

                                sg_offset += ddp_pgsz;
                                if (sg_offset == sgl->len) {
                                        /*
                                         * This sgl entry is done.  Go
                                         * to the next.
                                         */
                                        entries--;
                                        sgl++;
                                        sg_offset = 0;
                                        if (entries != 0)
                                                pva = trunc_page(
                                                    (vm_offset_t)sgl->addr);
                                }
                        }
                }

                mbufq_enqueue(wrq, m);
        }

        return (0);
}

/*
 * Prepare a pageset for DDP.  This sets up page pods.
 */
static int
prep_pageset(struct adapter *sc, struct toepcb *toep, struct pageset *ps)
{
        struct tom_data *td = sc->tom_softc;

        if (ps->prsv.prsv_nppods == 0 &&
            t4_alloc_page_pods_for_ps(&td->pr, ps) != 0) {
                return (0);
        }
        if (!(ps->flags & PS_PPODS_WRITTEN) &&
            t4_write_page_pods_for_ps(sc, toep->ctrlq, toep->tid, ps) != 0) {
                return (0);
        }

        return (1);
}

int
t4_init_ppod_region(struct ppod_region *pr, struct t4_range *r, u_int psz,
    const char *name)
{
        int i;

        MPASS(pr != NULL);
        MPASS(r->size > 0);

        pr->pr_start = r->start;
        pr->pr_len = r->size;
        pr->pr_page_shift[0] = 12 + G_HPZ0(psz);
        pr->pr_page_shift[1] = 12 + G_HPZ1(psz);
        pr->pr_page_shift[2] = 12 + G_HPZ2(psz);
        pr->pr_page_shift[3] = 12 + G_HPZ3(psz);

        /* The SGL -> page pod algorithm requires the sizes to be in order. */
        for (i = 1; i < nitems(pr->pr_page_shift); i++) {
                if (pr->pr_page_shift[i] <= pr->pr_page_shift[i - 1])
                        return (ENXIO);
        }

        pr->pr_tag_mask = ((1 << fls(r->size)) - 1) & V_PPOD_TAG(M_PPOD_TAG);
        pr->pr_alias_mask = V_PPOD_TAG(M_PPOD_TAG) & ~pr->pr_tag_mask;
        if (pr->pr_tag_mask == 0 || pr->pr_alias_mask == 0)
                return (ENXIO);
        pr->pr_alias_shift = fls(pr->pr_tag_mask);
        pr->pr_invalid_bit = 1 << (pr->pr_alias_shift - 1);

        pr->pr_arena = vmem_create(name, 0, pr->pr_len, PPOD_SIZE, 0,
            M_FIRSTFIT | M_NOWAIT);
        if (pr->pr_arena == NULL)
                return (ENOMEM);

        return (0);
}

void
t4_free_ppod_region(struct ppod_region *pr)
{

        MPASS(pr != NULL);

        if (pr->pr_arena)
                vmem_destroy(pr->pr_arena);
        bzero(pr, sizeof(*pr));
}

static int
pscmp(struct pageset *ps, struct vmspace *vm, vm_offset_t start, int npages,
    int pgoff, int len)
{

        if (ps->start != start || ps->npages != npages ||
            ps->offset != pgoff || ps->len != len)
                return (1);

        return (ps->vm != vm || ps->vm_timestamp != vm->vm_map.timestamp);
}

static int
hold_aio(struct toepcb *toep, struct kaiocb *job, struct pageset **pps)
{
        struct vmspace *vm;
        vm_map_t map;
        vm_offset_t start, end, pgoff;
        struct pageset *ps;
        int n;

        DDP_ASSERT_LOCKED(toep);

        /*
         * The AIO subsystem will cancel and drain all requests before
         * permitting a process to exit or exec, so p_vmspace should
         * be stable here.
         */
        vm = job->userproc->p_vmspace;
        map = &vm->vm_map;
        start = (uintptr_t)job->uaiocb.aio_buf;
        pgoff = start & PAGE_MASK;
        end = round_page(start + job->uaiocb.aio_nbytes);
        start = trunc_page(start);

        if (end - start > MAX_DDP_BUFFER_SIZE) {
                /*
                 * Truncate the request to a short read.
                 * Alternatively, we could DDP in chunks to the larger
                 * buffer, but that would be quite a bit more work.
                 *
                 * When truncating, round the request down to avoid
                 * crossing a cache line on the final transaction.
                 */
                end = rounddown2(start + MAX_DDP_BUFFER_SIZE, CACHE_LINE_SIZE);
#ifdef VERBOSE_TRACES
                CTR4(KTR_CXGBE, "%s: tid %d, truncating size from %lu to %lu",
                    __func__, toep->tid, (unsigned long)job->uaiocb.aio_nbytes,
                    (unsigned long)(end - (start + pgoff)));
                job->uaiocb.aio_nbytes = end - (start + pgoff);
#endif
                end = round_page(end);
        }

        n = atop(end - start);

        /*
         * Try to reuse a cached pageset.
         */
        TAILQ_FOREACH(ps, &toep->ddp.cached_pagesets, link) {
                if (pscmp(ps, vm, start, n, pgoff,
                    job->uaiocb.aio_nbytes) == 0) {
                        TAILQ_REMOVE(&toep->ddp.cached_pagesets, ps, link);
                        toep->ddp.cached_count--;
                        *pps = ps;
                        return (0);
                }
        }

        /*
         * If there are too many cached pagesets to create a new one,
         * free a pageset before creating a new one.
         */
        KASSERT(toep->ddp.active_count + toep->ddp.cached_count <=
            nitems(toep->ddp.db), ("%s: too many wired pagesets", __func__));
        if (toep->ddp.active_count + toep->ddp.cached_count ==
            nitems(toep->ddp.db)) {
                KASSERT(toep->ddp.cached_count > 0,
                    ("no cached pageset to free"));
                ps = TAILQ_LAST(&toep->ddp.cached_pagesets, pagesetq);
                TAILQ_REMOVE(&toep->ddp.cached_pagesets, ps, link);
                toep->ddp.cached_count--;
                free_pageset(toep->td, ps);
        }
        DDP_UNLOCK(toep);

        /* Create a new pageset. */
        ps = malloc(sizeof(*ps) + n * sizeof(vm_page_t), M_CXGBE, M_WAITOK |
            M_ZERO);
        ps->pages = (vm_page_t *)(ps + 1);
        ps->vm_timestamp = map->timestamp;
        ps->npages = vm_fault_quick_hold_pages(map, start, end - start,
            VM_PROT_WRITE, ps->pages, n);

        DDP_LOCK(toep);
        if (ps->npages < 0) {
                free(ps, M_CXGBE);
                return (EFAULT);
        }

        KASSERT(ps->npages == n, ("hold_aio: page count mismatch: %d vs %d",
            ps->npages, n));

        ps->offset = pgoff;
        ps->len = job->uaiocb.aio_nbytes;
        refcount_acquire(&vm->vm_refcnt);
        ps->vm = vm;
        ps->start = start;

        CTR5(KTR_CXGBE, "%s: tid %d, new pageset %p for job %p, npages %d",
            __func__, toep->tid, ps, job, ps->npages);
        *pps = ps;
        return (0);
}

static void
ddp_complete_all(struct toepcb *toep, int error)
{
        struct kaiocb *job;

        DDP_ASSERT_LOCKED(toep);
        KASSERT((toep->ddp.flags & DDP_AIO) != 0, ("%s: DDP_RCVBUF", __func__));
        while (!TAILQ_EMPTY(&toep->ddp.aiojobq)) {
                job = TAILQ_FIRST(&toep->ddp.aiojobq);
                TAILQ_REMOVE(&toep->ddp.aiojobq, job, list);
                toep->ddp.waiting_count--;
                if (aio_clear_cancel_function(job))
                        ddp_complete_one(job, error);
        }
}

static void
aio_ddp_cancel_one(struct kaiocb *job)
{
        long copied;

        /*
         * If this job had copied data out of the socket buffer before
         * it was cancelled, report it as a short read rather than an
         * error.
         */
        copied = job->aio_received;
        if (copied != 0)
                aio_complete(job, copied, 0);
        else
                aio_cancel(job);
}

/*
 * Called when the main loop wants to requeue a job to retry it later.
 * Deals with the race of the job being cancelled while it was being
 * examined.
 */
static void
aio_ddp_requeue_one(struct toepcb *toep, struct kaiocb *job)
{

        DDP_ASSERT_LOCKED(toep);
        if (!(toep->ddp.flags & DDP_DEAD) &&
            aio_set_cancel_function(job, t4_aio_cancel_queued)) {
                TAILQ_INSERT_HEAD(&toep->ddp.aiojobq, job, list);
                toep->ddp.waiting_count++;
        } else
                aio_ddp_cancel_one(job);
}

static void
aio_ddp_requeue(struct toepcb *toep)
{
        struct adapter *sc = td_adapter(toep->td);
        struct socket *so;
        struct sockbuf *sb;
        struct inpcb *inp;
        struct kaiocb *job;
        struct ddp_buffer *db;
        size_t copied, offset, resid;
        struct pageset *ps;
        struct mbuf *m;
        uint64_t ddp_flags, ddp_flags_mask;
        struct wrqe *wr;
        int buf_flag, db_idx, error;

        DDP_ASSERT_LOCKED(toep);

restart:
        if (toep->ddp.flags & DDP_DEAD) {
                MPASS(toep->ddp.waiting_count == 0);
                MPASS(toep->ddp.active_count == 0);
                return;
        }

        if (toep->ddp.waiting_count == 0 ||
            toep->ddp.active_count == nitems(toep->ddp.db)) {
                return;
        }

        job = TAILQ_FIRST(&toep->ddp.aiojobq);
        so = job->fd_file->f_data;
        sb = &so->so_rcv;
        SOCKBUF_LOCK(sb);

        /* We will never get anything unless we are or were connected. */
        if (!(so->so_state & (SS_ISCONNECTED|SS_ISDISCONNECTED))) {
                SOCKBUF_UNLOCK(sb);
                ddp_complete_all(toep, ENOTCONN);
                return;
        }

        KASSERT(toep->ddp.active_count == 0 || sbavail(sb) == 0,
            ("%s: pending sockbuf data and DDP is active", __func__));

        /* Abort if socket has reported problems. */
        /* XXX: Wait for any queued DDP's to finish and/or flush them? */
        if (so->so_error && sbavail(sb) == 0) {
                toep->ddp.waiting_count--;
                TAILQ_REMOVE(&toep->ddp.aiojobq, job, list);
                if (!aio_clear_cancel_function(job)) {
                        SOCKBUF_UNLOCK(sb);
                        goto restart;
                }

                /*
                 * If this job has previously copied some data, report
                 * a short read and leave the error to be reported by
                 * a future request.
                 */
                copied = job->aio_received;
                if (copied != 0) {
                        SOCKBUF_UNLOCK(sb);
                        aio_complete(job, copied, 0);
                        goto restart;
                }
                error = so->so_error;
                so->so_error = 0;
                SOCKBUF_UNLOCK(sb);
                aio_complete(job, -1, error);
                goto restart;
        }

        /*
         * Door is closed.  If there is pending data in the socket buffer,
         * deliver it.  If there are pending DDP requests, wait for those
         * to complete.  Once they have completed, return EOF reads.
         */
        if (sb->sb_state & SBS_CANTRCVMORE && sbavail(sb) == 0) {
                SOCKBUF_UNLOCK(sb);
                if (toep->ddp.active_count != 0)
                        return;
                ddp_complete_all(toep, 0);
                return;
        }

        /*
         * If DDP is not enabled and there is no pending socket buffer
         * data, try to enable DDP.
         */
        if (sbavail(sb) == 0 && (toep->ddp.flags & DDP_ON) == 0) {
                SOCKBUF_UNLOCK(sb);

                /*
                 * Wait for the card to ACK that DDP is enabled before
                 * queueing any buffers.  Currently this waits for an
                 * indicate to arrive.  This could use a TCB_SET_FIELD_RPL
                 * message to know that DDP was enabled instead of waiting
                 * for the indicate which would avoid copying the indicate
                 * if no data is pending.
                 *
                 * XXX: Might want to limit the indicate size to the size
                 * of the first queued request.
                 */
                if ((toep->ddp.flags & DDP_SC_REQ) == 0)
                        enable_ddp(sc, toep);
                return;
        }
        SOCKBUF_UNLOCK(sb);

        /*
         * If another thread is queueing a buffer for DDP, let it
         * drain any work and return.
         */
        if (toep->ddp.queueing != NULL)
                return;

        /* Take the next job to prep it for DDP. */
        toep->ddp.waiting_count--;
        TAILQ_REMOVE(&toep->ddp.aiojobq, job, list);
        if (!aio_clear_cancel_function(job))
                goto restart;
        toep->ddp.queueing = job;

        /* NB: This drops DDP_LOCK while it holds the backing VM pages. */
        error = hold_aio(toep, job, &ps);
        if (error != 0) {
                ddp_complete_one(job, error);
                toep->ddp.queueing = NULL;
                goto restart;
        }

        SOCKBUF_LOCK(sb);
        if (so->so_error && sbavail(sb) == 0) {
                copied = job->aio_received;
                if (copied != 0) {
                        SOCKBUF_UNLOCK(sb);
                        recycle_pageset(toep, ps);
                        aio_complete(job, copied, 0);
                        toep->ddp.queueing = NULL;
                        goto restart;
                }

                error = so->so_error;
                so->so_error = 0;
                SOCKBUF_UNLOCK(sb);
                recycle_pageset(toep, ps);
                aio_complete(job, -1, error);
                toep->ddp.queueing = NULL;
                goto restart;
        }

        if (sb->sb_state & SBS_CANTRCVMORE && sbavail(sb) == 0) {
                SOCKBUF_UNLOCK(sb);
                recycle_pageset(toep, ps);
                if (toep->ddp.active_count != 0) {
                        /*
                         * The door is closed, but there are still pending
                         * DDP buffers.  Requeue.  These jobs will all be
                         * completed once those buffers drain.
                         */
                        aio_ddp_requeue_one(toep, job);
                        toep->ddp.queueing = NULL;
                        return;
                }
                ddp_complete_one(job, 0);
                ddp_complete_all(toep, 0);
                toep->ddp.queueing = NULL;
                return;
        }

sbcopy:
        /*
         * If the toep is dead, there shouldn't be any data in the socket
         * buffer, so the above case should have handled this.
         */
        MPASS(!(toep->ddp.flags & DDP_DEAD));

        /*
         * If there is pending data in the socket buffer (either
         * from before the requests were queued or a DDP indicate),
         * copy those mbufs out directly.
         */
        copied = 0;
        offset = ps->offset + job->aio_received;
        MPASS(job->aio_received <= job->uaiocb.aio_nbytes);
        resid = job->uaiocb.aio_nbytes - job->aio_received;
        m = sb->sb_mb;
        KASSERT(m == NULL || toep->ddp.active_count == 0,
            ("%s: sockbuf data with active DDP", __func__));
        while (m != NULL && resid > 0) {
                struct iovec iov[1];
                struct uio uio;
#ifdef INVARIANTS
                int error;
#endif

                iov[0].iov_base = mtod(m, void *);
                iov[0].iov_len = m->m_len;
                if (iov[0].iov_len > resid)
                        iov[0].iov_len = resid;
                uio.uio_iov = iov;
                uio.uio_iovcnt = 1;
                uio.uio_offset = 0;
                uio.uio_resid = iov[0].iov_len;
                uio.uio_segflg = UIO_SYSSPACE;
                uio.uio_rw = UIO_WRITE;
#ifdef INVARIANTS
                error = uiomove_fromphys(ps->pages, offset + copied,
                    uio.uio_resid, &uio);
#else
                uiomove_fromphys(ps->pages, offset + copied, uio.uio_resid, &uio);
#endif
                MPASS(error == 0 && uio.uio_resid == 0);
                copied += uio.uio_offset;
                resid -= uio.uio_offset;
                m = m->m_next;
        }
        if (copied != 0) {
                sbdrop_locked(sb, copied);
                job->aio_received += copied;
                job->msgrcv = 1;
                copied = job->aio_received;
                inp = sotoinpcb(so);
                if (!INP_TRY_WLOCK(inp)) {
                        /*
                         * The reference on the socket file descriptor in
                         * the AIO job should keep 'sb' and 'inp' stable.
                         * Our caller has a reference on the 'toep' that
                         * keeps it stable.
                         */
                        SOCKBUF_UNLOCK(sb);
                        DDP_UNLOCK(toep);
                        INP_WLOCK(inp);
                        DDP_LOCK(toep);
                        SOCKBUF_LOCK(sb);

                        /*
                         * If the socket has been closed, we should detect
                         * that and complete this request if needed on
                         * the next trip around the loop.
                         */
                }
                t4_rcvd_locked(&toep->td->tod, intotcpcb(inp));
                INP_WUNLOCK(inp);
                if (resid == 0 || toep->ddp.flags & DDP_DEAD) {
                        /*
                         * We filled the entire buffer with socket
                         * data, DDP is not being used, or the socket
                         * is being shut down, so complete the
                         * request.
                         */
                        SOCKBUF_UNLOCK(sb);
                        recycle_pageset(toep, ps);
                        aio_complete(job, copied, 0);
                        toep->ddp.queueing = NULL;
                        goto restart;
                }

                /*
                 * If DDP is not enabled, requeue this request and restart.
                 * This will either enable DDP or wait for more data to
                 * arrive on the socket buffer.
                 */
                if ((toep->ddp.flags & (DDP_ON | DDP_SC_REQ)) != DDP_ON) {
                        SOCKBUF_UNLOCK(sb);
                        recycle_pageset(toep, ps);
                        aio_ddp_requeue_one(toep, job);
                        toep->ddp.queueing = NULL;
                        goto restart;
                }

                /*
                 * An indicate might have arrived and been added to
                 * the socket buffer while it was unlocked after the
                 * copy to lock the INP.  If so, restart the copy.
                 */
                if (sbavail(sb) != 0)
                        goto sbcopy;
        }
        SOCKBUF_UNLOCK(sb);

        if (prep_pageset(sc, toep, ps) == 0) {
                recycle_pageset(toep, ps);
                aio_ddp_requeue_one(toep, job);
                toep->ddp.queueing = NULL;

                /*
                 * XXX: Need to retry this later.  Mostly need a trigger
                 * when page pods are freed up.
                 */
                printf("%s: prep_pageset failed\n", __func__);
                return;
        }

        /* Determine which DDP buffer to use. */
        if (toep->ddp.db[0].job == NULL) {
                db_idx = 0;
        } else {
                MPASS(toep->ddp.db[1].job == NULL);
                db_idx = 1;
        }

        ddp_flags = 0;
        ddp_flags_mask = 0;
        if (db_idx == 0) {
                ddp_flags |= V_TF_DDP_BUF0_VALID(1);
                if (so->so_state & SS_NBIO)
                        ddp_flags |= V_TF_DDP_BUF0_FLUSH(1);
                ddp_flags_mask |= V_TF_DDP_PSH_NO_INVALIDATE0(1) |
                    V_TF_DDP_PUSH_DISABLE_0(1) | V_TF_DDP_PSHF_ENABLE_0(1) |
                    V_TF_DDP_BUF0_FLUSH(1) | V_TF_DDP_BUF0_VALID(1);
                buf_flag = DDP_BUF0_ACTIVE;
        } else {
                ddp_flags |= V_TF_DDP_BUF1_VALID(1);
                if (so->so_state & SS_NBIO)
                        ddp_flags |= V_TF_DDP_BUF1_FLUSH(1);
                ddp_flags_mask |= V_TF_DDP_PSH_NO_INVALIDATE1(1) |
                    V_TF_DDP_PUSH_DISABLE_1(1) | V_TF_DDP_PSHF_ENABLE_1(1) |
                    V_TF_DDP_BUF1_FLUSH(1) | V_TF_DDP_BUF1_VALID(1);
                buf_flag = DDP_BUF1_ACTIVE;
        }
        MPASS((toep->ddp.flags & buf_flag) == 0);
        if ((toep->ddp.flags & (DDP_BUF0_ACTIVE | DDP_BUF1_ACTIVE)) == 0) {
                MPASS(db_idx == 0);
                MPASS(toep->ddp.active_id == -1);
                MPASS(toep->ddp.active_count == 0);
                ddp_flags_mask |= V_TF_DDP_ACTIVE_BUF(1);
        }

        /*
         * The TID for this connection should still be valid.  If DDP_DEAD
         * is set, SBS_CANTRCVMORE should be set, so we shouldn't be
         * this far anyway.  Even if the socket is closing on the other
         * end, the AIO job holds a reference on this end of the socket
         * which will keep it open and keep the TCP PCB attached until
         * after the job is completed.
         */
        wr = mk_update_tcb_for_ddp(sc, toep, db_idx, &ps->prsv,
            job->aio_received, ps->len, ddp_flags, ddp_flags_mask);
        if (wr == NULL) {
                recycle_pageset(toep, ps);
                aio_ddp_requeue_one(toep, job);
                toep->ddp.queueing = NULL;

                /*
                 * XXX: Need a way to kick a retry here.
                 *
                 * XXX: We know the fixed size needed and could
                 * preallocate this using a blocking request at the
                 * start of the task to avoid having to handle this
                 * edge case.
                 */
                printf("%s: mk_update_tcb_for_ddp failed\n", __func__);
                return;
        }

        if (!aio_set_cancel_function(job, t4_aio_cancel_active)) {
                free_wrqe(wr);
                recycle_pageset(toep, ps);
                aio_ddp_cancel_one(job);
                toep->ddp.queueing = NULL;
                goto restart;
        }

#ifdef VERBOSE_TRACES
        CTR6(KTR_CXGBE,
            "%s: tid %u, scheduling %p for DDP[%d] (flags %#lx/%#lx)", __func__,
            toep->tid, job, db_idx, ddp_flags, ddp_flags_mask);
#endif
        /* Give the chip the go-ahead. */
        t4_wrq_tx(sc, wr);
        db = &toep->ddp.db[db_idx];
        db->cancel_pending = 0;
        db->job = job;
        db->ps = ps;
        toep->ddp.queueing = NULL;
        toep->ddp.flags |= buf_flag;
        toep->ddp.active_count++;
        if (toep->ddp.active_count == 1) {
                MPASS(toep->ddp.active_id == -1);
                toep->ddp.active_id = db_idx;
                CTR2(KTR_CXGBE, "%s: ddp_active_id = %d", __func__,
                    toep->ddp.active_id);
        }
        goto restart;
}

void
ddp_queue_toep(struct toepcb *toep)
{

        DDP_ASSERT_LOCKED(toep);
        if (toep->ddp.flags & DDP_TASK_ACTIVE)
                return;
        toep->ddp.flags |= DDP_TASK_ACTIVE;
        hold_toepcb(toep);
        soaio_enqueue(&toep->ddp.requeue_task);
}

static void
aio_ddp_requeue_task(void *context, int pending)
{
        struct toepcb *toep = context;

        DDP_LOCK(toep);
        aio_ddp_requeue(toep);
        toep->ddp.flags &= ~DDP_TASK_ACTIVE;
        DDP_UNLOCK(toep);

        free_toepcb(toep);
}

static void
t4_aio_cancel_active(struct kaiocb *job)
{
        struct socket *so = job->fd_file->f_data;
        struct tcpcb *tp = sototcpcb(so);
        struct toepcb *toep = tp->t_toe;
        struct adapter *sc = td_adapter(toep->td);
        uint64_t valid_flag;
        int i;

        DDP_LOCK(toep);
        if (aio_cancel_cleared(job)) {
                DDP_UNLOCK(toep);
                aio_ddp_cancel_one(job);
                return;
        }

        for (i = 0; i < nitems(toep->ddp.db); i++) {
                if (toep->ddp.db[i].job == job) {
                        /* Should only ever get one cancel request for a job. */
                        MPASS(toep->ddp.db[i].cancel_pending == 0);

                        /*
                         * Invalidate this buffer.  It will be
                         * cancelled or partially completed once the
                         * card ACKs the invalidate.
                         */
                        valid_flag = i == 0 ? V_TF_DDP_BUF0_VALID(1) :
                            V_TF_DDP_BUF1_VALID(1);
                        t4_set_tcb_field(sc, toep->ctrlq, toep,
                            W_TCB_RX_DDP_FLAGS, valid_flag, 0, 1,
                            CPL_COOKIE_DDP0 + i);
                        toep->ddp.db[i].cancel_pending = 1;
                        CTR2(KTR_CXGBE, "%s: request %p marked pending",
                            __func__, job);
                        break;
                }
        }
        DDP_UNLOCK(toep);
}

static void
t4_aio_cancel_queued(struct kaiocb *job)
{
        struct socket *so = job->fd_file->f_data;
        struct tcpcb *tp = sototcpcb(so);
        struct toepcb *toep = tp->t_toe;

        DDP_LOCK(toep);
        if (!aio_cancel_cleared(job)) {
                TAILQ_REMOVE(&toep->ddp.aiojobq, job, list);
                toep->ddp.waiting_count--;
                if (toep->ddp.waiting_count == 0)
                        ddp_queue_toep(toep);
        }
        CTR2(KTR_CXGBE, "%s: request %p cancelled", __func__, job);
        DDP_UNLOCK(toep);

        aio_ddp_cancel_one(job);
}

int
t4_aio_queue_ddp(struct socket *so, struct kaiocb *job)
{
        struct inpcb *inp = sotoinpcb(so);
        struct tcpcb *tp = intotcpcb(inp);
        struct toepcb *toep = tp->t_toe;

        /* Ignore writes. */
        if (job->uaiocb.aio_lio_opcode != LIO_READ)
                return (EOPNOTSUPP);

        INP_WLOCK(inp);
        if (__predict_false(ulp_mode(toep) == ULP_MODE_NONE)) {
                if (!set_ddp_ulp_mode(toep)) {
                        INP_WUNLOCK(inp);
                        return (EOPNOTSUPP);
                }
        }
        INP_WUNLOCK(inp);

        DDP_LOCK(toep);

        /*
         * If DDP is being used for all normal receive, don't use it
         * for AIO.
         */
        if ((toep->ddp.flags & DDP_RCVBUF) != 0) {
                DDP_UNLOCK(toep);
                return (EOPNOTSUPP);
        }

        if ((toep->ddp.flags & DDP_AIO) == 0) {
                toep->ddp.flags |= DDP_AIO;
                TAILQ_INIT(&toep->ddp.cached_pagesets);
                TAILQ_INIT(&toep->ddp.aiojobq);
                TASK_INIT(&toep->ddp.requeue_task, 0, aio_ddp_requeue_task,
                    toep);
        }

        /*
         * XXX: Think about possibly returning errors for ENOTCONN,
         * etc.  Perhaps the caller would only queue the request
         * if it failed with EOPNOTSUPP?
         */

#ifdef VERBOSE_TRACES
        CTR3(KTR_CXGBE, "%s: queueing %p for tid %u", __func__, job, toep->tid);
#endif
        if (!aio_set_cancel_function(job, t4_aio_cancel_queued))
                panic("new job was cancelled");
        TAILQ_INSERT_TAIL(&toep->ddp.aiojobq, job, list);
        toep->ddp.waiting_count++;

        /*
         * Try to handle this request synchronously.  If this has
         * to block because the task is running, it will just bail
         * and let the task handle it instead.
         */
        aio_ddp_requeue(toep);
        DDP_UNLOCK(toep);
        return (0);
}

static void
ddp_rcvbuf_requeue(struct toepcb *toep)
{
        struct socket *so;
        struct sockbuf *sb;
        struct inpcb *inp;
        struct ddp_rcv_buffer *drb;

        DDP_ASSERT_LOCKED(toep);
restart:
        if ((toep->ddp.flags & DDP_DEAD) != 0) {
                MPASS(toep->ddp.active_count == 0);
                return;
        }

        /* If both buffers are active, nothing to do. */
        if (toep->ddp.active_count == nitems(toep->ddp.db)) {
                return;
        }

        inp = toep->inp;
        so = inp->inp_socket;
        sb = &so->so_rcv;

        drb = alloc_cached_ddp_rcv_buffer(toep);
        DDP_UNLOCK(toep);

        if (drb == NULL) {
                drb = alloc_ddp_rcv_buffer(toep, M_WAITOK);
                if (drb == NULL) {
                        printf("%s: failed to allocate buffer\n", __func__);
                        DDP_LOCK(toep);
                        return;
                }
        }

        DDP_LOCK(toep);
        if ((toep->ddp.flags & DDP_DEAD) != 0 ||
            toep->ddp.active_count == nitems(toep->ddp.db)) {
                recycle_ddp_rcv_buffer(toep, drb);
                return;
        }

        /* We will never get anything unless we are or were connected. */
        SOCKBUF_LOCK(sb);
        if (!(so->so_state & (SS_ISCONNECTED|SS_ISDISCONNECTED))) {
                SOCKBUF_UNLOCK(sb);
                recycle_ddp_rcv_buffer(toep, drb);
                return;
        }

        /* Abort if socket has reported problems or is closed. */
        if (so->so_error != 0 || (sb->sb_state & SBS_CANTRCVMORE) != 0) {
                SOCKBUF_UNLOCK(sb);
                recycle_ddp_rcv_buffer(toep, drb);
                return;
        }
        SOCKBUF_UNLOCK(sb);

        if (!queue_ddp_rcvbuf(toep, drb)) {
                /*
                 * XXX: Need a way to kick a retry here.
                 *
                 * XXX: We know the fixed size needed and could
                 * preallocate the work request using a blocking
                 * request at the start of the task to avoid having to
                 * handle this edge case.
                 */
                return;
        }
        goto restart;
}

static void
ddp_rcvbuf_requeue_task(void *context, int pending)
{
        struct toepcb *toep = context;

        DDP_LOCK(toep);
        ddp_rcvbuf_requeue(toep);
        toep->ddp.flags &= ~DDP_TASK_ACTIVE;
        DDP_UNLOCK(toep);

        free_toepcb(toep);
}

int
t4_enable_ddp_rcv(struct socket *so, struct toepcb *toep)
{
        struct inpcb *inp = sotoinpcb(so);
        struct adapter *sc = td_adapter(toep->td);

        INP_WLOCK(inp);
        switch (ulp_mode(toep)) {
        case ULP_MODE_TCPDDP:
                break;
        case ULP_MODE_NONE:
                if (set_ddp_ulp_mode(toep))
                        break;
                /* FALLTHROUGH */
        default:
                INP_WUNLOCK(inp);
                return (EOPNOTSUPP);
        }
        INP_WUNLOCK(inp);

        DDP_LOCK(toep);

        /*
         * If DDP is being used for AIO already, don't use it for
         * normal receive.
         */
        if ((toep->ddp.flags & DDP_AIO) != 0) {
                DDP_UNLOCK(toep);
                return (EOPNOTSUPP);
        }

        if ((toep->ddp.flags & DDP_RCVBUF) != 0) {
                DDP_UNLOCK(toep);
                return (EBUSY);
        }

        toep->ddp.flags |= DDP_RCVBUF;
        TAILQ_INIT(&toep->ddp.cached_buffers);
        enable_ddp(sc, toep);
        TASK_INIT(&toep->ddp.requeue_task, 0, ddp_rcvbuf_requeue_task, toep);
        ddp_queue_toep(toep);
        DDP_UNLOCK(toep);
        return (0);
}

void
t4_ddp_mod_load(void)
{
        if (t4_ddp_rcvbuf_len < PAGE_SIZE)
                t4_ddp_rcvbuf_len = PAGE_SIZE;
        if (t4_ddp_rcvbuf_len > MAX_DDP_BUFFER_SIZE)
                t4_ddp_rcvbuf_len = MAX_DDP_BUFFER_SIZE;
        if (!powerof2(t4_ddp_rcvbuf_len))
                t4_ddp_rcvbuf_len = 1 << fls(t4_ddp_rcvbuf_len);

        t4_register_shared_cpl_handler(CPL_SET_TCB_RPL, do_ddp_tcb_rpl,
            CPL_COOKIE_DDP0);
        t4_register_shared_cpl_handler(CPL_SET_TCB_RPL, do_ddp_tcb_rpl,
            CPL_COOKIE_DDP1);
        t4_register_cpl_handler(CPL_RX_DATA_DDP, do_rx_data_ddp);
        t4_register_cpl_handler(CPL_RX_DDP_COMPLETE, do_rx_ddp_complete);
        TAILQ_INIT(&ddp_orphan_pagesets);
        mtx_init(&ddp_orphan_pagesets_lock, "ddp orphans", NULL, MTX_DEF);
        TASK_INIT(&ddp_orphan_task, 0, ddp_free_orphan_pagesets, NULL);
}

void
t4_ddp_mod_unload(void)
{

        taskqueue_drain(taskqueue_thread, &ddp_orphan_task);
        MPASS(TAILQ_EMPTY(&ddp_orphan_pagesets));
        mtx_destroy(&ddp_orphan_pagesets_lock);
        t4_register_shared_cpl_handler(CPL_SET_TCB_RPL, NULL, CPL_COOKIE_DDP0);
        t4_register_shared_cpl_handler(CPL_SET_TCB_RPL, NULL, CPL_COOKIE_DDP1);
        t4_register_cpl_handler(CPL_RX_DATA_DDP, NULL);
        t4_register_cpl_handler(CPL_RX_DDP_COMPLETE, NULL);
}
#endif