/*
 * Copyright(c) 2015 - 2018 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/dmapool.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/mmu_context.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/string.h>

#include "hfi.h"
#include "sdma.h"
#include "mmu_rb.h"
#include "user_sdma.h"
#include "verbs.h"  /* for the headers */
#include "common.h" /* for struct hfi1_tid_info */
#include "trace.h"

static uint hfi1_sdma_comp_ring_size = 128;
module_param_named(sdma_comp_size, hfi1_sdma_comp_ring_size, uint, S_IRUGO);
MODULE_PARM_DESC(sdma_comp_size, "Size of User SDMA completion ring. Default: 128");

static unsigned initial_pkt_count = 8;

static int user_sdma_send_pkts(struct user_sdma_request *req, u16 maxpkts);
static void user_sdma_txreq_cb(struct sdma_txreq *txreq, int status);
static inline void pq_update(struct hfi1_user_sdma_pkt_q *pq);
static void user_sdma_free_request(struct user_sdma_request *req, bool unpin);
static int pin_vector_pages(struct user_sdma_request *req,
                            struct user_sdma_iovec *iovec);
static void unpin_vector_pages(struct mm_struct *mm, struct page **pages,
                               unsigned start, unsigned npages);
static int check_header_template(struct user_sdma_request *req,
                                 struct hfi1_pkt_header *hdr, u32 lrhlen,
                                 u32 datalen);
static int set_txreq_header(struct user_sdma_request *req,
                            struct user_sdma_txreq *tx, u32 datalen);
static int set_txreq_header_ahg(struct user_sdma_request *req,
                                struct user_sdma_txreq *tx, u32 len);
static inline void set_comp_state(struct hfi1_user_sdma_pkt_q *pq,
                                  struct hfi1_user_sdma_comp_q *cq,
                                  u16 idx, enum hfi1_sdma_comp_state state,
                                  int ret);
static inline u32 set_pkt_bth_psn(__be32 bthpsn, u8 expct, u32 frags);
static inline u32 get_lrh_len(struct hfi1_pkt_header, u32 len);

static int defer_packet_queue(
        struct sdma_engine *sde,
        struct iowait_work *wait,
        struct sdma_txreq *txreq,
        uint seq,
        bool pkts_sent);
static void activate_packet_queue(struct iowait *wait, int reason);
static bool sdma_rb_filter(struct mmu_rb_node *node, unsigned long addr,
                           unsigned long len);
static int sdma_rb_insert(void *arg, struct mmu_rb_node *mnode);
static int sdma_rb_evict(void *arg, struct mmu_rb_node *mnode,
                         void *arg2, bool *stop);
static void sdma_rb_remove(void *arg, struct mmu_rb_node *mnode);
static int sdma_rb_invalidate(void *arg, struct mmu_rb_node *mnode);

static struct mmu_rb_ops sdma_rb_ops = {
        .filter = sdma_rb_filter,
        .insert = sdma_rb_insert,
        .evict = sdma_rb_evict,
        .remove = sdma_rb_remove,
        .invalidate = sdma_rb_invalidate
};

static int defer_packet_queue(
        struct sdma_engine *sde,
        struct iowait_work *wait,
        struct sdma_txreq *txreq,
        uint seq,
        bool pkts_sent)
{
        struct hfi1_user_sdma_pkt_q *pq =
                container_of(wait->iow, struct hfi1_user_sdma_pkt_q, busy);

        write_seqlock(&sde->waitlock);
        if (sdma_progress(sde, seq, txreq))
                goto eagain;
        /*
         * We are assuming that if the list is enqueued somewhere, it
         * is to the dmawait list since that is the only place where
         * it is supposed to be enqueued.
         */
        xchg(&pq->state, SDMA_PKT_Q_DEFERRED);
        if (list_empty(&pq->busy.list)) {
                iowait_get_priority(&pq->busy);
                iowait_queue(pkts_sent, &pq->busy, &sde->dmawait);
        }
        write_sequnlock(&sde->waitlock);
        return -EBUSY;
eagain:
        write_sequnlock(&sde->waitlock);
        return -EAGAIN;
}

static void activate_packet_queue(struct iowait *wait, int reason)
{
        struct hfi1_user_sdma_pkt_q *pq =
                container_of(wait, struct hfi1_user_sdma_pkt_q, busy);
        xchg(&pq->state, SDMA_PKT_Q_ACTIVE);
        wake_up(&wait->wait_dma);
};

int hfi1_user_sdma_alloc_queues(struct hfi1_ctxtdata *uctxt,
                                struct hfi1_filedata *fd)
{
        int ret = -ENOMEM;
        char buf[64];
        struct hfi1_devdata *dd;
        struct hfi1_user_sdma_comp_q *cq;
        struct hfi1_user_sdma_pkt_q *pq;

        if (!uctxt || !fd)
                return -EBADF;

        if (!hfi1_sdma_comp_ring_size)
                return -EINVAL;

        dd = uctxt->dd;

        pq = kzalloc(sizeof(*pq), GFP_KERNEL);
        if (!pq)
                return -ENOMEM;

        pq->dd = dd;
        pq->ctxt = uctxt->ctxt;
        pq->subctxt = fd->subctxt;
        pq->n_max_reqs = hfi1_sdma_comp_ring_size;
        atomic_set(&pq->n_reqs, 0);
        init_waitqueue_head(&pq->wait);
        atomic_set(&pq->n_locked, 0);
        pq->mm = fd->mm;

        iowait_init(&pq->busy, 0, NULL, NULL, defer_packet_queue,
                    activate_packet_queue, NULL, NULL);
        pq->reqidx = 0;

        pq->reqs = kcalloc(hfi1_sdma_comp_ring_size,
                           sizeof(*pq->reqs),
                           GFP_KERNEL);
        if (!pq->reqs)
                goto pq_reqs_nomem;

        pq->req_in_use = kcalloc(BITS_TO_LONGS(hfi1_sdma_comp_ring_size),
                                 sizeof(*pq->req_in_use),
                                 GFP_KERNEL);
        if (!pq->req_in_use)
                goto pq_reqs_no_in_use;

        snprintf(buf, 64, "txreq-kmem-cache-%u-%u-%u", dd->unit, uctxt->ctxt,
                 fd->subctxt);
        pq->txreq_cache = kmem_cache_create(buf,
                                            sizeof(struct user_sdma_txreq),
                                            L1_CACHE_BYTES,
                                            SLAB_HWCACHE_ALIGN,
                                            NULL);
        if (!pq->txreq_cache) {
                dd_dev_err(dd, "[%u] Failed to allocate TxReq cache\n",
                           uctxt->ctxt);
                goto pq_txreq_nomem;
        }

        cq = kzalloc(sizeof(*cq), GFP_KERNEL);
        if (!cq)
                goto cq_nomem;

        cq->comps = vmalloc_user(PAGE_ALIGN(sizeof(*cq->comps)
                                 * hfi1_sdma_comp_ring_size));
        if (!cq->comps)
                goto cq_comps_nomem;

        cq->nentries = hfi1_sdma_comp_ring_size;

        ret = hfi1_mmu_rb_register(pq, pq->mm, &sdma_rb_ops, dd->pport->hfi1_wq,
                                   &pq->handler);
        if (ret) {
                dd_dev_err(dd, "Failed to register with MMU %d", ret);
                goto pq_mmu_fail;
        }

        fd->pq = pq;
        fd->cq = cq;

        return 0;

pq_mmu_fail:
        vfree(cq->comps);
cq_comps_nomem:
        kfree(cq);
cq_nomem:
        kmem_cache_destroy(pq->txreq_cache);
pq_txreq_nomem:
        kfree(pq->req_in_use);
pq_reqs_no_in_use:
        kfree(pq->reqs);
pq_reqs_nomem:
        kfree(pq);

        return ret;
}

int hfi1_user_sdma_free_queues(struct hfi1_filedata *fd,
                               struct hfi1_ctxtdata *uctxt)
{
        struct hfi1_user_sdma_pkt_q *pq;

        trace_hfi1_sdma_user_free_queues(uctxt->dd, uctxt->ctxt, fd->subctxt);

        pq = fd->pq;
        if (pq) {
                if (pq->handler)
                        hfi1_mmu_rb_unregister(pq->handler);
                iowait_sdma_drain(&pq->busy);
                /* Wait until all requests have been freed. */
                wait_event_interruptible(
                        pq->wait,
                        !atomic_read(&pq->n_reqs));
                kfree(pq->reqs);
                kfree(pq->req_in_use);
                kmem_cache_destroy(pq->txreq_cache);
                kfree(pq);
                fd->pq = NULL;
        }
        if (fd->cq) {
                vfree(fd->cq->comps);
                kfree(fd->cq);
                fd->cq = NULL;
        }
        return 0;
}

static u8 dlid_to_selector(u16 dlid)
{
        static u8 mapping[256];
        static int initialized;
        static u8 next;
        int hash;

        if (!initialized) {
                memset(mapping, 0xFF, 256);
                initialized = 1;
        }

        hash = ((dlid >> 8) ^ dlid) & 0xFF;
        if (mapping[hash] == 0xFF) {
                mapping[hash] = next;
                next = (next + 1) & 0x7F;
        }

        return mapping[hash];
}

/**
 * hfi1_user_sdma_process_request() - Process and start a user sdma request
 * @fd: valid file descriptor
 * @iovec: array of io vectors to process
 * @dim: overall iovec array size
 * @count: number of io vector array entries processed
 */
int hfi1_user_sdma_process_request(struct hfi1_filedata *fd,
                                   struct iovec *iovec, unsigned long dim,
                                   unsigned long *count)
{
        int ret = 0, i;
        struct hfi1_ctxtdata *uctxt = fd->uctxt;
        struct hfi1_user_sdma_pkt_q *pq = fd->pq;
        struct hfi1_user_sdma_comp_q *cq = fd->cq;
        struct hfi1_devdata *dd = pq->dd;
        unsigned long idx = 0;
        u8 pcount = initial_pkt_count;
        struct sdma_req_info info;
        struct user_sdma_request *req;
        u8 opcode, sc, vl;
        u16 pkey;
        u32 slid;
        u16 dlid;
        u32 selector;

        if (iovec[idx].iov_len < sizeof(info) + sizeof(req->hdr)) {
                hfi1_cdbg(
                   SDMA,
                   "[%u:%u:%u] First vector not big enough for header %lu/%lu",
                   dd->unit, uctxt->ctxt, fd->subctxt,
                   iovec[idx].iov_len, sizeof(info) + sizeof(req->hdr));
                return -EINVAL;
        }
        ret = copy_from_user(&info, iovec[idx].iov_base, sizeof(info));
        if (ret) {
                hfi1_cdbg(SDMA, "[%u:%u:%u] Failed to copy info QW (%d)",
                          dd->unit, uctxt->ctxt, fd->subctxt, ret);
                return -EFAULT;
        }

        trace_hfi1_sdma_user_reqinfo(dd, uctxt->ctxt, fd->subctxt,
                                     (u16 *)&info);
        if (info.comp_idx >= hfi1_sdma_comp_ring_size) {
                hfi1_cdbg(SDMA,
                          "[%u:%u:%u:%u] Invalid comp index",
                          dd->unit, uctxt->ctxt, fd->subctxt, info.comp_idx);
                return -EINVAL;
        }

        /*
         * Sanity check the header io vector count.  Need at least 1 vector
         * (header) and cannot be larger than the actual io vector count.
         */
        if (req_iovcnt(info.ctrl) < 1 || req_iovcnt(info.ctrl) > dim) {
                hfi1_cdbg(SDMA,
                          "[%u:%u:%u:%u] Invalid iov count %d, dim %ld",
                          dd->unit, uctxt->ctxt, fd->subctxt, info.comp_idx,
                          req_iovcnt(info.ctrl), dim);
                return -EINVAL;
        }

        if (!info.fragsize) {
                hfi1_cdbg(SDMA,
                          "[%u:%u:%u:%u] Request does not specify fragsize",
                          dd->unit, uctxt->ctxt, fd->subctxt, info.comp_idx);
                return -EINVAL;
        }

        /* Try to claim the request. */
        if (test_and_set_bit(info.comp_idx, pq->req_in_use)) {
                hfi1_cdbg(SDMA, "[%u:%u:%u] Entry %u is in use",
                          dd->unit, uctxt->ctxt, fd->subctxt,
                          info.comp_idx);
                return -EBADSLT;
        }
        /*
         * All safety checks have been done and this request has been claimed.
         */
        trace_hfi1_sdma_user_process_request(dd, uctxt->ctxt, fd->subctxt,
                                             info.comp_idx);
        req = pq->reqs + info.comp_idx;
        req->data_iovs = req_iovcnt(info.ctrl) - 1; /* subtract header vector */
        req->data_len  = 0;
        req->pq = pq;
        req->cq = cq;
        req->ahg_idx = -1;
        req->iov_idx = 0;
        req->sent = 0;
        req->seqnum = 0;
        req->seqcomp = 0;
        req->seqsubmitted = 0;
        req->tids = NULL;
        req->has_error = 0;
        INIT_LIST_HEAD(&req->txps);

        memcpy(&req->info, &info, sizeof(info));

        /* The request is initialized, count it */
        atomic_inc(&pq->n_reqs);

        if (req_opcode(info.ctrl) == EXPECTED) {
                /* expected must have a TID info and at least one data vector */
                if (req->data_iovs < 2) {
                        SDMA_DBG(req,
                                 "Not enough vectors for expected request");
                        ret = -EINVAL;
                        goto free_req;
                }
                req->data_iovs--;
        }

        if (!info.npkts || req->data_iovs > MAX_VECTORS_PER_REQ) {
                SDMA_DBG(req, "Too many vectors (%u/%u)", req->data_iovs,
                         MAX_VECTORS_PER_REQ);
                ret = -EINVAL;
                goto free_req;
        }
        /* Copy the header from the user buffer */
        ret = copy_from_user(&req->hdr, iovec[idx].iov_base + sizeof(info),
                             sizeof(req->hdr));
        if (ret) {
                SDMA_DBG(req, "Failed to copy header template (%d)", ret);
                ret = -EFAULT;
                goto free_req;
        }

        /* If Static rate control is not enabled, sanitize the header. */
        if (!HFI1_CAP_IS_USET(STATIC_RATE_CTRL))
                req->hdr.pbc[2] = 0;

        /* Validate the opcode. Do not trust packets from user space blindly. */
        opcode = (be32_to_cpu(req->hdr.bth[0]) >> 24) & 0xff;
        if ((opcode & USER_OPCODE_CHECK_MASK) !=
             USER_OPCODE_CHECK_VAL) {
                SDMA_DBG(req, "Invalid opcode (%d)", opcode);
                ret = -EINVAL;
                goto free_req;
        }
        /*
         * Validate the vl. Do not trust packets from user space blindly.
         * VL comes from PBC, SC comes from LRH, and the VL needs to
         * match the SC look up.
         */
        vl = (le16_to_cpu(req->hdr.pbc[0]) >> 12) & 0xF;
        sc = (((be16_to_cpu(req->hdr.lrh[0]) >> 12) & 0xF) |
              (((le16_to_cpu(req->hdr.pbc[1]) >> 14) & 0x1) << 4));
        if (vl >= dd->pport->vls_operational ||
            vl != sc_to_vlt(dd, sc)) {
                SDMA_DBG(req, "Invalid SC(%u)/VL(%u)", sc, vl);
                ret = -EINVAL;
                goto free_req;
        }

        /* Checking P_KEY for requests from user-space */
        pkey = (u16)be32_to_cpu(req->hdr.bth[0]);
        slid = be16_to_cpu(req->hdr.lrh[3]);
        if (egress_pkey_check(dd->pport, slid, pkey, sc, PKEY_CHECK_INVALID)) {
                ret = -EINVAL;
                goto free_req;
        }

        /*
         * Also should check the BTH.lnh. If it says the next header is GRH then
         * the RXE parsing will be off and will land in the middle of the KDETH
         * or miss it entirely.
         */
        if ((be16_to_cpu(req->hdr.lrh[0]) & 0x3) == HFI1_LRH_GRH) {
                SDMA_DBG(req, "User tried to pass in a GRH");
                ret = -EINVAL;
                goto free_req;
        }

        req->koffset = le32_to_cpu(req->hdr.kdeth.swdata[6]);
        /*
         * Calculate the initial TID offset based on the values of
         * KDETH.OFFSET and KDETH.OM that are passed in.
         */
        req->tidoffset = KDETH_GET(req->hdr.kdeth.ver_tid_offset, OFFSET) *
                (KDETH_GET(req->hdr.kdeth.ver_tid_offset, OM) ?
                 KDETH_OM_LARGE : KDETH_OM_SMALL);
        trace_hfi1_sdma_user_initial_tidoffset(dd, uctxt->ctxt, fd->subctxt,
                                               info.comp_idx, req->tidoffset);
        idx++;

        /* Save all the IO vector structures */
        for (i = 0; i < req->data_iovs; i++) {
                req->iovs[i].offset = 0;
                INIT_LIST_HEAD(&req->iovs[i].list);
                memcpy(&req->iovs[i].iov,
                       iovec + idx++,
                       sizeof(req->iovs[i].iov));
                ret = pin_vector_pages(req, &req->iovs[i]);
                if (ret) {
                        req->data_iovs = i;
                        goto free_req;
                }
                req->data_len += req->iovs[i].iov.iov_len;
        }
        trace_hfi1_sdma_user_data_length(dd, uctxt->ctxt, fd->subctxt,
                                         info.comp_idx, req->data_len);
        if (pcount > req->info.npkts)
                pcount = req->info.npkts;
        /*
         * Copy any TID info
         * User space will provide the TID info only when the
         * request type is EXPECTED. This is true even if there is
         * only one packet in the request and the header is already
         * setup. The reason for the singular TID case is that the
         * driver needs to perform safety checks.
         */
        if (req_opcode(req->info.ctrl) == EXPECTED) {
                u16 ntids = iovec[idx].iov_len / sizeof(*req->tids);
                u32 *tmp;

                if (!ntids || ntids > MAX_TID_PAIR_ENTRIES) {
                        ret = -EINVAL;
                        goto free_req;
                }

                /*
                 * We have to copy all of the tids because they may vary
                 * in size and, therefore, the TID count might not be
                 * equal to the pkt count. However, there is no way to
                 * tell at this point.
                 */
                tmp = memdup_user(iovec[idx].iov_base,
                                  ntids * sizeof(*req->tids));
                if (IS_ERR(tmp)) {
                        ret = PTR_ERR(tmp);
                        SDMA_DBG(req, "Failed to copy %d TIDs (%d)",
                                 ntids, ret);
                        goto free_req;
                }
                req->tids = tmp;
                req->n_tids = ntids;
                req->tididx = 0;
                idx++;
        }

        dlid = be16_to_cpu(req->hdr.lrh[1]);
        selector = dlid_to_selector(dlid);
        selector += uctxt->ctxt + fd->subctxt;
        req->sde = sdma_select_user_engine(dd, selector, vl);

        if (!req->sde || !sdma_running(req->sde)) {
                ret = -ECOMM;
                goto free_req;
        }

        /* We don't need an AHG entry if the request contains only one packet */
        if (req->info.npkts > 1 && HFI1_CAP_IS_USET(SDMA_AHG))
                req->ahg_idx = sdma_ahg_alloc(req->sde);

        set_comp_state(pq, cq, info.comp_idx, QUEUED, 0);
        pq->state = SDMA_PKT_Q_ACTIVE;
        /* Send the first N packets in the request to buy us some time */
        ret = user_sdma_send_pkts(req, pcount);
        if (unlikely(ret < 0 && ret != -EBUSY))
                goto free_req;

        /*
         * This is a somewhat blocking send implementation.
         * The driver will block the caller until all packets of the
         * request have been submitted to the SDMA engine. However, it
         * will not wait for send completions.
         */
        while (req->seqsubmitted != req->info.npkts) {
                ret = user_sdma_send_pkts(req, pcount);
                if (ret < 0) {
                        if (ret != -EBUSY)
                                goto free_req;
                        wait_event_interruptible_timeout(
                                pq->busy.wait_dma,
                                (pq->state == SDMA_PKT_Q_ACTIVE),
                                msecs_to_jiffies(
                                        SDMA_IOWAIT_TIMEOUT));
                }
        }
        *count += idx;
        return 0;
free_req:
        /*
         * If the submitted seqsubmitted == npkts, the completion routine
         * controls the final state.  If sequbmitted < npkts, wait for any
         * outstanding packets to finish before cleaning up.
         */
        if (req->seqsubmitted < req->info.npkts) {
                if (req->seqsubmitted)
                        wait_event(pq->busy.wait_dma,
                                   (req->seqcomp == req->seqsubmitted - 1));
                user_sdma_free_request(req, true);
                pq_update(pq);
                set_comp_state(pq, cq, info.comp_idx, ERROR, ret);
        }
        return ret;
}

static inline u32 compute_data_length(struct user_sdma_request *req,
                                      struct user_sdma_txreq *tx)
{
        /*
         * Determine the proper size of the packet data.
         * The size of the data of the first packet is in the header
         * template. However, it includes the header and ICRC, which need
         * to be subtracted.
         * The minimum representable packet data length in a header is 4 bytes,
         * therefore, when the data length request is less than 4 bytes, there's
         * only one packet, and the packet data length is equal to that of the
         * request data length.
         * The size of the remaining packets is the minimum of the frag
         * size (MTU) or remaining data in the request.
         */
        u32 len;

        if (!req->seqnum) {
                if (req->data_len < sizeof(u32))
                        len = req->data_len;
                else
                        len = ((be16_to_cpu(req->hdr.lrh[2]) << 2) -
                               (sizeof(tx->hdr) - 4));
        } else if (req_opcode(req->info.ctrl) == EXPECTED) {
                u32 tidlen = EXP_TID_GET(req->tids[req->tididx], LEN) *
                        PAGE_SIZE;
                /*
                 * Get the data length based on the remaining space in the
                 * TID pair.
                 */
                len = min(tidlen - req->tidoffset, (u32)req->info.fragsize);
                /* If we've filled up the TID pair, move to the next one. */
                if (unlikely(!len) && ++req->tididx < req->n_tids &&
                    req->tids[req->tididx]) {
                        tidlen = EXP_TID_GET(req->tids[req->tididx],
                                             LEN) * PAGE_SIZE;
                        req->tidoffset = 0;
                        len = min_t(u32, tidlen, req->info.fragsize);
                }
                /*
                 * Since the TID pairs map entire pages, make sure that we
                 * are not going to try to send more data that we have
                 * remaining.
                 */
                len = min(len, req->data_len - req->sent);
        } else {
                len = min(req->data_len - req->sent, (u32)req->info.fragsize);
        }
        trace_hfi1_sdma_user_compute_length(req->pq->dd,
                                            req->pq->ctxt,
                                            req->pq->subctxt,
                                            req->info.comp_idx,
                                            len);
        return len;
}

static inline u32 pad_len(u32 len)
{
        if (len & (sizeof(u32) - 1))
                len += sizeof(u32) - (len & (sizeof(u32) - 1));
        return len;
}

static inline u32 get_lrh_len(struct hfi1_pkt_header hdr, u32 len)
{
        /* (Size of complete header - size of PBC) + 4B ICRC + data length */
        return ((sizeof(hdr) - sizeof(hdr.pbc)) + 4 + len);
}

static int user_sdma_txadd_ahg(struct user_sdma_request *req,
                               struct user_sdma_txreq *tx,
                               u32 datalen)
{
        int ret;
        u16 pbclen = le16_to_cpu(req->hdr.pbc[0]);
        u32 lrhlen = get_lrh_len(req->hdr, pad_len(datalen));
        struct hfi1_user_sdma_pkt_q *pq = req->pq;

        /*
         * Copy the request header into the tx header
         * because the HW needs a cacheline-aligned
         * address.
         * This copy can be optimized out if the hdr
         * member of user_sdma_request were also
         * cacheline aligned.
         */
        memcpy(&tx->hdr, &req->hdr, sizeof(tx->hdr));
        if (PBC2LRH(pbclen) != lrhlen) {
                pbclen = (pbclen & 0xf000) | LRH2PBC(lrhlen);
                tx->hdr.pbc[0] = cpu_to_le16(pbclen);
        }
        ret = check_header_template(req, &tx->hdr, lrhlen, datalen);
        if (ret)
                return ret;
        ret = sdma_txinit_ahg(&tx->txreq, SDMA_TXREQ_F_AHG_COPY,
                              sizeof(tx->hdr) + datalen, req->ahg_idx,
                              0, NULL, 0, user_sdma_txreq_cb);
        if (ret)
                return ret;
        ret = sdma_txadd_kvaddr(pq->dd, &tx->txreq, &tx->hdr, sizeof(tx->hdr));
        if (ret)
                sdma_txclean(pq->dd, &tx->txreq);
        return ret;
}

static int user_sdma_txadd(struct user_sdma_request *req,
                           struct user_sdma_txreq *tx,
                           struct user_sdma_iovec *iovec, u32 datalen,
                           u32 *queued_ptr, u32 *data_sent_ptr,
                           u64 *iov_offset_ptr)
{
        int ret;
        unsigned int pageidx, len;
        unsigned long base, offset;
        u64 iov_offset = *iov_offset_ptr;
        u32 queued = *queued_ptr, data_sent = *data_sent_ptr;
        struct hfi1_user_sdma_pkt_q *pq = req->pq;

        base = (unsigned long)iovec->iov.iov_base;
        offset = offset_in_page(base + iovec->offset + iov_offset);
        pageidx = (((iovec->offset + iov_offset + base) - (base & PAGE_MASK)) >>
                   PAGE_SHIFT);
        len = offset + req->info.fragsize > PAGE_SIZE ?
                PAGE_SIZE - offset : req->info.fragsize;
        len = min((datalen - queued), len);
        ret = sdma_txadd_page(pq->dd, &tx->txreq, iovec->pages[pageidx],
                              offset, len);
        if (ret) {
                SDMA_DBG(req, "SDMA txreq add page failed %d\n", ret);
                return ret;
        }
        iov_offset += len;
        queued += len;
        data_sent += len;
        if (unlikely(queued < datalen && pageidx == iovec->npages &&
                     req->iov_idx < req->data_iovs - 1)) {
                iovec->offset += iov_offset;
                iovec = &req->iovs[++req->iov_idx];
                iov_offset = 0;
        }

        *queued_ptr = queued;
        *data_sent_ptr = data_sent;
        *iov_offset_ptr = iov_offset;
        return ret;
}

static int user_sdma_send_pkts(struct user_sdma_request *req, u16 maxpkts)
{
        int ret = 0;
        u16 count;
        unsigned npkts = 0;
        struct user_sdma_txreq *tx = NULL;
        struct hfi1_user_sdma_pkt_q *pq = NULL;
        struct user_sdma_iovec *iovec = NULL;

        if (!req->pq)
                return -EINVAL;

        pq = req->pq;

        /* If tx completion has reported an error, we are done. */
        if (READ_ONCE(req->has_error))
                return -EFAULT;

        /*
         * Check if we might have sent the entire request already
         */
        if (unlikely(req->seqnum == req->info.npkts)) {
                if (!list_empty(&req->txps))
                        goto dosend;
                return ret;
        }

        if (!maxpkts || maxpkts > req->info.npkts - req->seqnum)
                maxpkts = req->info.npkts - req->seqnum;

        while (npkts < maxpkts) {
                u32 datalen = 0, queued = 0, data_sent = 0;
                u64 iov_offset = 0;

                /*
                 * Check whether any of the completions have come back
                 * with errors. If so, we are not going to process any
                 * more packets from this request.
                 */
                if (READ_ONCE(req->has_error))
                        return -EFAULT;

                tx = kmem_cache_alloc(pq->txreq_cache, GFP_KERNEL);
                if (!tx)
                        return -ENOMEM;

                tx->flags = 0;
                tx->req = req;
                INIT_LIST_HEAD(&tx->list);

                /*
                 * For the last packet set the ACK request
                 * and disable header suppression.
                 */
                if (req->seqnum == req->info.npkts - 1)
                        tx->flags |= (TXREQ_FLAGS_REQ_ACK |
                                      TXREQ_FLAGS_REQ_DISABLE_SH);

                /*
                 * Calculate the payload size - this is min of the fragment
                 * (MTU) size or the remaining bytes in the request but only
                 * if we have payload data.
                 */
                if (req->data_len) {
                        iovec = &req->iovs[req->iov_idx];
                        if (READ_ONCE(iovec->offset) == iovec->iov.iov_len) {
                                if (++req->iov_idx == req->data_iovs) {
                                        ret = -EFAULT;
                                        goto free_tx;
                                }
                                iovec = &req->iovs[req->iov_idx];
                                WARN_ON(iovec->offset);
                        }

                        datalen = compute_data_length(req, tx);

                        /*
                         * Disable header suppression for the payload <= 8DWS.
                         * If there is an uncorrectable error in the receive
                         * data FIFO when the received payload size is less than
                         * or equal to 8DWS then the RxDmaDataFifoRdUncErr is
                         * not reported.There is set RHF.EccErr if the header
                         * is not suppressed.
                         */
                        if (!datalen) {
                                SDMA_DBG(req,
                                         "Request has data but pkt len is 0");
                                ret = -EFAULT;
                                goto free_tx;
                        } else if (datalen <= 32) {
                                tx->flags |= TXREQ_FLAGS_REQ_DISABLE_SH;
                        }
                }

                if (req->ahg_idx >= 0) {
                        if (!req->seqnum) {
                                ret = user_sdma_txadd_ahg(req, tx, datalen);
                                if (ret)
                                        goto free_tx;
                        } else {
                                int changes;

                                changes = set_txreq_header_ahg(req, tx,
                                                               datalen);
                                if (changes < 0) {
                                        ret = changes;
                                        goto free_tx;
                                }
                        }
                } else {
                        ret = sdma_txinit(&tx->txreq, 0, sizeof(req->hdr) +
                                          datalen, user_sdma_txreq_cb);
                        if (ret)
                                goto free_tx;
                        /*
                         * Modify the header for this packet. This only needs
                         * to be done if we are not going to use AHG. Otherwise,
                         * the HW will do it based on the changes we gave it
                         * during sdma_txinit_ahg().
                         */
                        ret = set_txreq_header(req, tx, datalen);
                        if (ret)
                                goto free_txreq;
                }

                /*
                 * If the request contains any data vectors, add up to
                 * fragsize bytes to the descriptor.
                 */
                while (queued < datalen &&
                       (req->sent + data_sent) < req->data_len) {
                        ret = user_sdma_txadd(req, tx, iovec, datalen,
                                              &queued, &data_sent, &iov_offset);
                        if (ret)
                                goto free_txreq;
                }
                /*
                 * The txreq was submitted successfully so we can update
                 * the counters.
                 */
                req->koffset += datalen;
                if (req_opcode(req->info.ctrl) == EXPECTED)
                        req->tidoffset += datalen;
                req->sent += data_sent;
                if (req->data_len)
                        iovec->offset += iov_offset;
                list_add_tail(&tx->txreq.list, &req->txps);
                /*
                 * It is important to increment this here as it is used to
                 * generate the BTH.PSN and, therefore, can't be bulk-updated
                 * outside of the loop.
                 */
                tx->seqnum = req->seqnum++;
                npkts++;
        }
dosend:
        ret = sdma_send_txlist(req->sde,
                               iowait_get_ib_work(&pq->busy),
                               &req->txps, &count);
        req->seqsubmitted += count;
        if (req->seqsubmitted == req->info.npkts) {
                /*
                 * The txreq has already been submitted to the HW queue
                 * so we can free the AHG entry now. Corruption will not
                 * happen due to the sequential manner in which
                 * descriptors are processed.
                 */
                if (req->ahg_idx >= 0)
                        sdma_ahg_free(req->sde, req->ahg_idx);
        }
        return ret;

free_txreq:
        sdma_txclean(pq->dd, &tx->txreq);
free_tx:
        kmem_cache_free(pq->txreq_cache, tx);
        return ret;
}

static u32 sdma_cache_evict(struct hfi1_user_sdma_pkt_q *pq, u32 npages)
{
        struct evict_data evict_data;

        evict_data.cleared = 0;
        evict_data.target = npages;
        hfi1_mmu_rb_evict(pq->handler, &evict_data);
        return evict_data.cleared;
}

static int pin_sdma_pages(struct user_sdma_request *req,
                          struct user_sdma_iovec *iovec,
                          struct sdma_mmu_node *node,
                          int npages)
{
        int pinned, cleared;
        struct page **pages;
        struct hfi1_user_sdma_pkt_q *pq = req->pq;

        pages = kcalloc(npages, sizeof(*pages), GFP_KERNEL);
        if (!pages)
                return -ENOMEM;
        memcpy(pages, node->pages, node->npages * sizeof(*pages));

        npages -= node->npages;
retry:
        if (!hfi1_can_pin_pages(pq->dd, pq->mm,
                                atomic_read(&pq->n_locked), npages)) {
                cleared = sdma_cache_evict(pq, npages);
                if (cleared >= npages)
                        goto retry;
        }
        pinned = hfi1_acquire_user_pages(pq->mm,
                                         ((unsigned long)iovec->iov.iov_base +
                                         (node->npages * PAGE_SIZE)), npages, 0,
                                         pages + node->npages);
        if (pinned < 0) {
                kfree(pages);
                return pinned;
        }
        if (pinned != npages) {
                unpin_vector_pages(pq->mm, pages, node->npages, pinned);
                return -EFAULT;
        }
        kfree(node->pages);
        node->rb.len = iovec->iov.iov_len;
        node->pages = pages;
        atomic_add(pinned, &pq->n_locked);
        return pinned;
}

static void unpin_sdma_pages(struct sdma_mmu_node *node)
{
        if (node->npages) {
                unpin_vector_pages(node->pq->mm, node->pages, 0, node->npages);
                atomic_sub(node->npages, &node->pq->n_locked);
        }
}

static int pin_vector_pages(struct user_sdma_request *req,
                            struct user_sdma_iovec *iovec)
{
        int ret = 0, pinned, npages;
        struct hfi1_user_sdma_pkt_q *pq = req->pq;
        struct sdma_mmu_node *node = NULL;
        struct mmu_rb_node *rb_node;

        struct iovec *iov;
        bool extracted;

        extracted =
                hfi1_mmu_rb_remove_unless_exact(pq->handler,
                                                (unsigned long)
                                                iovec->iov.iov_base,
                                                iovec->iov.iov_len, &rb_node);
        if (rb_node) {
                node = container_of(rb_node, struct sdma_mmu_node, rb);
                if (!extracted) {
                        atomic_inc(&node->refcount);
                        iovec->pages = node->pages;
                        iovec->npages = node->npages;
                        iovec->node = node;
                        return 0;
                }
        }

        if (!node) {
                node = kzalloc(sizeof(*node), GFP_KERNEL);
                if (!node)
                        return -ENOMEM;

                node->rb.addr = (unsigned long)iovec->iov.iov_base;
                node->pq = pq;
                atomic_set(&node->refcount, 0);
        }

        iov = &iovec->iov;
        npages = num_user_pages((unsigned long)iov->iov_base, iov->iov_len);
        if (node->npages < npages) {
                pinned = pin_sdma_pages(req, iovec, node, npages);
                if (pinned < 0) {
                        ret = pinned;
                        goto bail;
                }
                node->npages += pinned;
                npages = node->npages;
        }
        iovec->pages = node->pages;
        iovec->npages = npages;
        iovec->node = node;

        ret = hfi1_mmu_rb_insert(req->pq->handler, &node->rb);
        if (ret) {
                iovec->node = NULL;
                goto bail;
        }
        return 0;
bail:
        unpin_sdma_pages(node);
        kfree(node);
        return ret;
}

static void unpin_vector_pages(struct mm_struct *mm, struct page **pages,
                               unsigned start, unsigned npages)
{
        hfi1_release_user_pages(mm, pages + start, npages, false);
        kfree(pages);
}

static int check_header_template(struct user_sdma_request *req,
                                 struct hfi1_pkt_header *hdr, u32 lrhlen,
                                 u32 datalen)
{
        /*
         * Perform safety checks for any type of packet:
         *    - transfer size is multiple of 64bytes
         *    - packet length is multiple of 4 bytes
         *    - packet length is not larger than MTU size
         *
         * These checks are only done for the first packet of the
         * transfer since the header is "given" to us by user space.
         * For the remainder of the packets we compute the values.
         */
        if (req->info.fragsize % PIO_BLOCK_SIZE || lrhlen & 0x3 ||
            lrhlen > get_lrh_len(*hdr, req->info.fragsize))
                return -EINVAL;

        if (req_opcode(req->info.ctrl) == EXPECTED) {
                /*
                 * The header is checked only on the first packet. Furthermore,
                 * we ensure that at least one TID entry is copied when the
                 * request is submitted. Therefore, we don't have to verify that
                 * tididx points to something sane.
                 */
                u32 tidval = req->tids[req->tididx],
                        tidlen = EXP_TID_GET(tidval, LEN) * PAGE_SIZE,
                        tididx = EXP_TID_GET(tidval, IDX),
                        tidctrl = EXP_TID_GET(tidval, CTRL),
                        tidoff;
                __le32 kval = hdr->kdeth.ver_tid_offset;

                tidoff = KDETH_GET(kval, OFFSET) *
                          (KDETH_GET(req->hdr.kdeth.ver_tid_offset, OM) ?
                           KDETH_OM_LARGE : KDETH_OM_SMALL);
                /*
                 * Expected receive packets have the following
                 * additional checks:
                 *     - offset is not larger than the TID size
                 *     - TIDCtrl values match between header and TID array
                 *     - TID indexes match between header and TID array
                 */
                if ((tidoff + datalen > tidlen) ||
                    KDETH_GET(kval, TIDCTRL) != tidctrl ||
                    KDETH_GET(kval, TID) != tididx)
                        return -EINVAL;
        }
        return 0;
}

/*
 * Correctly set the BTH.PSN field based on type of
 * transfer - eager packets can just increment the PSN but
 * expected packets encode generation and sequence in the
 * BTH.PSN field so just incrementing will result in errors.
 */
static inline u32 set_pkt_bth_psn(__be32 bthpsn, u8 expct, u32 frags)
{
        u32 val = be32_to_cpu(bthpsn),
                mask = (HFI1_CAP_IS_KSET(EXTENDED_PSN) ? 0x7fffffffull :
                        0xffffffull),
                psn = val & mask;
        if (expct)
                psn = (psn & ~HFI1_KDETH_BTH_SEQ_MASK) |
                        ((psn + frags) & HFI1_KDETH_BTH_SEQ_MASK);
        else
                psn = psn + frags;
        return psn & mask;
}

static int set_txreq_header(struct user_sdma_request *req,
                            struct user_sdma_txreq *tx, u32 datalen)
{
        struct hfi1_user_sdma_pkt_q *pq = req->pq;
        struct hfi1_pkt_header *hdr = &tx->hdr;
        u8 omfactor; /* KDETH.OM */
        u16 pbclen;
        int ret;
        u32 tidval = 0, lrhlen = get_lrh_len(*hdr, pad_len(datalen));

        /* Copy the header template to the request before modification */
        memcpy(hdr, &req->hdr, sizeof(*hdr));

        /*
         * Check if the PBC and LRH length are mismatched. If so
         * adjust both in the header.
         */
        pbclen = le16_to_cpu(hdr->pbc[0]);
        if (PBC2LRH(pbclen) != lrhlen) {
                pbclen = (pbclen & 0xf000) | LRH2PBC(lrhlen);
                hdr->pbc[0] = cpu_to_le16(pbclen);
                hdr->lrh[2] = cpu_to_be16(lrhlen >> 2);
                /*
                 * Third packet
                 * This is the first packet in the sequence that has
                 * a "static" size that can be used for the rest of
                 * the packets (besides the last one).
                 */
                if (unlikely(req->seqnum == 2)) {
                        /*
                         * From this point on the lengths in both the
                         * PBC and LRH are the same until the last
                         * packet.
                         * Adjust the template so we don't have to update
                         * every packet
                         */
                        req->hdr.pbc[0] = hdr->pbc[0];
                        req->hdr.lrh[2] = hdr->lrh[2];
                }
        }
        /*
         * We only have to modify the header if this is not the
         * first packet in the request. Otherwise, we use the
         * header given to us.
         */
        if (unlikely(!req->seqnum)) {
                ret = check_header_template(req, hdr, lrhlen, datalen);
                if (ret)
                        return ret;
                goto done;
        }

        hdr->bth[2] = cpu_to_be32(
                set_pkt_bth_psn(hdr->bth[2],
                                (req_opcode(req->info.ctrl) == EXPECTED),
                                req->seqnum));

        /* Set ACK request on last packet */
        if (unlikely(tx->flags & TXREQ_FLAGS_REQ_ACK))
                hdr->bth[2] |= cpu_to_be32(1UL << 31);

        /* Set the new offset */
        hdr->kdeth.swdata[6] = cpu_to_le32(req->koffset);
        /* Expected packets have to fill in the new TID information */
        if (req_opcode(req->info.ctrl) == EXPECTED) {
                tidval = req->tids[req->tididx];
                /*
                 * If the offset puts us at the end of the current TID,
                 * advance everything.
                 */
                if ((req->tidoffset) == (EXP_TID_GET(tidval, LEN) *
                                         PAGE_SIZE)) {
                        req->tidoffset = 0;
                        /*
                         * Since we don't copy all the TIDs, all at once,
                         * we have to check again.
                         */
                        if (++req->tididx > req->n_tids - 1 ||
                            !req->tids[req->tididx]) {
                                return -EINVAL;
                        }
                        tidval = req->tids[req->tididx];
                }
                omfactor = EXP_TID_GET(tidval, LEN) * PAGE_SIZE >=
                        KDETH_OM_MAX_SIZE ? KDETH_OM_LARGE_SHIFT :
                        KDETH_OM_SMALL_SHIFT;
                /* Set KDETH.TIDCtrl based on value for this TID. */
                KDETH_SET(hdr->kdeth.ver_tid_offset, TIDCTRL,
                          EXP_TID_GET(tidval, CTRL));
                /* Set KDETH.TID based on value for this TID */
                KDETH_SET(hdr->kdeth.ver_tid_offset, TID,
                          EXP_TID_GET(tidval, IDX));
                /* Clear KDETH.SH when DISABLE_SH flag is set */
                if (unlikely(tx->flags & TXREQ_FLAGS_REQ_DISABLE_SH))
                        KDETH_SET(hdr->kdeth.ver_tid_offset, SH, 0);
                /*
                 * Set the KDETH.OFFSET and KDETH.OM based on size of
                 * transfer.
                 */
                trace_hfi1_sdma_user_tid_info(
                        pq->dd, pq->ctxt, pq->subctxt, req->info.comp_idx,
                        req->tidoffset, req->tidoffset >> omfactor,
                        omfactor != KDETH_OM_SMALL_SHIFT);
                KDETH_SET(hdr->kdeth.ver_tid_offset, OFFSET,
                          req->tidoffset >> omfactor);
                KDETH_SET(hdr->kdeth.ver_tid_offset, OM,
                          omfactor != KDETH_OM_SMALL_SHIFT);
        }
done:
        trace_hfi1_sdma_user_header(pq->dd, pq->ctxt, pq->subctxt,
                                    req->info.comp_idx, hdr, tidval);
        return sdma_txadd_kvaddr(pq->dd, &tx->txreq, hdr, sizeof(*hdr));
}

static int set_txreq_header_ahg(struct user_sdma_request *req,
                                struct user_sdma_txreq *tx, u32 datalen)
{
        u32 ahg[AHG_KDETH_ARRAY_SIZE];
        int idx = 0;
        u8 omfactor; /* KDETH.OM */
        struct hfi1_user_sdma_pkt_q *pq = req->pq;
        struct hfi1_pkt_header *hdr = &req->hdr;
        u16 pbclen = le16_to_cpu(hdr->pbc[0]);
        u32 val32, tidval = 0, lrhlen = get_lrh_len(*hdr, pad_len(datalen));
        size_t array_size = ARRAY_SIZE(ahg);

        if (PBC2LRH(pbclen) != lrhlen) {
                /* PBC.PbcLengthDWs */
                idx = ahg_header_set(ahg, idx, array_size, 0, 0, 12,
                                     (__force u16)cpu_to_le16(LRH2PBC(lrhlen)));
                if (idx < 0)
                        return idx;
                /* LRH.PktLen (we need the full 16 bits due to byte swap) */
                idx = ahg_header_set(ahg, idx, array_size, 3, 0, 16,
                                     (__force u16)cpu_to_be16(lrhlen >> 2));
                if (idx < 0)
                        return idx;
        }

        /*
         * Do the common updates
         */
        /* BTH.PSN and BTH.A */
        val32 = (be32_to_cpu(hdr->bth[2]) + req->seqnum) &
                (HFI1_CAP_IS_KSET(EXTENDED_PSN) ? 0x7fffffff : 0xffffff);
        if (unlikely(tx->flags & TXREQ_FLAGS_REQ_ACK))
                val32 |= 1UL << 31;
        idx = ahg_header_set(ahg, idx, array_size, 6, 0, 16,
                             (__force u16)cpu_to_be16(val32 >> 16));
        if (idx < 0)
                return idx;
        idx = ahg_header_set(ahg, idx, array_size, 6, 16, 16,
                             (__force u16)cpu_to_be16(val32 & 0xffff));
        if (idx < 0)
                return idx;
        /* KDETH.Offset */
        idx = ahg_header_set(ahg, idx, array_size, 15, 0, 16,
                             (__force u16)cpu_to_le16(req->koffset & 0xffff));
        if (idx < 0)
                return idx;
        idx = ahg_header_set(ahg, idx, array_size, 15, 16, 16,
                             (__force u16)cpu_to_le16(req->koffset >> 16));
        if (idx < 0)
                return idx;
        if (req_opcode(req->info.ctrl) == EXPECTED) {
                __le16 val;

                tidval = req->tids[req->tididx];

                /*
                 * If the offset puts us at the end of the current TID,
                 * advance everything.
                 */
                if ((req->tidoffset) == (EXP_TID_GET(tidval, LEN) *
                                         PAGE_SIZE)) {
                        req->tidoffset = 0;
                        /*
                         * Since we don't copy all the TIDs, all at once,
                         * we have to check again.
                         */
                        if (++req->tididx > req->n_tids - 1 ||
                            !req->tids[req->tididx])
                                return -EINVAL;
                        tidval = req->tids[req->tididx];
                }
                omfactor = ((EXP_TID_GET(tidval, LEN) *
                                  PAGE_SIZE) >=
                                 KDETH_OM_MAX_SIZE) ? KDETH_OM_LARGE_SHIFT :
                                 KDETH_OM_SMALL_SHIFT;
                /* KDETH.OM and KDETH.OFFSET (TID) */
                idx = ahg_header_set(
                                ahg, idx, array_size, 7, 0, 16,
                                ((!!(omfactor - KDETH_OM_SMALL_SHIFT)) << 15 |
                                ((req->tidoffset >> omfactor)
                                & 0x7fff)));
                if (idx < 0)
                        return idx;
                /* KDETH.TIDCtrl, KDETH.TID, KDETH.Intr, KDETH.SH */
                val = cpu_to_le16(((EXP_TID_GET(tidval, CTRL) & 0x3) << 10) |
                                   (EXP_TID_GET(tidval, IDX) & 0x3ff));

                if (unlikely(tx->flags & TXREQ_FLAGS_REQ_DISABLE_SH)) {
                        val |= cpu_to_le16((KDETH_GET(hdr->kdeth.ver_tid_offset,
                                                      INTR) <<
                                            AHG_KDETH_INTR_SHIFT));
                } else {
                        val |= KDETH_GET(hdr->kdeth.ver_tid_offset, SH) ?
                               cpu_to_le16(0x1 << AHG_KDETH_SH_SHIFT) :
                               cpu_to_le16((KDETH_GET(hdr->kdeth.ver_tid_offset,
                                                      INTR) <<
                                             AHG_KDETH_INTR_SHIFT));
                }

                idx = ahg_header_set(ahg, idx, array_size,
                                     7, 16, 14, (__force u16)val);
                if (idx < 0)
                        return idx;
        }

        trace_hfi1_sdma_user_header_ahg(pq->dd, pq->ctxt, pq->subctxt,
                                        req->info.comp_idx, req->sde->this_idx,
                                        req->ahg_idx, ahg, idx, tidval);
        sdma_txinit_ahg(&tx->txreq,
                        SDMA_TXREQ_F_USE_AHG,
                        datalen, req->ahg_idx, idx,
                        ahg, sizeof(req->hdr),
                        user_sdma_txreq_cb);

        return idx;
}

/**
 * user_sdma_txreq_cb() - SDMA tx request completion callback.
 * @txreq: valid sdma tx request
 * @status: success/failure of request
 *
 * Called when the SDMA progress state machine gets notification that
 * the SDMA descriptors for this tx request have been processed by the
 * DMA engine. Called in interrupt context.
 * Only do work on completed sequences.
 */
static void user_sdma_txreq_cb(struct sdma_txreq *txreq, int status)
{
        struct user_sdma_txreq *tx =
                container_of(txreq, struct user_sdma_txreq, txreq);
        struct user_sdma_request *req;
        struct hfi1_user_sdma_pkt_q *pq;
        struct hfi1_user_sdma_comp_q *cq;
        enum hfi1_sdma_comp_state state = COMPLETE;

        if (!tx->req)
                return;

        req = tx->req;
        pq = req->pq;
        cq = req->cq;

        if (status != SDMA_TXREQ_S_OK) {
                SDMA_DBG(req, "SDMA completion with error %d",
                         status);
                WRITE_ONCE(req->has_error, 1);
                state = ERROR;
        }

        req->seqcomp = tx->seqnum;
        kmem_cache_free(pq->txreq_cache, tx);

        /* sequence isn't complete?  We are done */
        if (req->seqcomp != req->info.npkts - 1)
                return;

        user_sdma_free_request(req, false);
        set_comp_state(pq, cq, req->info.comp_idx, state, status);
        pq_update(pq);
}

static inline void pq_update(struct hfi1_user_sdma_pkt_q *pq)
{
        if (atomic_dec_and_test(&pq->n_reqs))
                wake_up(&pq->wait);
}

static void user_sdma_free_request(struct user_sdma_request *req, bool unpin)
{
        int i;

        if (!list_empty(&req->txps)) {
                struct sdma_txreq *t, *p;

                list_for_each_entry_safe(t, p, &req->txps, list) {
                        struct user_sdma_txreq *tx =
                                container_of(t, struct user_sdma_txreq, txreq);
                        list_del_init(&t->list);
                        sdma_txclean(req->pq->dd, t);
                        kmem_cache_free(req->pq->txreq_cache, tx);
                }
        }

        for (i = 0; i < req->data_iovs; i++) {
                struct sdma_mmu_node *node = req->iovs[i].node;

                if (!node)
                        continue;

                req->iovs[i].node = NULL;

                if (unpin)
                        hfi1_mmu_rb_remove(req->pq->handler,
                                           &node->rb);
                else
                        atomic_dec(&node->refcount);
        }

        kfree(req->tids);
        clear_bit(req->info.comp_idx, req->pq->req_in_use);
}

static inline void set_comp_state(struct hfi1_user_sdma_pkt_q *pq,
                                  struct hfi1_user_sdma_comp_q *cq,
                                  u16 idx, enum hfi1_sdma_comp_state state,
                                  int ret)
{
        if (state == ERROR)
                cq->comps[idx].errcode = -ret;
        smp_wmb(); /* make sure errcode is visible first */
        cq->comps[idx].status = state;
        trace_hfi1_sdma_user_completion(pq->dd, pq->ctxt, pq->subctxt,
                                        idx, state, ret);
}

static bool sdma_rb_filter(struct mmu_rb_node *node, unsigned long addr,
                           unsigned long len)
{
        return (bool)(node->addr == addr);
}

static int sdma_rb_insert(void *arg, struct mmu_rb_node *mnode)
{
        struct sdma_mmu_node *node =
                container_of(mnode, struct sdma_mmu_node, rb);

        atomic_inc(&node->refcount);
        return 0;
}

/*
 * Return 1 to remove the node from the rb tree and call the remove op.
 *
 * Called with the rb tree lock held.
 */
static int sdma_rb_evict(void *arg, struct mmu_rb_node *mnode,
                         void *evict_arg, bool *stop)
{
        struct sdma_mmu_node *node =
                container_of(mnode, struct sdma_mmu_node, rb);
        struct evict_data *evict_data = evict_arg;

        /* is this node still being used? */
        if (atomic_read(&node->refcount))
                return 0; /* keep this node */

        /* this node will be evicted, add its pages to our count */
        evict_data->cleared += node->npages;

        /* have enough pages been cleared? */
        if (evict_data->cleared >= evict_data->target)
                *stop = true;

        return 1; /* remove this node */
}

static void sdma_rb_remove(void *arg, struct mmu_rb_node *mnode)
{
        struct sdma_mmu_node *node =
                container_of(mnode, struct sdma_mmu_node, rb);

        unpin_sdma_pages(node);
        kfree(node);
}

static int sdma_rb_invalidate(void *arg, struct mmu_rb_node *mnode)
{
        struct sdma_mmu_node *node =
                container_of(mnode, struct sdma_mmu_node, rb);

        if (!atomic_read(&node->refcount))
                return 1;
        return 0;
}