/*
 * Copyright(c) 2016 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/slab.h>
#include <linux/vmalloc.h>
#include <rdma/ib_umem.h>
#include <rdma/rdma_vt.h>
#include "vt.h"
#include "mr.h"
#include "trace.h"

/**
 * rvt_driver_mr_init - Init MR resources per driver
 * @rdi: rvt dev struct
 *
 * Do any intilization needed when a driver registers with rdmavt.
 *
 * Return: 0 on success or errno on failure
 */
int rvt_driver_mr_init(struct rvt_dev_info *rdi)
{
        unsigned int lkey_table_size = rdi->dparms.lkey_table_size;
        unsigned lk_tab_size;
        int i;

        /*
         * The top hfi1_lkey_table_size bits are used to index the
         * table.  The lower 8 bits can be owned by the user (copied from
         * the LKEY).  The remaining bits act as a generation number or tag.
         */
        if (!lkey_table_size)
                return -EINVAL;

        spin_lock_init(&rdi->lkey_table.lock);

        /* ensure generation is at least 4 bits */
        if (lkey_table_size > RVT_MAX_LKEY_TABLE_BITS) {
                rvt_pr_warn(rdi, "lkey bits %u too large, reduced to %u\n",
                            lkey_table_size, RVT_MAX_LKEY_TABLE_BITS);
                rdi->dparms.lkey_table_size = RVT_MAX_LKEY_TABLE_BITS;
                lkey_table_size = rdi->dparms.lkey_table_size;
        }
        rdi->lkey_table.max = 1 << lkey_table_size;
        rdi->lkey_table.shift = 32 - lkey_table_size;
        lk_tab_size = rdi->lkey_table.max * sizeof(*rdi->lkey_table.table);
        rdi->lkey_table.table = (struct rvt_mregion __rcu **)
                               vmalloc_node(lk_tab_size, rdi->dparms.node);
        if (!rdi->lkey_table.table)
                return -ENOMEM;

        RCU_INIT_POINTER(rdi->dma_mr, NULL);
        for (i = 0; i < rdi->lkey_table.max; i++)
                RCU_INIT_POINTER(rdi->lkey_table.table[i], NULL);

        rdi->dparms.props.max_mr = rdi->lkey_table.max;
        return 0;
}

/**
 * rvt_mr_exit - clean up MR
 * @rdi: rvt dev structure
 *
 * called when drivers have unregistered or perhaps failed to register with us
 */
void rvt_mr_exit(struct rvt_dev_info *rdi)
{
        if (rdi->dma_mr)
                rvt_pr_err(rdi, "DMA MR not null!\n");

        vfree(rdi->lkey_table.table);
}

static void rvt_deinit_mregion(struct rvt_mregion *mr)
{
        int i = mr->mapsz;

        mr->mapsz = 0;
        while (i)
                kfree(mr->map[--i]);
        percpu_ref_exit(&mr->refcount);
}

static void __rvt_mregion_complete(struct percpu_ref *ref)
{
        struct rvt_mregion *mr = container_of(ref, struct rvt_mregion,
                                              refcount);

        complete(&mr->comp);
}

static int rvt_init_mregion(struct rvt_mregion *mr, struct ib_pd *pd,
                            int count, unsigned int percpu_flags)
{
        int m, i = 0;
        struct rvt_dev_info *dev = ib_to_rvt(pd->device);

        mr->mapsz = 0;
        m = (count + RVT_SEGSZ - 1) / RVT_SEGSZ;
        for (; i < m; i++) {
                mr->map[i] = kzalloc_node(sizeof(*mr->map[0]), GFP_KERNEL,
                                          dev->dparms.node);
                if (!mr->map[i])
                        goto bail;
                mr->mapsz++;
        }
        init_completion(&mr->comp);
        /* count returning the ptr to user */
        if (percpu_ref_init(&mr->refcount, &__rvt_mregion_complete,
                            percpu_flags, GFP_KERNEL))
                goto bail;

        atomic_set(&mr->lkey_invalid, 0);
        mr->pd = pd;
        mr->max_segs = count;
        return 0;
bail:
        rvt_deinit_mregion(mr);
        return -ENOMEM;
}

/**
 * rvt_alloc_lkey - allocate an lkey
 * @mr: memory region that this lkey protects
 * @dma_region: 0->normal key, 1->restricted DMA key
 *
 * Returns 0 if successful, otherwise returns -errno.
 *
 * Increments mr reference count as required.
 *
 * Sets the lkey field mr for non-dma regions.
 *
 */
static int rvt_alloc_lkey(struct rvt_mregion *mr, int dma_region)
{
        unsigned long flags;
        u32 r;
        u32 n;
        int ret = 0;
        struct rvt_dev_info *dev = ib_to_rvt(mr->pd->device);
        struct rvt_lkey_table *rkt = &dev->lkey_table;

        rvt_get_mr(mr);
        spin_lock_irqsave(&rkt->lock, flags);

        /* special case for dma_mr lkey == 0 */
        if (dma_region) {
                struct rvt_mregion *tmr;

                tmr = rcu_access_pointer(dev->dma_mr);
                if (!tmr) {
                        mr->lkey_published = 1;
                        /* Insure published written first */
                        rcu_assign_pointer(dev->dma_mr, mr);
                        rvt_get_mr(mr);
                }
                goto success;
        }

        /* Find the next available LKEY */
        r = rkt->next;
        n = r;
        for (;;) {
                if (!rcu_access_pointer(rkt->table[r]))
                        break;
                r = (r + 1) & (rkt->max - 1);
                if (r == n)
                        goto bail;
        }
        rkt->next = (r + 1) & (rkt->max - 1);
        /*
         * Make sure lkey is never zero which is reserved to indicate an
         * unrestricted LKEY.
         */
        rkt->gen++;
        /*
         * bits are capped to ensure enough bits for generation number
         */
        mr->lkey = (r << (32 - dev->dparms.lkey_table_size)) |
                ((((1 << (24 - dev->dparms.lkey_table_size)) - 1) & rkt->gen)
                 << 8);
        if (mr->lkey == 0) {
                mr->lkey |= 1 << 8;
                rkt->gen++;
        }
        mr->lkey_published = 1;
        /* Insure published written first */
        rcu_assign_pointer(rkt->table[r], mr);
success:
        spin_unlock_irqrestore(&rkt->lock, flags);
out:
        return ret;
bail:
        rvt_put_mr(mr);
        spin_unlock_irqrestore(&rkt->lock, flags);
        ret = -ENOMEM;
        goto out;
}

/**
 * rvt_free_lkey - free an lkey
 * @mr: mr to free from tables
 */
static void rvt_free_lkey(struct rvt_mregion *mr)
{
        unsigned long flags;
        u32 lkey = mr->lkey;
        u32 r;
        struct rvt_dev_info *dev = ib_to_rvt(mr->pd->device);
        struct rvt_lkey_table *rkt = &dev->lkey_table;
        int freed = 0;

        spin_lock_irqsave(&rkt->lock, flags);
        if (!lkey) {
                if (mr->lkey_published) {
                        mr->lkey_published = 0;
                        /* insure published is written before pointer */
                        rcu_assign_pointer(dev->dma_mr, NULL);
                        rvt_put_mr(mr);
                }
        } else {
                if (!mr->lkey_published)
                        goto out;
                r = lkey >> (32 - dev->dparms.lkey_table_size);
                mr->lkey_published = 0;
                /* insure published is written before pointer */
                rcu_assign_pointer(rkt->table[r], NULL);
        }
        freed++;
out:
        spin_unlock_irqrestore(&rkt->lock, flags);
        if (freed)
                percpu_ref_kill(&mr->refcount);
}

static struct rvt_mr *__rvt_alloc_mr(int count, struct ib_pd *pd)
{
        struct rvt_mr *mr;
        int rval = -ENOMEM;
        int m;

        /* Allocate struct plus pointers to first level page tables. */
        m = (count + RVT_SEGSZ - 1) / RVT_SEGSZ;
        mr = kzalloc(struct_size(mr, mr.map, m), GFP_KERNEL);
        if (!mr)
                goto bail;

        rval = rvt_init_mregion(&mr->mr, pd, count, 0);
        if (rval)
                goto bail;
        /*
         * ib_reg_phys_mr() will initialize mr->ibmr except for
         * lkey and rkey.
         */
        rval = rvt_alloc_lkey(&mr->mr, 0);
        if (rval)
                goto bail_mregion;
        mr->ibmr.lkey = mr->mr.lkey;
        mr->ibmr.rkey = mr->mr.lkey;
done:
        return mr;

bail_mregion:
        rvt_deinit_mregion(&mr->mr);
bail:
        kfree(mr);
        mr = ERR_PTR(rval);
        goto done;
}

static void __rvt_free_mr(struct rvt_mr *mr)
{
        rvt_free_lkey(&mr->mr);
        rvt_deinit_mregion(&mr->mr);
        kfree(mr);
}

/**
 * rvt_get_dma_mr - get a DMA memory region
 * @pd: protection domain for this memory region
 * @acc: access flags
 *
 * Return: the memory region on success, otherwise returns an errno.
 */
struct ib_mr *rvt_get_dma_mr(struct ib_pd *pd, int acc)
{
        struct rvt_mr *mr;
        struct ib_mr *ret;
        int rval;

        if (ibpd_to_rvtpd(pd)->user)
                return ERR_PTR(-EPERM);

        mr = kzalloc(sizeof(*mr), GFP_KERNEL);
        if (!mr) {
                ret = ERR_PTR(-ENOMEM);
                goto bail;
        }

        rval = rvt_init_mregion(&mr->mr, pd, 0, 0);
        if (rval) {
                ret = ERR_PTR(rval);
                goto bail;
        }

        rval = rvt_alloc_lkey(&mr->mr, 1);
        if (rval) {
                ret = ERR_PTR(rval);
                goto bail_mregion;
        }

        mr->mr.access_flags = acc;
        ret = &mr->ibmr;
done:
        return ret;

bail_mregion:
        rvt_deinit_mregion(&mr->mr);
bail:
        kfree(mr);
        goto done;
}

/**
 * rvt_reg_user_mr - register a userspace memory region
 * @pd: protection domain for this memory region
 * @start: starting userspace address
 * @length: length of region to register
 * @virt_addr: associated virtual address
 * @mr_access_flags: access flags for this memory region
 * @udata: unused by the driver
 *
 * Return: the memory region on success, otherwise returns an errno.
 */
struct ib_mr *rvt_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
                              u64 virt_addr, int mr_access_flags,
                              struct ib_udata *udata)
{
        struct rvt_mr *mr;
        struct ib_umem *umem;
        struct sg_page_iter sg_iter;
        int n, m;
        struct ib_mr *ret;

        if (length == 0)
                return ERR_PTR(-EINVAL);

        umem = ib_umem_get(pd->device, start, length, mr_access_flags);
        if (IS_ERR(umem))
                return (void *)umem;

        n = ib_umem_num_pages(umem);

        mr = __rvt_alloc_mr(n, pd);
        if (IS_ERR(mr)) {
                ret = (struct ib_mr *)mr;
                goto bail_umem;
        }

        mr->mr.user_base = start;
        mr->mr.iova = virt_addr;
        mr->mr.length = length;
        mr->mr.offset = ib_umem_offset(umem);
        mr->mr.access_flags = mr_access_flags;
        mr->umem = umem;

        mr->mr.page_shift = PAGE_SHIFT;
        m = 0;
        n = 0;
        for_each_sg_page (umem->sg_head.sgl, &sg_iter, umem->nmap, 0) {
                void *vaddr;

                vaddr = page_address(sg_page_iter_page(&sg_iter));
                if (!vaddr) {
                        ret = ERR_PTR(-EINVAL);
                        goto bail_inval;
                }
                mr->mr.map[m]->segs[n].vaddr = vaddr;
                mr->mr.map[m]->segs[n].length = PAGE_SIZE;
                trace_rvt_mr_user_seg(&mr->mr, m, n, vaddr, PAGE_SIZE);
                if (++n == RVT_SEGSZ) {
                        m++;
                        n = 0;
                }
        }
        return &mr->ibmr;

bail_inval:
        __rvt_free_mr(mr);

bail_umem:
        ib_umem_release(umem);

        return ret;
}

/**
 * rvt_dereg_clean_qp_cb - callback from iterator
 * @qp: the qp
 * @v: the mregion (as u64)
 *
 * This routine fields the callback for all QPs and
 * for QPs in the same PD as the MR will call the
 * rvt_qp_mr_clean() to potentially cleanup references.
 */
static void rvt_dereg_clean_qp_cb(struct rvt_qp *qp, u64 v)
{
        struct rvt_mregion *mr = (struct rvt_mregion *)v;

        /* skip PDs that are not ours */
        if (mr->pd != qp->ibqp.pd)
                return;
        rvt_qp_mr_clean(qp, mr->lkey);
}

/**
 * rvt_dereg_clean_qps - find QPs for reference cleanup
 * @mr: the MR that is being deregistered
 *
 * This routine iterates RC QPs looking for references
 * to the lkey noted in mr.
 */
static void rvt_dereg_clean_qps(struct rvt_mregion *mr)
{
        struct rvt_dev_info *rdi = ib_to_rvt(mr->pd->device);

        rvt_qp_iter(rdi, (u64)mr, rvt_dereg_clean_qp_cb);
}

/**
 * rvt_check_refs - check references
 * @mr: the megion
 * @t: the caller identification
 *
 * This routine checks MRs holding a reference during
 * when being de-registered.
 *
 * If the count is non-zero, the code calls a clean routine then
 * waits for the timeout for the count to zero.
 */
static int rvt_check_refs(struct rvt_mregion *mr, const char *t)
{
        unsigned long timeout;
        struct rvt_dev_info *rdi = ib_to_rvt(mr->pd->device);

        if (mr->lkey) {
                /* avoid dma mr */
                rvt_dereg_clean_qps(mr);
                /* @mr was indexed on rcu protected @lkey_table */
                synchronize_rcu();
        }

        timeout = wait_for_completion_timeout(&mr->comp, 5 * HZ);
        if (!timeout) {
                rvt_pr_err(rdi,
                           "%s timeout mr %p pd %p lkey %x refcount %ld\n",
                           t, mr, mr->pd, mr->lkey,
                           atomic_long_read(&mr->refcount.data->count));
                rvt_get_mr(mr);
                return -EBUSY;
        }
        return 0;
}

/**
 * rvt_mr_has_lkey - is MR
 * @mr: the mregion
 * @lkey: the lkey
 */
bool rvt_mr_has_lkey(struct rvt_mregion *mr, u32 lkey)
{
        return mr && lkey == mr->lkey;
}

/**
 * rvt_ss_has_lkey - is mr in sge tests
 * @ss: the sge state
 * @lkey: the lkey
 *
 * This code tests for an MR in the indicated
 * sge state.
 */
bool rvt_ss_has_lkey(struct rvt_sge_state *ss, u32 lkey)
{
        int i;
        bool rval = false;

        if (!ss->num_sge)
                return rval;
        /* first one */
        rval = rvt_mr_has_lkey(ss->sge.mr, lkey);
        /* any others */
        for (i = 0; !rval && i < ss->num_sge - 1; i++)
                rval = rvt_mr_has_lkey(ss->sg_list[i].mr, lkey);
        return rval;
}

/**
 * rvt_dereg_mr - unregister and free a memory region
 * @ibmr: the memory region to free
 * @udata: unused by the driver
 *
 * Note that this is called to free MRs created by rvt_get_dma_mr()
 * or rvt_reg_user_mr().
 *
 * Returns 0 on success.
 */
int rvt_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
{
        struct rvt_mr *mr = to_imr(ibmr);
        int ret;

        rvt_free_lkey(&mr->mr);

        rvt_put_mr(&mr->mr); /* will set completion if last */
        ret = rvt_check_refs(&mr->mr, __func__);
        if (ret)
                goto out;
        rvt_deinit_mregion(&mr->mr);
        ib_umem_release(mr->umem);
        kfree(mr);
out:
        return ret;
}

/**
 * rvt_alloc_mr - Allocate a memory region usable with the
 * @pd: protection domain for this memory region
 * @mr_type: mem region type
 * @max_num_sg: Max number of segments allowed
 *
 * Return: the memory region on success, otherwise return an errno.
 */
struct ib_mr *rvt_alloc_mr(struct ib_pd *pd, enum ib_mr_type mr_type,
                           u32 max_num_sg)
{
        struct rvt_mr *mr;

        if (mr_type != IB_MR_TYPE_MEM_REG)
                return ERR_PTR(-EINVAL);

        mr = __rvt_alloc_mr(max_num_sg, pd);
        if (IS_ERR(mr))
                return (struct ib_mr *)mr;

        return &mr->ibmr;
}

/**
 * rvt_set_page - page assignment function called by ib_sg_to_pages
 * @ibmr: memory region
 * @addr: dma address of mapped page
 *
 * Return: 0 on success
 */
static int rvt_set_page(struct ib_mr *ibmr, u64 addr)
{
        struct rvt_mr *mr = to_imr(ibmr);
        u32 ps = 1 << mr->mr.page_shift;
        u32 mapped_segs = mr->mr.length >> mr->mr.page_shift;
        int m, n;

        if (unlikely(mapped_segs == mr->mr.max_segs))
                return -ENOMEM;

        m = mapped_segs / RVT_SEGSZ;
        n = mapped_segs % RVT_SEGSZ;
        mr->mr.map[m]->segs[n].vaddr = (void *)addr;
        mr->mr.map[m]->segs[n].length = ps;
        mr->mr.length += ps;
        trace_rvt_mr_page_seg(&mr->mr, m, n, (void *)addr, ps);

        return 0;
}

/**
 * rvt_map_mr_sg - map sg list and set it the memory region
 * @ibmr: memory region
 * @sg: dma mapped scatterlist
 * @sg_nents: number of entries in sg
 * @sg_offset: offset in bytes into sg
 *
 * Overwrite rvt_mr length with mr length calculated by ib_sg_to_pages.
 *
 * Return: number of sg elements mapped to the memory region
 */
int rvt_map_mr_sg(struct ib_mr *ibmr, struct scatterlist *sg,
                  int sg_nents, unsigned int *sg_offset)
{
        struct rvt_mr *mr = to_imr(ibmr);
        int ret;

        mr->mr.length = 0;
        mr->mr.page_shift = PAGE_SHIFT;
        ret = ib_sg_to_pages(ibmr, sg, sg_nents, sg_offset, rvt_set_page);
        mr->mr.user_base = ibmr->iova;
        mr->mr.iova = ibmr->iova;
        mr->mr.offset = ibmr->iova - (u64)mr->mr.map[0]->segs[0].vaddr;
        mr->mr.length = (size_t)ibmr->length;
        trace_rvt_map_mr_sg(ibmr, sg_nents, sg_offset);
        return ret;
}

/**
 * rvt_fast_reg_mr - fast register physical MR
 * @qp: the queue pair where the work request comes from
 * @ibmr: the memory region to be registered
 * @key: updated key for this memory region
 * @access: access flags for this memory region
 *
 * Returns 0 on success.
 */
int rvt_fast_reg_mr(struct rvt_qp *qp, struct ib_mr *ibmr, u32 key,
                    int access)
{
        struct rvt_mr *mr = to_imr(ibmr);

        if (qp->ibqp.pd != mr->mr.pd)
                return -EACCES;

        /* not applicable to dma MR or user MR */
        if (!mr->mr.lkey || mr->umem)
                return -EINVAL;

        if ((key & 0xFFFFFF00) != (mr->mr.lkey & 0xFFFFFF00))
                return -EINVAL;

        ibmr->lkey = key;
        ibmr->rkey = key;
        mr->mr.lkey = key;
        mr->mr.access_flags = access;
        mr->mr.iova = ibmr->iova;
        atomic_set(&mr->mr.lkey_invalid, 0);

        return 0;
}
EXPORT_SYMBOL(rvt_fast_reg_mr);

/**
 * rvt_invalidate_rkey - invalidate an MR rkey
 * @qp: queue pair associated with the invalidate op
 * @rkey: rkey to invalidate
 *
 * Returns 0 on success.
 */
int rvt_invalidate_rkey(struct rvt_qp *qp, u32 rkey)
{
        struct rvt_dev_info *dev = ib_to_rvt(qp->ibqp.device);
        struct rvt_lkey_table *rkt = &dev->lkey_table;
        struct rvt_mregion *mr;

        if (rkey == 0)
                return -EINVAL;

        rcu_read_lock();
        mr = rcu_dereference(
                rkt->table[(rkey >> (32 - dev->dparms.lkey_table_size))]);
        if (unlikely(!mr || mr->lkey != rkey || qp->ibqp.pd != mr->pd))
                goto bail;

        atomic_set(&mr->lkey_invalid, 1);
        rcu_read_unlock();
        return 0;

bail:
        rcu_read_unlock();
        return -EINVAL;
}
EXPORT_SYMBOL(rvt_invalidate_rkey);

/**
 * rvt_sge_adjacent - is isge compressible
 * @last_sge: last outgoing SGE written
 * @sge: SGE to check
 *
 * If adjacent will update last_sge to add length.
 *
 * Return: true if isge is adjacent to last sge
 */
static inline bool rvt_sge_adjacent(struct rvt_sge *last_sge,
                                    struct ib_sge *sge)
{
        if (last_sge && sge->lkey == last_sge->mr->lkey &&
            ((uint64_t)(last_sge->vaddr + last_sge->length) == sge->addr)) {
                if (sge->lkey) {
                        if (unlikely((sge->addr - last_sge->mr->user_base +
                              sge->length > last_sge->mr->length)))
                                return false; /* overrun, caller will catch */
                } else {
                        last_sge->length += sge->length;
                }
                last_sge->sge_length += sge->length;
                trace_rvt_sge_adjacent(last_sge, sge);
                return true;
        }
        return false;
}

/**
 * rvt_lkey_ok - check IB SGE for validity and initialize
 * @rkt: table containing lkey to check SGE against
 * @pd: protection domain
 * @isge: outgoing internal SGE
 * @last_sge: last outgoing SGE written
 * @sge: SGE to check
 * @acc: access flags
 *
 * Check the IB SGE for validity and initialize our internal version
 * of it.
 *
 * Increments the reference count when a new sge is stored.
 *
 * Return: 0 if compressed, 1 if added , otherwise returns -errno.
 */
int rvt_lkey_ok(struct rvt_lkey_table *rkt, struct rvt_pd *pd,
                struct rvt_sge *isge, struct rvt_sge *last_sge,
                struct ib_sge *sge, int acc)
{
        struct rvt_mregion *mr;
        unsigned n, m;
        size_t off;

        /*
         * We use LKEY == zero for kernel virtual addresses
         * (see rvt_get_dma_mr()).
         */
        if (sge->lkey == 0) {
                struct rvt_dev_info *dev = ib_to_rvt(pd->ibpd.device);

                if (pd->user)
                        return -EINVAL;
                if (rvt_sge_adjacent(last_sge, sge))
                        return 0;
                rcu_read_lock();
                mr = rcu_dereference(dev->dma_mr);
                if (!mr)
                        goto bail;
                rvt_get_mr(mr);
                rcu_read_unlock();

                isge->mr = mr;
                isge->vaddr = (void *)sge->addr;
                isge->length = sge->length;
                isge->sge_length = sge->length;
                isge->m = 0;
                isge->n = 0;
                goto ok;
        }
        if (rvt_sge_adjacent(last_sge, sge))
                return 0;
        rcu_read_lock();
        mr = rcu_dereference(rkt->table[sge->lkey >> rkt->shift]);
        if (!mr)
                goto bail;
        rvt_get_mr(mr);
        if (!READ_ONCE(mr->lkey_published))
                goto bail_unref;

        if (unlikely(atomic_read(&mr->lkey_invalid) ||
                     mr->lkey != sge->lkey || mr->pd != &pd->ibpd))
                goto bail_unref;

        off = sge->addr - mr->user_base;
        if (unlikely(sge->addr < mr->user_base ||
                     off + sge->length > mr->length ||
                     (mr->access_flags & acc) != acc))
                goto bail_unref;
        rcu_read_unlock();

        off += mr->offset;
        if (mr->page_shift) {
                /*
                 * page sizes are uniform power of 2 so no loop is necessary
                 * entries_spanned_by_off is the number of times the loop below
                 * would have executed.
                */
                size_t entries_spanned_by_off;

                entries_spanned_by_off = off >> mr->page_shift;
                off -= (entries_spanned_by_off << mr->page_shift);
                m = entries_spanned_by_off / RVT_SEGSZ;
                n = entries_spanned_by_off % RVT_SEGSZ;
        } else {
                m = 0;
                n = 0;
                while (off >= mr->map[m]->segs[n].length) {
                        off -= mr->map[m]->segs[n].length;
                        n++;
                        if (n >= RVT_SEGSZ) {
                                m++;
                                n = 0;
                        }
                }
        }
        isge->mr = mr;
        isge->vaddr = mr->map[m]->segs[n].vaddr + off;
        isge->length = mr->map[m]->segs[n].length - off;
        isge->sge_length = sge->length;
        isge->m = m;
        isge->n = n;
ok:
        trace_rvt_sge_new(isge, sge);
        return 1;
bail_unref:
        rvt_put_mr(mr);
bail:
        rcu_read_unlock();
        return -EINVAL;
}
EXPORT_SYMBOL(rvt_lkey_ok);

/**
 * rvt_rkey_ok - check the IB virtual address, length, and RKEY
 * @qp: qp for validation
 * @sge: SGE state
 * @len: length of data
 * @vaddr: virtual address to place data
 * @rkey: rkey to check
 * @acc: access flags
 *
 * Return: 1 if successful, otherwise 0.
 *
 * increments the reference count upon success
 */
int rvt_rkey_ok(struct rvt_qp *qp, struct rvt_sge *sge,
                u32 len, u64 vaddr, u32 rkey, int acc)
{
        struct rvt_dev_info *dev = ib_to_rvt(qp->ibqp.device);
        struct rvt_lkey_table *rkt = &dev->lkey_table;
        struct rvt_mregion *mr;
        unsigned n, m;
        size_t off;

        /*
         * We use RKEY == zero for kernel virtual addresses
         * (see rvt_get_dma_mr()).
         */
        rcu_read_lock();
        if (rkey == 0) {
                struct rvt_pd *pd = ibpd_to_rvtpd(qp->ibqp.pd);
                struct rvt_dev_info *rdi = ib_to_rvt(pd->ibpd.device);

                if (pd->user)
                        goto bail;
                mr = rcu_dereference(rdi->dma_mr);
                if (!mr)
                        goto bail;
                rvt_get_mr(mr);
                rcu_read_unlock();

                sge->mr = mr;
                sge->vaddr = (void *)vaddr;
                sge->length = len;
                sge->sge_length = len;
                sge->m = 0;
                sge->n = 0;
                goto ok;
        }

        mr = rcu_dereference(rkt->table[rkey >> rkt->shift]);
        if (!mr)
                goto bail;
        rvt_get_mr(mr);
        /* insure mr read is before test */
        if (!READ_ONCE(mr->lkey_published))
                goto bail_unref;
        if (unlikely(atomic_read(&mr->lkey_invalid) ||
                     mr->lkey != rkey || qp->ibqp.pd != mr->pd))
                goto bail_unref;

        off = vaddr - mr->iova;
        if (unlikely(vaddr < mr->iova || off + len > mr->length ||
                     (mr->access_flags & acc) == 0))
                goto bail_unref;
        rcu_read_unlock();

        off += mr->offset;
        if (mr->page_shift) {
                /*
                 * page sizes are uniform power of 2 so no loop is necessary
                 * entries_spanned_by_off is the number of times the loop below
                 * would have executed.
                */
                size_t entries_spanned_by_off;

                entries_spanned_by_off = off >> mr->page_shift;
                off -= (entries_spanned_by_off << mr->page_shift);
                m = entries_spanned_by_off / RVT_SEGSZ;
                n = entries_spanned_by_off % RVT_SEGSZ;
        } else {
                m = 0;
                n = 0;
                while (off >= mr->map[m]->segs[n].length) {
                        off -= mr->map[m]->segs[n].length;
                        n++;
                        if (n >= RVT_SEGSZ) {
                                m++;
                                n = 0;
                        }
                }
        }
        sge->mr = mr;
        sge->vaddr = mr->map[m]->segs[n].vaddr + off;
        sge->length = mr->map[m]->segs[n].length - off;
        sge->sge_length = len;
        sge->m = m;
        sge->n = n;
ok:
        return 1;
bail_unref:
        rvt_put_mr(mr);
bail:
        rcu_read_unlock();
        return 0;
}
EXPORT_SYMBOL(rvt_rkey_ok);