/*
 * Copyright (c) 2013-2015, Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <rdma/ib_umem.h>
#include <rdma/ib_umem_odp.h>

#include "mlx5_ib.h"
#include "cmd.h"

#define MAX_PREFETCH_LEN (4*1024*1024U)

/* Timeout in ms to wait for an active mmu notifier to complete when handling
 * a pagefault. */
#define MMU_NOTIFIER_TIMEOUT 1000

#define MLX5_IMR_MTT_BITS (30 - PAGE_SHIFT)
#define MLX5_IMR_MTT_SHIFT (MLX5_IMR_MTT_BITS + PAGE_SHIFT)
#define MLX5_IMR_MTT_ENTRIES BIT_ULL(MLX5_IMR_MTT_BITS)
#define MLX5_IMR_MTT_SIZE BIT_ULL(MLX5_IMR_MTT_SHIFT)
#define MLX5_IMR_MTT_MASK (~(MLX5_IMR_MTT_SIZE - 1))

#define MLX5_KSM_PAGE_SHIFT MLX5_IMR_MTT_SHIFT

static u64 mlx5_imr_ksm_entries;

static int check_parent(struct ib_umem_odp *odp,
                               struct mlx5_ib_mr *parent)
{
        struct mlx5_ib_mr *mr = odp->private;

        return mr && mr->parent == parent && !odp->dying;
}

static struct ib_umem_odp *odp_next(struct ib_umem_odp *odp)
{
        struct mlx5_ib_mr *mr = odp->private, *parent = mr->parent;
        struct ib_ucontext *ctx = odp->umem->context;
        struct rb_node *rb;

        down_read(&ctx->umem_rwsem);
        while (1) {
                rb = rb_next(&odp->interval_tree.rb);
                if (!rb)
                        goto not_found;
                odp = rb_entry(rb, struct ib_umem_odp, interval_tree.rb);
                if (check_parent(odp, parent))
                        goto end;
        }
not_found:
        odp = NULL;
end:
        up_read(&ctx->umem_rwsem);
        return odp;
}

static struct ib_umem_odp *odp_lookup(struct ib_ucontext *ctx,
                                      u64 start, u64 length,
                                      struct mlx5_ib_mr *parent)
{
        struct ib_umem_odp *odp;
        struct rb_node *rb;

        down_read(&ctx->umem_rwsem);
        odp = rbt_ib_umem_lookup(&ctx->umem_tree, start, length);
        if (!odp)
                goto end;

        while (1) {
                if (check_parent(odp, parent))
                        goto end;
                rb = rb_next(&odp->interval_tree.rb);
                if (!rb)
                        goto not_found;
                odp = rb_entry(rb, struct ib_umem_odp, interval_tree.rb);
                if (ib_umem_start(odp->umem) > start + length)
                        goto not_found;
        }
not_found:
        odp = NULL;
end:
        up_read(&ctx->umem_rwsem);
        return odp;
}

void mlx5_odp_populate_klm(struct mlx5_klm *pklm, size_t offset,
                           size_t nentries, struct mlx5_ib_mr *mr, int flags)
{
        struct ib_pd *pd = mr->ibmr.pd;
        struct ib_ucontext *ctx = pd->uobject->context;
        struct mlx5_ib_dev *dev = to_mdev(pd->device);
        struct ib_umem_odp *odp;
        unsigned long va;
        int i;

        if (flags & MLX5_IB_UPD_XLT_ZAP) {
                for (i = 0; i < nentries; i++, pklm++) {
                        pklm->bcount = cpu_to_be32(MLX5_IMR_MTT_SIZE);
                        pklm->key = cpu_to_be32(dev->null_mkey);
                        pklm->va = 0;
                }
                return;
        }

        odp = odp_lookup(ctx, offset * MLX5_IMR_MTT_SIZE,
                             nentries * MLX5_IMR_MTT_SIZE, mr);

        for (i = 0; i < nentries; i++, pklm++) {
                pklm->bcount = cpu_to_be32(MLX5_IMR_MTT_SIZE);
                va = (offset + i) * MLX5_IMR_MTT_SIZE;
                if (odp && odp->umem->address == va) {
                        struct mlx5_ib_mr *mtt = odp->private;

                        pklm->key = cpu_to_be32(mtt->ibmr.lkey);
                        odp = odp_next(odp);
                } else {
                        pklm->key = cpu_to_be32(dev->null_mkey);
                }
                mlx5_ib_dbg(dev, "[%d] va %lx key %x\n",
                            i, va, be32_to_cpu(pklm->key));
        }
}

static void mr_leaf_free_action(struct work_struct *work)
{
        struct ib_umem_odp *odp = container_of(work, struct ib_umem_odp, work);
        int idx = ib_umem_start(odp->umem) >> MLX5_IMR_MTT_SHIFT;
        struct mlx5_ib_mr *mr = odp->private, *imr = mr->parent;

        mr->parent = NULL;
        synchronize_srcu(&mr->dev->mr_srcu);

        ib_umem_release(odp->umem);
        if (imr->live)
                mlx5_ib_update_xlt(imr, idx, 1, 0,
                                   MLX5_IB_UPD_XLT_INDIRECT |
                                   MLX5_IB_UPD_XLT_ATOMIC);
        mlx5_mr_cache_free(mr->dev, mr);

        if (atomic_dec_and_test(&imr->num_leaf_free))
                wake_up(&imr->q_leaf_free);
}

void mlx5_ib_invalidate_range(struct ib_umem *umem, unsigned long start,
                              unsigned long end)
{
        struct mlx5_ib_mr *mr;
        const u64 umr_block_mask = (MLX5_UMR_MTT_ALIGNMENT /
                                    sizeof(struct mlx5_mtt)) - 1;
        u64 idx = 0, blk_start_idx = 0;
        int in_block = 0;
        u64 addr;

        if (!umem || !umem->odp_data) {
                pr_err("invalidation called on NULL umem or non-ODP umem\n");
                return;
        }

        mr = umem->odp_data->private;

        if (!mr || !mr->ibmr.pd)
                return;

        start = max_t(u64, ib_umem_start(umem), start);
        end = min_t(u64, ib_umem_end(umem), end);

        /*
         * Iteration one - zap the HW's MTTs. The notifiers_count ensures that
         * while we are doing the invalidation, no page fault will attempt to
         * overwrite the same MTTs.  Concurent invalidations might race us,
         * but they will write 0s as well, so no difference in the end result.
         */

        for (addr = start; addr < end; addr += BIT(umem->page_shift)) {
                idx = (addr - ib_umem_start(umem)) >> umem->page_shift;
                /*
                 * Strive to write the MTTs in chunks, but avoid overwriting
                 * non-existing MTTs. The huristic here can be improved to
                 * estimate the cost of another UMR vs. the cost of bigger
                 * UMR.
                 */
                if (umem->odp_data->dma_list[idx] &
                    (ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT)) {
                        if (!in_block) {
                                blk_start_idx = idx;
                                in_block = 1;
                        }
                } else {
                        u64 umr_offset = idx & umr_block_mask;

                        if (in_block && umr_offset == 0) {
                                mlx5_ib_update_xlt(mr, blk_start_idx,
                                                   idx - blk_start_idx, 0,
                                                   MLX5_IB_UPD_XLT_ZAP |
                                                   MLX5_IB_UPD_XLT_ATOMIC);
                                in_block = 0;
                        }
                }
        }
        if (in_block)
                mlx5_ib_update_xlt(mr, blk_start_idx,
                                   idx - blk_start_idx + 1, 0,
                                   MLX5_IB_UPD_XLT_ZAP |
                                   MLX5_IB_UPD_XLT_ATOMIC);
        /*
         * We are now sure that the device will not access the
         * memory. We can safely unmap it, and mark it as dirty if
         * needed.
         */

        ib_umem_odp_unmap_dma_pages(umem, start, end);

        if (unlikely(!umem->npages && mr->parent &&
                     !umem->odp_data->dying)) {
                WRITE_ONCE(umem->odp_data->dying, 1);
                atomic_inc(&mr->parent->num_leaf_free);
                schedule_work(&umem->odp_data->work);
        }
}

void mlx5_ib_internal_fill_odp_caps(struct mlx5_ib_dev *dev)
{
        struct ib_odp_caps *caps = &dev->odp_caps;

        memset(caps, 0, sizeof(*caps));

        if (!MLX5_CAP_GEN(dev->mdev, pg))
                return;

        caps->general_caps = IB_ODP_SUPPORT;

        if (MLX5_CAP_GEN(dev->mdev, umr_extended_translation_offset))
                dev->odp_max_size = U64_MAX;
        else
                dev->odp_max_size = BIT_ULL(MLX5_MAX_UMR_SHIFT + PAGE_SHIFT);

        if (MLX5_CAP_ODP(dev->mdev, ud_odp_caps.send))
                caps->per_transport_caps.ud_odp_caps |= IB_ODP_SUPPORT_SEND;

        if (MLX5_CAP_ODP(dev->mdev, rc_odp_caps.send))
                caps->per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_SEND;

        if (MLX5_CAP_ODP(dev->mdev, rc_odp_caps.receive))
                caps->per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_RECV;

        if (MLX5_CAP_ODP(dev->mdev, rc_odp_caps.write))
                caps->per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_WRITE;

        if (MLX5_CAP_ODP(dev->mdev, rc_odp_caps.read))
                caps->per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_READ;

        if (MLX5_CAP_ODP(dev->mdev, rc_odp_caps.atomic))
                caps->per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_ATOMIC;

        if (MLX5_CAP_GEN(dev->mdev, fixed_buffer_size) &&
            MLX5_CAP_GEN(dev->mdev, null_mkey) &&
            MLX5_CAP_GEN(dev->mdev, umr_extended_translation_offset))
                caps->general_caps |= IB_ODP_SUPPORT_IMPLICIT;

        return;
}

static void mlx5_ib_page_fault_resume(struct mlx5_ib_dev *dev,
                                      struct mlx5_pagefault *pfault,
                                      int error)
{
        int wq_num = pfault->event_subtype == MLX5_PFAULT_SUBTYPE_WQE ?
                     pfault->wqe.wq_num : pfault->token;
        int ret = mlx5_core_page_fault_resume(dev->mdev,
                                              pfault->token,
                                              wq_num,
                                              pfault->type,
                                              error);
        if (ret)
                mlx5_ib_err(dev, "Failed to resolve the page fault on WQ 0x%x\n",
                            wq_num);
}

static struct mlx5_ib_mr *implicit_mr_alloc(struct ib_pd *pd,
                                            struct ib_umem *umem,
                                            bool ksm, int access_flags)
{
        struct mlx5_ib_dev *dev = to_mdev(pd->device);
        struct mlx5_ib_mr *mr;
        int err;

        mr = mlx5_mr_cache_alloc(dev, ksm ? MLX5_IMR_KSM_CACHE_ENTRY :
                                            MLX5_IMR_MTT_CACHE_ENTRY);

        if (IS_ERR(mr))
                return mr;

        mr->ibmr.pd = pd;

        mr->dev = dev;
        mr->access_flags = access_flags;
        mr->mmkey.iova = 0;
        mr->umem = umem;

        if (ksm) {
                err = mlx5_ib_update_xlt(mr, 0,
                                         mlx5_imr_ksm_entries,
                                         MLX5_KSM_PAGE_SHIFT,
                                         MLX5_IB_UPD_XLT_INDIRECT |
                                         MLX5_IB_UPD_XLT_ZAP |
                                         MLX5_IB_UPD_XLT_ENABLE);

        } else {
                err = mlx5_ib_update_xlt(mr, 0,
                                         MLX5_IMR_MTT_ENTRIES,
                                         PAGE_SHIFT,
                                         MLX5_IB_UPD_XLT_ZAP |
                                         MLX5_IB_UPD_XLT_ENABLE |
                                         MLX5_IB_UPD_XLT_ATOMIC);
        }

        if (err)
                goto fail;

        mr->ibmr.lkey = mr->mmkey.key;
        mr->ibmr.rkey = mr->mmkey.key;

        mr->live = 1;

        mlx5_ib_dbg(dev, "key %x dev %p mr %p\n",
                    mr->mmkey.key, dev->mdev, mr);

        return mr;

fail:
        mlx5_ib_err(dev, "Failed to register MKEY %d\n", err);
        mlx5_mr_cache_free(dev, mr);

        return ERR_PTR(err);
}

static struct ib_umem_odp *implicit_mr_get_data(struct mlx5_ib_mr *mr,
                                                u64 io_virt, size_t bcnt)
{
        struct ib_ucontext *ctx = mr->ibmr.pd->uobject->context;
        struct mlx5_ib_dev *dev = to_mdev(mr->ibmr.pd->device);
        struct ib_umem_odp *odp, *result = NULL;
        u64 addr = io_virt & MLX5_IMR_MTT_MASK;
        int nentries = 0, start_idx = 0, ret;
        struct mlx5_ib_mr *mtt;
        struct ib_umem *umem;

        mutex_lock(&mr->umem->odp_data->umem_mutex);
        odp = odp_lookup(ctx, addr, 1, mr);

        mlx5_ib_dbg(dev, "io_virt:%llx bcnt:%zx addr:%llx odp:%p\n",
                    io_virt, bcnt, addr, odp);

next_mr:
        if (likely(odp)) {
                if (nentries)
                        nentries++;
        } else {
                umem = ib_alloc_odp_umem(ctx, addr, MLX5_IMR_MTT_SIZE);
                if (IS_ERR(umem)) {
                        mutex_unlock(&mr->umem->odp_data->umem_mutex);
                        return ERR_CAST(umem);
                }

                mtt = implicit_mr_alloc(mr->ibmr.pd, umem, 0, mr->access_flags);
                if (IS_ERR(mtt)) {
                        mutex_unlock(&mr->umem->odp_data->umem_mutex);
                        ib_umem_release(umem);
                        return ERR_CAST(mtt);
                }

                odp = umem->odp_data;
                odp->private = mtt;
                mtt->umem = umem;
                mtt->mmkey.iova = addr;
                mtt->parent = mr;
                INIT_WORK(&odp->work, mr_leaf_free_action);

                if (!nentries)
                        start_idx = addr >> MLX5_IMR_MTT_SHIFT;
                nentries++;
        }

        /* Return first odp if region not covered by single one */
        if (likely(!result))
                result = odp;

        addr += MLX5_IMR_MTT_SIZE;
        if (unlikely(addr < io_virt + bcnt)) {
                odp = odp_next(odp);
                if (odp && odp->umem->address != addr)
                        odp = NULL;
                goto next_mr;
        }

        if (unlikely(nentries)) {
                ret = mlx5_ib_update_xlt(mr, start_idx, nentries, 0,
                                         MLX5_IB_UPD_XLT_INDIRECT |
                                         MLX5_IB_UPD_XLT_ATOMIC);
                if (ret) {
                        mlx5_ib_err(dev, "Failed to update PAS\n");
                        result = ERR_PTR(ret);
                }
        }

        mutex_unlock(&mr->umem->odp_data->umem_mutex);
        return result;
}

struct mlx5_ib_mr *mlx5_ib_alloc_implicit_mr(struct mlx5_ib_pd *pd,
                                             int access_flags)
{
        struct ib_ucontext *ctx = pd->ibpd.uobject->context;
        struct mlx5_ib_mr *imr;
        struct ib_umem *umem;

        umem = ib_umem_get(ctx, 0, 0, IB_ACCESS_ON_DEMAND, 0);
        if (IS_ERR(umem))
                return ERR_CAST(umem);

        imr = implicit_mr_alloc(&pd->ibpd, umem, 1, access_flags);
        if (IS_ERR(imr)) {
                ib_umem_release(umem);
                return ERR_CAST(imr);
        }

        imr->umem = umem;
        init_waitqueue_head(&imr->q_leaf_free);
        atomic_set(&imr->num_leaf_free, 0);

        return imr;
}

static int mr_leaf_free(struct ib_umem *umem, u64 start,
                        u64 end, void *cookie)
{
        struct mlx5_ib_mr *mr = umem->odp_data->private, *imr = cookie;

        if (mr->parent != imr)
                return 0;

        ib_umem_odp_unmap_dma_pages(umem,
                                    ib_umem_start(umem),
                                    ib_umem_end(umem));

        if (umem->odp_data->dying)
                return 0;

        WRITE_ONCE(umem->odp_data->dying, 1);
        atomic_inc(&imr->num_leaf_free);
        schedule_work(&umem->odp_data->work);

        return 0;
}

void mlx5_ib_free_implicit_mr(struct mlx5_ib_mr *imr)
{
        struct ib_ucontext *ctx = imr->ibmr.pd->uobject->context;

        down_read(&ctx->umem_rwsem);
        rbt_ib_umem_for_each_in_range(&ctx->umem_tree, 0, ULLONG_MAX,
                                      mr_leaf_free, imr);
        up_read(&ctx->umem_rwsem);

        wait_event(imr->q_leaf_free, !atomic_read(&imr->num_leaf_free));
}

static int pagefault_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr,
                        u64 io_virt, size_t bcnt, u32 *bytes_mapped)
{
        u64 access_mask = ODP_READ_ALLOWED_BIT;
        int npages = 0, page_shift, np;
        u64 start_idx, page_mask;
        struct ib_umem_odp *odp;
        int current_seq;
        size_t size;
        int ret;

        if (!mr->umem->odp_data->page_list) {
                odp = implicit_mr_get_data(mr, io_virt, bcnt);

                if (IS_ERR(odp))
                        return PTR_ERR(odp);
                mr = odp->private;

        } else {
                odp = mr->umem->odp_data;
        }

next_mr:
        size = min_t(size_t, bcnt, ib_umem_end(odp->umem) - io_virt);

        page_shift = mr->umem->page_shift;
        page_mask = ~(BIT(page_shift) - 1);
        start_idx = (io_virt - (mr->mmkey.iova & page_mask)) >> page_shift;

        if (mr->umem->writable)
                access_mask |= ODP_WRITE_ALLOWED_BIT;

        current_seq = READ_ONCE(odp->notifiers_seq);
        /*
         * Ensure the sequence number is valid for some time before we call
         * gup.
         */
        smp_rmb();

        ret = ib_umem_odp_map_dma_pages(mr->umem, io_virt, size,
                                        access_mask, current_seq);

        if (ret < 0)
                goto out;

        np = ret;

        mutex_lock(&odp->umem_mutex);
        if (!ib_umem_mmu_notifier_retry(mr->umem, current_seq)) {
                /*
                 * No need to check whether the MTTs really belong to
                 * this MR, since ib_umem_odp_map_dma_pages already
                 * checks this.
                 */
                ret = mlx5_ib_update_xlt(mr, start_idx, np,
                                         page_shift, MLX5_IB_UPD_XLT_ATOMIC);
        } else {
                ret = -EAGAIN;
        }
        mutex_unlock(&odp->umem_mutex);

        if (ret < 0) {
                if (ret != -EAGAIN)
                        mlx5_ib_err(dev, "Failed to update mkey page tables\n");
                goto out;
        }

        if (bytes_mapped) {
                u32 new_mappings = (np << page_shift) -
                        (io_virt - round_down(io_virt, 1 << page_shift));
                *bytes_mapped += min_t(u32, new_mappings, size);
        }

        npages += np << (page_shift - PAGE_SHIFT);
        bcnt -= size;

        if (unlikely(bcnt)) {
                struct ib_umem_odp *next;

                io_virt += size;
                next = odp_next(odp);
                if (unlikely(!next || next->umem->address != io_virt)) {
                        mlx5_ib_dbg(dev, "next implicit leaf removed at 0x%llx. got %p\n",
                                    io_virt, next);
                        return -EAGAIN;
                }
                odp = next;
                mr = odp->private;
                goto next_mr;
        }

        return npages;

out:
        if (ret == -EAGAIN) {
                if (mr->parent || !odp->dying) {
                        unsigned long timeout =
                                msecs_to_jiffies(MMU_NOTIFIER_TIMEOUT);

                        if (!wait_for_completion_timeout(
                                        &odp->notifier_completion,
                                        timeout)) {
                                mlx5_ib_warn(dev, "timeout waiting for mmu notifier. seq %d against %d\n",
                                             current_seq, odp->notifiers_seq);
                        }
                } else {
                        /* The MR is being killed, kill the QP as well. */
                        ret = -EFAULT;
                }
        }

        return ret;
}

struct pf_frame {
        struct pf_frame *next;
        u32 key;
        u64 io_virt;
        size_t bcnt;
        int depth;
};

/*
 * Handle a single data segment in a page-fault WQE or RDMA region.
 *
 * Returns number of OS pages retrieved on success. The caller may continue to
 * the next data segment.
 * Can return the following error codes:
 * -EAGAIN to designate a temporary error. The caller will abort handling the
 *  page fault and resolve it.
 * -EFAULT when there's an error mapping the requested pages. The caller will
 *  abort the page fault handling.
 */
static int pagefault_single_data_segment(struct mlx5_ib_dev *dev,
                                         u32 key, u64 io_virt, size_t bcnt,
                                         u32 *bytes_committed,
                                         u32 *bytes_mapped)
{
        int npages = 0, srcu_key, ret, i, outlen, cur_outlen = 0, depth = 0;
        struct pf_frame *head = NULL, *frame;
        struct mlx5_core_mkey *mmkey;
        struct mlx5_ib_mw *mw;
        struct mlx5_ib_mr *mr;
        struct mlx5_klm *pklm;
        u32 *out = NULL;
        size_t offset;

        srcu_key = srcu_read_lock(&dev->mr_srcu);

        io_virt += *bytes_committed;
        bcnt -= *bytes_committed;

next_mr:
        mmkey = __mlx5_mr_lookup(dev->mdev, mlx5_base_mkey(key));
        if (!mmkey || mmkey->key != key) {
                mlx5_ib_dbg(dev, "failed to find mkey %x\n", key);
                ret = -EFAULT;
                goto srcu_unlock;
        }

        switch (mmkey->type) {
        case MLX5_MKEY_MR:
                mr = container_of(mmkey, struct mlx5_ib_mr, mmkey);
                if (!mr->live || !mr->ibmr.pd) {
                        mlx5_ib_dbg(dev, "got dead MR\n");
                        ret = -EFAULT;
                        goto srcu_unlock;
                }

                ret = pagefault_mr(dev, mr, io_virt, bcnt, bytes_mapped);
                if (ret < 0)
                        goto srcu_unlock;

                npages += ret;
                ret = 0;
                break;

        case MLX5_MKEY_MW:
                mw = container_of(mmkey, struct mlx5_ib_mw, mmkey);

                if (depth >= MLX5_CAP_GEN(dev->mdev, max_indirection)) {
                        mlx5_ib_dbg(dev, "indirection level exceeded\n");
                        ret = -EFAULT;
                        goto srcu_unlock;
                }

                outlen = MLX5_ST_SZ_BYTES(query_mkey_out) +
                        sizeof(*pklm) * (mw->ndescs - 2);

                if (outlen > cur_outlen) {
                        kfree(out);
                        out = kzalloc(outlen, GFP_KERNEL);
                        if (!out) {
                                ret = -ENOMEM;
                                goto srcu_unlock;
                        }
                        cur_outlen = outlen;
                }

                pklm = (struct mlx5_klm *)MLX5_ADDR_OF(query_mkey_out, out,
                                                       bsf0_klm0_pas_mtt0_1);

                ret = mlx5_core_query_mkey(dev->mdev, &mw->mmkey, out, outlen);
                if (ret)
                        goto srcu_unlock;

                offset = io_virt - MLX5_GET64(query_mkey_out, out,
                                              memory_key_mkey_entry.start_addr);

                for (i = 0; bcnt && i < mw->ndescs; i++, pklm++) {
                        if (offset >= be32_to_cpu(pklm->bcount)) {
                                offset -= be32_to_cpu(pklm->bcount);
                                continue;
                        }

                        frame = kzalloc(sizeof(*frame), GFP_KERNEL);
                        if (!frame) {
                                ret = -ENOMEM;
                                goto srcu_unlock;
                        }

                        frame->key = be32_to_cpu(pklm->key);
                        frame->io_virt = be64_to_cpu(pklm->va) + offset;
                        frame->bcnt = min_t(size_t, bcnt,
                                            be32_to_cpu(pklm->bcount) - offset);
                        frame->depth = depth + 1;
                        frame->next = head;
                        head = frame;

                        bcnt -= frame->bcnt;
                }
                break;

        default:
                mlx5_ib_dbg(dev, "wrong mkey type %d\n", mmkey->type);
                ret = -EFAULT;
                goto srcu_unlock;
        }

        if (head) {
                frame = head;
                head = frame->next;

                key = frame->key;
                io_virt = frame->io_virt;
                bcnt = frame->bcnt;
                depth = frame->depth;
                kfree(frame);

                goto next_mr;
        }

srcu_unlock:
        while (head) {
                frame = head;
                head = frame->next;
                kfree(frame);
        }
        kfree(out);

        srcu_read_unlock(&dev->mr_srcu, srcu_key);
        *bytes_committed = 0;
        return ret ? ret : npages;
}

/**
 * Parse a series of data segments for page fault handling.
 *
 * @qp the QP on which the fault occurred.
 * @pfault contains page fault information.
 * @wqe points at the first data segment in the WQE.
 * @wqe_end points after the end of the WQE.
 * @bytes_mapped receives the number of bytes that the function was able to
 *               map. This allows the caller to decide intelligently whether
 *               enough memory was mapped to resolve the page fault
 *               successfully (e.g. enough for the next MTU, or the entire
 *               WQE).
 * @total_wqe_bytes receives the total data size of this WQE in bytes (minus
 *                  the committed bytes).
 *
 * Returns the number of pages loaded if positive, zero for an empty WQE, or a
 * negative error code.
 */
static int pagefault_data_segments(struct mlx5_ib_dev *dev,
                                   struct mlx5_pagefault *pfault,
                                   struct mlx5_ib_qp *qp, void *wqe,
                                   void *wqe_end, u32 *bytes_mapped,
                                   u32 *total_wqe_bytes, int receive_queue)
{
        int ret = 0, npages = 0;
        u64 io_virt;
        u32 key;
        u32 byte_count;
        size_t bcnt;
        int inline_segment;

        /* Skip SRQ next-WQE segment. */
        if (receive_queue && qp->ibqp.srq)
                wqe += sizeof(struct mlx5_wqe_srq_next_seg);

        if (bytes_mapped)
                *bytes_mapped = 0;
        if (total_wqe_bytes)
                *total_wqe_bytes = 0;

        while (wqe < wqe_end) {
                struct mlx5_wqe_data_seg *dseg = wqe;

                io_virt = be64_to_cpu(dseg->addr);
                key = be32_to_cpu(dseg->lkey);
                byte_count = be32_to_cpu(dseg->byte_count);
                inline_segment = !!(byte_count &  MLX5_INLINE_SEG);
                bcnt           = byte_count & ~MLX5_INLINE_SEG;

                if (inline_segment) {
                        bcnt = bcnt & MLX5_WQE_INLINE_SEG_BYTE_COUNT_MASK;
                        wqe += ALIGN(sizeof(struct mlx5_wqe_inline_seg) + bcnt,
                                     16);
                } else {
                        wqe += sizeof(*dseg);
                }

                /* receive WQE end of sg list. */
                if (receive_queue && bcnt == 0 && key == MLX5_INVALID_LKEY &&
                    io_virt == 0)
                        break;

                if (!inline_segment && total_wqe_bytes) {
                        *total_wqe_bytes += bcnt - min_t(size_t, bcnt,
                                        pfault->bytes_committed);
                }

                /* A zero length data segment designates a length of 2GB. */
                if (bcnt == 0)
                        bcnt = 1U << 31;

                if (inline_segment || bcnt <= pfault->bytes_committed) {
                        pfault->bytes_committed -=
                                min_t(size_t, bcnt,
                                      pfault->bytes_committed);
                        continue;
                }

                ret = pagefault_single_data_segment(dev, key, io_virt, bcnt,
                                                    &pfault->bytes_committed,
                                                    bytes_mapped);
                if (ret < 0)
                        break;
                npages += ret;
        }

        return ret < 0 ? ret : npages;
}

static const u32 mlx5_ib_odp_opcode_cap[] = {
        [MLX5_OPCODE_SEND]             = IB_ODP_SUPPORT_SEND,
        [MLX5_OPCODE_SEND_IMM]         = IB_ODP_SUPPORT_SEND,
        [MLX5_OPCODE_SEND_INVAL]       = IB_ODP_SUPPORT_SEND,
        [MLX5_OPCODE_RDMA_WRITE]       = IB_ODP_SUPPORT_WRITE,
        [MLX5_OPCODE_RDMA_WRITE_IMM]   = IB_ODP_SUPPORT_WRITE,
        [MLX5_OPCODE_RDMA_READ]        = IB_ODP_SUPPORT_READ,
        [MLX5_OPCODE_ATOMIC_CS]        = IB_ODP_SUPPORT_ATOMIC,
        [MLX5_OPCODE_ATOMIC_FA]        = IB_ODP_SUPPORT_ATOMIC,
};

/*
 * Parse initiator WQE. Advances the wqe pointer to point at the
 * scatter-gather list, and set wqe_end to the end of the WQE.
 */
static int mlx5_ib_mr_initiator_pfault_handler(
        struct mlx5_ib_dev *dev, struct mlx5_pagefault *pfault,
        struct mlx5_ib_qp *qp, void **wqe, void **wqe_end, int wqe_length)
{
        struct mlx5_wqe_ctrl_seg *ctrl = *wqe;
        u16 wqe_index = pfault->wqe.wqe_index;
        u32 transport_caps;
        struct mlx5_base_av *av;
        unsigned ds, opcode;
#if defined(DEBUG)
        u32 ctrl_wqe_index, ctrl_qpn;
#endif
        u32 qpn = qp->trans_qp.base.mqp.qpn;

        ds = be32_to_cpu(ctrl->qpn_ds) & MLX5_WQE_CTRL_DS_MASK;
        if (ds * MLX5_WQE_DS_UNITS > wqe_length) {
                mlx5_ib_err(dev, "Unable to read the complete WQE. ds = 0x%x, ret = 0x%x\n",
                            ds, wqe_length);
                return -EFAULT;
        }

        if (ds == 0) {
                mlx5_ib_err(dev, "Got WQE with zero DS. wqe_index=%x, qpn=%x\n",
                            wqe_index, qpn);
                return -EFAULT;
        }

#if defined(DEBUG)
        ctrl_wqe_index = (be32_to_cpu(ctrl->opmod_idx_opcode) &
                        MLX5_WQE_CTRL_WQE_INDEX_MASK) >>
                        MLX5_WQE_CTRL_WQE_INDEX_SHIFT;
        if (wqe_index != ctrl_wqe_index) {
                mlx5_ib_err(dev, "Got WQE with invalid wqe_index. wqe_index=0x%x, qpn=0x%x ctrl->wqe_index=0x%x\n",
                            wqe_index, qpn,
                            ctrl_wqe_index);
                return -EFAULT;
        }

        ctrl_qpn = (be32_to_cpu(ctrl->qpn_ds) & MLX5_WQE_CTRL_QPN_MASK) >>
                MLX5_WQE_CTRL_QPN_SHIFT;
        if (qpn != ctrl_qpn) {
                mlx5_ib_err(dev, "Got WQE with incorrect QP number. wqe_index=0x%x, qpn=0x%x ctrl->qpn=0x%x\n",
                            wqe_index, qpn,
                            ctrl_qpn);
                return -EFAULT;
        }
#endif /* DEBUG */

        *wqe_end = *wqe + ds * MLX5_WQE_DS_UNITS;
        *wqe += sizeof(*ctrl);

        opcode = be32_to_cpu(ctrl->opmod_idx_opcode) &
                 MLX5_WQE_CTRL_OPCODE_MASK;

        switch (qp->ibqp.qp_type) {
        case IB_QPT_RC:
                transport_caps = dev->odp_caps.per_transport_caps.rc_odp_caps;
                break;
        case IB_QPT_UD:
                transport_caps = dev->odp_caps.per_transport_caps.ud_odp_caps;
                break;
        default:
                mlx5_ib_err(dev, "ODP fault on QP of an unsupported transport 0x%x\n",
                            qp->ibqp.qp_type);
                return -EFAULT;
        }

        if (unlikely(opcode >= sizeof(mlx5_ib_odp_opcode_cap) /
            sizeof(mlx5_ib_odp_opcode_cap[0]) ||
            !(transport_caps & mlx5_ib_odp_opcode_cap[opcode]))) {
                mlx5_ib_err(dev, "ODP fault on QP of an unsupported opcode 0x%x\n",
                            opcode);
                return -EFAULT;
        }

        if (qp->ibqp.qp_type != IB_QPT_RC) {
                av = *wqe;
                if (av->dqp_dct & cpu_to_be32(MLX5_EXTENDED_UD_AV))
                        *wqe += sizeof(struct mlx5_av);
                else
                        *wqe += sizeof(struct mlx5_base_av);
        }

        switch (opcode) {
        case MLX5_OPCODE_RDMA_WRITE:
        case MLX5_OPCODE_RDMA_WRITE_IMM:
        case MLX5_OPCODE_RDMA_READ:
                *wqe += sizeof(struct mlx5_wqe_raddr_seg);
                break;
        case MLX5_OPCODE_ATOMIC_CS:
        case MLX5_OPCODE_ATOMIC_FA:
                *wqe += sizeof(struct mlx5_wqe_raddr_seg);
                *wqe += sizeof(struct mlx5_wqe_atomic_seg);
                break;
        }

        return 0;
}

/*
 * Parse responder WQE. Advances the wqe pointer to point at the
 * scatter-gather list, and set wqe_end to the end of the WQE.
 */
static int mlx5_ib_mr_responder_pfault_handler(
        struct mlx5_ib_dev *dev, struct mlx5_pagefault *pfault,
        struct mlx5_ib_qp *qp, void **wqe, void **wqe_end, int wqe_length)
{
        struct mlx5_ib_wq *wq = &qp->rq;
        int wqe_size = 1 << wq->wqe_shift;

        if (qp->ibqp.srq) {
                mlx5_ib_err(dev, "ODP fault on SRQ is not supported\n");
                return -EFAULT;
        }

        if (qp->wq_sig) {
                mlx5_ib_err(dev, "ODP fault with WQE signatures is not supported\n");
                return -EFAULT;
        }

        if (wqe_size > wqe_length) {
                mlx5_ib_err(dev, "Couldn't read all of the receive WQE's content\n");
                return -EFAULT;
        }

        switch (qp->ibqp.qp_type) {
        case IB_QPT_RC:
                if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &
                      IB_ODP_SUPPORT_RECV))
                        goto invalid_transport_or_opcode;
                break;
        default:
invalid_transport_or_opcode:
                mlx5_ib_err(dev, "ODP fault on QP of an unsupported transport. transport: 0x%x\n",
                            qp->ibqp.qp_type);
                return -EFAULT;

        }

        *wqe_end = *wqe + wqe_size;

        return 0;
}

static struct mlx5_ib_qp *mlx5_ib_odp_find_qp(struct mlx5_ib_dev *dev,
                                              u32 wq_num)
{
        struct mlx5_core_qp *mqp = __mlx5_qp_lookup(dev->mdev, wq_num);

        if (!mqp) {
                mlx5_ib_err(dev, "QPN 0x%6x not found\n", wq_num);
                return NULL;
        }

        return to_mibqp(mqp);
}

static void mlx5_ib_mr_wqe_pfault_handler(struct mlx5_ib_dev *dev,
                                          struct mlx5_pagefault *pfault)
{
        int ret;
        void *wqe, *wqe_end;
        u32 bytes_mapped, total_wqe_bytes;
        char *buffer = NULL;
        int resume_with_error = 1;
        u16 wqe_index = pfault->wqe.wqe_index;
        int requestor = pfault->type & MLX5_PFAULT_REQUESTOR;
        struct mlx5_ib_qp *qp;

        buffer = (char *)__get_free_page(GFP_KERNEL);
        if (!buffer) {
                mlx5_ib_err(dev, "Error allocating memory for IO page fault handling.\n");
                goto resolve_page_fault;
        }

        qp = mlx5_ib_odp_find_qp(dev, pfault->wqe.wq_num);
        if (!qp)
                goto resolve_page_fault;

        ret = mlx5_ib_read_user_wqe(qp, requestor, wqe_index, buffer,
                                    PAGE_SIZE, &qp->trans_qp.base);
        if (ret < 0) {
                mlx5_ib_err(dev, "Failed reading a WQE following page fault, error=%d, wqe_index=%x, qpn=%x\n",
                            ret, wqe_index, pfault->token);
                goto resolve_page_fault;
        }

        wqe = buffer;
        if (requestor)
                ret = mlx5_ib_mr_initiator_pfault_handler(dev, pfault, qp, &wqe,
                                                          &wqe_end, ret);
        else
                ret = mlx5_ib_mr_responder_pfault_handler(dev, pfault, qp, &wqe,
                                                          &wqe_end, ret);
        if (ret < 0)
                goto resolve_page_fault;

        if (wqe >= wqe_end) {
                mlx5_ib_err(dev, "ODP fault on invalid WQE.\n");
                goto resolve_page_fault;
        }

        ret = pagefault_data_segments(dev, pfault, qp, wqe, wqe_end,
                                      &bytes_mapped, &total_wqe_bytes,
                                      !requestor);
        if (ret == -EAGAIN) {
                resume_with_error = 0;
                goto resolve_page_fault;
        } else if (ret < 0 || total_wqe_bytes > bytes_mapped) {
                goto resolve_page_fault;
        }

        resume_with_error = 0;
resolve_page_fault:
        mlx5_ib_page_fault_resume(dev, pfault, resume_with_error);
        mlx5_ib_dbg(dev, "PAGE FAULT completed. QP 0x%x resume_with_error=%d, type: 0x%x\n",
                    pfault->wqe.wq_num, resume_with_error,
                    pfault->type);
        free_page((unsigned long)buffer);
}

static int pages_in_range(u64 address, u32 length)
{
        return (ALIGN(address + length, PAGE_SIZE) -
                (address & PAGE_MASK)) >> PAGE_SHIFT;
}

static void mlx5_ib_mr_rdma_pfault_handler(struct mlx5_ib_dev *dev,
                                           struct mlx5_pagefault *pfault)
{
        u64 address;
        u32 length;
        u32 prefetch_len = pfault->bytes_committed;
        int prefetch_activated = 0;
        u32 rkey = pfault->rdma.r_key;
        int ret;

        /* The RDMA responder handler handles the page fault in two parts.
         * First it brings the necessary pages for the current packet
         * (and uses the pfault context), and then (after resuming the QP)
         * prefetches more pages. The second operation cannot use the pfault
         * context and therefore uses the dummy_pfault context allocated on
         * the stack */
        pfault->rdma.rdma_va += pfault->bytes_committed;
        pfault->rdma.rdma_op_len -= min(pfault->bytes_committed,
                                         pfault->rdma.rdma_op_len);
        pfault->bytes_committed = 0;

        address = pfault->rdma.rdma_va;
        length  = pfault->rdma.rdma_op_len;

        /* For some operations, the hardware cannot tell the exact message
         * length, and in those cases it reports zero. Use prefetch
         * logic. */
        if (length == 0) {
                prefetch_activated = 1;
                length = pfault->rdma.packet_size;
                prefetch_len = min(MAX_PREFETCH_LEN, prefetch_len);
        }

        ret = pagefault_single_data_segment(dev, rkey, address, length,
                                            &pfault->bytes_committed, NULL);
        if (ret == -EAGAIN) {
                /* We're racing with an invalidation, don't prefetch */
                prefetch_activated = 0;
        } else if (ret < 0 || pages_in_range(address, length) > ret) {
                mlx5_ib_page_fault_resume(dev, pfault, 1);
                if (ret != -ENOENT)
                        mlx5_ib_dbg(dev, "PAGE FAULT error %d. QP 0x%x, type: 0x%x\n",
                                    ret, pfault->token, pfault->type);
                return;
        }

        mlx5_ib_page_fault_resume(dev, pfault, 0);
        mlx5_ib_dbg(dev, "PAGE FAULT completed. QP 0x%x, type: 0x%x, prefetch_activated: %d\n",
                    pfault->token, pfault->type,
                    prefetch_activated);

        /* At this point, there might be a new pagefault already arriving in
         * the eq, switch to the dummy pagefault for the rest of the
         * processing. We're still OK with the objects being alive as the
         * work-queue is being fenced. */

        if (prefetch_activated) {
                u32 bytes_committed = 0;

                ret = pagefault_single_data_segment(dev, rkey, address,
                                                    prefetch_len,
                                                    &bytes_committed, NULL);
                if (ret < 0 && ret != -EAGAIN) {
                        mlx5_ib_dbg(dev, "Prefetch failed. ret: %d, QP 0x%x, address: 0x%.16llx, length = 0x%.16x\n",
                                    ret, pfault->token, address, prefetch_len);
                }
        }
}

void mlx5_ib_pfault(struct mlx5_core_dev *mdev, void *context,
                    struct mlx5_pagefault *pfault)
{
        struct mlx5_ib_dev *dev = context;
        u8 event_subtype = pfault->event_subtype;

        switch (event_subtype) {
        case MLX5_PFAULT_SUBTYPE_WQE:
                mlx5_ib_mr_wqe_pfault_handler(dev, pfault);
                break;
        case MLX5_PFAULT_SUBTYPE_RDMA:
                mlx5_ib_mr_rdma_pfault_handler(dev, pfault);
                break;
        default:
                mlx5_ib_err(dev, "Invalid page fault event subtype: 0x%x\n",
                            event_subtype);
                mlx5_ib_page_fault_resume(dev, pfault, 1);
        }
}

void mlx5_odp_init_mr_cache_entry(struct mlx5_cache_ent *ent)
{
        if (!(ent->dev->odp_caps.general_caps & IB_ODP_SUPPORT_IMPLICIT))
                return;

        switch (ent->order - 2) {
        case MLX5_IMR_MTT_CACHE_ENTRY:
                ent->page = PAGE_SHIFT;
                ent->xlt = MLX5_IMR_MTT_ENTRIES *
                           sizeof(struct mlx5_mtt) /
                           MLX5_IB_UMR_OCTOWORD;
                ent->access_mode = MLX5_MKC_ACCESS_MODE_MTT;
                ent->limit = 0;
                break;

        case MLX5_IMR_KSM_CACHE_ENTRY:
                ent->page = MLX5_KSM_PAGE_SHIFT;
                ent->xlt = mlx5_imr_ksm_entries *
                           sizeof(struct mlx5_klm) /
                           MLX5_IB_UMR_OCTOWORD;
                ent->access_mode = MLX5_MKC_ACCESS_MODE_KSM;
                ent->limit = 0;
                break;
        }
}

int mlx5_ib_odp_init_one(struct mlx5_ib_dev *dev)
{
        int ret;

        ret = init_srcu_struct(&dev->mr_srcu);
        if (ret)
                return ret;

        if (dev->odp_caps.general_caps & IB_ODP_SUPPORT_IMPLICIT) {
                ret = mlx5_cmd_null_mkey(dev->mdev, &dev->null_mkey);
                if (ret) {
                        mlx5_ib_err(dev, "Error getting null_mkey %d\n", ret);
                        return ret;
                }
        }

        return 0;
}

void mlx5_ib_odp_remove_one(struct mlx5_ib_dev *dev)
{
        cleanup_srcu_struct(&dev->mr_srcu);
}

int mlx5_ib_odp_init(void)
{
        mlx5_imr_ksm_entries = BIT_ULL(get_order(TASK_SIZE) -
                                       MLX5_IMR_MTT_BITS);

        return 0;
}