/*
 * 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"

#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

struct workqueue_struct *mlx5_ib_page_fault_wq;

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(u64)) - 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 += (u64)umem->page_size) {
                idx = (addr - ib_umem_start(umem)) / PAGE_SIZE;
                /*
                 * 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_mtt(mr, blk_start_idx,
                                                   idx - blk_start_idx, 1);
                                in_block = 0;
                        }
                }
        }
        if (in_block)
                mlx5_ib_update_mtt(mr, blk_start_idx, idx - blk_start_idx + 1,
                                   1);

        /*
         * 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);
}

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_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;

        return;
}

static struct mlx5_ib_mr *mlx5_ib_odp_find_mr_lkey(struct mlx5_ib_dev *dev,
                                                   u32 key)
{
        u32 base_key = mlx5_base_mkey(key);
        struct mlx5_core_mr *mmr = __mlx5_mr_lookup(dev->mdev, base_key);
        struct mlx5_ib_mr *mr = container_of(mmr, struct mlx5_ib_mr, mmr);

        if (!mmr || mmr->key != key || !mr->live)
                return NULL;

        return container_of(mmr, struct mlx5_ib_mr, mmr);
}

static void mlx5_ib_page_fault_resume(struct mlx5_ib_qp *qp,
                                      struct mlx5_ib_pfault *pfault,
                                      int error)
{
        struct mlx5_ib_dev *dev = to_mdev(qp->ibqp.pd->device);
        u32 qpn = qp->trans_qp.base.mqp.qpn;
        int ret = mlx5_core_page_fault_resume(dev->mdev,
                                              qpn,
                                              pfault->mpfault.flags,
                                              error);
        if (ret)
                pr_err("Failed to resolve the page fault on QP 0x%x\n", qpn);
}

/*
 * Handle a single data segment in a page-fault WQE.
 *
 * Returns number of pages retrieved on success. The caller will 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 and possibly move the QP to an error state.
 * On other errors the QP should also be closed with an error.
 */
static int pagefault_single_data_segment(struct mlx5_ib_qp *qp,
                                         struct mlx5_ib_pfault *pfault,
                                         u32 key, u64 io_virt, size_t bcnt,
                                         u32 *bytes_mapped)
{
        struct mlx5_ib_dev *mib_dev = to_mdev(qp->ibqp.pd->device);
        int srcu_key;
        unsigned int current_seq;
        u64 start_idx;
        int npages = 0, ret = 0;
        struct mlx5_ib_mr *mr;
        u64 access_mask = ODP_READ_ALLOWED_BIT;

        srcu_key = srcu_read_lock(&mib_dev->mr_srcu);
        mr = mlx5_ib_odp_find_mr_lkey(mib_dev, key);
        /*
         * If we didn't find the MR, it means the MR was closed while we were
         * handling the ODP event. In this case we return -EFAULT so that the
         * QP will be closed.
         */
        if (!mr || !mr->ibmr.pd) {
                pr_err("Failed to find relevant mr for lkey=0x%06x, probably the MR was destroyed\n",
                       key);
                ret = -EFAULT;
                goto srcu_unlock;
        }
        if (!mr->umem->odp_data) {
                pr_debug("skipping non ODP MR (lkey=0x%06x) in page fault handler.\n",
                         key);
                if (bytes_mapped)
                        *bytes_mapped +=
                                (bcnt - pfault->mpfault.bytes_committed);
                goto srcu_unlock;
        }
        if (mr->ibmr.pd != qp->ibqp.pd) {
                pr_err("Page-fault with different PDs for QP and MR.\n");
                ret = -EFAULT;
                goto srcu_unlock;
        }

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

        /*
         * Avoid branches - this code will perform correctly
         * in all iterations (in iteration 2 and above,
         * bytes_committed == 0).
         */
        io_virt += pfault->mpfault.bytes_committed;
        bcnt -= pfault->mpfault.bytes_committed;

        start_idx = (io_virt - (mr->mmr.iova & PAGE_MASK)) >> PAGE_SHIFT;

        if (mr->umem->writable)
                access_mask |= ODP_WRITE_ALLOWED_BIT;
        npages = ib_umem_odp_map_dma_pages(mr->umem, io_virt, bcnt,
                                           access_mask, current_seq);
        if (npages < 0) {
                ret = npages;
                goto srcu_unlock;
        }

        if (npages > 0) {
                mutex_lock(&mr->umem->odp_data->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_mtt(mr, start_idx, npages, 0);
                } else {
                        ret = -EAGAIN;
                }
                mutex_unlock(&mr->umem->odp_data->umem_mutex);
                if (ret < 0) {
                        if (ret != -EAGAIN)
                                pr_err("Failed to update mkey page tables\n");
                        goto srcu_unlock;
                }

                if (bytes_mapped) {
                        u32 new_mappings = npages * PAGE_SIZE -
                                (io_virt - round_down(io_virt, PAGE_SIZE));
                        *bytes_mapped += min_t(u32, new_mappings, bcnt);
                }
        }

srcu_unlock:
        if (ret == -EAGAIN) {
                if (!mr->umem->odp_data->dying) {
                        struct ib_umem_odp *odp_data = mr->umem->odp_data;
                        unsigned long timeout =
                                msecs_to_jiffies(MMU_NOTIFIER_TIMEOUT);

                        if (!wait_for_completion_timeout(
                                        &odp_data->notifier_completion,
                                        timeout)) {
                                pr_warn("timeout waiting for mmu notifier completion\n");
                        }
                } else {
                        /* The MR is being killed, kill the QP as well. */
                        ret = -EFAULT;
                }
        }
        srcu_read_unlock(&mib_dev->mr_srcu, srcu_key);
        pfault->mpfault.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_qp *qp,
                                   struct mlx5_ib_pfault *pfault, 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->mpfault.bytes_committed);
                }

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

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

                ret = pagefault_single_data_segment(qp, pfault, key, io_virt,
                                                    bcnt, bytes_mapped);
                if (ret < 0)
                        break;
                npages += ret;
        }

        return ret < 0 ? ret : npages;
}

/*
 * 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_qp *qp, struct mlx5_ib_pfault *pfault,
        void **wqe, void **wqe_end, int wqe_length)
{
        struct mlx5_ib_dev *dev = to_mdev(qp->ibqp.pd->device);
        struct mlx5_wqe_ctrl_seg *ctrl = *wqe;
        u16 wqe_index = pfault->mpfault.wqe.wqe_index;
        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:
                switch (opcode) {
                case MLX5_OPCODE_SEND:
                case MLX5_OPCODE_SEND_IMM:
                case MLX5_OPCODE_SEND_INVAL:
                        if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &
                              IB_ODP_SUPPORT_SEND))
                                goto invalid_transport_or_opcode;
                        break;
                case MLX5_OPCODE_RDMA_WRITE:
                case MLX5_OPCODE_RDMA_WRITE_IMM:
                        if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &
                              IB_ODP_SUPPORT_WRITE))
                                goto invalid_transport_or_opcode;
                        *wqe += sizeof(struct mlx5_wqe_raddr_seg);
                        break;
                case MLX5_OPCODE_RDMA_READ:
                        if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &
                              IB_ODP_SUPPORT_READ))
                                goto invalid_transport_or_opcode;
                        *wqe += sizeof(struct mlx5_wqe_raddr_seg);
                        break;
                default:
                        goto invalid_transport_or_opcode;
                }
                break;
        case IB_QPT_UD:
                switch (opcode) {
                case MLX5_OPCODE_SEND:
                case MLX5_OPCODE_SEND_IMM:
                        if (!(dev->odp_caps.per_transport_caps.ud_odp_caps &
                              IB_ODP_SUPPORT_SEND))
                                goto invalid_transport_or_opcode;
                        *wqe += sizeof(struct mlx5_wqe_datagram_seg);
                        break;
                default:
                        goto invalid_transport_or_opcode;
                }
                break;
        default:
invalid_transport_or_opcode:
                mlx5_ib_err(dev, "ODP fault on QP of an unsupported opcode or transport. transport: 0x%x opcode: 0x%x.\n",
                            qp->ibqp.qp_type, opcode);
                return -EFAULT;
        }

        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_qp *qp, struct mlx5_ib_pfault *pfault,
        void **wqe, void **wqe_end, int wqe_length)
{
        struct mlx5_ib_dev *dev = to_mdev(qp->ibqp.pd->device);
        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 void mlx5_ib_mr_wqe_pfault_handler(struct mlx5_ib_qp *qp,
                                          struct mlx5_ib_pfault *pfault)
{
        struct mlx5_ib_dev *dev = to_mdev(qp->ibqp.pd->device);
        int ret;
        void *wqe, *wqe_end;
        u32 bytes_mapped, total_wqe_bytes;
        char *buffer = NULL;
        int resume_with_error = 0;
        u16 wqe_index = pfault->mpfault.wqe.wqe_index;
        int requestor = pfault->mpfault.flags & MLX5_PFAULT_REQUESTOR;
        u32 qpn = qp->trans_qp.base.mqp.qpn;

        buffer = (char *)__get_free_page(GFP_KERNEL);
        if (!buffer) {
                mlx5_ib_err(dev, "Error allocating memory for IO page fault handling.\n");
                resume_with_error = 1;
                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=%x, wqe_index=%x, qpn=%x\n",
                            -ret, wqe_index, qpn);
                resume_with_error = 1;
                goto resolve_page_fault;
        }

        wqe = buffer;
        if (requestor)
                ret = mlx5_ib_mr_initiator_pfault_handler(qp, pfault, &wqe,
                                                          &wqe_end, ret);
        else
                ret = mlx5_ib_mr_responder_pfault_handler(qp, pfault, &wqe,
                                                          &wqe_end, ret);
        if (ret < 0) {
                resume_with_error = 1;
                goto resolve_page_fault;
        }

        if (wqe >= wqe_end) {
                mlx5_ib_err(dev, "ODP fault on invalid WQE.\n");
                resume_with_error = 1;
                goto resolve_page_fault;
        }

        ret = pagefault_data_segments(qp, pfault, wqe, wqe_end, &bytes_mapped,
                                      &total_wqe_bytes, !requestor);
        if (ret == -EAGAIN) {
                goto resolve_page_fault;
        } else if (ret < 0 || total_wqe_bytes > bytes_mapped) {
                mlx5_ib_err(dev, "Error getting user pages for page fault. Error: 0x%x\n",
                            -ret);
                resume_with_error = 1;
                goto resolve_page_fault;
        }

resolve_page_fault:
        mlx5_ib_page_fault_resume(qp, pfault, resume_with_error);
        mlx5_ib_dbg(dev, "PAGE FAULT completed. QP 0x%x resume_with_error=%d, flags: 0x%x\n",
                    qpn, resume_with_error,
                    pfault->mpfault.flags);

        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_qp *qp,
                                           struct mlx5_ib_pfault *pfault)
{
        struct mlx5_pagefault *mpfault = &pfault->mpfault;
        u64 address;
        u32 length;
        u32 prefetch_len = mpfault->bytes_committed;
        int prefetch_activated = 0;
        u32 rkey = mpfault->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 */
        struct mlx5_ib_pfault dummy_pfault = {};

        dummy_pfault.mpfault.bytes_committed = 0;

        mpfault->rdma.rdma_va += mpfault->bytes_committed;
        mpfault->rdma.rdma_op_len -= min(mpfault->bytes_committed,
                                         mpfault->rdma.rdma_op_len);
        mpfault->bytes_committed = 0;

        address = mpfault->rdma.rdma_va;
        length  = mpfault->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 = mpfault->rdma.packet_size;
                prefetch_len = min(MAX_PREFETCH_LEN, prefetch_len);
        }

        ret = pagefault_single_data_segment(qp, pfault, rkey, address, length,
                                            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(qp, pfault, 1);
                return;
        }

        mlx5_ib_page_fault_resume(qp, pfault, 0);

        /* 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) {
                ret = pagefault_single_data_segment(qp, &dummy_pfault, rkey,
                                                    address,
                                                    prefetch_len,
                                                    NULL);
                if (ret < 0) {
                        pr_warn("Prefetch failed (ret = %d, prefetch_activated = %d) for QPN %d, address: 0x%.16llx, length = 0x%.16x\n",
                                ret, prefetch_activated,
                                qp->ibqp.qp_num, address, prefetch_len);
                }
        }
}

void mlx5_ib_mr_pfault_handler(struct mlx5_ib_qp *qp,
                               struct mlx5_ib_pfault *pfault)
{
        u8 event_subtype = pfault->mpfault.event_subtype;

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

static void mlx5_ib_qp_pfault_action(struct work_struct *work)
{
        struct mlx5_ib_pfault *pfault = container_of(work,
                                                     struct mlx5_ib_pfault,
                                                     work);
        enum mlx5_ib_pagefault_context context =
                mlx5_ib_get_pagefault_context(&pfault->mpfault);
        struct mlx5_ib_qp *qp = container_of(pfault, struct mlx5_ib_qp,
                                             pagefaults[context]);
        mlx5_ib_mr_pfault_handler(qp, pfault);
}

void mlx5_ib_qp_disable_pagefaults(struct mlx5_ib_qp *qp)
{
        unsigned long flags;

        spin_lock_irqsave(&qp->disable_page_faults_lock, flags);
        qp->disable_page_faults = 1;
        spin_unlock_irqrestore(&qp->disable_page_faults_lock, flags);

        /*
         * Note that at this point, we are guarenteed that no more
         * work queue elements will be posted to the work queue with
         * the QP we are closing.
         */
        flush_workqueue(mlx5_ib_page_fault_wq);
}

void mlx5_ib_qp_enable_pagefaults(struct mlx5_ib_qp *qp)
{
        unsigned long flags;

        spin_lock_irqsave(&qp->disable_page_faults_lock, flags);
        qp->disable_page_faults = 0;
        spin_unlock_irqrestore(&qp->disable_page_faults_lock, flags);
}

static void mlx5_ib_pfault_handler(struct mlx5_core_qp *qp,
                                   struct mlx5_pagefault *pfault)
{
        /*
         * Note that we will only get one fault event per QP per context
         * (responder/initiator, read/write), until we resolve the page fault
         * with the mlx5_ib_page_fault_resume command. Since this function is
         * called from within the work element, there is no risk of missing
         * events.
         */
        struct mlx5_ib_qp *mibqp = to_mibqp(qp);
        enum mlx5_ib_pagefault_context context =
                mlx5_ib_get_pagefault_context(pfault);
        struct mlx5_ib_pfault *qp_pfault = &mibqp->pagefaults[context];

        qp_pfault->mpfault = *pfault;

        /* No need to stop interrupts here since we are in an interrupt */
        spin_lock(&mibqp->disable_page_faults_lock);
        if (!mibqp->disable_page_faults)
                queue_work(mlx5_ib_page_fault_wq, &qp_pfault->work);
        spin_unlock(&mibqp->disable_page_faults_lock);
}

void mlx5_ib_odp_create_qp(struct mlx5_ib_qp *qp)
{
        int i;

        qp->disable_page_faults = 1;
        spin_lock_init(&qp->disable_page_faults_lock);

        qp->trans_qp.base.mqp.pfault_handler = mlx5_ib_pfault_handler;

        for (i = 0; i < MLX5_IB_PAGEFAULT_CONTEXTS; ++i)
                INIT_WORK(&qp->pagefaults[i].work, mlx5_ib_qp_pfault_action);
}

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

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

        return 0;
}

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

int __init mlx5_ib_odp_init(void)
{
        mlx5_ib_page_fault_wq =
                create_singlethread_workqueue("mlx5_ib_page_faults");
        if (!mlx5_ib_page_fault_wq)
                return -ENOMEM;

        return 0;
}

void mlx5_ib_odp_cleanup(void)
{
        destroy_workqueue(mlx5_ib_page_fault_wq);
}