Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[mirror_ubuntu-focal-kernel.git] / drivers / infiniband / hw / mlx5 / odp.c

/*
 * 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 <linux/kernel.h>

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

#include <linux/mlx5/eq.h>

/* Contains the details of a pagefault. */
struct mlx5_pagefault {
        u32                     bytes_committed;
        u32                     token;
        u8                      event_subtype;
        u8                      type;
        union {
                /* Initiator or send message responder pagefault details. */
                struct {
                        /* Received packet size, only valid for responders. */
                        u32     packet_size;
                        /*
                         * Number of resource holding WQE, depends on type.
                         */
                        u32     wq_num;
                        /*
                         * WQE index. Refers to either the send queue or
                         * receive queue, according to event_subtype.
                         */
                        u16     wqe_index;
                } wqe;
                /* RDMA responder pagefault details */
                struct {
                        u32     r_key;
                        /*
                         * Received packet size, minimal size page fault
                         * resolution required for forward progress.
                         */
                        u32     packet_size;
                        u32     rdma_op_len;
                        u64     rdma_va;
                } rdma;
        };

        struct mlx5_ib_pf_eq    *eq;
        struct work_struct      work;
};

#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_ucontext_per_mm *mr_to_per_mm(struct mlx5_ib_mr *mr)
{
        if (WARN_ON(!mr || !is_odp_mr(mr)))
                return NULL;

        return to_ib_umem_odp(mr->umem)->per_mm;
}

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_per_mm *per_mm = odp->per_mm;
        struct rb_node *rb;

        down_read(&per_mm->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(&per_mm->umem_rwsem);
        return odp;
}

static struct ib_umem_odp *odp_lookup(u64 start, u64 length,
                                      struct mlx5_ib_mr *parent)
{
        struct ib_ucontext_per_mm *per_mm = mr_to_per_mm(parent);
        struct ib_umem_odp *odp;
        struct rb_node *rb;

        down_read(&per_mm->umem_rwsem);
        odp = rbt_ib_umem_lookup(&per_mm->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) > start + length)
                        goto not_found;
        }
not_found:
        odp = NULL;
end:
        up_read(&per_mm->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 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;
        }

        /*
         * The locking here is pretty subtle. Ideally the implicit children
         * list would be protected by the umem_mutex, however that is not
         * possible. Instead this uses a weaker update-then-lock pattern:
         *
         *  srcu_read_lock()
         *    <change children list>
         *    mutex_lock(umem_mutex)
         *     mlx5_ib_update_xlt()
         *    mutex_unlock(umem_mutex)
         *    destroy lkey
         *
         * ie any change the children list must be followed by the locked
         * update_xlt before destroying.
         *
         * The umem_mutex provides the acquire/release semantic needed to make
         * the children list visible to a racing thread. While SRCU is not
         * technically required, using it gives consistent use of the SRCU
         * locking around the children list.
         */
        lockdep_assert_held(&to_ib_umem_odp(mr->umem)->umem_mutex);
        lockdep_assert_held(&mr->dev->mr_srcu);

        odp = odp_lookup(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 && ib_umem_start(odp) == 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) >> MLX5_IMR_MTT_SHIFT;
        struct mlx5_ib_mr *mr = odp->private, *imr = mr->parent;
        struct ib_umem_odp *odp_imr = to_ib_umem_odp(imr->umem);
        int srcu_key;

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

        if (smp_load_acquire(&imr->live)) {
                srcu_key = srcu_read_lock(&mr->dev->mr_srcu);
                mutex_lock(&odp_imr->umem_mutex);
                mlx5_ib_update_xlt(imr, idx, 1, 0,
                                   MLX5_IB_UPD_XLT_INDIRECT |
                                   MLX5_IB_UPD_XLT_ATOMIC);
                mutex_unlock(&odp_imr->umem_mutex);
                srcu_read_unlock(&mr->dev->mr_srcu, srcu_key);
        }
        ib_umem_odp_release(odp);
        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_odp *umem_odp, 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_odp) {
                pr_err("invalidation called on NULL umem or non-ODP umem\n");
                return;
        }

        mr = umem_odp->private;

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

        start = max_t(u64, ib_umem_start(umem_odp), start);
        end = min_t(u64, ib_umem_end(umem_odp), 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.
         */
        mutex_lock(&umem_odp->umem_mutex);
        for (addr = start; addr < end; addr += BIT(umem_odp->page_shift)) {
                idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->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->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_odp, start, end);

        if (unlikely(!umem_odp->npages && mr->parent &&
                     !umem_odp->dying)) {
                WRITE_ONCE(mr->live, 0);
                umem_odp->dying = 1;
                atomic_inc(&mr->parent->num_leaf_free);
                schedule_work(&umem_odp->work);
        }
        mutex_unlock(&umem_odp->umem_mutex);
}

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) ||
            !mlx5_ib_can_use_umr(dev, true))
                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, ud_odp_caps.srq_receive))
                caps->per_transport_caps.ud_odp_caps |= IB_ODP_SUPPORT_SRQ_RECV;

        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_ODP(dev->mdev, rc_odp_caps.srq_receive))
                caps->per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_SRQ_RECV;

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

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

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

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

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

        if (MLX5_CAP_ODP(dev->mdev, xrc_odp_caps.srq_receive))
                caps->per_transport_caps.xrc_odp_caps |= IB_ODP_SUPPORT_SRQ_RECV;

        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) &&
            !MLX5_CAP_GEN(dev->mdev, umr_indirect_mkey_disabled))
                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;
        u32 out[MLX5_ST_SZ_DW(page_fault_resume_out)] = { };
        u32 in[MLX5_ST_SZ_DW(page_fault_resume_in)]   = { };
        int err;

        MLX5_SET(page_fault_resume_in, in, opcode, MLX5_CMD_OP_PAGE_FAULT_RESUME);
        MLX5_SET(page_fault_resume_in, in, page_fault_type, pfault->type);
        MLX5_SET(page_fault_resume_in, in, token, pfault->token);
        MLX5_SET(page_fault_resume_in, in, wq_number, wq_num);
        MLX5_SET(page_fault_resume_in, in, error, !!error);

        err = mlx5_cmd_exec(dev->mdev, in, sizeof(in), out, sizeof(out));
        if (err)
                mlx5_ib_err(dev, "Failed to resolve the page fault on WQ 0x%x err %d\n",
                            wq_num, err);
}

static struct mlx5_ib_mr *implicit_mr_alloc(struct ib_pd *pd,
                                            struct ib_umem_odp *umem_odp,
                                            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_odp->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;

        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 mlx5_ib_dev *dev = to_mdev(mr->ibmr.pd->device);
        struct ib_umem_odp *odp, *result = NULL;
        struct ib_umem_odp *odp_mr = to_ib_umem_odp(mr->umem);
        u64 addr = io_virt & MLX5_IMR_MTT_MASK;
        int nentries = 0, start_idx = 0, ret;
        struct mlx5_ib_mr *mtt;

        mutex_lock(&odp_mr->umem_mutex);
        odp = odp_lookup(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 {
                odp = ib_umem_odp_alloc_child(odp_mr, addr, MLX5_IMR_MTT_SIZE);
                if (IS_ERR(odp)) {
                        mutex_unlock(&odp_mr->umem_mutex);
                        return ERR_CAST(odp);
                }

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

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

                smp_store_release(&mtt->live, 1);

                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 && ib_umem_start(odp) != 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(&odp_mr->umem_mutex);
        return result;
}

struct mlx5_ib_mr *mlx5_ib_alloc_implicit_mr(struct mlx5_ib_pd *pd,
                                             struct ib_udata *udata,
                                             int access_flags)
{
        struct mlx5_ib_mr *imr;
        struct ib_umem_odp *umem_odp;

        umem_odp = ib_umem_odp_alloc_implicit(udata, access_flags);
        if (IS_ERR(umem_odp))
                return ERR_CAST(umem_odp);

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

        imr->umem = &umem_odp->umem;
        init_waitqueue_head(&imr->q_leaf_free);
        atomic_set(&imr->num_leaf_free, 0);
        atomic_set(&imr->num_pending_prefetch, 0);
        smp_store_release(&imr->live, 1);

        return imr;
}

void mlx5_ib_free_implicit_mr(struct mlx5_ib_mr *imr)
{
        struct ib_ucontext_per_mm *per_mm = mr_to_per_mm(imr);
        struct rb_node *node;

        down_read(&per_mm->umem_rwsem);
        for (node = rb_first_cached(&per_mm->umem_tree); node;
             node = rb_next(node)) {
                struct ib_umem_odp *umem_odp =
                        rb_entry(node, struct ib_umem_odp, interval_tree.rb);
                struct mlx5_ib_mr *mr = umem_odp->private;

                if (mr->parent != imr)
                        continue;

                mutex_lock(&umem_odp->umem_mutex);
                ib_umem_odp_unmap_dma_pages(umem_odp, ib_umem_start(umem_odp),
                                            ib_umem_end(umem_odp));

                if (umem_odp->dying) {
                        mutex_unlock(&umem_odp->umem_mutex);
                        continue;
                }

                umem_odp->dying = 1;
                atomic_inc(&imr->num_leaf_free);
                schedule_work(&umem_odp->work);
                mutex_unlock(&umem_odp->umem_mutex);
        }
        up_read(&per_mm->umem_rwsem);

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

#define MLX5_PF_FLAGS_PREFETCH  BIT(0)
#define MLX5_PF_FLAGS_DOWNGRADE BIT(1)
static int pagefault_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr,
                        u64 io_virt, size_t bcnt, u32 *bytes_mapped,
                        u32 flags)
{
        int npages = 0, current_seq, page_shift, ret, np;
        struct ib_umem_odp *odp_mr = to_ib_umem_odp(mr->umem);
        bool downgrade = flags & MLX5_PF_FLAGS_DOWNGRADE;
        bool prefetch = flags & MLX5_PF_FLAGS_PREFETCH;
        u64 access_mask;
        u64 start_idx, page_mask;
        struct ib_umem_odp *odp;
        size_t size;

        if (odp_mr->is_implicit_odp) {
                odp = implicit_mr_get_data(mr, io_virt, bcnt);

                if (IS_ERR(odp))
                        return PTR_ERR(odp);
                mr = odp->private;
        } else {
                odp = odp_mr;
        }

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

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

        if (prefetch && !downgrade && !odp->umem.writable) {
                /* prefetch with write-access must
                 * be supported by the MR
                 */
                ret = -EINVAL;
                goto out;
        }

        if (odp->umem.writable && !downgrade)
                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(odp, 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(odp, 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 || ib_umem_start(next) != 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) {
                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. notifiers_count=%d\n",
                                current_seq, odp->notifiers_seq,
                                odp->notifiers_count);
                }
        }

        return ret;
}

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

static bool mkey_is_eq(struct mlx5_core_mkey *mmkey, u32 key)
{
        if (!mmkey)
                return false;
        if (mmkey->type == MLX5_MKEY_MW)
                return mlx5_base_mkey(mmkey->key) == mlx5_base_mkey(key);
        return mmkey->key == key;
}

static int get_indirect_num_descs(struct mlx5_core_mkey *mmkey)
{
        struct mlx5_ib_mw *mw;
        struct mlx5_ib_devx_mr *devx_mr;

        if (mmkey->type == MLX5_MKEY_MW) {
                mw = container_of(mmkey, struct mlx5_ib_mw, mmkey);
                return mw->ndescs;
        }

        devx_mr = container_of(mmkey, struct mlx5_ib_devx_mr,
                               mmkey);
        return devx_mr->ndescs;
}

/*
 * 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,
                                         struct ib_pd *pd, u32 key,
                                         u64 io_virt, size_t bcnt,
                                         u32 *bytes_committed,
                                         u32 *bytes_mapped, u32 flags)
{
        int npages = 0, srcu_key, ret, i, outlen, cur_outlen = 0, depth = 0;
        bool prefetch = flags & MLX5_PF_FLAGS_PREFETCH;
        struct pf_frame *head = NULL, *frame;
        struct mlx5_core_mkey *mmkey;
        struct mlx5_ib_mr *mr;
        struct mlx5_klm *pklm;
        u32 *out = NULL;
        size_t offset;
        int ndescs;

        srcu_key = srcu_read_lock(&dev->mr_srcu);

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

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

        if (prefetch && mmkey->type != MLX5_MKEY_MR) {
                mlx5_ib_dbg(dev, "prefetch is allowed only for MR\n");
                ret = -EINVAL;
                goto srcu_unlock;
        }

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

                if (prefetch) {
                        if (!is_odp_mr(mr) ||
                            mr->ibmr.pd != pd) {
                                mlx5_ib_dbg(dev, "Invalid prefetch request: %s\n",
                                            is_odp_mr(mr) ?  "MR is not ODP" :
                                            "PD is not of the MR");
                                ret = -EINVAL;
                                goto srcu_unlock;
                        }
                }

                if (!is_odp_mr(mr)) {
                        mlx5_ib_dbg(dev, "skipping non ODP MR (lkey=0x%06x) in page fault handler.\n",
                                    key);
                        if (bytes_mapped)
                                *bytes_mapped += bcnt;
                        ret = 0;
                        goto srcu_unlock;
                }

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

                npages += ret;
                ret = 0;
                break;

        case MLX5_MKEY_MW:
        case MLX5_MKEY_INDIRECT_DEVX:
                ndescs = get_indirect_num_descs(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) * (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, 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 < 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;
                        offset = 0;
                }
                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.
 *
 * @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,
                                   void *wqe,
                                   void *wqe_end, u32 *bytes_mapped,
                                   u32 *total_wqe_bytes, bool receive_queue)
{
        int ret = 0, npages = 0;
        u64 io_virt;
        u32 key;
        u32 byte_count;
        size_t bcnt;
        int inline_segment;

        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, NULL, key,
                                                    io_virt, bcnt,
                                                    &pfault->bytes_committed,
                                                    bytes_mapped, 0);
                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_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;
        struct mlx5_base_av *av;
        unsigned ds, opcode;
        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;
        }

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

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

        if (qp->ibqp.qp_type == IB_QPT_XRC_INI)
                *wqe += sizeof(struct mlx5_wqe_xrc_seg);

        if (qp->ibqp.qp_type == IB_QPT_UD ||
            qp->qp_sub_type == MLX5_IB_QPT_DCI) {
                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 and set wqe_end to the end of the WQE.
 */
static int mlx5_ib_mr_responder_pfault_handler_srq(struct mlx5_ib_dev *dev,
                                                   struct mlx5_ib_srq *srq,
                                                   void **wqe, void **wqe_end,
                                                   int wqe_length)
{
        int wqe_size = 1 << srq->msrq.wqe_shift;

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

        *wqe_end = *wqe + wqe_size;
        *wqe += sizeof(struct mlx5_wqe_srq_next_seg);

        return 0;
}

static int mlx5_ib_mr_responder_pfault_handler_rq(struct mlx5_ib_dev *dev,
                                                  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->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;
        }

        *wqe_end = wqe + wqe_size;

        return 0;
}

static inline struct mlx5_core_rsc_common *odp_get_rsc(struct mlx5_ib_dev *dev,
                                                       u32 wq_num, int pf_type)
{
        struct mlx5_core_rsc_common *common = NULL;
        struct mlx5_core_srq *srq;

        switch (pf_type) {
        case MLX5_WQE_PF_TYPE_RMP:
                srq = mlx5_cmd_get_srq(dev, wq_num);
                if (srq)
                        common = &srq->common;
                break;
        case MLX5_WQE_PF_TYPE_REQ_SEND_OR_WRITE:
        case MLX5_WQE_PF_TYPE_RESP:
        case MLX5_WQE_PF_TYPE_REQ_READ_OR_ATOMIC:
                common = mlx5_core_res_hold(dev->mdev, wq_num, MLX5_RES_QP);
                break;
        default:
                break;
        }

        return common;
}

static inline struct mlx5_ib_qp *res_to_qp(struct mlx5_core_rsc_common *res)
{
        struct mlx5_core_qp *mqp = (struct mlx5_core_qp *)res;

        return to_mibqp(mqp);
}

static inline struct mlx5_ib_srq *res_to_srq(struct mlx5_core_rsc_common *res)
{
        struct mlx5_core_srq *msrq =
                container_of(res, struct mlx5_core_srq, common);

        return to_mibsrq(msrq);
}

static void mlx5_ib_mr_wqe_pfault_handler(struct mlx5_ib_dev *dev,
                                          struct mlx5_pagefault *pfault)
{
        bool sq = pfault->type & MLX5_PFAULT_REQUESTOR;
        u16 wqe_index = pfault->wqe.wqe_index;
        void *wqe, *wqe_start = NULL, *wqe_end = NULL;
        u32 bytes_mapped, total_wqe_bytes;
        struct mlx5_core_rsc_common *res;
        int resume_with_error = 1;
        struct mlx5_ib_qp *qp;
        size_t bytes_copied;
        int ret = 0;

        res = odp_get_rsc(dev, pfault->wqe.wq_num, pfault->type);
        if (!res) {
                mlx5_ib_dbg(dev, "wqe page fault for missing resource %d\n", pfault->wqe.wq_num);
                return;
        }

        if (res->res != MLX5_RES_QP && res->res != MLX5_RES_SRQ &&
            res->res != MLX5_RES_XSRQ) {
                mlx5_ib_err(dev, "wqe page fault for unsupported type %d\n",
                            pfault->type);
                goto resolve_page_fault;
        }

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

        wqe = wqe_start;
        qp = (res->res == MLX5_RES_QP) ? res_to_qp(res) : NULL;
        if (qp && sq) {
                ret = mlx5_ib_read_user_wqe_sq(qp, wqe_index, wqe, PAGE_SIZE,
                                               &bytes_copied);
                if (ret)
                        goto read_user;
                ret = mlx5_ib_mr_initiator_pfault_handler(
                        dev, pfault, qp, &wqe, &wqe_end, bytes_copied);
        } else if (qp && !sq) {
                ret = mlx5_ib_read_user_wqe_rq(qp, wqe_index, wqe, PAGE_SIZE,
                                               &bytes_copied);
                if (ret)
                        goto read_user;
                ret = mlx5_ib_mr_responder_pfault_handler_rq(
                        dev, qp, wqe, &wqe_end, bytes_copied);
        } else if (!qp) {
                struct mlx5_ib_srq *srq = res_to_srq(res);

                ret = mlx5_ib_read_user_wqe_srq(srq, wqe_index, wqe, PAGE_SIZE,
                                                &bytes_copied);
                if (ret)
                        goto read_user;
                ret = mlx5_ib_mr_responder_pfault_handler_srq(
                        dev, srq, &wqe, &wqe_end, bytes_copied);
        }

        if (ret < 0 || wqe >= wqe_end)
                goto resolve_page_fault;

        ret = pagefault_data_segments(dev, pfault, wqe, wqe_end, &bytes_mapped,
                                      &total_wqe_bytes, !sq);
        if (ret == -EAGAIN)
                goto out;

        if (ret < 0 || total_wqe_bytes > bytes_mapped)
                goto resolve_page_fault;

out:
        ret = 0;
        resume_with_error = 0;

read_user:
        if (ret)
                mlx5_ib_err(
                        dev,
                        "Failed reading a WQE following page fault, error %d, wqe_index %x, qpn %x\n",
                        ret, wqe_index, pfault->token);

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);
        mlx5_core_res_put(res);
        free_page((unsigned long)wqe_start);
}

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, NULL, rkey, address, length,
                                            &pfault->bytes_committed, NULL,
                                            0);
        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, NULL, rkey, address,
                                                    prefetch_len,
                                                    &bytes_committed, NULL,
                                                    0);
                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);
                }
        }
}

static void mlx5_ib_pfault(struct mlx5_ib_dev *dev, struct mlx5_pagefault *pfault)
{
        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);
        }
}

static void mlx5_ib_eqe_pf_action(struct work_struct *work)
{
        struct mlx5_pagefault *pfault = container_of(work,
                                                     struct mlx5_pagefault,
                                                     work);
        struct mlx5_ib_pf_eq *eq = pfault->eq;

        mlx5_ib_pfault(eq->dev, pfault);
        mempool_free(pfault, eq->pool);
}

static void mlx5_ib_eq_pf_process(struct mlx5_ib_pf_eq *eq)
{
        struct mlx5_eqe_page_fault *pf_eqe;
        struct mlx5_pagefault *pfault;
        struct mlx5_eqe *eqe;
        int cc = 0;

        while ((eqe = mlx5_eq_get_eqe(eq->core, cc))) {
                pfault = mempool_alloc(eq->pool, GFP_ATOMIC);
                if (!pfault) {
                        schedule_work(&eq->work);
                        break;
                }

                pf_eqe = &eqe->data.page_fault;
                pfault->event_subtype = eqe->sub_type;
                pfault->bytes_committed = be32_to_cpu(pf_eqe->bytes_committed);

                mlx5_ib_dbg(eq->dev,
                            "PAGE_FAULT: subtype: 0x%02x, bytes_committed: 0x%06x\n",
                            eqe->sub_type, pfault->bytes_committed);

                switch (eqe->sub_type) {
                case MLX5_PFAULT_SUBTYPE_RDMA:
                        /* RDMA based event */
                        pfault->type =
                                be32_to_cpu(pf_eqe->rdma.pftype_token) >> 24;
                        pfault->token =
                                be32_to_cpu(pf_eqe->rdma.pftype_token) &
                                MLX5_24BIT_MASK;
                        pfault->rdma.r_key =
                                be32_to_cpu(pf_eqe->rdma.r_key);
                        pfault->rdma.packet_size =
                                be16_to_cpu(pf_eqe->rdma.packet_length);
                        pfault->rdma.rdma_op_len =
                                be32_to_cpu(pf_eqe->rdma.rdma_op_len);
                        pfault->rdma.rdma_va =
                                be64_to_cpu(pf_eqe->rdma.rdma_va);
                        mlx5_ib_dbg(eq->dev,
                                    "PAGE_FAULT: type:0x%x, token: 0x%06x, r_key: 0x%08x\n",
                                    pfault->type, pfault->token,
                                    pfault->rdma.r_key);
                        mlx5_ib_dbg(eq->dev,
                                    "PAGE_FAULT: rdma_op_len: 0x%08x, rdma_va: 0x%016llx\n",
                                    pfault->rdma.rdma_op_len,
                                    pfault->rdma.rdma_va);
                        break;

                case MLX5_PFAULT_SUBTYPE_WQE:
                        /* WQE based event */
                        pfault->type =
                                (be32_to_cpu(pf_eqe->wqe.pftype_wq) >> 24) & 0x7;
                        pfault->token =
                                be32_to_cpu(pf_eqe->wqe.token);
                        pfault->wqe.wq_num =
                                be32_to_cpu(pf_eqe->wqe.pftype_wq) &
                                MLX5_24BIT_MASK;
                        pfault->wqe.wqe_index =
                                be16_to_cpu(pf_eqe->wqe.wqe_index);
                        pfault->wqe.packet_size =
                                be16_to_cpu(pf_eqe->wqe.packet_length);
                        mlx5_ib_dbg(eq->dev,
                                    "PAGE_FAULT: type:0x%x, token: 0x%06x, wq_num: 0x%06x, wqe_index: 0x%04x\n",
                                    pfault->type, pfault->token,
                                    pfault->wqe.wq_num,
                                    pfault->wqe.wqe_index);
                        break;

                default:
                        mlx5_ib_warn(eq->dev,
                                     "Unsupported page fault event sub-type: 0x%02hhx\n",
                                     eqe->sub_type);
                        /* Unsupported page faults should still be
                         * resolved by the page fault handler
                         */
                }

                pfault->eq = eq;
                INIT_WORK(&pfault->work, mlx5_ib_eqe_pf_action);
                queue_work(eq->wq, &pfault->work);

                cc = mlx5_eq_update_cc(eq->core, ++cc);
        }

        mlx5_eq_update_ci(eq->core, cc, 1);
}

static int mlx5_ib_eq_pf_int(struct notifier_block *nb, unsigned long type,
                             void *data)
{
        struct mlx5_ib_pf_eq *eq =
                container_of(nb, struct mlx5_ib_pf_eq, irq_nb);
        unsigned long flags;

        if (spin_trylock_irqsave(&eq->lock, flags)) {
                mlx5_ib_eq_pf_process(eq);
                spin_unlock_irqrestore(&eq->lock, flags);
        } else {
                schedule_work(&eq->work);
        }

        return IRQ_HANDLED;
}

/* mempool_refill() was proposed but unfortunately wasn't accepted
 * http://lkml.iu.edu/hypermail/linux/kernel/1512.1/05073.html
 * Cheap workaround.
 */
static void mempool_refill(mempool_t *pool)
{
        while (pool->curr_nr < pool->min_nr)
                mempool_free(mempool_alloc(pool, GFP_KERNEL), pool);
}

static void mlx5_ib_eq_pf_action(struct work_struct *work)
{
        struct mlx5_ib_pf_eq *eq =
                container_of(work, struct mlx5_ib_pf_eq, work);

        mempool_refill(eq->pool);

        spin_lock_irq(&eq->lock);
        mlx5_ib_eq_pf_process(eq);
        spin_unlock_irq(&eq->lock);
}

enum {
        MLX5_IB_NUM_PF_EQE      = 0x1000,
        MLX5_IB_NUM_PF_DRAIN    = 64,
};

static int
mlx5_ib_create_pf_eq(struct mlx5_ib_dev *dev, struct mlx5_ib_pf_eq *eq)
{
        struct mlx5_eq_param param = {};
        int err;

        INIT_WORK(&eq->work, mlx5_ib_eq_pf_action);
        spin_lock_init(&eq->lock);
        eq->dev = dev;

        eq->pool = mempool_create_kmalloc_pool(MLX5_IB_NUM_PF_DRAIN,
                                               sizeof(struct mlx5_pagefault));
        if (!eq->pool)
                return -ENOMEM;

        eq->wq = alloc_workqueue("mlx5_ib_page_fault",
                                 WQ_HIGHPRI | WQ_UNBOUND | WQ_MEM_RECLAIM,
                                 MLX5_NUM_CMD_EQE);
        if (!eq->wq) {
                err = -ENOMEM;
                goto err_mempool;
        }

        eq->irq_nb.notifier_call = mlx5_ib_eq_pf_int;
        param = (struct mlx5_eq_param) {
                .irq_index = 0,
                .nent = MLX5_IB_NUM_PF_EQE,
        };
        param.mask[0] = 1ull << MLX5_EVENT_TYPE_PAGE_FAULT;
        eq->core = mlx5_eq_create_generic(dev->mdev, &param);
        if (IS_ERR(eq->core)) {
                err = PTR_ERR(eq->core);
                goto err_wq;
        }
        err = mlx5_eq_enable(dev->mdev, eq->core, &eq->irq_nb);
        if (err) {
                mlx5_ib_err(dev, "failed to enable odp EQ %d\n", err);
                goto err_eq;
        }

        return 0;
err_eq:
        mlx5_eq_destroy_generic(dev->mdev, eq->core);
err_wq:
        destroy_workqueue(eq->wq);
err_mempool:
        mempool_destroy(eq->pool);
        return err;
}

static int
mlx5_ib_destroy_pf_eq(struct mlx5_ib_dev *dev, struct mlx5_ib_pf_eq *eq)
{
        int err;

        mlx5_eq_disable(dev->mdev, eq->core, &eq->irq_nb);
        err = mlx5_eq_destroy_generic(dev->mdev, eq->core);
        cancel_work_sync(&eq->work);
        destroy_workqueue(eq->wq);
        mempool_destroy(eq->pool);

        return err;
}

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;
        }
}

static const struct ib_device_ops mlx5_ib_dev_odp_ops = {
        .advise_mr = mlx5_ib_advise_mr,
        .invalidate_range = mlx5_ib_invalidate_range,
};

int mlx5_ib_odp_init_one(struct mlx5_ib_dev *dev)
{
        int ret = 0;

        if (!(dev->odp_caps.general_caps & IB_ODP_SUPPORT))
                return ret;

        ib_set_device_ops(&dev->ib_dev, &mlx5_ib_dev_odp_ops);

        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;
                }
        }

        ret = mlx5_ib_create_pf_eq(dev, &dev->odp_pf_eq);

        return ret;
}

void mlx5_ib_odp_cleanup_one(struct mlx5_ib_dev *dev)
{
        if (!(dev->odp_caps.general_caps & IB_ODP_SUPPORT))
                return;

        mlx5_ib_destroy_pf_eq(dev, &dev->odp_pf_eq);
}

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

        return 0;
}

struct prefetch_mr_work {
        struct work_struct work;
        struct ib_pd *pd;
        u32 pf_flags;
        u32 num_sge;
        struct ib_sge sg_list[0];
};

static void num_pending_prefetch_dec(struct mlx5_ib_dev *dev,
                                     struct ib_sge *sg_list, u32 num_sge,
                                     u32 from)
{
        u32 i;
        int srcu_key;

        srcu_key = srcu_read_lock(&dev->mr_srcu);

        for (i = from; i < num_sge; ++i) {
                struct mlx5_core_mkey *mmkey;
                struct mlx5_ib_mr *mr;

                mmkey = xa_load(&dev->mdev->priv.mkey_table,
                                mlx5_base_mkey(sg_list[i].lkey));
                mr = container_of(mmkey, struct mlx5_ib_mr, mmkey);
                atomic_dec(&mr->num_pending_prefetch);
        }

        srcu_read_unlock(&dev->mr_srcu, srcu_key);
}

static bool num_pending_prefetch_inc(struct ib_pd *pd,
                                     struct ib_sge *sg_list, u32 num_sge)
{
        struct mlx5_ib_dev *dev = to_mdev(pd->device);
        bool ret = true;
        u32 i;

        for (i = 0; i < num_sge; ++i) {
                struct mlx5_core_mkey *mmkey;
                struct mlx5_ib_mr *mr;

                mmkey = xa_load(&dev->mdev->priv.mkey_table,
                                mlx5_base_mkey(sg_list[i].lkey));
                if (!mmkey || mmkey->key != sg_list[i].lkey) {
                        ret = false;
                        break;
                }

                if (mmkey->type != MLX5_MKEY_MR) {
                        ret = false;
                        break;
                }

                mr = container_of(mmkey, struct mlx5_ib_mr, mmkey);

                if (!smp_load_acquire(&mr->live)) {
                        ret = false;
                        break;
                }

                if (mr->ibmr.pd != pd) {
                        ret = false;
                        break;
                }

                atomic_inc(&mr->num_pending_prefetch);
        }

        if (!ret)
                num_pending_prefetch_dec(dev, sg_list, i, 0);

        return ret;
}

static int mlx5_ib_prefetch_sg_list(struct ib_pd *pd, u32 pf_flags,
                                    struct ib_sge *sg_list, u32 num_sge)
{
        u32 i;
        int ret = 0;
        struct mlx5_ib_dev *dev = to_mdev(pd->device);

        for (i = 0; i < num_sge; ++i) {
                struct ib_sge *sg = &sg_list[i];
                int bytes_committed = 0;

                ret = pagefault_single_data_segment(dev, pd, sg->lkey, sg->addr,
                                                    sg->length,
                                                    &bytes_committed, NULL,
                                                    pf_flags);
                if (ret < 0)
                        break;
        }

        return ret < 0 ? ret : 0;
}

static void mlx5_ib_prefetch_mr_work(struct work_struct *work)
{
        struct prefetch_mr_work *w =
                container_of(work, struct prefetch_mr_work, work);

        if (ib_device_try_get(w->pd->device)) {
                mlx5_ib_prefetch_sg_list(w->pd, w->pf_flags, w->sg_list,
                                         w->num_sge);
                ib_device_put(w->pd->device);
        }

        num_pending_prefetch_dec(to_mdev(w->pd->device), w->sg_list,
                                 w->num_sge, 0);
        kvfree(w);
}

int mlx5_ib_advise_mr_prefetch(struct ib_pd *pd,
                               enum ib_uverbs_advise_mr_advice advice,
                               u32 flags, struct ib_sge *sg_list, u32 num_sge)
{
        struct mlx5_ib_dev *dev = to_mdev(pd->device);
        u32 pf_flags = MLX5_PF_FLAGS_PREFETCH;
        struct prefetch_mr_work *work;
        bool valid_req;
        int srcu_key;

        if (advice == IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH)
                pf_flags |= MLX5_PF_FLAGS_DOWNGRADE;

        if (flags & IB_UVERBS_ADVISE_MR_FLAG_FLUSH)
                return mlx5_ib_prefetch_sg_list(pd, pf_flags, sg_list,
                                                num_sge);

        work = kvzalloc(struct_size(work, sg_list, num_sge), GFP_KERNEL);
        if (!work)
                return -ENOMEM;

        memcpy(work->sg_list, sg_list, num_sge * sizeof(struct ib_sge));

        /* It is guaranteed that the pd when work is executed is the pd when
         * work was queued since pd can't be destroyed while it holds MRs and
         * destroying a MR leads to flushing the workquque
         */
        work->pd = pd;
        work->pf_flags = pf_flags;
        work->num_sge = num_sge;

        INIT_WORK(&work->work, mlx5_ib_prefetch_mr_work);

        srcu_key = srcu_read_lock(&dev->mr_srcu);

        valid_req = num_pending_prefetch_inc(pd, sg_list, num_sge);
        if (valid_req)
                queue_work(system_unbound_wq, &work->work);
        else
                kvfree(work);

        srcu_read_unlock(&dev->mr_srcu, srcu_key);

        return valid_req ? 0 : -EINVAL;
}