Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1821 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
new file mode 100644
index 000000000..bc9795881
--- /dev/null
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -0,0 +1,1821 @@
+/*
+ * 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_odp.h>
+#include <linux/kernel.h>
+#include <linux/dma-buf.h>
+#include <linux/dma-resv.h>
+
+#include "mlx5_ib.h"
+#include "cmd.h"
+#include "umr.h"
+#include "qp.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 void populate_klm(struct mlx5_klm *pklm, size_t idx, size_t nentries,
+			struct mlx5_ib_mr *imr, int flags)
+{
+	struct mlx5_klm *end = pklm + nentries;
+
+	if (flags & MLX5_IB_UPD_XLT_ZAP) {
+		for (; pklm != end; pklm++, idx++) {
+			pklm->bcount = cpu_to_be32(MLX5_IMR_MTT_SIZE);
+			pklm->key = cpu_to_be32(mr_to_mdev(imr)->null_mkey);
+			pklm->va = 0;
+		}
+		return;
+	}
+
+	/*
+	 * The locking here is pretty subtle. Ideally the implicit_children
+	 * xarray would be protected by the umem_mutex, however that is not
+	 * possible. Instead this uses a weaker update-then-lock pattern:
+	 *
+	 *    xa_store()
+	 *    mutex_lock(umem_mutex)
+	 *     mlx5r_umr_update_xlt()
+	 *    mutex_unlock(umem_mutex)
+	 *    destroy lkey
+	 *
+	 * ie any change the xarray must be followed by the locked update_xlt
+	 * before destroying.
+	 *
+	 * The umem_mutex provides the acquire/release semantic needed to make
+	 * the xa_store() visible to a racing thread.
+	 */
+	lockdep_assert_held(&to_ib_umem_odp(imr->umem)->umem_mutex);
+
+	for (; pklm != end; pklm++, idx++) {
+		struct mlx5_ib_mr *mtt = xa_load(&imr->implicit_children, idx);
+
+		pklm->bcount = cpu_to_be32(MLX5_IMR_MTT_SIZE);
+		if (mtt) {
+			pklm->key = cpu_to_be32(mtt->ibmr.lkey);
+			pklm->va = cpu_to_be64(idx * MLX5_IMR_MTT_SIZE);
+		} else {
+			pklm->key = cpu_to_be32(mr_to_mdev(imr)->null_mkey);
+			pklm->va = 0;
+		}
+	}
+}
+
+static u64 umem_dma_to_mtt(dma_addr_t umem_dma)
+{
+	u64 mtt_entry = umem_dma & ODP_DMA_ADDR_MASK;
+
+	if (umem_dma & ODP_READ_ALLOWED_BIT)
+		mtt_entry |= MLX5_IB_MTT_READ;
+	if (umem_dma & ODP_WRITE_ALLOWED_BIT)
+		mtt_entry |= MLX5_IB_MTT_WRITE;
+
+	return mtt_entry;
+}
+
+static void populate_mtt(__be64 *pas, size_t idx, size_t nentries,
+			 struct mlx5_ib_mr *mr, int flags)
+{
+	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+	dma_addr_t pa;
+	size_t i;
+
+	if (flags & MLX5_IB_UPD_XLT_ZAP)
+		return;
+
+	for (i = 0; i < nentries; i++) {
+		pa = odp->dma_list[idx + i];
+		pas[i] = cpu_to_be64(umem_dma_to_mtt(pa));
+	}
+}
+
+void mlx5_odp_populate_xlt(void *xlt, size_t idx, size_t nentries,
+			   struct mlx5_ib_mr *mr, int flags)
+{
+	if (flags & MLX5_IB_UPD_XLT_INDIRECT) {
+		populate_klm(xlt, idx, nentries, mr, flags);
+	} else {
+		populate_mtt(xlt, idx, nentries, mr, flags);
+	}
+}
+
+/*
+ * This must be called after the mr has been removed from implicit_children.
+ * NOTE: The MR does not necessarily have to be
+ * empty here, parallel page faults could have raced with the free process and
+ * added pages to it.
+ */
+static void free_implicit_child_mr_work(struct work_struct *work)
+{
+	struct mlx5_ib_mr *mr =
+		container_of(work, struct mlx5_ib_mr, odp_destroy.work);
+	struct mlx5_ib_mr *imr = mr->parent;
+	struct ib_umem_odp *odp_imr = to_ib_umem_odp(imr->umem);
+	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+
+	mlx5r_deref_wait_odp_mkey(&mr->mmkey);
+
+	mutex_lock(&odp_imr->umem_mutex);
+	mlx5r_umr_update_xlt(mr->parent,
+			     ib_umem_start(odp) >> MLX5_IMR_MTT_SHIFT, 1, 0,
+			     MLX5_IB_UPD_XLT_INDIRECT | MLX5_IB_UPD_XLT_ATOMIC);
+	mutex_unlock(&odp_imr->umem_mutex);
+	mlx5_ib_dereg_mr(&mr->ibmr, NULL);
+
+	mlx5r_deref_odp_mkey(&imr->mmkey);
+}
+
+static void destroy_unused_implicit_child_mr(struct mlx5_ib_mr *mr)
+{
+	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+	unsigned long idx = ib_umem_start(odp) >> MLX5_IMR_MTT_SHIFT;
+	struct mlx5_ib_mr *imr = mr->parent;
+
+	if (!refcount_inc_not_zero(&imr->mmkey.usecount))
+		return;
+
+	xa_erase(&imr->implicit_children, idx);
+
+	/* Freeing a MR is a sleeping operation, so bounce to a work queue */
+	INIT_WORK(&mr->odp_destroy.work, free_implicit_child_mr_work);
+	queue_work(system_unbound_wq, &mr->odp_destroy.work);
+}
+
+static bool mlx5_ib_invalidate_range(struct mmu_interval_notifier *mni,
+				     const struct mmu_notifier_range *range,
+				     unsigned long cur_seq)
+{
+	struct ib_umem_odp *umem_odp =
+		container_of(mni, struct ib_umem_odp, notifier);
+	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;
+	u64 invalidations = 0;
+	unsigned long start;
+	unsigned long end;
+	int in_block = 0;
+	u64 addr;
+
+	if (!mmu_notifier_range_blockable(range))
+		return false;
+
+	mutex_lock(&umem_odp->umem_mutex);
+	mmu_interval_set_seq(mni, cur_seq);
+	/*
+	 * If npages is zero then umem_odp->private may not be setup yet. This
+	 * does not complete until after the first page is mapped for DMA.
+	 */
+	if (!umem_odp->npages)
+		goto out;
+	mr = umem_odp->private;
+
+	start = max_t(u64, ib_umem_start(umem_odp), range->start);
+	end = min_t(u64, ib_umem_end(umem_odp), range->end);
+
+	/*
+	 * Iteration one - zap the HW's MTTs. The notifiers_count ensures that
+	 * while we are doing the invalidation, no page fault will attempt to
+	 * overwrite the same MTTs.  Concurent invalidations might race us,
+	 * but they will write 0s as well, so no difference in the end result.
+	 */
+	for (addr = start; addr < end; addr += BIT(umem_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;
+			}
+
+			/* Count page invalidations */
+			invalidations += idx - blk_start_idx + 1;
+		} else {
+			u64 umr_offset = idx & umr_block_mask;
+
+			if (in_block && umr_offset == 0) {
+				mlx5r_umr_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)
+		mlx5r_umr_update_xlt(mr, blk_start_idx,
+				     idx - blk_start_idx + 1, 0,
+				     MLX5_IB_UPD_XLT_ZAP |
+				     MLX5_IB_UPD_XLT_ATOMIC);
+
+	mlx5_update_odp_stats(mr, invalidations, invalidations);
+
+	/*
+	 * 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))
+		destroy_unused_implicit_child_mr(mr);
+out:
+	mutex_unlock(&umem_odp->umem_mutex);
+	return true;
+}
+
+const struct mmu_interval_notifier_ops mlx5_mn_ops = {
+	.invalidate = mlx5_ib_invalidate_range,
+};
+
+static void 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) || !mlx5r_umr_can_load_pas(dev, 0))
+		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;
+}
+
+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 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_in(dev->mdev, page_fault_resume, in);
+	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_get_child_mr(struct mlx5_ib_mr *imr,
+						unsigned long idx)
+{
+	struct mlx5_ib_dev *dev = mr_to_mdev(imr);
+	struct ib_umem_odp *odp;
+	struct mlx5_ib_mr *mr;
+	struct mlx5_ib_mr *ret;
+	int err;
+
+	odp = ib_umem_odp_alloc_child(to_ib_umem_odp(imr->umem),
+				      idx * MLX5_IMR_MTT_SIZE,
+				      MLX5_IMR_MTT_SIZE, &mlx5_mn_ops);
+	if (IS_ERR(odp))
+		return ERR_CAST(odp);
+
+	mr = mlx5_mr_cache_alloc(dev, &dev->cache.ent[MLX5_IMR_MTT_CACHE_ENTRY],
+				 imr->access_flags);
+	if (IS_ERR(mr)) {
+		ib_umem_odp_release(odp);
+		return mr;
+	}
+
+	mr->access_flags = imr->access_flags;
+	mr->ibmr.pd = imr->ibmr.pd;
+	mr->ibmr.device = &mr_to_mdev(imr)->ib_dev;
+	mr->umem = &odp->umem;
+	mr->ibmr.lkey = mr->mmkey.key;
+	mr->ibmr.rkey = mr->mmkey.key;
+	mr->ibmr.iova = idx * MLX5_IMR_MTT_SIZE;
+	mr->parent = imr;
+	odp->private = mr;
+
+	/*
+	 * First refcount is owned by the xarray and second refconut
+	 * is returned to the caller.
+	 */
+	refcount_set(&mr->mmkey.usecount, 2);
+
+	err = mlx5r_umr_update_xlt(mr, 0,
+				   MLX5_IMR_MTT_ENTRIES,
+				   PAGE_SHIFT,
+				   MLX5_IB_UPD_XLT_ZAP |
+				   MLX5_IB_UPD_XLT_ENABLE);
+	if (err) {
+		ret = ERR_PTR(err);
+		goto out_mr;
+	}
+
+	xa_lock(&imr->implicit_children);
+	ret = __xa_cmpxchg(&imr->implicit_children, idx, NULL, mr,
+			   GFP_KERNEL);
+	if (unlikely(ret)) {
+		if (xa_is_err(ret)) {
+			ret = ERR_PTR(xa_err(ret));
+			goto out_lock;
+		}
+		/*
+		 * Another thread beat us to creating the child mr, use
+		 * theirs.
+		 */
+		refcount_inc(&ret->mmkey.usecount);
+		goto out_lock;
+	}
+	xa_unlock(&imr->implicit_children);
+
+	mlx5_ib_dbg(mr_to_mdev(imr), "key %x mr %p\n", mr->mmkey.key, mr);
+	return mr;
+
+out_lock:
+	xa_unlock(&imr->implicit_children);
+out_mr:
+	mlx5_ib_dereg_mr(&mr->ibmr, NULL);
+	return ret;
+}
+
+struct mlx5_ib_mr *mlx5_ib_alloc_implicit_mr(struct mlx5_ib_pd *pd,
+					     int access_flags)
+{
+	struct mlx5_ib_dev *dev = to_mdev(pd->ibpd.device);
+	struct ib_umem_odp *umem_odp;
+	struct mlx5_ib_mr *imr;
+	int err;
+
+	if (!mlx5r_umr_can_load_pas(dev, MLX5_IMR_MTT_ENTRIES * PAGE_SIZE))
+		return ERR_PTR(-EOPNOTSUPP);
+
+	umem_odp = ib_umem_odp_alloc_implicit(&dev->ib_dev, access_flags);
+	if (IS_ERR(umem_odp))
+		return ERR_CAST(umem_odp);
+
+	imr = mlx5_mr_cache_alloc(dev,
+				  &dev->cache.ent[MLX5_IMR_KSM_CACHE_ENTRY],
+				  access_flags);
+	if (IS_ERR(imr)) {
+		ib_umem_odp_release(umem_odp);
+		return imr;
+	}
+
+	imr->access_flags = access_flags;
+	imr->ibmr.pd = &pd->ibpd;
+	imr->ibmr.iova = 0;
+	imr->umem = &umem_odp->umem;
+	imr->ibmr.lkey = imr->mmkey.key;
+	imr->ibmr.rkey = imr->mmkey.key;
+	imr->ibmr.device = &dev->ib_dev;
+	imr->is_odp_implicit = true;
+	xa_init(&imr->implicit_children);
+
+	err = mlx5r_umr_update_xlt(imr, 0,
+				   mlx5_imr_ksm_entries,
+				   MLX5_KSM_PAGE_SHIFT,
+				   MLX5_IB_UPD_XLT_INDIRECT |
+				   MLX5_IB_UPD_XLT_ZAP |
+				   MLX5_IB_UPD_XLT_ENABLE);
+	if (err)
+		goto out_mr;
+
+	err = mlx5r_store_odp_mkey(dev, &imr->mmkey);
+	if (err)
+		goto out_mr;
+
+	mlx5_ib_dbg(dev, "key %x mr %p\n", imr->mmkey.key, imr);
+	return imr;
+out_mr:
+	mlx5_ib_err(dev, "Failed to register MKEY %d\n", err);
+	mlx5_ib_dereg_mr(&imr->ibmr, NULL);
+	return ERR_PTR(err);
+}
+
+void mlx5_ib_free_odp_mr(struct mlx5_ib_mr *mr)
+{
+	struct mlx5_ib_mr *mtt;
+	unsigned long idx;
+
+	/*
+	 * If this is an implicit MR it is already invalidated so we can just
+	 * delete the children mkeys.
+	 */
+	xa_for_each(&mr->implicit_children, idx, mtt) {
+		xa_erase(&mr->implicit_children, idx);
+		mlx5_ib_dereg_mr(&mtt->ibmr, NULL);
+	}
+}
+
+#define MLX5_PF_FLAGS_DOWNGRADE BIT(1)
+#define MLX5_PF_FLAGS_SNAPSHOT BIT(2)
+#define MLX5_PF_FLAGS_ENABLE BIT(3)
+static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
+			     u64 user_va, size_t bcnt, u32 *bytes_mapped,
+			     u32 flags)
+{
+	int page_shift, ret, np;
+	bool downgrade = flags & MLX5_PF_FLAGS_DOWNGRADE;
+	u64 access_mask;
+	u64 start_idx;
+	bool fault = !(flags & MLX5_PF_FLAGS_SNAPSHOT);
+	u32 xlt_flags = MLX5_IB_UPD_XLT_ATOMIC;
+
+	if (flags & MLX5_PF_FLAGS_ENABLE)
+		xlt_flags |= MLX5_IB_UPD_XLT_ENABLE;
+
+	page_shift = odp->page_shift;
+	start_idx = (user_va - ib_umem_start(odp)) >> page_shift;
+	access_mask = ODP_READ_ALLOWED_BIT;
+
+	if (odp->umem.writable && !downgrade)
+		access_mask |= ODP_WRITE_ALLOWED_BIT;
+
+	np = ib_umem_odp_map_dma_and_lock(odp, user_va, bcnt, access_mask, fault);
+	if (np < 0)
+		return np;
+
+	/*
+	 * No need to check whether the MTTs really belong to this MR, since
+	 * ib_umem_odp_map_dma_and_lock already checks this.
+	 */
+	ret = mlx5r_umr_update_xlt(mr, start_idx, np, page_shift, xlt_flags);
+	mutex_unlock(&odp->umem_mutex);
+
+	if (ret < 0) {
+		if (ret != -EAGAIN)
+			mlx5_ib_err(mr_to_mdev(mr),
+				    "Failed to update mkey page tables\n");
+		goto out;
+	}
+
+	if (bytes_mapped) {
+		u32 new_mappings = (np << page_shift) -
+			(user_va - round_down(user_va, 1 << page_shift));
+
+		*bytes_mapped += min_t(u32, new_mappings, bcnt);
+	}
+
+	return np << (page_shift - PAGE_SHIFT);
+
+out:
+	return ret;
+}
+
+static int pagefault_implicit_mr(struct mlx5_ib_mr *imr,
+				 struct ib_umem_odp *odp_imr, u64 user_va,
+				 size_t bcnt, u32 *bytes_mapped, u32 flags)
+{
+	unsigned long end_idx = (user_va + bcnt - 1) >> MLX5_IMR_MTT_SHIFT;
+	unsigned long upd_start_idx = end_idx + 1;
+	unsigned long upd_len = 0;
+	unsigned long npages = 0;
+	int err;
+	int ret;
+
+	if (unlikely(user_va >= mlx5_imr_ksm_entries * MLX5_IMR_MTT_SIZE ||
+		     mlx5_imr_ksm_entries * MLX5_IMR_MTT_SIZE - user_va < bcnt))
+		return -EFAULT;
+
+	/* Fault each child mr that intersects with our interval. */
+	while (bcnt) {
+		unsigned long idx = user_va >> MLX5_IMR_MTT_SHIFT;
+		struct ib_umem_odp *umem_odp;
+		struct mlx5_ib_mr *mtt;
+		u64 len;
+
+		xa_lock(&imr->implicit_children);
+		mtt = xa_load(&imr->implicit_children, idx);
+		if (unlikely(!mtt)) {
+			xa_unlock(&imr->implicit_children);
+			mtt = implicit_get_child_mr(imr, idx);
+			if (IS_ERR(mtt)) {
+				ret = PTR_ERR(mtt);
+				goto out;
+			}
+			upd_start_idx = min(upd_start_idx, idx);
+			upd_len = idx - upd_start_idx + 1;
+		} else {
+			refcount_inc(&mtt->mmkey.usecount);
+			xa_unlock(&imr->implicit_children);
+		}
+
+		umem_odp = to_ib_umem_odp(mtt->umem);
+		len = min_t(u64, user_va + bcnt, ib_umem_end(umem_odp)) -
+		      user_va;
+
+		ret = pagefault_real_mr(mtt, umem_odp, user_va, len,
+					bytes_mapped, flags);
+
+		mlx5r_deref_odp_mkey(&mtt->mmkey);
+
+		if (ret < 0)
+			goto out;
+		user_va += len;
+		bcnt -= len;
+		npages += ret;
+	}
+
+	ret = npages;
+
+	/*
+	 * Any time the implicit_children are changed we must perform an
+	 * update of the xlt before exiting to ensure the HW and the
+	 * implicit_children remains synchronized.
+	 */
+out:
+	if (likely(!upd_len))
+		return ret;
+
+	/*
+	 * Notice this is not strictly ordered right, the KSM is updated after
+	 * the implicit_children is updated, so a parallel page fault could
+	 * see a MR that is not yet visible in the KSM.  This is similar to a
+	 * parallel page fault seeing a MR that is being concurrently removed
+	 * from the KSM. Both of these improbable situations are resolved
+	 * safely by resuming the HW and then taking another page fault. The
+	 * next pagefault handler will see the new information.
+	 */
+	mutex_lock(&odp_imr->umem_mutex);
+	err = mlx5r_umr_update_xlt(imr, upd_start_idx, upd_len, 0,
+				   MLX5_IB_UPD_XLT_INDIRECT |
+					  MLX5_IB_UPD_XLT_ATOMIC);
+	mutex_unlock(&odp_imr->umem_mutex);
+	if (err) {
+		mlx5_ib_err(mr_to_mdev(imr), "Failed to update PAS\n");
+		return err;
+	}
+	return ret;
+}
+
+static int pagefault_dmabuf_mr(struct mlx5_ib_mr *mr, size_t bcnt,
+			       u32 *bytes_mapped, u32 flags)
+{
+	struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(mr->umem);
+	u32 xlt_flags = 0;
+	int err;
+	unsigned int page_size;
+
+	if (flags & MLX5_PF_FLAGS_ENABLE)
+		xlt_flags |= MLX5_IB_UPD_XLT_ENABLE;
+
+	dma_resv_lock(umem_dmabuf->attach->dmabuf->resv, NULL);
+	err = ib_umem_dmabuf_map_pages(umem_dmabuf);
+	if (err) {
+		dma_resv_unlock(umem_dmabuf->attach->dmabuf->resv);
+		return err;
+	}
+
+	page_size = mlx5_umem_find_best_pgsz(&umem_dmabuf->umem, mkc,
+					     log_page_size, 0,
+					     umem_dmabuf->umem.iova);
+	if (unlikely(page_size < PAGE_SIZE)) {
+		ib_umem_dmabuf_unmap_pages(umem_dmabuf);
+		err = -EINVAL;
+	} else {
+		err = mlx5r_umr_update_mr_pas(mr, xlt_flags);
+	}
+	dma_resv_unlock(umem_dmabuf->attach->dmabuf->resv);
+
+	if (err)
+		return err;
+
+	if (bytes_mapped)
+		*bytes_mapped += bcnt;
+
+	return ib_umem_num_pages(mr->umem);
+}
+
+/*
+ * Returns:
+ *  -EFAULT: The io_virt->bcnt is not within the MR, it covers pages that are
+ *           not accessible, or the MR is no longer valid.
+ *  -EAGAIN/-ENOMEM: The operation should be retried
+ *
+ *  -EINVAL/others: General internal malfunction
+ *  >0: Number of pages mapped
+ */
+static int pagefault_mr(struct mlx5_ib_mr *mr, u64 io_virt, size_t bcnt,
+			u32 *bytes_mapped, u32 flags)
+{
+	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+
+	if (unlikely(io_virt < mr->ibmr.iova))
+		return -EFAULT;
+
+	if (mr->umem->is_dmabuf)
+		return pagefault_dmabuf_mr(mr, bcnt, bytes_mapped, flags);
+
+	if (!odp->is_implicit_odp) {
+		u64 user_va;
+
+		if (check_add_overflow(io_virt - mr->ibmr.iova,
+				       (u64)odp->umem.address, &user_va))
+			return -EFAULT;
+		if (unlikely(user_va >= ib_umem_end(odp) ||
+			     ib_umem_end(odp) - user_va < bcnt))
+			return -EFAULT;
+		return pagefault_real_mr(mr, odp, user_va, bcnt, bytes_mapped,
+					 flags);
+	}
+	return pagefault_implicit_mr(mr, odp, io_virt, bcnt, bytes_mapped,
+				     flags);
+}
+
+int mlx5_ib_init_odp_mr(struct mlx5_ib_mr *mr)
+{
+	int ret;
+
+	ret = pagefault_real_mr(mr, to_ib_umem_odp(mr->umem), mr->umem->address,
+				mr->umem->length, NULL,
+				MLX5_PF_FLAGS_SNAPSHOT | MLX5_PF_FLAGS_ENABLE);
+	return ret >= 0 ? 0 : ret;
+}
+
+int mlx5_ib_init_dmabuf_mr(struct mlx5_ib_mr *mr)
+{
+	int ret;
+
+	ret = pagefault_dmabuf_mr(mr, mr->umem->length, NULL,
+				  MLX5_PF_FLAGS_ENABLE);
+
+	return ret >= 0 ? 0 : 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_ib_mkey *mmkey, u32 key)
+{
+	if (!mmkey)
+		return false;
+	if (mmkey->type == MLX5_MKEY_MW ||
+	    mmkey->type == MLX5_MKEY_INDIRECT_DEVX)
+		return mlx5_base_mkey(mmkey->key) == mlx5_base_mkey(key);
+	return mmkey->key == key;
+}
+
+/*
+ * 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)
+{
+	int npages = 0, ret, i, outlen, cur_outlen = 0, depth = 0;
+	struct pf_frame *head = NULL, *frame;
+	struct mlx5_ib_mkey *mmkey;
+	struct mlx5_ib_mr *mr;
+	struct mlx5_klm *pklm;
+	u32 *out = NULL;
+	size_t offset;
+
+	io_virt += *bytes_committed;
+	bcnt -= *bytes_committed;
+
+next_mr:
+	xa_lock(&dev->odp_mkeys);
+	mmkey = xa_load(&dev->odp_mkeys, mlx5_base_mkey(key));
+	if (!mmkey) {
+		xa_unlock(&dev->odp_mkeys);
+		mlx5_ib_dbg(
+			dev,
+			"skipping non ODP MR (lkey=0x%06x) in page fault handler.\n",
+			key);
+		if (bytes_mapped)
+			*bytes_mapped += bcnt;
+		/*
+		 * The user could specify a SGL with multiple lkeys and only
+		 * some of them are ODP. Treat the non-ODP ones as fully
+		 * faulted.
+		 */
+		ret = 0;
+		goto end;
+	}
+	refcount_inc(&mmkey->usecount);
+	xa_unlock(&dev->odp_mkeys);
+
+	if (!mkey_is_eq(mmkey, key)) {
+		mlx5_ib_dbg(dev, "failed to find mkey %x\n", key);
+		ret = -EFAULT;
+		goto end;
+	}
+
+	switch (mmkey->type) {
+	case MLX5_MKEY_MR:
+		mr = container_of(mmkey, struct mlx5_ib_mr, mmkey);
+
+		ret = pagefault_mr(mr, io_virt, bcnt, bytes_mapped, 0);
+		if (ret < 0)
+			goto end;
+
+		mlx5_update_odp_stats(mr, faults, ret);
+
+		npages += ret;
+		ret = 0;
+		break;
+
+	case MLX5_MKEY_MW:
+	case MLX5_MKEY_INDIRECT_DEVX:
+		if (depth >= MLX5_CAP_GEN(dev->mdev, max_indirection)) {
+			mlx5_ib_dbg(dev, "indirection level exceeded\n");
+			ret = -EFAULT;
+			goto end;
+		}
+
+		outlen = MLX5_ST_SZ_BYTES(query_mkey_out) +
+			sizeof(*pklm) * (mmkey->ndescs - 2);
+
+		if (outlen > cur_outlen) {
+			kfree(out);
+			out = kzalloc(outlen, GFP_KERNEL);
+			if (!out) {
+				ret = -ENOMEM;
+				goto end;
+			}
+			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->key, out, outlen);
+		if (ret)
+			goto end;
+
+		offset = io_virt - MLX5_GET64(query_mkey_out, out,
+					      memory_key_mkey_entry.start_addr);
+
+		for (i = 0; bcnt && i < mmkey->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 end;
+			}
+
+			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 end;
+	}
+
+	if (head) {
+		frame = head;
+		head = frame->next;
+
+		key = frame->key;
+		io_virt = frame->io_virt;
+		bcnt = frame->bcnt;
+		depth = frame->depth;
+		kfree(frame);
+
+		mlx5r_deref_odp_mkey(mmkey);
+		goto next_mr;
+	}
+
+end:
+	if (mmkey)
+		mlx5r_deref_odp_mkey(mmkey);
+	while (head) {
+		frame = head;
+		head = frame->next;
+		kfree(frame);
+	}
+	kfree(out);
+
+	*bytes_committed = 0;
+	return ret ? ret : npages;
+}
+
+/*
+ * Parse a series of data segments for page fault handling.
+ *
+ * @dev:  Pointer to mlx5 IB device
+ * @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).
+ * @receive_queue: receive WQE end of sg list
+ *
+ * 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);
+		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->type == IB_QPT_XRC_INI)
+		*wqe += sizeof(struct mlx5_wqe_xrc_seg);
+
+	if (qp->type == IB_QPT_UD || qp->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->flags_en & MLX5_QP_FLAG_SIGNATURE) {
+		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, 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_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_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_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);
+	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);
+		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,
+};
+
+int mlx5r_odp_create_eq(struct mlx5_ib_dev *dev, struct mlx5_ib_pf_eq *eq)
+{
+	struct mlx5_eq_param param = {};
+	int err = 0;
+
+	mutex_lock(&dev->odp_eq_mutex);
+	if (eq->core)
+		goto unlock;
+	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) {
+		err = -ENOMEM;
+		goto unlock;
+	}
+
+	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) {
+		.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;
+	}
+
+	mutex_unlock(&dev->odp_eq_mutex);
+	return 0;
+err_eq:
+	mlx5_eq_destroy_generic(dev->mdev, eq->core);
+err_wq:
+	eq->core = NULL;
+	destroy_workqueue(eq->wq);
+err_mempool:
+	mempool_destroy(eq->pool);
+unlock:
+	mutex_unlock(&dev->odp_eq_mutex);
+	return err;
+}
+
+static int
+mlx5_ib_odp_destroy_eq(struct mlx5_ib_dev *dev, struct mlx5_ib_pf_eq *eq)
+{
+	int err;
+
+	if (!eq->core)
+		return 0;
+	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_mkey_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->ndescs = MLX5_IMR_MTT_ENTRIES;
+		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->ndescs = mlx5_imr_ksm_entries;
+		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,
+};
+
+int mlx5_ib_odp_init_one(struct mlx5_ib_dev *dev)
+{
+	int ret = 0;
+
+	internal_fill_odp_caps(dev);
+
+	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;
+		}
+	}
+
+	mutex_init(&dev->odp_eq_mutex);
+	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_odp_destroy_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;
+	u32 pf_flags;
+	u32 num_sge;
+	struct {
+		u64 io_virt;
+		struct mlx5_ib_mr *mr;
+		size_t length;
+	} frags[];
+};
+
+static void destroy_prefetch_work(struct prefetch_mr_work *work)
+{
+	u32 i;
+
+	for (i = 0; i < work->num_sge; ++i)
+		mlx5r_deref_odp_mkey(&work->frags[i].mr->mmkey);
+
+	kvfree(work);
+}
+
+static struct mlx5_ib_mr *
+get_prefetchable_mr(struct ib_pd *pd, enum ib_uverbs_advise_mr_advice advice,
+		    u32 lkey)
+{
+	struct mlx5_ib_dev *dev = to_mdev(pd->device);
+	struct mlx5_ib_mr *mr = NULL;
+	struct mlx5_ib_mkey *mmkey;
+
+	xa_lock(&dev->odp_mkeys);
+	mmkey = xa_load(&dev->odp_mkeys, mlx5_base_mkey(lkey));
+	if (!mmkey || mmkey->key != lkey) {
+		mr = ERR_PTR(-ENOENT);
+		goto end;
+	}
+	if (mmkey->type != MLX5_MKEY_MR) {
+		mr = ERR_PTR(-EINVAL);
+		goto end;
+	}
+
+	mr = container_of(mmkey, struct mlx5_ib_mr, mmkey);
+
+	if (mr->ibmr.pd != pd) {
+		mr = ERR_PTR(-EPERM);
+		goto end;
+	}
+
+	/* prefetch with write-access must be supported by the MR */
+	if (advice == IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH_WRITE &&
+	    !mr->umem->writable) {
+		mr = ERR_PTR(-EPERM);
+		goto end;
+	}
+
+	refcount_inc(&mmkey->usecount);
+end:
+	xa_unlock(&dev->odp_mkeys);
+	return mr;
+}
+
+static void mlx5_ib_prefetch_mr_work(struct work_struct *w)
+{
+	struct prefetch_mr_work *work =
+		container_of(w, struct prefetch_mr_work, work);
+	u32 bytes_mapped = 0;
+	int ret;
+	u32 i;
+
+	/* We rely on IB/core that work is executed if we have num_sge != 0 only. */
+	WARN_ON(!work->num_sge);
+	for (i = 0; i < work->num_sge; ++i) {
+		ret = pagefault_mr(work->frags[i].mr, work->frags[i].io_virt,
+				   work->frags[i].length, &bytes_mapped,
+				   work->pf_flags);
+		if (ret <= 0)
+			continue;
+		mlx5_update_odp_stats(work->frags[i].mr, prefetch, ret);
+	}
+
+	destroy_prefetch_work(work);
+}
+
+static int init_prefetch_work(struct ib_pd *pd,
+			       enum ib_uverbs_advise_mr_advice advice,
+			       u32 pf_flags, struct prefetch_mr_work *work,
+			       struct ib_sge *sg_list, u32 num_sge)
+{
+	u32 i;
+
+	INIT_WORK(&work->work, mlx5_ib_prefetch_mr_work);
+	work->pf_flags = pf_flags;
+
+	for (i = 0; i < num_sge; ++i) {
+		struct mlx5_ib_mr *mr;
+
+		mr = get_prefetchable_mr(pd, advice, sg_list[i].lkey);
+		if (IS_ERR(mr)) {
+			work->num_sge = i;
+			return PTR_ERR(mr);
+		}
+		work->frags[i].io_virt = sg_list[i].addr;
+		work->frags[i].length = sg_list[i].length;
+		work->frags[i].mr = mr;
+	}
+	work->num_sge = num_sge;
+	return 0;
+}
+
+static int mlx5_ib_prefetch_sg_list(struct ib_pd *pd,
+				    enum ib_uverbs_advise_mr_advice advice,
+				    u32 pf_flags, struct ib_sge *sg_list,
+				    u32 num_sge)
+{
+	u32 bytes_mapped = 0;
+	int ret = 0;
+	u32 i;
+
+	for (i = 0; i < num_sge; ++i) {
+		struct mlx5_ib_mr *mr;
+
+		mr = get_prefetchable_mr(pd, advice, sg_list[i].lkey);
+		if (IS_ERR(mr))
+			return PTR_ERR(mr);
+		ret = pagefault_mr(mr, sg_list[i].addr, sg_list[i].length,
+				   &bytes_mapped, pf_flags);
+		if (ret < 0) {
+			mlx5r_deref_odp_mkey(&mr->mmkey);
+			return ret;
+		}
+		mlx5_update_odp_stats(mr, prefetch, ret);
+		mlx5r_deref_odp_mkey(&mr->mmkey);
+	}
+
+	return 0;
+}
+
+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)
+{
+	u32 pf_flags = 0;
+	struct prefetch_mr_work *work;
+	int rc;
+
+	if (advice == IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH)
+		pf_flags |= MLX5_PF_FLAGS_DOWNGRADE;
+
+	if (advice == IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH_NO_FAULT)
+		pf_flags |= MLX5_PF_FLAGS_SNAPSHOT;
+
+	if (flags & IB_UVERBS_ADVISE_MR_FLAG_FLUSH)
+		return mlx5_ib_prefetch_sg_list(pd, advice, pf_flags, sg_list,
+						num_sge);
+
+	work = kvzalloc(struct_size(work, frags, num_sge), GFP_KERNEL);
+	if (!work)
+		return -ENOMEM;
+
+	rc = init_prefetch_work(pd, advice, pf_flags, work, sg_list, num_sge);
+	if (rc) {
+		destroy_prefetch_work(work);
+		return rc;
+	}
+	queue_work(system_unbound_wq, &work->work);
+	return 0;
+}