diff --git a/drivers/staging/rdma/hfi1/user_exp_rcv.c b/drivers/staging/rdma/hfi1/user_exp_rcv.c
index 91950d225da5..6d21c1349b77 100644
--- a/drivers/staging/rdma/hfi1/user_exp_rcv.c
+++ b/drivers/staging/rdma/hfi1/user_exp_rcv.c
@@ -97,8 +97,7 @@ struct tid_pageset {
 
 static void unlock_exp_tids(struct hfi1_ctxtdata *, struct exp_tid_set *,
 			    struct rb_root *);
-static u32 find_phys_blocks(struct page **, unsigned,
-			    struct tid_pageset *) __maybe_unused;
+static u32 find_phys_blocks(struct page **, unsigned, struct tid_pageset *);
 static int set_rcvarray_entry(struct file *, unsigned long, u32,
 			      struct tid_group *, struct page **, unsigned);
 static inline int mmu_addr_cmp(struct mmu_rb_node *, unsigned long,
@@ -119,7 +118,7 @@ static inline void mmu_notifier_range_start(struct mmu_notifier *,
 					    unsigned long, unsigned long);
 static int program_rcvarray(struct file *, unsigned long, struct tid_group *,
 			    struct tid_pageset *, unsigned, u16, struct page **,
-			    u32 *, unsigned *, unsigned *) __maybe_unused;
+			    u32 *, unsigned *, unsigned *);
 static int unprogram_rcvarray(struct file *, u32, struct tid_group **);
 static void clear_tid_node(struct hfi1_filedata *, u16, struct mmu_rb_node *);
 
@@ -339,9 +338,265 @@ static inline void rcv_array_wc_fill(struct hfi1_devdata *dd, u32 index)
 		writeq(0, dd->rcvarray_wc + (index * 8));
 }
 
+/*
+ * RcvArray entry allocation for Expected Receives is done by the
+ * following algorithm:
+ *
+ * The context keeps 3 lists of groups of RcvArray entries:
+ *   1. List of empty groups - tid_group_list
+ *      This list is created during user context creation and
+ *      contains elements which describe sets (of 8) of empty
+ *      RcvArray entries.
+ *   2. List of partially used groups - tid_used_list
+ *      This list contains sets of RcvArray entries which are
+ *      not completely used up. Another mapping request could
+ *      use some of all of the remaining entries.
+ *   3. List of full groups - tid_full_list
+ *      This is the list where sets that are completely used
+ *      up go.
+ *
+ * An attempt to optimize the usage of RcvArray entries is
+ * made by finding all sets of physically contiguous pages in a
+ * user's buffer.
+ * These physically contiguous sets are further split into
+ * sizes supported by the receive engine of the HFI. The
+ * resulting sets of pages are stored in struct tid_pageset,
+ * which describes the sets as:
+ *    * .count - number of pages in this set
+ *    * .idx - starting index into struct page ** array
+ *                    of this set
+ *
+ * From this point on, the algorithm deals with the page sets
+ * described above. The number of pagesets is divided by the
+ * RcvArray group size to produce the number of full groups
+ * needed.
+ *
+ * Groups from the 3 lists are manipulated using the following
+ * rules:
+ *   1. For each set of 8 pagesets, a complete group from
+ *      tid_group_list is taken, programmed, and moved to
+ *      the tid_full_list list.
+ *   2. For all remaining pagesets:
+ *      2.1 If the tid_used_list is empty and the tid_group_list
+ *          is empty, stop processing pageset and return only
+ *          what has been programmed up to this point.
+ *      2.2 If the tid_used_list is empty and the tid_group_list
+ *          is not empty, move a group from tid_group_list to
+ *          tid_used_list.
+ *      2.3 For each group is tid_used_group, program as much as
+ *          can fit into the group. If the group becomes fully
+ *          used, move it to tid_full_list.
+ */
 int hfi1_user_exp_rcv_setup(struct file *fp, struct hfi1_tid_info *tinfo)
 {
-	return -EINVAL;
+	int ret = 0, need_group = 0, pinned;
+	struct hfi1_filedata *fd = fp->private_data;
+	struct hfi1_ctxtdata *uctxt = fd->uctxt;
+	struct hfi1_devdata *dd = uctxt->dd;
+	unsigned npages, ngroups, pageidx = 0, pageset_count, npagesets,
+		tididx = 0, mapped, mapped_pages = 0;
+	unsigned long vaddr = tinfo->vaddr;
+	struct page **pages = NULL;
+	u32 *tidlist = NULL;
+	struct tid_pageset *pagesets = NULL;
+
+	/* Get the number of pages the user buffer spans */
+	npages = num_user_pages(vaddr, tinfo->length);
+	if (!npages)
+		return -EINVAL;
+
+	if (npages > uctxt->expected_count) {
+		dd_dev_err(dd, "Expected buffer too big\n");
+		return -EINVAL;
+	}
+
+	/* Verify that access is OK for the user buffer */
+	if (!access_ok(VERIFY_WRITE, (void __user *)vaddr,
+		       npages * PAGE_SIZE)) {
+		dd_dev_err(dd, "Fail vaddr %p, %u pages, !access_ok\n",
+			   (void *)vaddr, npages);
+		return -EFAULT;
+	}
+
+	pagesets = kcalloc(uctxt->expected_count, sizeof(*pagesets),
+			   GFP_KERNEL);
+	if (!pagesets)
+		return -ENOMEM;
+
+	/* Allocate the array of struct page pointers needed for pinning */
+	pages = kcalloc(npages, sizeof(*pages), GFP_KERNEL);
+	if (!pages) {
+		ret = -ENOMEM;
+		goto bail;
+	}
+
+	/*
+	 * Pin all the pages of the user buffer. If we can't pin all the
+	 * pages, accept the amount pinned so far and program only that.
+	 * User space knows how to deal with partially programmed buffers.
+	 */
+	pinned = hfi1_acquire_user_pages(vaddr, npages, true, pages);
+	if (pinned <= 0) {
+		ret = pinned;
+		goto bail;
+	}
+
+	/* Find sets of physically contiguous pages */
+	npagesets = find_phys_blocks(pages, pinned, pagesets);
+
+	/*
+	 * We don't need to access this under a lock since tid_used is per
+	 * process and the same process cannot be in hfi1_user_exp_rcv_clear()
+	 * and hfi1_user_exp_rcv_setup() at the same time.
+	 */
+	spin_lock(&fd->tid_lock);
+	if (fd->tid_used + npagesets > fd->tid_limit)
+		pageset_count = fd->tid_limit - fd->tid_used;
+	else
+		pageset_count = npagesets;
+	spin_unlock(&fd->tid_lock);
+
+	if (!pageset_count)
+		goto bail;
+
+	ngroups = pageset_count / dd->rcv_entries.group_size;
+	tidlist = kcalloc(pageset_count, sizeof(*tidlist), GFP_KERNEL);
+	if (!tidlist) {
+		ret = -ENOMEM;
+		goto nomem;
+	}
+
+	tididx = 0;
+
+	/*
+	 * From this point on, we are going to be using shared (between master
+	 * and subcontexts) context resources. We need to take the lock.
+	 */
+	mutex_lock(&uctxt->exp_lock);
+	/*
+	 * The first step is to program the RcvArray entries which are complete
+	 * groups.
+	 */
+	while (ngroups && uctxt->tid_group_list.count) {
+		struct tid_group *grp =
+			tid_group_pop(&uctxt->tid_group_list);
+
+		ret = program_rcvarray(fp, vaddr, grp, pagesets,
+				       pageidx, dd->rcv_entries.group_size,
+				       pages, tidlist, &tididx, &mapped);
+		/*
+		 * If there was a failure to program the RcvArray
+		 * entries for the entire group, reset the grp fields
+		 * and add the grp back to the free group list.
+		 */
+		if (ret <= 0) {
+			tid_group_add_tail(grp, &uctxt->tid_group_list);
+			hfi1_cdbg(TID,
+				  "Failed to program RcvArray group %d", ret);
+			goto unlock;
+		}
+
+		tid_group_add_tail(grp, &uctxt->tid_full_list);
+		ngroups--;
+		pageidx += ret;
+		mapped_pages += mapped;
+	}
+
+	while (pageidx < pageset_count) {
+		struct tid_group *grp, *ptr;
+		/*
+		 * If we don't have any partially used tid groups, check
+		 * if we have empty groups. If so, take one from there and
+		 * put in the partially used list.
+		 */
+		if (!uctxt->tid_used_list.count || need_group) {
+			if (!uctxt->tid_group_list.count)
+				goto unlock;
+
+			grp = tid_group_pop(&uctxt->tid_group_list);
+			tid_group_add_tail(grp, &uctxt->tid_used_list);
+			need_group = 0;
+		}
+		/*
+		 * There is an optimization opportunity here - instead of
+		 * fitting as many page sets as we can, check for a group
+		 * later on in the list that could fit all of them.
+		 */
+		list_for_each_entry_safe(grp, ptr, &uctxt->tid_used_list.list,
+					 list) {
+			unsigned use = min_t(unsigned, pageset_count - pageidx,
+					     grp->size - grp->used);
+
+			ret = program_rcvarray(fp, vaddr, grp, pagesets,
+					       pageidx, use, pages, tidlist,
+					       &tididx, &mapped);
+			if (ret < 0) {
+				hfi1_cdbg(TID,
+					  "Failed to program RcvArray entries %d",
+					  ret);
+				ret = -EFAULT;
+				goto unlock;
+			} else if (ret > 0) {
+				if (grp->used == grp->size)
+					tid_group_move(grp,
+						       &uctxt->tid_used_list,
+						       &uctxt->tid_full_list);
+				pageidx += ret;
+				mapped_pages += mapped;
+				need_group = 0;
+				/* Check if we are done so we break out early */
+				if (pageidx >= pageset_count)
+					break;
+			} else if (WARN_ON(ret == 0)) {
+				/*
+				 * If ret is 0, we did not program any entries
+				 * into this group, which can only happen if
+				 * we've screwed up the accounting somewhere.
+				 * Warn and try to continue.
+				 */
+				need_group = 1;
+			}
+		}
+	}
+unlock:
+	mutex_unlock(&uctxt->exp_lock);
+nomem:
+	hfi1_cdbg(TID, "total mapped: tidpairs:%u pages:%u (%d)", tididx,
+		  mapped_pages, ret);
+	if (tididx) {
+		spin_lock(&fd->tid_lock);
+		fd->tid_used += tididx;
+		spin_unlock(&fd->tid_lock);
+		tinfo->tidcnt = tididx;
+		tinfo->length = mapped_pages * PAGE_SIZE;
+
+		if (copy_to_user((void __user *)(unsigned long)tinfo->tidlist,
+				 tidlist, sizeof(tidlist[0]) * tididx)) {
+			/*
+			 * On failure to copy to the user level, we need to undo
+			 * everything done so far so we don't leak resources.
+			 */
+			tinfo->tidlist = (unsigned long)&tidlist;
+			hfi1_user_exp_rcv_clear(fp, tinfo);
+			tinfo->tidlist = 0;
+			ret = -EFAULT;
+			goto bail;
+		}
+	}
+
+	/*
+	 * If not everything was mapped (due to insufficient RcvArray entries,
+	 * for example), unpin all unmapped pages so we can pin them nex time.
+	 */
+	if (mapped_pages != pinned)
+		hfi1_release_user_pages(&pages[mapped_pages],
+					pinned - mapped_pages,
+					false);
+bail:
+	kfree(pagesets);
+	kfree(pages);
+	kfree(tidlist);
+	return ret > 0 ? 0 : ret;
 }
 
 int hfi1_user_exp_rcv_clear(struct file *fp, struct hfi1_tid_info *tinfo)
