Boot Linux faster!

Check our new training course

Boot Linux faster!

Check our new training course
and Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Intel MIC Platform Software Stack (MPSS)
 *
 * Copyright(c) 2015 Intel Corporation.
 *
 * Intel SCIF driver.
 */
#include "scif_main.h"

/*
 * struct scif_vma_info - Information about a remote memory mapping
 *			  created via scif_mmap(..)
 * @vma: VM area struct
 * @list: link to list of active vmas
 */
struct scif_vma_info {
	struct vm_area_struct *vma;
	struct list_head list;
};

void scif_recv_munmap(struct scif_dev *scifdev, struct scifmsg *msg)
{
	struct scif_rma_req req;
	struct scif_window *window = NULL;
	struct scif_window *recv_window =
		(struct scif_window *)msg->payload[0];
	struct scif_endpt *ep;

	ep = (struct scif_endpt *)recv_window->ep;
	req.out_window = &window;
	req.offset = recv_window->offset;
	req.prot = recv_window->prot;
	req.nr_bytes = recv_window->nr_pages << PAGE_SHIFT;
	req.type = SCIF_WINDOW_FULL;
	req.head = &ep->rma_info.reg_list;
	msg->payload[0] = ep->remote_ep;

	mutex_lock(&ep->rma_info.rma_lock);
	/* Does a valid window exist? */
	if (scif_query_window(&req)) {
		dev_err(&scifdev->sdev->dev,
			"%s %d -ENXIO\n", __func__, __LINE__);
		msg->uop = SCIF_UNREGISTER_ACK;
		goto error;
	}

	scif_put_window(window, window->nr_pages);

	if (!window->ref_count) {
		atomic_inc(&ep->rma_info.tw_refcount);
		ep->rma_info.async_list_del = 1;
		list_del_init(&window->list);
		scif_free_window_offset(ep, window, window->offset);
	}
error:
	mutex_unlock(&ep->rma_info.rma_lock);
	if (window && !window->ref_count)
		scif_queue_for_cleanup(window, &scif_info.rma);
}

/*
 * Remove valid remote memory mappings created via scif_mmap(..) from the
 * process address space since the remote node is lost
 */
static void __scif_zap_mmaps(struct scif_endpt *ep)
{
	struct list_head *item;
	struct scif_vma_info *info;
	struct vm_area_struct *vma;
	unsigned long size;

	spin_lock(&ep->lock);
	list_for_each(item, &ep->rma_info.vma_list) {
		info = list_entry(item, struct scif_vma_info, list);
		vma = info->vma;
		size = vma->vm_end - vma->vm_start;
		zap_vma_ptes(vma, vma->vm_start, size);
		dev_dbg(scif_info.mdev.this_device,
			"%s ep %p zap vma %p size 0x%lx\n",
			__func__, ep, info->vma, size);
	}
	spin_unlock(&ep->lock);
}

/*
 * Traverse the list of endpoints for a particular remote node and
 * zap valid remote memory mappings since the remote node is lost
 */
static void _scif_zap_mmaps(int node, struct list_head *head)
{
	struct scif_endpt *ep;
	struct list_head *item;

	mutex_lock(&scif_info.connlock);
	list_for_each(item, head) {
		ep = list_entry(item, struct scif_endpt, list);
		if (ep->remote_dev->node == node)
			__scif_zap_mmaps(ep);
	}
	mutex_unlock(&scif_info.connlock);
}

/*
 * Wrapper for removing remote memory mappings for a particular node. This API
 * is called by peer nodes as part of handling a lost node.
 */
void scif_zap_mmaps(int node)
{
	_scif_zap_mmaps(node, &scif_info.connected);
	_scif_zap_mmaps(node, &scif_info.disconnected);
}

/*
 * This API is only called while handling a lost node:
 * a) Remote node is dead.
 * b) Remote memory mappings have been zapped
 * So we can traverse the remote_reg_list without any locks. Since
 * the window has not yet been unregistered we can drop the ref count
 * and queue it to the cleanup thread.
 */
static void __scif_cleanup_rma_for_zombies(struct scif_endpt *ep)
{
	struct list_head *pos, *tmp;
	struct scif_window *window;

	list_for_each_safe(pos, tmp, &ep->rma_info.remote_reg_list) {
		window = list_entry(pos, struct scif_window, list);
		if (window->ref_count)
			scif_put_window(window, window->nr_pages);
		else
			dev_err(scif_info.mdev.this_device,
				"%s %d unexpected\n",
				__func__, __LINE__);
		if (!window->ref_count) {
			atomic_inc(&ep->rma_info.tw_refcount);
			list_del_init(&window->list);
			scif_queue_for_cleanup(window, &scif_info.rma);
		}
	}
}

/* Cleanup remote registration lists for zombie endpoints */
void scif_cleanup_rma_for_zombies(int node)
{
	struct scif_endpt *ep;
	struct list_head *item;

	mutex_lock(&scif_info.eplock);
	list_for_each(item, &scif_info.zombie) {
		ep = list_entry(item, struct scif_endpt, list);
		if (ep->remote_dev && ep->remote_dev->node == node)
			__scif_cleanup_rma_for_zombies(ep);
	}
	mutex_unlock(&scif_info.eplock);
	flush_work(&scif_info.misc_work);
}

/* Insert the VMA into the per endpoint VMA list */
static int scif_insert_vma(struct scif_endpt *ep, struct vm_area_struct *vma)
{
	struct scif_vma_info *info;
	int err = 0;

	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (!info) {
		err = -ENOMEM;
		goto done;
	}
	info->vma = vma;
	spin_lock(&ep->lock);
	list_add_tail(&info->list, &ep->rma_info.vma_list);
	spin_unlock(&ep->lock);
done:
	return err;
}

/* Delete the VMA from the per endpoint VMA list */
static void scif_delete_vma(struct scif_endpt *ep, struct vm_area_struct *vma)
{
	struct list_head *item;
	struct scif_vma_info *info;

	spin_lock(&ep->lock);
	list_for_each(item, &ep->rma_info.vma_list) {
		info = list_entry(item, struct scif_vma_info, list);
		if (info->vma == vma) {
			list_del(&info->list);
			kfree(info);
			break;
		}
	}
	spin_unlock(&ep->lock);
}

static phys_addr_t scif_get_phys(phys_addr_t phys, struct scif_endpt *ep)
{
	struct scif_dev *scifdev = (struct scif_dev *)ep->remote_dev;
	struct scif_hw_dev *sdev = scifdev->sdev;
	phys_addr_t out_phys, apt_base = 0;

	/*
	 * If the DMA address is card relative then we need to add the
	 * aperture base for mmap to work correctly
	 */
	if (!scifdev_self(scifdev) && sdev->aper && sdev->card_rel_da)
		apt_base = sdev->aper->pa;
	out_phys = apt_base + phys;
	return out_phys;
}

int scif_get_pages(scif_epd_t epd, off_t offset, size_t len,
		   struct scif_range **pages)
{
	struct scif_endpt *ep = (struct scif_endpt *)epd;
	struct scif_rma_req req;
	struct scif_window *window = NULL;
	int nr_pages, err, i;

	dev_dbg(scif_info.mdev.this_device,
		"SCIFAPI get_pinned_pages: ep %p offset 0x%lx len 0x%lx\n",
		ep, offset, len);
	err = scif_verify_epd(ep);
	if (err)
		return err;

	if (!len || (offset < 0) ||
	    (offset + len < offset) ||
	    (ALIGN(offset, PAGE_SIZE) != offset) ||
	    (ALIGN(len, PAGE_SIZE) != len))
		return -EINVAL;

	nr_pages = len >> PAGE_SHIFT;

	req.out_window = &window;
	req.offset = offset;
	req.prot = 0;
	req.nr_bytes = len;
	req.type = SCIF_WINDOW_SINGLE;
	req.head = &ep->rma_info.remote_reg_list;

	mutex_lock(&ep->rma_info.rma_lock);
	/* Does a valid window exist? */
	err = scif_query_window(&req);
	if (err) {
		dev_err(&ep->remote_dev->sdev->dev,
			"%s %d err %d\n", __func__, __LINE__, err);
		goto error;
	}

	/* Allocate scif_range */
	*pages = kzalloc(sizeof(**pages), GFP_KERNEL);
	if (!*pages) {
		err = -ENOMEM;
		goto error;
	}

	/* Allocate phys addr array */
	(*pages)->phys_addr = scif_zalloc(nr_pages * sizeof(dma_addr_t));
	if (!((*pages)->phys_addr)) {
		err = -ENOMEM;
		goto error;
	}

	if (scif_is_mgmt_node() && !scifdev_self(ep->remote_dev)) {
		/* Allocate virtual address array */
		((*pages)->va = scif_zalloc(nr_pages * sizeof(void *)));
		if (!(*pages)->va) {
			err = -ENOMEM;
			goto error;
		}
	}
	/* Populate the values */
	(*pages)->cookie = window;
	(*pages)->nr_pages = nr_pages;
	(*pages)->prot_flags = window->prot;

	for (i = 0; i < nr_pages; i++) {
		(*pages)->phys_addr[i] =
			__scif_off_to_dma_addr(window, offset +
					       (i * PAGE_SIZE));
		(*pages)->phys_addr[i] = scif_get_phys((*pages)->phys_addr[i],
							ep);
		if (scif_is_mgmt_node() && !scifdev_self(ep->remote_dev))
			(*pages)->va[i] =
				ep->remote_dev->sdev->aper->va +
				(*pages)->phys_addr[i] -
				ep->remote_dev->sdev->aper->pa;
	}

	scif_get_window(window, nr_pages);
error:
	mutex_unlock(&ep->rma_info.rma_lock);
	if (err) {
		if (*pages) {
			scif_free((*pages)->phys_addr,
				  nr_pages * sizeof(dma_addr_t));
			scif_free((*pages)->va,
				  nr_pages * sizeof(void *));
			kfree(*pages);
			*pages = NULL;
		}
		dev_err(&ep->remote_dev->sdev->dev,
			"%s %d err %d\n", __func__, __LINE__, err);
	}
	return err;
}
EXPORT_SYMBOL_GPL(scif_get_pages);

int scif_put_pages(struct scif_range *pages)
{
	struct scif_endpt *ep;
	struct scif_window *window;
	struct scifmsg msg;

	if (!pages || !pages->cookie)
		return -EINVAL;

	window = pages->cookie;

	if (!window || window->magic != SCIFEP_MAGIC)
		return -EINVAL;

	ep = (struct scif_endpt *)window->ep;
	/*
	 * If the state is SCIFEP_CONNECTED or SCIFEP_DISCONNECTED then the
	 * callee should be allowed to release references to the pages,
	 * else the endpoint was not connected in the first place,
	 * hence the ENOTCONN.
	 */
	if (ep->state != SCIFEP_CONNECTED && ep->state != SCIFEP_DISCONNECTED)
		return -ENOTCONN;

	mutex_lock(&ep->rma_info.rma_lock);

	scif_put_window(window, pages->nr_pages);

	/* Initiate window destruction if ref count is zero */
	if (!window->ref_count) {
		list_del(&window->list);
		mutex_unlock(&ep->rma_info.rma_lock);
		scif_drain_dma_intr(ep->remote_dev->sdev,
				    ep->rma_info.dma_chan);
		/* Inform the peer about this window being destroyed. */
		msg.uop = SCIF_MUNMAP;
		msg.src = ep->port;
		msg.payload[0] = window->peer_window;
		/* No error handling for notification messages */
		scif_nodeqp_send(ep->remote_dev, &msg);
		/* Destroy this window from the peer's registered AS */
		scif_destroy_remote_window(window);
	} else {
		mutex_unlock(&ep->rma_info.rma_lock);
	}

	scif_free(pages->phys_addr, pages->nr_pages * sizeof(dma_addr_t));
	scif_free(pages->va, pages->nr_pages * sizeof(void *));
	kfree(pages);
	return 0;
}
EXPORT_SYMBOL_GPL(scif_put_pages);

/*
 * scif_rma_list_mmap:
 *
 * Traverse the remote registration list starting from start_window:
 * 1) Create VtoP mappings via remap_pfn_range(..)
 * 2) Once step 1) and 2) complete successfully then traverse the range of
 *    windows again and bump the reference count.
 * RMA lock must be held.
 */
static int scif_rma_list_mmap(struct scif_window *start_window, s64 offset,
			      int nr_pages, struct vm_area_struct *vma)
{
	s64 end_offset, loop_offset = offset;
	struct scif_window *window = start_window;
	int loop_nr_pages, nr_pages_left = nr_pages;
	struct scif_endpt *ep = (struct scif_endpt *)start_window->ep;
	struct list_head *head = &ep->rma_info.remote_reg_list;
	int i, err = 0;
	dma_addr_t phys_addr;
	struct scif_window_iter src_win_iter;
	size_t contig_bytes = 0;

	might_sleep();
	list_for_each_entry_from(window, head, list) {
		end_offset = window->offset +
			(window->nr_pages << PAGE_SHIFT);
		loop_nr_pages = min_t(int,
				      (end_offset - loop_offset) >> PAGE_SHIFT,
				      nr_pages_left);
		scif_init_window_iter(window, &src_win_iter);
		for (i = 0; i < loop_nr_pages; i++) {
			phys_addr = scif_off_to_dma_addr(window, loop_offset,
							 &contig_bytes,
							 &src_win_iter);
			phys_addr = scif_get_phys(phys_addr, ep);
			err = remap_pfn_range(vma,
					      vma->vm_start +
					      loop_offset - offset,
					      phys_addr >> PAGE_SHIFT,
					      PAGE_SIZE,
					      vma->vm_page_prot);
			if (err)
				goto error;
			loop_offset += PAGE_SIZE;
		}
		nr_pages_left -= loop_nr_pages;
		if (!nr_pages_left)
			break;
	}
	/*
	 * No more failures expected. Bump up the ref count for all
	 * the windows. Another traversal from start_window required
	 * for handling errors encountered across windows during
	 * remap_pfn_range(..).
	 */
	loop_offset = offset;
	nr_pages_left = nr_pages;
	window = start_window;
	head = &ep->rma_info.remote_reg_list;
	list_for_each_entry_from(window, head, list) {
		end_offset = window->offset +
			(window->nr_pages << PAGE_SHIFT);
		loop_nr_pages = min_t(int,
				      (end_offset - loop_offset) >> PAGE_SHIFT,
				      nr_pages_left);
		scif_get_window(window, loop_nr_pages);
		nr_pages_left -= loop_nr_pages;
		loop_offset += (loop_nr_pages << PAGE_SHIFT);
		if (!nr_pages_left)
			break;
	}
error:
	if (err)
		dev_err(scif_info.mdev.this_device,
			"%s %d err %d\n", __func__, __LINE__, err);
	return err;
}

/*
 * scif_rma_list_munmap:
 *
 * Traverse the remote registration list starting from window:
 * 1) Decrement ref count.
 * 2) If the ref count drops to zero then send a SCIF_MUNMAP message to peer.
 * RMA lock must be held.
 */
static void scif_rma_list_munmap(struct scif_window *start_window,
				 s64 offset, int nr_pages)
{
	struct scifmsg msg;
	s64 loop_offset = offset, end_offset;
	int loop_nr_pages, nr_pages_left = nr_pages;
	struct scif_endpt *ep = (struct scif_endpt *)start_window->ep;
	struct list_head *head = &ep->rma_info.remote_reg_list;
	struct scif_window *window = start_window, *_window;

	msg.uop = SCIF_MUNMAP;
	msg.src = ep->port;
	loop_offset = offset;
	nr_pages_left = nr_pages;
	list_for_each_entry_safe_from(window, _window, head, list) {
		end_offset = window->offset +
			(window->nr_pages << PAGE_SHIFT);
		loop_nr_pages = min_t(int,
				      (end_offset - loop_offset) >> PAGE_SHIFT,
				      nr_pages_left);
		scif_put_window(window, loop_nr_pages);
		if (!window->ref_count) {
			struct scif_dev *rdev = ep->remote_dev;

			scif_drain_dma_intr(rdev->sdev,
					    ep->rma_info.dma_chan);
			/* Inform the peer about this munmap */
			msg.payload[0] = window->peer_window;
			/* No error handling for Notification messages. */
			scif_nodeqp_send(ep->remote_dev, &msg);
			list_del(&window->list);
			/* Destroy this window from the peer's registered AS */
			scif_destroy_remote_window(window);
		}
		nr_pages_left -= loop_nr_pages;
		loop_offset += (loop_nr_pages << PAGE_SHIFT);
		if (!nr_pages_left)
			break;
	}
}

/*
 * The private data field of each VMA used to mmap a remote window
 * points to an instance of struct vma_pvt
 */
struct vma_pvt {
	struct scif_endpt *ep;	/* End point for remote window */
	s64 offset;		/* offset within remote window */
	bool valid_offset;	/* offset is valid only if the original
				 * mmap request was for a single page
				 * else the offset within the vma is
				 * the correct offset
				 */
	struct kref ref;
};

static void vma_pvt_release(struct kref *ref)
{
	struct vma_pvt *vmapvt = container_of(ref, struct vma_pvt, ref);

	kfree(vmapvt);
}

/**
 * scif_vma_open - VMA open driver callback
 * @vma: VMM memory area.
 * The open method is called by the kernel to allow the subsystem implementing
 * the VMA to initialize the area. This method is invoked any time a new
 * reference to the VMA is made (when a process forks, for example).
 * The one exception happens when the VMA is first created by mmap;
 * in this case, the driver's mmap method is called instead.
 * This function is also invoked when an existing VMA is split by the kernel
 * due to a call to munmap on a subset of the VMA resulting in two VMAs.
 * The kernel invokes this function only on one of the two VMAs.
 */
static void scif_vma_open(struct vm_area_struct *vma)
{
	struct vma_pvt *vmapvt = vma->vm_private_data;

	dev_dbg(scif_info.mdev.this_device,
		"SCIFAPI vma open: vma_start 0x%lx vma_end 0x%lx\n",
		vma->vm_start, vma->vm_end);
	scif_insert_vma(vmapvt->ep, vma);
	kref_get(&vmapvt->ref);
}

/**
 * scif_munmap - VMA close driver callback.
 * @vma: VMM memory area.
 * When an area is destroyed, the kernel calls its close operation.
 * Note that there's no usage count associated with VMA's; the area
 * is opened and closed exactly once by each process that uses it.
 */
static void scif_munmap(struct vm_area_struct *vma)
{
	struct scif_endpt *ep;
	struct vma_pvt *vmapvt = vma->vm_private_data;
	int nr_pages = vma_pages(vma);
	s64 offset;
	struct scif_rma_req req;
	struct scif_window *window = NULL;
	int err;

	might_sleep();
	dev_dbg(scif_info.mdev.this_device,
		"SCIFAPI munmap: vma_start 0x%lx vma_end 0x%lx\n",
		vma->vm_start, vma->vm_end);
	ep = vmapvt->ep;
	offset = vmapvt->valid_offset ? vmapvt->offset :
		(vma->vm_pgoff) << PAGE_SHIFT;
	dev_dbg(scif_info.mdev.this_device,
		"SCIFAPI munmap: ep %p nr_pages 0x%x offset 0x%llx\n",
		ep, nr_pages, offset);
	req.out_window = &window;
	req.offset = offset;
	req.nr_bytes = vma->vm_end - vma->vm_start;
	req.prot = vma->vm_flags & (VM_READ | VM_WRITE);
	req.type = SCIF_WINDOW_PARTIAL;
	req.head = &ep->rma_info.remote_reg_list;

	mutex_lock(&ep->rma_info.rma_lock);

	err = scif_query_window(&req);
	if (err)
		dev_err(scif_info.mdev.this_device,
			"%s %d err %d\n", __func__, __LINE__, err);
	else
		scif_rma_list_munmap(window, offset, nr_pages);

	mutex_unlock(&ep->rma_info.rma_lock);
	/*
	 * The kernel probably zeroes these out but we still want
	 * to clean up our own mess just in case.
	 */
	vma->vm_ops = NULL;
	vma->vm_private_data = NULL;
	kref_put(&vmapvt->ref, vma_pvt_release);
	scif_delete_vma(ep, vma);
}

static const struct vm_operations_struct scif_vm_ops = {
	.open = scif_vma_open,
	.close = scif_munmap,
};

/**
 * scif_mmap - Map pages in virtual address space to a remote window.
 * @vma: VMM memory area.
 * @epd: endpoint descriptor
 *
 * Return: Upon successful completion, scif_mmap() returns zero
 * else an apt error is returned as documented in scif.h
 */
int scif_mmap(struct vm_area_struct *vma, scif_epd_t epd)
{
	struct scif_rma_req req;
	struct scif_window *window = NULL;
	struct scif_endpt *ep = (struct scif_endpt *)epd;
	s64 start_offset = vma->vm_pgoff << PAGE_SHIFT;
	int nr_pages = vma_pages(vma);
	int err;
	struct vma_pvt *vmapvt;

	dev_dbg(scif_info.mdev.this_device,
		"SCIFAPI mmap: ep %p start_offset 0x%llx nr_pages 0x%x\n",
		ep, start_offset, nr_pages);
	err = scif_verify_epd(ep);
	if (err)
		return err;

	might_sleep();

	err = scif_insert_vma(ep, vma);
	if (err)
		return err;

	vmapvt = kzalloc(sizeof(*vmapvt), GFP_KERNEL);
	if (!vmapvt) {
		scif_delete_vma(ep, vma);
		return -ENOMEM;
	}

	vmapvt->ep = ep;
	kref_init(&vmapvt->ref);

	req.out_window = &window;
	req.offset = start_offset;
	req.nr_bytes = vma->vm_end - vma->vm_start;
	req.prot = vma->vm_flags & (VM_READ | VM_WRITE);
	req.type = SCIF_WINDOW_PARTIAL;
	req.head = &ep->rma_info.remote_reg_list;

	mutex_lock(&ep->rma_info.rma_lock);
	/* Does a valid window exist? */
	err = scif_query_window(&req);
	if (err) {
		dev_err(&ep->remote_dev->sdev->dev,
			"%s %d err %d\n", __func__, __LINE__, err);
		goto error_unlock;
	}

	/* Default prot for loopback */
	if (!scifdev_self(ep->remote_dev))
		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);

	/*
	 * VM_DONTCOPY - Do not copy this vma on fork
	 * VM_DONTEXPAND - Cannot expand with mremap()
	 * VM_RESERVED - Count as reserved_vm like IO
	 * VM_PFNMAP - Page-ranges managed without "struct page"
	 * VM_IO - Memory mapped I/O or similar
	 *
	 * We do not want to copy this VMA automatically on a fork(),
	 * expand this VMA due to mremap() or swap out these pages since
	 * the VMA is actually backed by physical pages in the remote
	 * node's physical memory and not via a struct page.
	 */
	vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP;

	if (!scifdev_self(ep->remote_dev))
		vma->vm_flags |= VM_IO | VM_PFNMAP;

	/* Map this range of windows */
	err = scif_rma_list_mmap(window, start_offset, nr_pages, vma);
	if (err) {
		dev_err(&ep->remote_dev->sdev->dev,
			"%s %d err %d\n", __func__, __LINE__, err);
		goto error_unlock;
	}
	/* Set up the driver call back */
	vma->vm_ops = &scif_vm_ops;
	vma->vm_private_data = vmapvt;
error_unlock:
	mutex_unlock(&ep->rma_info.rma_lock);
	if (err) {
		kfree(vmapvt);
		dev_err(&ep->remote_dev->sdev->dev,
			"%s %d err %d\n", __func__, __LINE__, err);
		scif_delete_vma(ep, vma);
	}
	return err;
}