summaryrefslogtreecommitdiff
path: root/drivers/dma/idxd/cdev.c
blob: 39935071174a3f466b0c2f77c2be4466a1c18117 (plain)
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
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2019 Intel Corporation. All rights rsvd. */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/device.h>
#include <linux/sched/task.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/iommu.h>
#include <linux/highmem.h>
#include <uapi/linux/idxd.h>
#include <linux/xarray.h>
#include "registers.h"
#include "idxd.h"

struct idxd_cdev_context {
	const char *name;
	dev_t devt;
	struct ida minor_ida;
};

/*
 * Since user file names are global in DSA devices, define their ida's as
 * global to avoid conflict file names.
 */
static DEFINE_IDA(file_ida);
static DEFINE_MUTEX(ida_lock);

/*
 * ictx is an array based off of accelerator types. enum idxd_type
 * is used as index
 */
static struct idxd_cdev_context ictx[IDXD_TYPE_MAX] = {
	{ .name = "dsa" },
	{ .name = "iax" }
};

struct idxd_user_context {
	struct idxd_wq *wq;
	struct task_struct *task;
	unsigned int pasid;
	struct mm_struct *mm;
	unsigned int flags;
	struct iommu_sva *sva;
	struct idxd_dev idxd_dev;
	u64 counters[COUNTER_MAX];
	int id;
	pid_t pid;
};

static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid);
static void idxd_xa_pasid_remove(struct idxd_user_context *ctx);

static inline struct idxd_user_context *dev_to_uctx(struct device *dev)
{
	struct idxd_dev *idxd_dev = confdev_to_idxd_dev(dev);

	return container_of(idxd_dev, struct idxd_user_context, idxd_dev);
}

static ssize_t cr_faults_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct idxd_user_context *ctx = dev_to_uctx(dev);

	return sysfs_emit(buf, "%llu\n", ctx->counters[COUNTER_FAULTS]);
}
static DEVICE_ATTR_RO(cr_faults);

static ssize_t cr_fault_failures_show(struct device *dev,
				      struct device_attribute *attr, char *buf)
{
	struct idxd_user_context *ctx = dev_to_uctx(dev);

	return sysfs_emit(buf, "%llu\n", ctx->counters[COUNTER_FAULT_FAILS]);
}
static DEVICE_ATTR_RO(cr_fault_failures);

static ssize_t pid_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct idxd_user_context *ctx = dev_to_uctx(dev);

	return sysfs_emit(buf, "%u\n", ctx->pid);
}
static DEVICE_ATTR_RO(pid);

static struct attribute *cdev_file_attributes[] = {
	&dev_attr_cr_faults.attr,
	&dev_attr_cr_fault_failures.attr,
	&dev_attr_pid.attr,
	NULL
};

static umode_t cdev_file_attr_visible(struct kobject *kobj, struct attribute *a, int n)
{
	struct device *dev = container_of(kobj, typeof(*dev), kobj);
	struct idxd_user_context *ctx = dev_to_uctx(dev);
	struct idxd_wq *wq = ctx->wq;

	if (!wq_pasid_enabled(wq))
		return 0;

	return a->mode;
}

static const struct attribute_group cdev_file_attribute_group = {
	.attrs = cdev_file_attributes,
	.is_visible = cdev_file_attr_visible,
};

static const struct attribute_group *cdev_file_attribute_groups[] = {
	&cdev_file_attribute_group,
	NULL
};

static void idxd_file_dev_release(struct device *dev)
{
	struct idxd_user_context *ctx = dev_to_uctx(dev);
	struct idxd_wq *wq = ctx->wq;
	struct idxd_device *idxd = wq->idxd;
	int rc;

	mutex_lock(&ida_lock);
	ida_free(&file_ida, ctx->id);
	mutex_unlock(&ida_lock);

	/* Wait for in-flight operations to complete. */
	if (wq_shared(wq)) {
		idxd_device_drain_pasid(idxd, ctx->pasid);
	} else {
		if (device_user_pasid_enabled(idxd)) {
			/* The wq disable in the disable pasid function will drain the wq */
			rc = idxd_wq_disable_pasid(wq);
			if (rc < 0)
				dev_err(dev, "wq disable pasid failed.\n");
		} else {
			idxd_wq_drain(wq);
		}
	}

	if (ctx->sva) {
		idxd_cdev_evl_drain_pasid(wq, ctx->pasid);
		iommu_sva_unbind_device(ctx->sva);
		idxd_xa_pasid_remove(ctx);
	}
	kfree(ctx);
	mutex_lock(&wq->wq_lock);
	idxd_wq_put(wq);
	mutex_unlock(&wq->wq_lock);
}

static const struct device_type idxd_cdev_file_type = {
	.name = "idxd_file",
	.release = idxd_file_dev_release,
	.groups = cdev_file_attribute_groups,
};

static void idxd_cdev_dev_release(struct device *dev)
{
	struct idxd_cdev *idxd_cdev = dev_to_cdev(dev);
	struct idxd_cdev_context *cdev_ctx;
	struct idxd_wq *wq = idxd_cdev->wq;

	cdev_ctx = &ictx[wq->idxd->data->type];
	ida_free(&cdev_ctx->minor_ida, idxd_cdev->minor);
	kfree(idxd_cdev);
}

static const struct device_type idxd_cdev_device_type = {
	.name = "idxd_cdev",
	.release = idxd_cdev_dev_release,
};

static inline struct idxd_cdev *inode_idxd_cdev(struct inode *inode)
{
	struct cdev *cdev = inode->i_cdev;

	return container_of(cdev, struct idxd_cdev, cdev);
}

static inline struct idxd_wq *inode_wq(struct inode *inode)
{
	struct idxd_cdev *idxd_cdev = inode_idxd_cdev(inode);

	return idxd_cdev->wq;
}

static void idxd_xa_pasid_remove(struct idxd_user_context *ctx)
{
	struct idxd_wq *wq = ctx->wq;
	void *ptr;

	mutex_lock(&wq->uc_lock);
	ptr = xa_cmpxchg(&wq->upasid_xa, ctx->pasid, ctx, NULL, GFP_KERNEL);
	if (ptr != (void *)ctx)
		dev_warn(&wq->idxd->pdev->dev, "xarray cmpxchg failed for pasid %u\n",
			 ctx->pasid);
	mutex_unlock(&wq->uc_lock);
}

void idxd_user_counter_increment(struct idxd_wq *wq, u32 pasid, int index)
{
	struct idxd_user_context *ctx;

	if (index >= COUNTER_MAX)
		return;

	mutex_lock(&wq->uc_lock);
	ctx = xa_load(&wq->upasid_xa, pasid);
	if (!ctx) {
		mutex_unlock(&wq->uc_lock);
		return;
	}
	ctx->counters[index]++;
	mutex_unlock(&wq->uc_lock);
}

static int idxd_cdev_open(struct inode *inode, struct file *filp)
{
	struct idxd_user_context *ctx;
	struct idxd_device *idxd;
	struct idxd_wq *wq;
	struct device *dev, *fdev;
	int rc = 0;
	struct iommu_sva *sva;
	unsigned int pasid;
	struct idxd_cdev *idxd_cdev;

	wq = inode_wq(inode);
	idxd = wq->idxd;
	dev = &idxd->pdev->dev;

	dev_dbg(dev, "%s called: %d\n", __func__, idxd_wq_refcount(wq));

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx)
		return -ENOMEM;

	mutex_lock(&wq->wq_lock);

	if (idxd_wq_refcount(wq) > 0 && wq_dedicated(wq)) {
		rc = -EBUSY;
		goto failed;
	}

	ctx->wq = wq;
	filp->private_data = ctx;
	ctx->pid = current->pid;

	if (device_user_pasid_enabled(idxd)) {
		sva = iommu_sva_bind_device(dev, current->mm);
		if (IS_ERR(sva)) {
			rc = PTR_ERR(sva);
			dev_err(dev, "pasid allocation failed: %d\n", rc);
			goto failed;
		}

		pasid = iommu_sva_get_pasid(sva);
		if (pasid == IOMMU_PASID_INVALID) {
			rc = -EINVAL;
			goto failed_get_pasid;
		}

		ctx->sva = sva;
		ctx->pasid = pasid;
		ctx->mm = current->mm;

		mutex_lock(&wq->uc_lock);
		rc = xa_insert(&wq->upasid_xa, pasid, ctx, GFP_KERNEL);
		mutex_unlock(&wq->uc_lock);
		if (rc < 0)
			dev_warn(dev, "PASID entry already exist in xarray.\n");

		if (wq_dedicated(wq)) {
			rc = idxd_wq_set_pasid(wq, pasid);
			if (rc < 0) {
				dev_err(dev, "wq set pasid failed: %d\n", rc);
				goto failed_set_pasid;
			}
		}
	}

	idxd_cdev = wq->idxd_cdev;
	mutex_lock(&ida_lock);
	ctx->id = ida_alloc(&file_ida, GFP_KERNEL);
	mutex_unlock(&ida_lock);
	if (ctx->id < 0) {
		dev_warn(dev, "ida alloc failure\n");
		goto failed_ida;
	}
	ctx->idxd_dev.type  = IDXD_DEV_CDEV_FILE;
	fdev = user_ctx_dev(ctx);
	device_initialize(fdev);
	fdev->parent = cdev_dev(idxd_cdev);
	fdev->bus = &dsa_bus_type;
	fdev->type = &idxd_cdev_file_type;

	rc = dev_set_name(fdev, "file%d", ctx->id);
	if (rc < 0) {
		dev_warn(dev, "set name failure\n");
		goto failed_dev_name;
	}

	rc = device_add(fdev);
	if (rc < 0) {
		dev_warn(dev, "file device add failure\n");
		goto failed_dev_add;
	}

	idxd_wq_get(wq);
	mutex_unlock(&wq->wq_lock);
	return 0;

failed_dev_add:
failed_dev_name:
	put_device(fdev);
failed_ida:
failed_set_pasid:
	if (device_user_pasid_enabled(idxd))
		idxd_xa_pasid_remove(ctx);
failed_get_pasid:
	if (device_user_pasid_enabled(idxd))
		iommu_sva_unbind_device(sva);
failed:
	mutex_unlock(&wq->wq_lock);
	kfree(ctx);
	return rc;
}

static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid)
{
	struct idxd_device *idxd = wq->idxd;
	struct idxd_evl *evl = idxd->evl;
	union evl_status_reg status;
	u16 h, t, size;
	int ent_size = evl_ent_size(idxd);
	struct __evl_entry *entry_head;

	if (!evl)
		return;

	mutex_lock(&evl->lock);
	status.bits = ioread64(idxd->reg_base + IDXD_EVLSTATUS_OFFSET);
	t = status.tail;
	h = status.head;
	size = evl->size;

	while (h != t) {
		entry_head = (struct __evl_entry *)(evl->log + (h * ent_size));
		if (entry_head->pasid == pasid && entry_head->wq_idx == wq->id)
			set_bit(h, evl->bmap);
		h = (h + 1) % size;
	}
	drain_workqueue(wq->wq);
	mutex_unlock(&evl->lock);
}

static int idxd_cdev_release(struct inode *node, struct file *filep)
{
	struct idxd_user_context *ctx = filep->private_data;
	struct idxd_wq *wq = ctx->wq;
	struct idxd_device *idxd = wq->idxd;
	struct device *dev = &idxd->pdev->dev;

	dev_dbg(dev, "%s called\n", __func__);
	filep->private_data = NULL;

	device_unregister(user_ctx_dev(ctx));

	return 0;
}

static int check_vma(struct idxd_wq *wq, struct vm_area_struct *vma,
		     const char *func)
{
	struct device *dev = &wq->idxd->pdev->dev;

	if ((vma->vm_end - vma->vm_start) > PAGE_SIZE) {
		dev_info_ratelimited(dev,
				     "%s: %s: mapping too large: %lu\n",
				     current->comm, func,
				     vma->vm_end - vma->vm_start);
		return -EINVAL;
	}

	return 0;
}

static int idxd_cdev_mmap(struct file *filp, struct vm_area_struct *vma)
{
	struct idxd_user_context *ctx = filp->private_data;
	struct idxd_wq *wq = ctx->wq;
	struct idxd_device *idxd = wq->idxd;
	struct pci_dev *pdev = idxd->pdev;
	phys_addr_t base = pci_resource_start(pdev, IDXD_WQ_BAR);
	unsigned long pfn;
	int rc;

	dev_dbg(&pdev->dev, "%s called\n", __func__);

	/*
	 * Due to an erratum in some of the devices supported by the driver,
	 * direct user submission to the device can be unsafe.
	 * (See the INTEL-SA-01084 security advisory)
	 *
	 * For the devices that exhibit this behavior, require that the user
	 * has CAP_SYS_RAWIO capabilities.
	 */
	if (!idxd->user_submission_safe && !capable(CAP_SYS_RAWIO))
		return -EPERM;

	rc = check_vma(wq, vma, __func__);
	if (rc < 0)
		return rc;

	vm_flags_set(vma, VM_DONTCOPY);
	pfn = (base + idxd_get_wq_portal_full_offset(wq->id,
				IDXD_PORTAL_LIMITED)) >> PAGE_SHIFT;
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	vma->vm_private_data = ctx;

	return io_remap_pfn_range(vma, vma->vm_start, pfn, PAGE_SIZE,
			vma->vm_page_prot);
}

static int idxd_submit_user_descriptor(struct idxd_user_context *ctx,
				       struct dsa_hw_desc __user *udesc)
{
	struct idxd_wq *wq = ctx->wq;
	struct idxd_dev *idxd_dev = &wq->idxd->idxd_dev;
	const uint64_t comp_addr_align = is_dsa_dev(idxd_dev) ? 0x20 : 0x40;
	void __iomem *portal = idxd_wq_portal_addr(wq);
	struct dsa_hw_desc descriptor __aligned(64);
	int rc;

	rc = copy_from_user(&descriptor, udesc, sizeof(descriptor));
	if (rc)
		return -EFAULT;

	/*
	 * DSA devices are capable of indirect ("batch") command submission.
	 * On devices where direct user submissions are not safe, we cannot
	 * allow this since there is no good way for us to verify these
	 * indirect commands.
	 */
	if (is_dsa_dev(idxd_dev) && descriptor.opcode == DSA_OPCODE_BATCH &&
		!wq->idxd->user_submission_safe)
		return -EINVAL;
	/*
	 * As per the programming specification, the completion address must be
	 * aligned to 32 or 64 bytes. If this is violated the hardware
	 * engine can get very confused (security issue).
	 */
	if (!IS_ALIGNED(descriptor.completion_addr, comp_addr_align))
		return -EINVAL;

	if (wq_dedicated(wq))
		iosubmit_cmds512(portal, &descriptor, 1);
	else {
		descriptor.priv = 0;
		descriptor.pasid = ctx->pasid;
		rc = idxd_enqcmds(wq, portal, &descriptor);
		if (rc < 0)
			return rc;
	}

	return 0;
}

static ssize_t idxd_cdev_write(struct file *filp, const char __user *buf, size_t len,
			       loff_t *unused)
{
	struct dsa_hw_desc __user *udesc = (struct dsa_hw_desc __user *)buf;
	struct idxd_user_context *ctx = filp->private_data;
	ssize_t written = 0;
	int i;

	for (i = 0; i < len/sizeof(struct dsa_hw_desc); i++) {
		int rc = idxd_submit_user_descriptor(ctx, udesc + i);

		if (rc)
			return written ? written : rc;

		written += sizeof(struct dsa_hw_desc);
	}

	return written;
}

static __poll_t idxd_cdev_poll(struct file *filp,
			       struct poll_table_struct *wait)
{
	struct idxd_user_context *ctx = filp->private_data;
	struct idxd_wq *wq = ctx->wq;
	struct idxd_device *idxd = wq->idxd;
	__poll_t out = 0;

	poll_wait(filp, &wq->err_queue, wait);
	spin_lock(&idxd->dev_lock);
	if (idxd->sw_err.valid)
		out = EPOLLIN | EPOLLRDNORM;
	spin_unlock(&idxd->dev_lock);

	return out;
}

static const struct file_operations idxd_cdev_fops = {
	.owner = THIS_MODULE,
	.open = idxd_cdev_open,
	.release = idxd_cdev_release,
	.mmap = idxd_cdev_mmap,
	.write = idxd_cdev_write,
	.poll = idxd_cdev_poll,
};

int idxd_cdev_get_major(struct idxd_device *idxd)
{
	return MAJOR(ictx[idxd->data->type].devt);
}

int idxd_wq_add_cdev(struct idxd_wq *wq)
{
	struct idxd_device *idxd = wq->idxd;
	struct idxd_cdev *idxd_cdev;
	struct cdev *cdev;
	struct device *dev;
	struct idxd_cdev_context *cdev_ctx;
	int rc, minor;

	idxd_cdev = kzalloc(sizeof(*idxd_cdev), GFP_KERNEL);
	if (!idxd_cdev)
		return -ENOMEM;

	idxd_cdev->idxd_dev.type = IDXD_DEV_CDEV;
	idxd_cdev->wq = wq;
	cdev = &idxd_cdev->cdev;
	dev = cdev_dev(idxd_cdev);
	cdev_ctx = &ictx[wq->idxd->data->type];
	minor = ida_alloc_max(&cdev_ctx->minor_ida, MINORMASK, GFP_KERNEL);
	if (minor < 0) {
		kfree(idxd_cdev);
		return minor;
	}
	idxd_cdev->minor = minor;

	device_initialize(dev);
	dev->parent = wq_confdev(wq);
	dev->bus = &dsa_bus_type;
	dev->type = &idxd_cdev_device_type;
	dev->devt = MKDEV(MAJOR(cdev_ctx->devt), minor);

	rc = dev_set_name(dev, "%s/wq%u.%u", idxd->data->name_prefix, idxd->id, wq->id);
	if (rc < 0)
		goto err;

	wq->idxd_cdev = idxd_cdev;
	cdev_init(cdev, &idxd_cdev_fops);
	rc = cdev_device_add(cdev, dev);
	if (rc) {
		dev_dbg(&wq->idxd->pdev->dev, "cdev_add failed: %d\n", rc);
		goto err;
	}

	return 0;

 err:
	put_device(dev);
	wq->idxd_cdev = NULL;
	return rc;
}

void idxd_wq_del_cdev(struct idxd_wq *wq)
{
	struct idxd_cdev *idxd_cdev;

	idxd_cdev = wq->idxd_cdev;
	ida_destroy(&file_ida);
	wq->idxd_cdev = NULL;
	cdev_device_del(&idxd_cdev->cdev, cdev_dev(idxd_cdev));
	put_device(cdev_dev(idxd_cdev));
}

static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
{
	struct device *dev = &idxd_dev->conf_dev;
	struct idxd_wq *wq = idxd_dev_to_wq(idxd_dev);
	struct idxd_device *idxd = wq->idxd;
	int rc;

	if (idxd->state != IDXD_DEV_ENABLED)
		return -ENXIO;

	/*
	 * User type WQ is enabled only when SVA is enabled for two reasons:
	 *   - If no IOMMU or IOMMU Passthrough without SVA, userspace
	 *     can directly access physical address through the WQ.
	 *   - The IDXD cdev driver does not provide any ways to pin
	 *     user pages and translate the address from user VA to IOVA or
	 *     PA without IOMMU SVA. Therefore the application has no way
	 *     to instruct the device to perform DMA function. This makes
	 *     the cdev not usable for normal application usage.
	 */
	if (!device_user_pasid_enabled(idxd)) {
		idxd->cmd_status = IDXD_SCMD_WQ_USER_NO_IOMMU;
		dev_dbg(&idxd->pdev->dev,
			"User type WQ cannot be enabled without SVA.\n");

		return -EOPNOTSUPP;
	}

	mutex_lock(&wq->wq_lock);

	if (!idxd_wq_driver_name_match(wq, dev)) {
		idxd->cmd_status = IDXD_SCMD_WQ_NO_DRV_NAME;
		rc = -ENODEV;
		goto wq_err;
	}

	wq->wq = create_workqueue(dev_name(wq_confdev(wq)));
	if (!wq->wq) {
		rc = -ENOMEM;
		goto wq_err;
	}

	wq->type = IDXD_WQT_USER;
	rc = idxd_drv_enable_wq(wq);
	if (rc < 0)
		goto err;

	rc = idxd_wq_add_cdev(wq);
	if (rc < 0) {
		idxd->cmd_status = IDXD_SCMD_CDEV_ERR;
		goto err_cdev;
	}

	idxd->cmd_status = 0;
	mutex_unlock(&wq->wq_lock);
	return 0;

err_cdev:
	idxd_drv_disable_wq(wq);
err:
	destroy_workqueue(wq->wq);
	wq->type = IDXD_WQT_NONE;
wq_err:
	mutex_unlock(&wq->wq_lock);
	return rc;
}

static void idxd_user_drv_remove(struct idxd_dev *idxd_dev)
{
	struct idxd_wq *wq = idxd_dev_to_wq(idxd_dev);

	mutex_lock(&wq->wq_lock);
	idxd_wq_del_cdev(wq);
	idxd_drv_disable_wq(wq);
	wq->type = IDXD_WQT_NONE;
	destroy_workqueue(wq->wq);
	wq->wq = NULL;
	mutex_unlock(&wq->wq_lock);
}

static enum idxd_dev_type dev_types[] = {
	IDXD_DEV_WQ,
	IDXD_DEV_NONE,
};

struct idxd_device_driver idxd_user_drv = {
	.probe = idxd_user_drv_probe,
	.remove = idxd_user_drv_remove,
	.name = "user",
	.type = dev_types,
};
EXPORT_SYMBOL_GPL(idxd_user_drv);

int idxd_cdev_register(void)
{
	int rc, i;

	for (i = 0; i < IDXD_TYPE_MAX; i++) {
		ida_init(&ictx[i].minor_ida);
		rc = alloc_chrdev_region(&ictx[i].devt, 0, MINORMASK,
					 ictx[i].name);
		if (rc)
			goto err_free_chrdev_region;
	}

	return 0;

err_free_chrdev_region:
	for (i--; i >= 0; i--)
		unregister_chrdev_region(ictx[i].devt, MINORMASK);

	return rc;
}

void idxd_cdev_remove(void)
{
	int i;

	for (i = 0; i < IDXD_TYPE_MAX; i++) {
		unregister_chrdev_region(ictx[i].devt, MINORMASK);
		ida_destroy(&ictx[i].minor_ida);
	}
}

/**
 * idxd_copy_cr - copy completion record to user address space found by wq and
 *		  PASID
 * @wq:		work queue
 * @pasid:	PASID
 * @addr:	user fault address to write
 * @cr:		completion record
 * @len:	number of bytes to copy
 *
 * This is called by a work that handles completion record fault.
 *
 * Return: number of bytes copied.
 */
int idxd_copy_cr(struct idxd_wq *wq, ioasid_t pasid, unsigned long addr,
		 void *cr, int len)
{
	struct device *dev = &wq->idxd->pdev->dev;
	int left = len, status_size = 1;
	struct idxd_user_context *ctx;
	struct mm_struct *mm;

	mutex_lock(&wq->uc_lock);

	ctx = xa_load(&wq->upasid_xa, pasid);
	if (!ctx) {
		dev_warn(dev, "No user context\n");
		goto out;
	}

	mm = ctx->mm;
	/*
	 * The completion record fault handling work is running in kernel
	 * thread context. It temporarily switches to the mm to copy cr
	 * to addr in the mm.
	 */
	kthread_use_mm(mm);
	left = copy_to_user((void __user *)addr + status_size, cr + status_size,
			    len - status_size);
	/*
	 * Copy status only after the rest of completion record is copied
	 * successfully so that the user gets the complete completion record
	 * when a non-zero status is polled.
	 */
	if (!left) {
		u8 status;

		/*
		 * Ensure that the completion record's status field is written
		 * after the rest of the completion record has been written.
		 * This ensures that the user receives the correct completion
		 * record information once polling for a non-zero status.
		 */
		wmb();
		status = *(u8 *)cr;
		if (put_user(status, (u8 __user *)addr))
			left += status_size;
	} else {
		left += status_size;
	}
	kthread_unuse_mm(mm);

out:
	mutex_unlock(&wq->uc_lock);

	return len - left;
}