summaryrefslogtreecommitdiffstats
path: root/drivers/virtio/virtio_pci_modern_dev.c
blob: cbd667496bb16aed3b4d2386736f8cfabd36b35b (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
// SPDX-License-Identifier: GPL-2.0-or-later

#include <linux/virtio_pci_modern.h>
#include <linux/module.h>
#include <linux/pci.h>

/*
 * vp_modern_map_capability - map a part of virtio pci capability
 * @mdev: the modern virtio-pci device
 * @off: offset of the capability
 * @minlen: minimal length of the capability
 * @align: align requirement
 * @start: start from the capability
 * @size: map size
 * @len: the length that is actually mapped
 *
 * Returns the io address of for the part of the capability
 */
void __iomem *vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
				       size_t minlen,
				       u32 align,
				       u32 start, u32 size,
				       size_t *len)
{
	struct pci_dev *dev = mdev->pci_dev;
	u8 bar;
	u32 offset, length;
	void __iomem *p;

	pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap,
						 bar),
			     &bar);
	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
			     &offset);
	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
			      &length);

	if (length <= start) {
		dev_err(&dev->dev,
			"virtio_pci: bad capability len %u (>%u expected)\n",
			length, start);
		return NULL;
	}

	if (length - start < minlen) {
		dev_err(&dev->dev,
			"virtio_pci: bad capability len %u (>=%zu expected)\n",
			length, minlen);
		return NULL;
	}

	length -= start;

	if (start + offset < offset) {
		dev_err(&dev->dev,
			"virtio_pci: map wrap-around %u+%u\n",
			start, offset);
		return NULL;
	}

	offset += start;

	if (offset & (align - 1)) {
		dev_err(&dev->dev,
			"virtio_pci: offset %u not aligned to %u\n",
			offset, align);
		return NULL;
	}

	if (length > size)
		length = size;

	if (len)
		*len = length;

	if (minlen + offset < minlen ||
	    minlen + offset > pci_resource_len(dev, bar)) {
		dev_err(&dev->dev,
			"virtio_pci: map virtio %zu@%u "
			"out of range on bar %i length %lu\n",
			minlen, offset,
			bar, (unsigned long)pci_resource_len(dev, bar));
		return NULL;
	}

	p = pci_iomap_range(dev, bar, offset, length);
	if (!p)
		dev_err(&dev->dev,
			"virtio_pci: unable to map virtio %u@%u on bar %i\n",
			length, offset, bar);
	return p;
}
EXPORT_SYMBOL_GPL(vp_modern_map_capability);

/**
 * virtio_pci_find_capability - walk capabilities to find device info.
 * @dev: the pci device
 * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
 * @ioresource_types: IORESOURCE_MEM and/or IORESOURCE_IO.
 * @bars: the bitmask of BARs
 *
 * Returns offset of the capability, or 0.
 */
static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
					     u32 ioresource_types, int *bars)
{
	int pos;

	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
	     pos > 0;
	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
		u8 type, bar;
		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
							 cfg_type),
				     &type);
		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
							 bar),
				     &bar);

		/* Ignore structures with reserved BAR values */
		if (bar > 0x5)
			continue;

		if (type == cfg_type) {
			if (pci_resource_len(dev, bar) &&
			    pci_resource_flags(dev, bar) & ioresource_types) {
				*bars |= (1 << bar);
				return pos;
			}
		}
	}
	return 0;
}

/* This is part of the ABI.  Don't screw with it. */
static inline void check_offsets(void)
{
	/* Note: disk space was harmed in compilation of this function. */
	BUILD_BUG_ON(VIRTIO_PCI_CAP_VNDR !=
		     offsetof(struct virtio_pci_cap, cap_vndr));
	BUILD_BUG_ON(VIRTIO_PCI_CAP_NEXT !=
		     offsetof(struct virtio_pci_cap, cap_next));
	BUILD_BUG_ON(VIRTIO_PCI_CAP_LEN !=
		     offsetof(struct virtio_pci_cap, cap_len));
	BUILD_BUG_ON(VIRTIO_PCI_CAP_CFG_TYPE !=
		     offsetof(struct virtio_pci_cap, cfg_type));
	BUILD_BUG_ON(VIRTIO_PCI_CAP_BAR !=
		     offsetof(struct virtio_pci_cap, bar));
	BUILD_BUG_ON(VIRTIO_PCI_CAP_OFFSET !=
		     offsetof(struct virtio_pci_cap, offset));
	BUILD_BUG_ON(VIRTIO_PCI_CAP_LENGTH !=
		     offsetof(struct virtio_pci_cap, length));
	BUILD_BUG_ON(VIRTIO_PCI_NOTIFY_CAP_MULT !=
		     offsetof(struct virtio_pci_notify_cap,
			      notify_off_multiplier));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DFSELECT !=
		     offsetof(struct virtio_pci_common_cfg,
			      device_feature_select));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DF !=
		     offsetof(struct virtio_pci_common_cfg, device_feature));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GFSELECT !=
		     offsetof(struct virtio_pci_common_cfg,
			      guest_feature_select));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GF !=
		     offsetof(struct virtio_pci_common_cfg, guest_feature));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_MSIX !=
		     offsetof(struct virtio_pci_common_cfg, msix_config));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_NUMQ !=
		     offsetof(struct virtio_pci_common_cfg, num_queues));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_STATUS !=
		     offsetof(struct virtio_pci_common_cfg, device_status));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_CFGGENERATION !=
		     offsetof(struct virtio_pci_common_cfg, config_generation));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SELECT !=
		     offsetof(struct virtio_pci_common_cfg, queue_select));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SIZE !=
		     offsetof(struct virtio_pci_common_cfg, queue_size));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_MSIX !=
		     offsetof(struct virtio_pci_common_cfg, queue_msix_vector));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_ENABLE !=
		     offsetof(struct virtio_pci_common_cfg, queue_enable));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NOFF !=
		     offsetof(struct virtio_pci_common_cfg, queue_notify_off));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCLO !=
		     offsetof(struct virtio_pci_common_cfg, queue_desc_lo));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCHI !=
		     offsetof(struct virtio_pci_common_cfg, queue_desc_hi));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILLO !=
		     offsetof(struct virtio_pci_common_cfg, queue_avail_lo));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILHI !=
		     offsetof(struct virtio_pci_common_cfg, queue_avail_hi));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDLO !=
		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI !=
		     offsetof(struct virtio_pci_common_cfg, queue_used_hi));
}

/*
 * vp_modern_probe: probe the modern virtio pci device, note that the
 * caller is required to enable PCI device before calling this function.
 * @mdev: the modern virtio-pci device
 *
 * Return 0 on succeed otherwise fail
 */
int vp_modern_probe(struct virtio_pci_modern_device *mdev)
{
	struct pci_dev *pci_dev = mdev->pci_dev;
	int err, common, isr, notify, device;
	u32 notify_length;
	u32 notify_offset;

	check_offsets();

	mdev->pci_dev = pci_dev;

	/* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */
	if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f)
		return -ENODEV;

	if (pci_dev->device < 0x1040) {
		/* Transitional devices: use the PCI subsystem device id as
		 * virtio device id, same as legacy driver always did.
		 */
		mdev->id.device = pci_dev->subsystem_device;
	} else {
		/* Modern devices: simply use PCI device id, but start from 0x1040. */
		mdev->id.device = pci_dev->device - 0x1040;
	}
	mdev->id.vendor = pci_dev->subsystem_vendor;

	/* check for a common config: if not, use legacy mode (bar 0). */
	common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG,
					    IORESOURCE_IO | IORESOURCE_MEM,
					    &mdev->modern_bars);
	if (!common) {
		dev_info(&pci_dev->dev,
			 "virtio_pci: leaving for legacy driver\n");
		return -ENODEV;
	}

	/* If common is there, these should be too... */
	isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG,
					 IORESOURCE_IO | IORESOURCE_MEM,
					 &mdev->modern_bars);
	notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG,
					    IORESOURCE_IO | IORESOURCE_MEM,
					    &mdev->modern_bars);
	if (!isr || !notify) {
		dev_err(&pci_dev->dev,
			"virtio_pci: missing capabilities %i/%i/%i\n",
			common, isr, notify);
		return -EINVAL;
	}

	err = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(64));
	if (err)
		err = dma_set_mask_and_coherent(&pci_dev->dev,
						DMA_BIT_MASK(32));
	if (err)
		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");

	/* Device capability is only mandatory for devices that have
	 * device-specific configuration.
	 */
	device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG,
					    IORESOURCE_IO | IORESOURCE_MEM,
					    &mdev->modern_bars);

	err = pci_request_selected_regions(pci_dev, mdev->modern_bars,
					   "virtio-pci-modern");
	if (err)
		return err;

	err = -EINVAL;
	mdev->common = vp_modern_map_capability(mdev, common,
				      sizeof(struct virtio_pci_common_cfg), 4,
				      0, sizeof(struct virtio_pci_common_cfg),
				      NULL);
	if (!mdev->common)
		goto err_map_common;
	mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
					     0, 1,
					     NULL);
	if (!mdev->isr)
		goto err_map_isr;

	/* Read notify_off_multiplier from config space. */
	pci_read_config_dword(pci_dev,
			      notify + offsetof(struct virtio_pci_notify_cap,
						notify_off_multiplier),
			      &mdev->notify_offset_multiplier);
	/* Read notify length and offset from config space. */
	pci_read_config_dword(pci_dev,
			      notify + offsetof(struct virtio_pci_notify_cap,
						cap.length),
			      &notify_length);

	pci_read_config_dword(pci_dev,
			      notify + offsetof(struct virtio_pci_notify_cap,
						cap.offset),
			      &notify_offset);

	/* We don't know how many VQs we'll map, ahead of the time.
	 * If notify length is small, map it all now.
	 * Otherwise, map each VQ individually later.
	 */
	if ((u64)notify_length + (notify_offset % PAGE_SIZE) <= PAGE_SIZE) {
		mdev->notify_base = vp_modern_map_capability(mdev, notify,
							     2, 2,
							     0, notify_length,
							     &mdev->notify_len);
		if (!mdev->notify_base)
			goto err_map_notify;
	} else {
		mdev->notify_map_cap = notify;
	}

	/* Again, we don't know how much we should map, but PAGE_SIZE
	 * is more than enough for all existing devices.
	 */
	if (device) {
		mdev->device = vp_modern_map_capability(mdev, device, 0, 4,
							0, PAGE_SIZE,
							&mdev->device_len);
		if (!mdev->device)
			goto err_map_device;
	}

	return 0;

err_map_device:
	if (mdev->notify_base)
		pci_iounmap(pci_dev, mdev->notify_base);
err_map_notify:
	pci_iounmap(pci_dev, mdev->isr);
err_map_isr:
	pci_iounmap(pci_dev, mdev->common);
err_map_common:
	return err;
}
EXPORT_SYMBOL_GPL(vp_modern_probe);

/*
 * vp_modern_probe: remove and cleanup the modern virtio pci device
 * @mdev: the modern virtio-pci device
 */
void vp_modern_remove(struct virtio_pci_modern_device *mdev)
{
	struct pci_dev *pci_dev = mdev->pci_dev;

	if (mdev->device)
		pci_iounmap(pci_dev, mdev->device);
	if (mdev->notify_base)
		pci_iounmap(pci_dev, mdev->notify_base);
	pci_iounmap(pci_dev, mdev->isr);
	pci_iounmap(pci_dev, mdev->common);
	pci_release_selected_regions(pci_dev, mdev->modern_bars);
}
EXPORT_SYMBOL_GPL(vp_modern_remove);

/*
 * vp_modern_get_features - get features from device
 * @mdev: the modern virtio-pci device
 *
 * Returns the features read from the device
 */
u64 vp_modern_get_features(struct virtio_pci_modern_device *mdev)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	u64 features;

	vp_iowrite32(0, &cfg->device_feature_select);
	features = vp_ioread32(&cfg->device_feature);
	vp_iowrite32(1, &cfg->device_feature_select);
	features |= ((u64)vp_ioread32(&cfg->device_feature) << 32);

	return features;
}
EXPORT_SYMBOL_GPL(vp_modern_get_features);

/*
 * vp_modern_set_features - set features to device
 * @mdev: the modern virtio-pci device
 * @features: the features set to device
 */
void vp_modern_set_features(struct virtio_pci_modern_device *mdev,
			    u64 features)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	vp_iowrite32(0, &cfg->guest_feature_select);
	vp_iowrite32((u32)features, &cfg->guest_feature);
	vp_iowrite32(1, &cfg->guest_feature_select);
	vp_iowrite32(features >> 32, &cfg->guest_feature);
}
EXPORT_SYMBOL_GPL(vp_modern_set_features);

/*
 * vp_modern_generation - get the device genreation
 * @mdev: the modern virtio-pci device
 *
 * Returns the genreation read from device
 */
u32 vp_modern_generation(struct virtio_pci_modern_device *mdev)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	return vp_ioread8(&cfg->config_generation);
}
EXPORT_SYMBOL_GPL(vp_modern_generation);

/*
 * vp_modern_get_status - get the device status
 * @mdev: the modern virtio-pci device
 *
 * Returns the status read from device
 */
u8 vp_modern_get_status(struct virtio_pci_modern_device *mdev)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	return vp_ioread8(&cfg->device_status);
}
EXPORT_SYMBOL_GPL(vp_modern_get_status);

/*
 * vp_modern_set_status - set status to device
 * @mdev: the modern virtio-pci device
 * @status: the status set to device
 */
void vp_modern_set_status(struct virtio_pci_modern_device *mdev,
				 u8 status)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	vp_iowrite8(status, &cfg->device_status);
}
EXPORT_SYMBOL_GPL(vp_modern_set_status);

/*
 * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
 * @mdev: the modern virtio-pci device
 * @index: queue index
 * @vector: the config vector
 *
 * Returns the config vector read from the device
 */
u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
			   u16 index, u16 vector)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	vp_iowrite16(index, &cfg->queue_select);
	vp_iowrite16(vector, &cfg->queue_msix_vector);
	/* Flush the write out to device */
	return vp_ioread16(&cfg->queue_msix_vector);
}
EXPORT_SYMBOL_GPL(vp_modern_queue_vector);

/*
 * vp_modern_config_vector - set the vector for config interrupt
 * @mdev: the modern virtio-pci device
 * @vector: the config vector
 *
 * Returns the config vector read from the device
 */
u16 vp_modern_config_vector(struct virtio_pci_modern_device *mdev,
			    u16 vector)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	/* Setup the vector used for configuration events */
	vp_iowrite16(vector, &cfg->msix_config);
	/* Verify we had enough resources to assign the vector */
	/* Will also flush the write out to device */
	return vp_ioread16(&cfg->msix_config);
}
EXPORT_SYMBOL_GPL(vp_modern_config_vector);

/*
 * vp_modern_queue_address - set the virtqueue address
 * @mdev: the modern virtio-pci device
 * @index: the queue index
 * @desc_addr: address of the descriptor area
 * @driver_addr: address of the driver area
 * @device_addr: address of the device area
 */
void vp_modern_queue_address(struct virtio_pci_modern_device *mdev,
			     u16 index, u64 desc_addr, u64 driver_addr,
			     u64 device_addr)
{
	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

	vp_iowrite16(index, &cfg->queue_select);

	vp_iowrite64_twopart(desc_addr, &cfg->queue_desc_lo,
			     &cfg->queue_desc_hi);
	vp_iowrite64_twopart(driver_addr, &cfg->queue_avail_lo,
			     &cfg->queue_avail_hi);
	vp_iowrite64_twopart(device_addr, &cfg->queue_used_lo,
			     &cfg->queue_used_hi);
}
EXPORT_SYMBOL_GPL(vp_modern_queue_address);

/*
 * vp_modern_set_queue_enable - enable a virtqueue
 * @mdev: the modern virtio-pci device
 * @index: the queue index
 * @enable: whether the virtqueue is enable or not
 */
void vp_modern_set_queue_enable(struct virtio_pci_modern_device *mdev,
				u16 index, bool enable)
{
	vp_iowrite16(index, &mdev->common->queue_select);
	vp_iowrite16(enable, &mdev->common->queue_enable);
}
EXPORT_SYMBOL_GPL(vp_modern_set_queue_enable);

/*
 * vp_modern_get_queue_enable - enable a virtqueue
 * @mdev: the modern virtio-pci device
 * @index: the queue index
 *
 * Returns whether a virtqueue is enabled or not
 */
bool vp_modern_get_queue_enable(struct virtio_pci_modern_device *mdev,
				u16 index)
{
	vp_iowrite16(index, &mdev->common->queue_select);

	return vp_ioread16(&mdev->common->queue_enable);
}
EXPORT_SYMBOL_GPL(vp_modern_get_queue_enable);

/*
 * vp_modern_set_queue_size - set size for a virtqueue
 * @mdev: the modern virtio-pci device
 * @index: the queue index
 * @size: the size of the virtqueue
 */
void vp_modern_set_queue_size(struct virtio_pci_modern_device *mdev,
			      u16 index, u16 size)
{
	vp_iowrite16(index, &mdev->common->queue_select);
	vp_iowrite16(size, &mdev->common->queue_size);

}
EXPORT_SYMBOL_GPL(vp_modern_set_queue_size);

/*
 * vp_modern_get_queue_size - get size for a virtqueue
 * @mdev: the modern virtio-pci device
 * @index: the queue index
 *
 * Returns the size of the virtqueue
 */
u16 vp_modern_get_queue_size(struct virtio_pci_modern_device *mdev,
			     u16 index)
{
	vp_iowrite16(index, &mdev->common->queue_select);

	return vp_ioread16(&mdev->common->queue_size);

}
EXPORT_SYMBOL_GPL(vp_modern_get_queue_size);

/*
 * vp_modern_get_num_queues - get the number of virtqueues
 * @mdev: the modern virtio-pci device
 *
 * Returns the number of virtqueues
 */
u16 vp_modern_get_num_queues(struct virtio_pci_modern_device *mdev)
{
	return vp_ioread16(&mdev->common->num_queues);
}
EXPORT_SYMBOL_GPL(vp_modern_get_num_queues);

/*
 * vp_modern_get_queue_notify_off - get notification offset for a virtqueue
 * @mdev: the modern virtio-pci device
 * @index: the queue index
 *
 * Returns the notification offset for a virtqueue
 */
u16 vp_modern_get_queue_notify_off(struct virtio_pci_modern_device *mdev,
				   u16 index)
{
	vp_iowrite16(index, &mdev->common->queue_select);

	return vp_ioread16(&mdev->common->queue_notify_off);
}
EXPORT_SYMBOL_GPL(vp_modern_get_queue_notify_off);

MODULE_VERSION("0.1");
MODULE_DESCRIPTION("Modern Virtio PCI Device");
MODULE_AUTHOR("Jason Wang <jasowang@redhat.com>");
MODULE_LICENSE("GPL");