1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Virtio PCI driver - modern (virtio 1.0) device support
4  *
5  * This module allows virtio devices to be used over a virtual PCI device.
6  * This can be used with QEMU based VMMs like KVM or Xen.
7  *
8  * Copyright IBM Corp. 2007
9  * Copyright Red Hat, Inc. 2014
10  *
11  * Authors:
12  *  Anthony Liguori  <aliguori@us.ibm.com>
13  *  Rusty Russell <rusty@rustcorp.com.au>
14  *  Michael S. Tsirkin <mst@redhat.com>
15  */
16 
17 #include <linux/delay.h>
18 #define VIRTIO_PCI_NO_LEGACY
19 #define VIRTIO_RING_NO_LEGACY
20 #include "virtio_pci_common.h"
21 
22 /*
23  * Type-safe wrappers for io accesses.
24  * Use these to enforce at compile time the following spec requirement:
25  *
26  * The driver MUST access each field using the “natural” access
27  * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses
28  * for 16-bit fields and 8-bit accesses for 8-bit fields.
29  */
30 static inline u8 vp_ioread8(const u8 __iomem *addr)
31 {
32 	return ioread8(addr);
33 }
34 static inline u16 vp_ioread16 (const __le16 __iomem *addr)
35 {
36 	return ioread16(addr);
37 }
38 
39 static inline u32 vp_ioread32(const __le32 __iomem *addr)
40 {
41 	return ioread32(addr);
42 }
43 
44 static inline void vp_iowrite8(u8 value, u8 __iomem *addr)
45 {
46 	iowrite8(value, addr);
47 }
48 
49 static inline void vp_iowrite16(u16 value, __le16 __iomem *addr)
50 {
51 	iowrite16(value, addr);
52 }
53 
54 static inline void vp_iowrite32(u32 value, __le32 __iomem *addr)
55 {
56 	iowrite32(value, addr);
57 }
58 
59 static void vp_iowrite64_twopart(u64 val,
60 				 __le32 __iomem *lo, __le32 __iomem *hi)
61 {
62 	vp_iowrite32((u32)val, lo);
63 	vp_iowrite32(val >> 32, hi);
64 }
65 
66 static void __iomem *map_capability(struct pci_dev *dev, int off,
67 				    size_t minlen,
68 				    u32 align,
69 				    u32 start, u32 size,
70 				    size_t *len)
71 {
72 	u8 bar;
73 	u32 offset, length;
74 	void __iomem *p;
75 
76 	pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap,
77 						 bar),
78 			     &bar);
79 	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
80 			     &offset);
81 	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
82 			      &length);
83 
84 	if (length <= start) {
85 		dev_err(&dev->dev,
86 			"virtio_pci: bad capability len %u (>%u expected)\n",
87 			length, start);
88 		return NULL;
89 	}
90 
91 	if (length - start < minlen) {
92 		dev_err(&dev->dev,
93 			"virtio_pci: bad capability len %u (>=%zu expected)\n",
94 			length, minlen);
95 		return NULL;
96 	}
97 
98 	length -= start;
99 
100 	if (start + offset < offset) {
101 		dev_err(&dev->dev,
102 			"virtio_pci: map wrap-around %u+%u\n",
103 			start, offset);
104 		return NULL;
105 	}
106 
107 	offset += start;
108 
109 	if (offset & (align - 1)) {
110 		dev_err(&dev->dev,
111 			"virtio_pci: offset %u not aligned to %u\n",
112 			offset, align);
113 		return NULL;
114 	}
115 
116 	if (length > size)
117 		length = size;
118 
119 	if (len)
120 		*len = length;
121 
122 	if (minlen + offset < minlen ||
123 	    minlen + offset > pci_resource_len(dev, bar)) {
124 		dev_err(&dev->dev,
125 			"virtio_pci: map virtio %zu@%u "
126 			"out of range on bar %i length %lu\n",
127 			minlen, offset,
128 			bar, (unsigned long)pci_resource_len(dev, bar));
129 		return NULL;
130 	}
131 
132 	p = pci_iomap_range(dev, bar, offset, length);
133 	if (!p)
134 		dev_err(&dev->dev,
135 			"virtio_pci: unable to map virtio %u@%u on bar %i\n",
136 			length, offset, bar);
137 	return p;
138 }
139 
140 /* virtio config->get_features() implementation */
141 static u64 vp_get_features(struct virtio_device *vdev)
142 {
143 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
144 	u64 features;
145 
146 	vp_iowrite32(0, &vp_dev->common->device_feature_select);
147 	features = vp_ioread32(&vp_dev->common->device_feature);
148 	vp_iowrite32(1, &vp_dev->common->device_feature_select);
149 	features |= ((u64)vp_ioread32(&vp_dev->common->device_feature) << 32);
150 
151 	return features;
152 }
153 
154 static void vp_transport_features(struct virtio_device *vdev, u64 features)
155 {
156 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
157 	struct pci_dev *pci_dev = vp_dev->pci_dev;
158 
159 	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
160 			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
161 		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
162 }
163 
164 /* virtio config->finalize_features() implementation */
165 static int vp_finalize_features(struct virtio_device *vdev)
166 {
167 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
168 	u64 features = vdev->features;
169 
170 	/* Give virtio_ring a chance to accept features. */
171 	vring_transport_features(vdev);
172 
173 	/* Give virtio_pci a chance to accept features. */
174 	vp_transport_features(vdev, features);
175 
176 	if (!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
177 		dev_err(&vdev->dev, "virtio: device uses modern interface "
178 			"but does not have VIRTIO_F_VERSION_1\n");
179 		return -EINVAL;
180 	}
181 
182 	vp_iowrite32(0, &vp_dev->common->guest_feature_select);
183 	vp_iowrite32((u32)vdev->features, &vp_dev->common->guest_feature);
184 	vp_iowrite32(1, &vp_dev->common->guest_feature_select);
185 	vp_iowrite32(vdev->features >> 32, &vp_dev->common->guest_feature);
186 
187 	return 0;
188 }
189 
190 /* virtio config->get() implementation */
191 static void vp_get(struct virtio_device *vdev, unsigned offset,
192 		   void *buf, unsigned len)
193 {
194 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
195 	u8 b;
196 	__le16 w;
197 	__le32 l;
198 
199 	BUG_ON(offset + len > vp_dev->device_len);
200 
201 	switch (len) {
202 	case 1:
203 		b = ioread8(vp_dev->device + offset);
204 		memcpy(buf, &b, sizeof b);
205 		break;
206 	case 2:
207 		w = cpu_to_le16(ioread16(vp_dev->device + offset));
208 		memcpy(buf, &w, sizeof w);
209 		break;
210 	case 4:
211 		l = cpu_to_le32(ioread32(vp_dev->device + offset));
212 		memcpy(buf, &l, sizeof l);
213 		break;
214 	case 8:
215 		l = cpu_to_le32(ioread32(vp_dev->device + offset));
216 		memcpy(buf, &l, sizeof l);
217 		l = cpu_to_le32(ioread32(vp_dev->device + offset + sizeof l));
218 		memcpy(buf + sizeof l, &l, sizeof l);
219 		break;
220 	default:
221 		BUG();
222 	}
223 }
224 
225 /* the config->set() implementation.  it's symmetric to the config->get()
226  * implementation */
227 static void vp_set(struct virtio_device *vdev, unsigned offset,
228 		   const void *buf, unsigned len)
229 {
230 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
231 	u8 b;
232 	__le16 w;
233 	__le32 l;
234 
235 	BUG_ON(offset + len > vp_dev->device_len);
236 
237 	switch (len) {
238 	case 1:
239 		memcpy(&b, buf, sizeof b);
240 		iowrite8(b, vp_dev->device + offset);
241 		break;
242 	case 2:
243 		memcpy(&w, buf, sizeof w);
244 		iowrite16(le16_to_cpu(w), vp_dev->device + offset);
245 		break;
246 	case 4:
247 		memcpy(&l, buf, sizeof l);
248 		iowrite32(le32_to_cpu(l), vp_dev->device + offset);
249 		break;
250 	case 8:
251 		memcpy(&l, buf, sizeof l);
252 		iowrite32(le32_to_cpu(l), vp_dev->device + offset);
253 		memcpy(&l, buf + sizeof l, sizeof l);
254 		iowrite32(le32_to_cpu(l), vp_dev->device + offset + sizeof l);
255 		break;
256 	default:
257 		BUG();
258 	}
259 }
260 
261 static u32 vp_generation(struct virtio_device *vdev)
262 {
263 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
264 	return vp_ioread8(&vp_dev->common->config_generation);
265 }
266 
267 /* config->{get,set}_status() implementations */
268 static u8 vp_get_status(struct virtio_device *vdev)
269 {
270 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
271 	return vp_ioread8(&vp_dev->common->device_status);
272 }
273 
274 static void vp_set_status(struct virtio_device *vdev, u8 status)
275 {
276 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
277 	/* We should never be setting status to 0. */
278 	BUG_ON(status == 0);
279 	vp_iowrite8(status, &vp_dev->common->device_status);
280 }
281 
282 static void vp_reset(struct virtio_device *vdev)
283 {
284 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
285 	/* 0 status means a reset. */
286 	vp_iowrite8(0, &vp_dev->common->device_status);
287 	/* After writing 0 to device_status, the driver MUST wait for a read of
288 	 * device_status to return 0 before reinitializing the device.
289 	 * This will flush out the status write, and flush in device writes,
290 	 * including MSI-X interrupts, if any.
291 	 */
292 	while (vp_ioread8(&vp_dev->common->device_status))
293 		msleep(1);
294 	/* Flush pending VQ/configuration callbacks. */
295 	vp_synchronize_vectors(vdev);
296 }
297 
298 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
299 {
300 	/* Setup the vector used for configuration events */
301 	vp_iowrite16(vector, &vp_dev->common->msix_config);
302 	/* Verify we had enough resources to assign the vector */
303 	/* Will also flush the write out to device */
304 	return vp_ioread16(&vp_dev->common->msix_config);
305 }
306 
307 static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
308 				  struct virtio_pci_vq_info *info,
309 				  unsigned index,
310 				  void (*callback)(struct virtqueue *vq),
311 				  const char *name,
312 				  bool ctx,
313 				  u16 msix_vec)
314 {
315 	struct virtio_pci_common_cfg __iomem *cfg = vp_dev->common;
316 	struct virtqueue *vq;
317 	u16 num, off;
318 	int err;
319 
320 	if (index >= vp_ioread16(&cfg->num_queues))
321 		return ERR_PTR(-ENOENT);
322 
323 	/* Select the queue we're interested in */
324 	vp_iowrite16(index, &cfg->queue_select);
325 
326 	/* Check if queue is either not available or already active. */
327 	num = vp_ioread16(&cfg->queue_size);
328 	if (!num || vp_ioread16(&cfg->queue_enable))
329 		return ERR_PTR(-ENOENT);
330 
331 	if (num & (num - 1)) {
332 		dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u", num);
333 		return ERR_PTR(-EINVAL);
334 	}
335 
336 	/* get offset of notification word for this vq */
337 	off = vp_ioread16(&cfg->queue_notify_off);
338 
339 	info->msix_vector = msix_vec;
340 
341 	/* create the vring */
342 	vq = vring_create_virtqueue(index, num,
343 				    SMP_CACHE_BYTES, &vp_dev->vdev,
344 				    true, true, ctx,
345 				    vp_notify, callback, name);
346 	if (!vq)
347 		return ERR_PTR(-ENOMEM);
348 
349 	/* activate the queue */
350 	vp_iowrite16(virtqueue_get_vring_size(vq), &cfg->queue_size);
351 	vp_iowrite64_twopart(virtqueue_get_desc_addr(vq),
352 			     &cfg->queue_desc_lo, &cfg->queue_desc_hi);
353 	vp_iowrite64_twopart(virtqueue_get_avail_addr(vq),
354 			     &cfg->queue_avail_lo, &cfg->queue_avail_hi);
355 	vp_iowrite64_twopart(virtqueue_get_used_addr(vq),
356 			     &cfg->queue_used_lo, &cfg->queue_used_hi);
357 
358 	if (vp_dev->notify_base) {
359 		/* offset should not wrap */
360 		if ((u64)off * vp_dev->notify_offset_multiplier + 2
361 		    > vp_dev->notify_len) {
362 			dev_warn(&vp_dev->pci_dev->dev,
363 				 "bad notification offset %u (x %u) "
364 				 "for queue %u > %zd",
365 				 off, vp_dev->notify_offset_multiplier,
366 				 index, vp_dev->notify_len);
367 			err = -EINVAL;
368 			goto err_map_notify;
369 		}
370 		vq->priv = (void __force *)vp_dev->notify_base +
371 			off * vp_dev->notify_offset_multiplier;
372 	} else {
373 		vq->priv = (void __force *)map_capability(vp_dev->pci_dev,
374 					  vp_dev->notify_map_cap, 2, 2,
375 					  off * vp_dev->notify_offset_multiplier, 2,
376 					  NULL);
377 	}
378 
379 	if (!vq->priv) {
380 		err = -ENOMEM;
381 		goto err_map_notify;
382 	}
383 
384 	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
385 		vp_iowrite16(msix_vec, &cfg->queue_msix_vector);
386 		msix_vec = vp_ioread16(&cfg->queue_msix_vector);
387 		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
388 			err = -EBUSY;
389 			goto err_assign_vector;
390 		}
391 	}
392 
393 	return vq;
394 
395 err_assign_vector:
396 	if (!vp_dev->notify_base)
397 		pci_iounmap(vp_dev->pci_dev, (void __iomem __force *)vq->priv);
398 err_map_notify:
399 	vring_del_virtqueue(vq);
400 	return ERR_PTR(err);
401 }
402 
403 static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned nvqs,
404 			      struct virtqueue *vqs[],
405 			      vq_callback_t *callbacks[],
406 			      const char * const names[], const bool *ctx,
407 			      struct irq_affinity *desc)
408 {
409 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
410 	struct virtqueue *vq;
411 	int rc = vp_find_vqs(vdev, nvqs, vqs, callbacks, names, ctx, desc);
412 
413 	if (rc)
414 		return rc;
415 
416 	/* Select and activate all queues. Has to be done last: once we do
417 	 * this, there's no way to go back except reset.
418 	 */
419 	list_for_each_entry(vq, &vdev->vqs, list) {
420 		vp_iowrite16(vq->index, &vp_dev->common->queue_select);
421 		vp_iowrite16(1, &vp_dev->common->queue_enable);
422 	}
423 
424 	return 0;
425 }
426 
427 static void del_vq(struct virtio_pci_vq_info *info)
428 {
429 	struct virtqueue *vq = info->vq;
430 	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
431 
432 	vp_iowrite16(vq->index, &vp_dev->common->queue_select);
433 
434 	if (vp_dev->msix_enabled) {
435 		vp_iowrite16(VIRTIO_MSI_NO_VECTOR,
436 			     &vp_dev->common->queue_msix_vector);
437 		/* Flush the write out to device */
438 		vp_ioread16(&vp_dev->common->queue_msix_vector);
439 	}
440 
441 	if (!vp_dev->notify_base)
442 		pci_iounmap(vp_dev->pci_dev, (void __force __iomem *)vq->priv);
443 
444 	vring_del_virtqueue(vq);
445 }
446 
447 static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
448 	.get		= NULL,
449 	.set		= NULL,
450 	.generation	= vp_generation,
451 	.get_status	= vp_get_status,
452 	.set_status	= vp_set_status,
453 	.reset		= vp_reset,
454 	.find_vqs	= vp_modern_find_vqs,
455 	.del_vqs	= vp_del_vqs,
456 	.get_features	= vp_get_features,
457 	.finalize_features = vp_finalize_features,
458 	.bus_name	= vp_bus_name,
459 	.set_vq_affinity = vp_set_vq_affinity,
460 	.get_vq_affinity = vp_get_vq_affinity,
461 };
462 
463 static const struct virtio_config_ops virtio_pci_config_ops = {
464 	.get		= vp_get,
465 	.set		= vp_set,
466 	.generation	= vp_generation,
467 	.get_status	= vp_get_status,
468 	.set_status	= vp_set_status,
469 	.reset		= vp_reset,
470 	.find_vqs	= vp_modern_find_vqs,
471 	.del_vqs	= vp_del_vqs,
472 	.get_features	= vp_get_features,
473 	.finalize_features = vp_finalize_features,
474 	.bus_name	= vp_bus_name,
475 	.set_vq_affinity = vp_set_vq_affinity,
476 	.get_vq_affinity = vp_get_vq_affinity,
477 };
478 
479 /**
480  * virtio_pci_find_capability - walk capabilities to find device info.
481  * @dev: the pci device
482  * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
483  * @ioresource_types: IORESOURCE_MEM and/or IORESOURCE_IO.
484  * @bars: the bitmask of BARs
485  *
486  * Returns offset of the capability, or 0.
487  */
488 static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
489 					     u32 ioresource_types, int *bars)
490 {
491 	int pos;
492 
493 	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
494 	     pos > 0;
495 	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
496 		u8 type, bar;
497 		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
498 							 cfg_type),
499 				     &type);
500 		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
501 							 bar),
502 				     &bar);
503 
504 		/* Ignore structures with reserved BAR values */
505 		if (bar > 0x5)
506 			continue;
507 
508 		if (type == cfg_type) {
509 			if (pci_resource_len(dev, bar) &&
510 			    pci_resource_flags(dev, bar) & ioresource_types) {
511 				*bars |= (1 << bar);
512 				return pos;
513 			}
514 		}
515 	}
516 	return 0;
517 }
518 
519 /* This is part of the ABI.  Don't screw with it. */
520 static inline void check_offsets(void)
521 {
522 	/* Note: disk space was harmed in compilation of this function. */
523 	BUILD_BUG_ON(VIRTIO_PCI_CAP_VNDR !=
524 		     offsetof(struct virtio_pci_cap, cap_vndr));
525 	BUILD_BUG_ON(VIRTIO_PCI_CAP_NEXT !=
526 		     offsetof(struct virtio_pci_cap, cap_next));
527 	BUILD_BUG_ON(VIRTIO_PCI_CAP_LEN !=
528 		     offsetof(struct virtio_pci_cap, cap_len));
529 	BUILD_BUG_ON(VIRTIO_PCI_CAP_CFG_TYPE !=
530 		     offsetof(struct virtio_pci_cap, cfg_type));
531 	BUILD_BUG_ON(VIRTIO_PCI_CAP_BAR !=
532 		     offsetof(struct virtio_pci_cap, bar));
533 	BUILD_BUG_ON(VIRTIO_PCI_CAP_OFFSET !=
534 		     offsetof(struct virtio_pci_cap, offset));
535 	BUILD_BUG_ON(VIRTIO_PCI_CAP_LENGTH !=
536 		     offsetof(struct virtio_pci_cap, length));
537 	BUILD_BUG_ON(VIRTIO_PCI_NOTIFY_CAP_MULT !=
538 		     offsetof(struct virtio_pci_notify_cap,
539 			      notify_off_multiplier));
540 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DFSELECT !=
541 		     offsetof(struct virtio_pci_common_cfg,
542 			      device_feature_select));
543 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DF !=
544 		     offsetof(struct virtio_pci_common_cfg, device_feature));
545 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GFSELECT !=
546 		     offsetof(struct virtio_pci_common_cfg,
547 			      guest_feature_select));
548 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GF !=
549 		     offsetof(struct virtio_pci_common_cfg, guest_feature));
550 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_MSIX !=
551 		     offsetof(struct virtio_pci_common_cfg, msix_config));
552 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_NUMQ !=
553 		     offsetof(struct virtio_pci_common_cfg, num_queues));
554 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_STATUS !=
555 		     offsetof(struct virtio_pci_common_cfg, device_status));
556 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_CFGGENERATION !=
557 		     offsetof(struct virtio_pci_common_cfg, config_generation));
558 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SELECT !=
559 		     offsetof(struct virtio_pci_common_cfg, queue_select));
560 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SIZE !=
561 		     offsetof(struct virtio_pci_common_cfg, queue_size));
562 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_MSIX !=
563 		     offsetof(struct virtio_pci_common_cfg, queue_msix_vector));
564 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_ENABLE !=
565 		     offsetof(struct virtio_pci_common_cfg, queue_enable));
566 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NOFF !=
567 		     offsetof(struct virtio_pci_common_cfg, queue_notify_off));
568 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCLO !=
569 		     offsetof(struct virtio_pci_common_cfg, queue_desc_lo));
570 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCHI !=
571 		     offsetof(struct virtio_pci_common_cfg, queue_desc_hi));
572 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILLO !=
573 		     offsetof(struct virtio_pci_common_cfg, queue_avail_lo));
574 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILHI !=
575 		     offsetof(struct virtio_pci_common_cfg, queue_avail_hi));
576 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDLO !=
577 		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
578 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI !=
579 		     offsetof(struct virtio_pci_common_cfg, queue_used_hi));
580 }
581 
582 /* the PCI probing function */
583 int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev)
584 {
585 	struct pci_dev *pci_dev = vp_dev->pci_dev;
586 	int err, common, isr, notify, device;
587 	u32 notify_length;
588 	u32 notify_offset;
589 
590 	check_offsets();
591 
592 	/* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */
593 	if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f)
594 		return -ENODEV;
595 
596 	if (pci_dev->device < 0x1040) {
597 		/* Transitional devices: use the PCI subsystem device id as
598 		 * virtio device id, same as legacy driver always did.
599 		 */
600 		vp_dev->vdev.id.device = pci_dev->subsystem_device;
601 	} else {
602 		/* Modern devices: simply use PCI device id, but start from 0x1040. */
603 		vp_dev->vdev.id.device = pci_dev->device - 0x1040;
604 	}
605 	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
606 
607 	/* check for a common config: if not, use legacy mode (bar 0). */
608 	common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG,
609 					    IORESOURCE_IO | IORESOURCE_MEM,
610 					    &vp_dev->modern_bars);
611 	if (!common) {
612 		dev_info(&pci_dev->dev,
613 			 "virtio_pci: leaving for legacy driver\n");
614 		return -ENODEV;
615 	}
616 
617 	/* If common is there, these should be too... */
618 	isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG,
619 					 IORESOURCE_IO | IORESOURCE_MEM,
620 					 &vp_dev->modern_bars);
621 	notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG,
622 					    IORESOURCE_IO | IORESOURCE_MEM,
623 					    &vp_dev->modern_bars);
624 	if (!isr || !notify) {
625 		dev_err(&pci_dev->dev,
626 			"virtio_pci: missing capabilities %i/%i/%i\n",
627 			common, isr, notify);
628 		return -EINVAL;
629 	}
630 
631 	err = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(64));
632 	if (err)
633 		err = dma_set_mask_and_coherent(&pci_dev->dev,
634 						DMA_BIT_MASK(32));
635 	if (err)
636 		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
637 
638 	/* Device capability is only mandatory for devices that have
639 	 * device-specific configuration.
640 	 */
641 	device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG,
642 					    IORESOURCE_IO | IORESOURCE_MEM,
643 					    &vp_dev->modern_bars);
644 
645 	err = pci_request_selected_regions(pci_dev, vp_dev->modern_bars,
646 					   "virtio-pci-modern");
647 	if (err)
648 		return err;
649 
650 	err = -EINVAL;
651 	vp_dev->common = map_capability(pci_dev, common,
652 					sizeof(struct virtio_pci_common_cfg), 4,
653 					0, sizeof(struct virtio_pci_common_cfg),
654 					NULL);
655 	if (!vp_dev->common)
656 		goto err_map_common;
657 	vp_dev->isr = map_capability(pci_dev, isr, sizeof(u8), 1,
658 				     0, 1,
659 				     NULL);
660 	if (!vp_dev->isr)
661 		goto err_map_isr;
662 
663 	/* Read notify_off_multiplier from config space. */
664 	pci_read_config_dword(pci_dev,
665 			      notify + offsetof(struct virtio_pci_notify_cap,
666 						notify_off_multiplier),
667 			      &vp_dev->notify_offset_multiplier);
668 	/* Read notify length and offset from config space. */
669 	pci_read_config_dword(pci_dev,
670 			      notify + offsetof(struct virtio_pci_notify_cap,
671 						cap.length),
672 			      &notify_length);
673 
674 	pci_read_config_dword(pci_dev,
675 			      notify + offsetof(struct virtio_pci_notify_cap,
676 						cap.offset),
677 			      &notify_offset);
678 
679 	/* We don't know how many VQs we'll map, ahead of the time.
680 	 * If notify length is small, map it all now.
681 	 * Otherwise, map each VQ individually later.
682 	 */
683 	if ((u64)notify_length + (notify_offset % PAGE_SIZE) <= PAGE_SIZE) {
684 		vp_dev->notify_base = map_capability(pci_dev, notify, 2, 2,
685 						     0, notify_length,
686 						     &vp_dev->notify_len);
687 		if (!vp_dev->notify_base)
688 			goto err_map_notify;
689 	} else {
690 		vp_dev->notify_map_cap = notify;
691 	}
692 
693 	/* Again, we don't know how much we should map, but PAGE_SIZE
694 	 * is more than enough for all existing devices.
695 	 */
696 	if (device) {
697 		vp_dev->device = map_capability(pci_dev, device, 0, 4,
698 						0, PAGE_SIZE,
699 						&vp_dev->device_len);
700 		if (!vp_dev->device)
701 			goto err_map_device;
702 
703 		vp_dev->vdev.config = &virtio_pci_config_ops;
704 	} else {
705 		vp_dev->vdev.config = &virtio_pci_config_nodev_ops;
706 	}
707 
708 	vp_dev->config_vector = vp_config_vector;
709 	vp_dev->setup_vq = setup_vq;
710 	vp_dev->del_vq = del_vq;
711 
712 	return 0;
713 
714 err_map_device:
715 	if (vp_dev->notify_base)
716 		pci_iounmap(pci_dev, vp_dev->notify_base);
717 err_map_notify:
718 	pci_iounmap(pci_dev, vp_dev->isr);
719 err_map_isr:
720 	pci_iounmap(pci_dev, vp_dev->common);
721 err_map_common:
722 	return err;
723 }
724 
725 void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev)
726 {
727 	struct pci_dev *pci_dev = vp_dev->pci_dev;
728 
729 	if (vp_dev->device)
730 		pci_iounmap(pci_dev, vp_dev->device);
731 	if (vp_dev->notify_base)
732 		pci_iounmap(pci_dev, vp_dev->notify_base);
733 	pci_iounmap(pci_dev, vp_dev->isr);
734 	pci_iounmap(pci_dev, vp_dev->common);
735 	pci_release_selected_regions(pci_dev, vp_dev->modern_bars);
736 }
737