1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/virtio.h>
3#include <linux/spinlock.h>
4#include <linux/virtio_config.h>
5#include <linux/virtio_anchor.h>
6#include <linux/module.h>
7#include <linux/idr.h>
8#include <linux/of.h>
9#include <uapi/linux/virtio_ids.h>
10
11/* Unique numbering for virtio devices. */
12static DEFINE_IDA(virtio_index_ida);
13
14static ssize_t device_show(struct device *_d,
15 struct device_attribute *attr, char *buf)
16{
17 struct virtio_device *dev = dev_to_virtio(_d);
18 return sysfs_emit(buf, fmt: "0x%04x\n", dev->id.device);
19}
20static DEVICE_ATTR_RO(device);
21
22static ssize_t vendor_show(struct device *_d,
23 struct device_attribute *attr, char *buf)
24{
25 struct virtio_device *dev = dev_to_virtio(_d);
26 return sysfs_emit(buf, fmt: "0x%04x\n", dev->id.vendor);
27}
28static DEVICE_ATTR_RO(vendor);
29
30static ssize_t status_show(struct device *_d,
31 struct device_attribute *attr, char *buf)
32{
33 struct virtio_device *dev = dev_to_virtio(_d);
34 return sysfs_emit(buf, fmt: "0x%08x\n", dev->config->get_status(dev));
35}
36static DEVICE_ATTR_RO(status);
37
38static ssize_t modalias_show(struct device *_d,
39 struct device_attribute *attr, char *buf)
40{
41 struct virtio_device *dev = dev_to_virtio(_d);
42 return sysfs_emit(buf, fmt: "virtio:d%08Xv%08X\n",
43 dev->id.device, dev->id.vendor);
44}
45static DEVICE_ATTR_RO(modalias);
46
47static ssize_t features_show(struct device *_d,
48 struct device_attribute *attr, char *buf)
49{
50 struct virtio_device *dev = dev_to_virtio(_d);
51 unsigned int i;
52 ssize_t len = 0;
53
54 /* We actually represent this as a bitstring, as it could be
55 * arbitrary length in future. */
56 for (i = 0; i < VIRTIO_FEATURES_BITS; i++)
57 len += sysfs_emit_at(buf, at: len, fmt: "%c",
58 __virtio_test_bit(vdev: dev, fbit: i) ? '1' : '0');
59 len += sysfs_emit_at(buf, at: len, fmt: "\n");
60 return len;
61}
62static DEVICE_ATTR_RO(features);
63
64static struct attribute *virtio_dev_attrs[] = {
65 &dev_attr_device.attr,
66 &dev_attr_vendor.attr,
67 &dev_attr_status.attr,
68 &dev_attr_modalias.attr,
69 &dev_attr_features.attr,
70 NULL,
71};
72ATTRIBUTE_GROUPS(virtio_dev);
73
74static inline int virtio_id_match(const struct virtio_device *dev,
75 const struct virtio_device_id *id)
76{
77 if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
78 return 0;
79
80 return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
81}
82
83/* This looks through all the IDs a driver claims to support. If any of them
84 * match, we return 1 and the kernel will call virtio_dev_probe(). */
85static int virtio_dev_match(struct device *_dv, const struct device_driver *_dr)
86{
87 unsigned int i;
88 struct virtio_device *dev = dev_to_virtio(_dv);
89 const struct virtio_device_id *ids;
90
91 ids = drv_to_virtio(_dr)->id_table;
92 for (i = 0; ids[i].device; i++)
93 if (virtio_id_match(dev, id: &ids[i]))
94 return 1;
95 return 0;
96}
97
98static int virtio_uevent(const struct device *_dv, struct kobj_uevent_env *env)
99{
100 const struct virtio_device *dev = dev_to_virtio(_dv);
101
102 return add_uevent_var(env, format: "MODALIAS=virtio:d%08Xv%08X",
103 dev->id.device, dev->id.vendor);
104}
105
106void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
107 unsigned int fbit)
108{
109 unsigned int i;
110 struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
111
112 for (i = 0; i < drv->feature_table_size; i++)
113 if (drv->feature_table[i] == fbit)
114 return;
115
116 if (drv->feature_table_legacy) {
117 for (i = 0; i < drv->feature_table_size_legacy; i++)
118 if (drv->feature_table_legacy[i] == fbit)
119 return;
120 }
121
122 BUG();
123}
124EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
125
126static void __virtio_config_changed(struct virtio_device *dev)
127{
128 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
129
130 if (!dev->config_core_enabled || dev->config_driver_disabled)
131 dev->config_change_pending = true;
132 else if (drv && drv->config_changed) {
133 drv->config_changed(dev);
134 dev->config_change_pending = false;
135 }
136}
137
138void virtio_config_changed(struct virtio_device *dev)
139{
140 unsigned long flags;
141
142 spin_lock_irqsave(&dev->config_lock, flags);
143 __virtio_config_changed(dev);
144 spin_unlock_irqrestore(lock: &dev->config_lock, flags);
145}
146EXPORT_SYMBOL_GPL(virtio_config_changed);
147
148/**
149 * virtio_config_driver_disable - disable config change reporting by drivers
150 * @dev: the device to disable
151 *
152 * This is only allowed to be called by a driver and disabling can't
153 * be nested.
154 */
155void virtio_config_driver_disable(struct virtio_device *dev)
156{
157 spin_lock_irq(lock: &dev->config_lock);
158 dev->config_driver_disabled = true;
159 spin_unlock_irq(lock: &dev->config_lock);
160}
161EXPORT_SYMBOL_GPL(virtio_config_driver_disable);
162
163/**
164 * virtio_config_driver_enable - enable config change reporting by drivers
165 * @dev: the device to enable
166 *
167 * This is only allowed to be called by a driver and enabling can't
168 * be nested.
169 */
170void virtio_config_driver_enable(struct virtio_device *dev)
171{
172 spin_lock_irq(lock: &dev->config_lock);
173 dev->config_driver_disabled = false;
174 if (dev->config_change_pending)
175 __virtio_config_changed(dev);
176 spin_unlock_irq(lock: &dev->config_lock);
177}
178EXPORT_SYMBOL_GPL(virtio_config_driver_enable);
179
180static void virtio_config_core_disable(struct virtio_device *dev)
181{
182 spin_lock_irq(lock: &dev->config_lock);
183 dev->config_core_enabled = false;
184 spin_unlock_irq(lock: &dev->config_lock);
185}
186
187static void virtio_config_core_enable(struct virtio_device *dev)
188{
189 spin_lock_irq(lock: &dev->config_lock);
190 dev->config_core_enabled = true;
191 if (dev->config_change_pending)
192 __virtio_config_changed(dev);
193 spin_unlock_irq(lock: &dev->config_lock);
194}
195
196void virtio_add_status(struct virtio_device *dev, unsigned int status)
197{
198 might_sleep();
199 dev->config->set_status(dev, dev->config->get_status(dev) | status);
200}
201EXPORT_SYMBOL_GPL(virtio_add_status);
202
203/* Do some validation, then set FEATURES_OK */
204static int virtio_features_ok(struct virtio_device *dev)
205{
206 unsigned int status;
207
208 might_sleep();
209
210 if (virtio_check_mem_acc_cb(dev)) {
211 if (!virtio_has_feature(vdev: dev, VIRTIO_F_VERSION_1)) {
212 dev_warn(&dev->dev,
213 "device must provide VIRTIO_F_VERSION_1\n");
214 return -ENODEV;
215 }
216
217 if (!virtio_has_feature(vdev: dev, VIRTIO_F_ACCESS_PLATFORM)) {
218 dev_warn(&dev->dev,
219 "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
220 return -ENODEV;
221 }
222 }
223
224 if (!virtio_has_feature(vdev: dev, VIRTIO_F_VERSION_1))
225 return 0;
226
227 virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
228 status = dev->config->get_status(dev);
229 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
230 dev_err(&dev->dev, "virtio: device refuses features: %x\n",
231 status);
232 return -ENODEV;
233 }
234 return 0;
235}
236
237/**
238 * virtio_reset_device - quiesce device for removal
239 * @dev: the device to reset
240 *
241 * Prevents device from sending interrupts and accessing memory.
242 *
243 * Generally used for cleanup during driver / device removal.
244 *
245 * Once this has been invoked, caller must ensure that
246 * virtqueue_notify / virtqueue_kick are not in progress.
247 *
248 * Note: this guarantees that vq callbacks are not in progress, however caller
249 * is responsible for preventing access from other contexts, such as a system
250 * call/workqueue/bh. Invoking virtio_break_device then flushing any such
251 * contexts is one way to handle that.
252 * */
253void virtio_reset_device(struct virtio_device *dev)
254{
255#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
256 /*
257 * The below virtio_synchronize_cbs() guarantees that any
258 * interrupt for this line arriving after
259 * virtio_synchronize_vqs() has completed is guaranteed to see
260 * vq->broken as true.
261 */
262 virtio_break_device(dev);
263 virtio_synchronize_cbs(dev);
264#endif
265
266 dev->config->reset(dev);
267}
268EXPORT_SYMBOL_GPL(virtio_reset_device);
269
270static int virtio_dev_probe(struct device *_d)
271{
272 int err, i;
273 struct virtio_device *dev = dev_to_virtio(_d);
274 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
275 u64 device_features[VIRTIO_FEATURES_U64S];
276 u64 driver_features[VIRTIO_FEATURES_U64S];
277 u64 driver_features_legacy;
278
279 /* We have a driver! */
280 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
281
282 /* Figure out what features the device supports. */
283 virtio_get_features(vdev: dev, features_out: device_features);
284
285 /* Figure out what features the driver supports. */
286 virtio_features_zero(features: driver_features);
287 for (i = 0; i < drv->feature_table_size; i++) {
288 unsigned int f = drv->feature_table[i];
289 if (!WARN_ON_ONCE(f >= VIRTIO_FEATURES_BITS))
290 virtio_features_set_bit(features: driver_features, bit: f);
291 }
292
293 /* Some drivers have a separate feature table for virtio v1.0 */
294 if (drv->feature_table_legacy) {
295 driver_features_legacy = 0;
296 for (i = 0; i < drv->feature_table_size_legacy; i++) {
297 unsigned int f = drv->feature_table_legacy[i];
298 if (!WARN_ON_ONCE(f >= 64))
299 driver_features_legacy |= (1ULL << f);
300 }
301 } else {
302 driver_features_legacy = driver_features[0];
303 }
304
305 if (virtio_features_test_bit(features: device_features, VIRTIO_F_VERSION_1)) {
306 for (i = 0; i < VIRTIO_FEATURES_U64S; ++i)
307 dev->features_array[i] = driver_features[i] &
308 device_features[i];
309 } else {
310 virtio_features_from_u64(features: dev->features_array,
311 from: driver_features_legacy &
312 device_features[0]);
313 }
314
315 /* When debugging, user may filter some features by hand. */
316 virtio_debug_device_filter_features(dev);
317
318 /* Transport features always preserved to pass to finalize_features. */
319 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
320 if (virtio_features_test_bit(features: device_features, bit: i))
321 __virtio_set_bit(vdev: dev, fbit: i);
322
323 err = dev->config->finalize_features(dev);
324 if (err)
325 goto err;
326
327 if (drv->validate) {
328 u64 features[VIRTIO_FEATURES_U64S];
329
330 virtio_features_copy(to: features, from: dev->features_array);
331 err = drv->validate(dev);
332 if (err)
333 goto err;
334
335 /* Did validation change any features? Then write them again. */
336 if (!virtio_features_equal(f1: features, f2: dev->features_array)) {
337 err = dev->config->finalize_features(dev);
338 if (err)
339 goto err;
340 }
341 }
342
343 err = virtio_features_ok(dev);
344 if (err)
345 goto err;
346
347 err = drv->probe(dev);
348 if (err)
349 goto err;
350
351 /* If probe didn't do it, mark device DRIVER_OK ourselves. */
352 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
353 virtio_device_ready(dev);
354
355 if (drv->scan)
356 drv->scan(dev);
357
358 virtio_config_core_enable(dev);
359
360 return 0;
361
362err:
363 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
364 return err;
365
366}
367
368static void virtio_dev_remove(struct device *_d)
369{
370 struct virtio_device *dev = dev_to_virtio(_d);
371 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
372
373 virtio_config_core_disable(dev);
374
375 drv->remove(dev);
376
377 /* Driver should have reset device. */
378 WARN_ON_ONCE(dev->config->get_status(dev));
379
380 /* Acknowledge the device's existence again. */
381 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
382
383 of_node_put(node: dev->dev.of_node);
384}
385
386/*
387 * virtio_irq_get_affinity - get IRQ affinity mask for device
388 * @_d: ptr to dev structure
389 * @irq_vec: interrupt vector number
390 *
391 * Return the CPU affinity mask for @_d and @irq_vec.
392 */
393static const struct cpumask *virtio_irq_get_affinity(struct device *_d,
394 unsigned int irq_vec)
395{
396 struct virtio_device *dev = dev_to_virtio(_d);
397
398 if (!dev->config->get_vq_affinity)
399 return NULL;
400
401 return dev->config->get_vq_affinity(dev, irq_vec);
402}
403
404static void virtio_dev_shutdown(struct device *_d)
405{
406 struct virtio_device *dev = dev_to_virtio(_d);
407 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
408
409 /*
410 * Stop accesses to or from the device.
411 * We only need to do it if there's a driver - no accesses otherwise.
412 */
413 if (!drv)
414 return;
415
416 /* If the driver has its own shutdown method, use that. */
417 if (drv->shutdown) {
418 drv->shutdown(dev);
419 return;
420 }
421
422 /*
423 * Some devices get wedged if you kick them after they are
424 * reset. Mark all vqs as broken to make sure we don't.
425 */
426 virtio_break_device(dev);
427 /*
428 * Guarantee that any callback will see vq->broken as true.
429 */
430 virtio_synchronize_cbs(dev);
431 /*
432 * As IOMMUs are reset on shutdown, this will block device access to memory.
433 * Some devices get wedged if this happens, so reset to make sure it does not.
434 */
435 dev->config->reset(dev);
436}
437
438static const struct bus_type virtio_bus = {
439 .name = "virtio",
440 .match = virtio_dev_match,
441 .dev_groups = virtio_dev_groups,
442 .uevent = virtio_uevent,
443 .probe = virtio_dev_probe,
444 .remove = virtio_dev_remove,
445 .irq_get_affinity = virtio_irq_get_affinity,
446 .shutdown = virtio_dev_shutdown,
447};
448
449int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
450{
451 /* Catch this early. */
452 BUG_ON(driver->feature_table_size && !driver->feature_table);
453 driver->driver.bus = &virtio_bus;
454 driver->driver.owner = owner;
455
456 return driver_register(drv: &driver->driver);
457}
458EXPORT_SYMBOL_GPL(__register_virtio_driver);
459
460void unregister_virtio_driver(struct virtio_driver *driver)
461{
462 driver_unregister(drv: &driver->driver);
463}
464EXPORT_SYMBOL_GPL(unregister_virtio_driver);
465
466static int virtio_device_of_init(struct virtio_device *dev)
467{
468 struct device_node *np, *pnode = dev_of_node(dev: dev->dev.parent);
469 char compat[] = "virtio,deviceXXXXXXXX";
470 int ret, count;
471
472 if (!pnode)
473 return 0;
474
475 count = of_get_available_child_count(np: pnode);
476 if (!count)
477 return 0;
478
479 /* There can be only 1 child node */
480 if (WARN_ON(count > 1))
481 return -EINVAL;
482
483 np = of_get_next_available_child(node: pnode, NULL);
484 if (WARN_ON(!np))
485 return -ENODEV;
486
487 ret = snprintf(buf: compat, size: sizeof(compat), fmt: "virtio,device%x", dev->id.device);
488 BUG_ON(ret >= sizeof(compat));
489
490 /*
491 * On powerpc/pseries virtio devices are PCI devices so PCI
492 * vendor/device ids play the role of the "compatible" property.
493 * Simply don't init of_node in this case.
494 */
495 if (!of_device_is_compatible(device: np, compat)) {
496 ret = 0;
497 goto out;
498 }
499
500 dev->dev.of_node = np;
501 return 0;
502
503out:
504 of_node_put(node: np);
505 return ret;
506}
507
508/**
509 * register_virtio_device - register virtio device
510 * @dev : virtio device to be registered
511 *
512 * On error, the caller must call put_device on &@dev->dev (and not kfree),
513 * as another code path may have obtained a reference to @dev.
514 *
515 * Returns: 0 on success, -error on failure
516 */
517int register_virtio_device(struct virtio_device *dev)
518{
519 int err;
520
521 dev->dev.bus = &virtio_bus;
522 device_initialize(dev: &dev->dev);
523
524 /* Assign a unique device index and hence name. */
525 err = ida_alloc(ida: &virtio_index_ida, GFP_KERNEL);
526 if (err < 0)
527 goto out;
528
529 dev->index = err;
530 err = dev_set_name(dev: &dev->dev, name: "virtio%u", dev->index);
531 if (err)
532 goto out_ida_remove;
533
534 err = virtio_device_of_init(dev);
535 if (err)
536 goto out_ida_remove;
537
538 spin_lock_init(&dev->config_lock);
539 dev->config_driver_disabled = false;
540 dev->config_core_enabled = false;
541 dev->config_change_pending = false;
542
543 INIT_LIST_HEAD(list: &dev->vqs);
544 spin_lock_init(&dev->vqs_list_lock);
545
546 /* We always start by resetting the device, in case a previous
547 * driver messed it up. This also tests that code path a little. */
548 virtio_reset_device(dev);
549
550 /* Acknowledge that we've seen the device. */
551 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
552
553 virtio_debug_device_init(dev);
554
555 /*
556 * device_add() causes the bus infrastructure to look for a matching
557 * driver.
558 */
559 err = device_add(dev: &dev->dev);
560 if (err)
561 goto out_of_node_put;
562
563 return 0;
564
565out_of_node_put:
566 of_node_put(node: dev->dev.of_node);
567out_ida_remove:
568 ida_free(&virtio_index_ida, id: dev->index);
569out:
570 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
571 return err;
572}
573EXPORT_SYMBOL_GPL(register_virtio_device);
574
575bool is_virtio_device(struct device *dev)
576{
577 return dev->bus == &virtio_bus;
578}
579EXPORT_SYMBOL_GPL(is_virtio_device);
580
581void unregister_virtio_device(struct virtio_device *dev)
582{
583 int index = dev->index; /* save for after device release */
584
585 device_unregister(dev: &dev->dev);
586 virtio_debug_device_exit(dev);
587 ida_free(&virtio_index_ida, id: index);
588}
589EXPORT_SYMBOL_GPL(unregister_virtio_device);
590
591static int virtio_device_restore_priv(struct virtio_device *dev, bool restore)
592{
593 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
594 int ret;
595
596 /* We always start by resetting the device, in case a previous
597 * driver messed it up. */
598 virtio_reset_device(dev);
599
600 /* Acknowledge that we've seen the device. */
601 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
602
603 /* Maybe driver failed before freeze.
604 * Restore the failed status, for debugging. */
605 if (dev->failed)
606 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
607
608 if (!drv)
609 return 0;
610
611 /* We have a driver! */
612 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
613
614 ret = dev->config->finalize_features(dev);
615 if (ret)
616 goto err;
617
618 ret = virtio_features_ok(dev);
619 if (ret)
620 goto err;
621
622 if (restore) {
623 if (drv->restore) {
624 ret = drv->restore(dev);
625 if (ret)
626 goto err;
627 }
628 } else {
629 ret = drv->reset_done(dev);
630 if (ret)
631 goto err;
632 }
633
634 /* If restore didn't do it, mark device DRIVER_OK ourselves. */
635 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
636 virtio_device_ready(dev);
637
638 virtio_config_core_enable(dev);
639
640 return 0;
641
642err:
643 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
644 return ret;
645}
646
647#ifdef CONFIG_PM_SLEEP
648int virtio_device_freeze(struct virtio_device *dev)
649{
650 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
651 int ret;
652
653 virtio_config_core_disable(dev);
654
655 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
656
657 if (drv && drv->freeze) {
658 ret = drv->freeze(dev);
659 if (ret) {
660 virtio_config_core_enable(dev);
661 return ret;
662 }
663 }
664
665 return 0;
666}
667EXPORT_SYMBOL_GPL(virtio_device_freeze);
668
669int virtio_device_restore(struct virtio_device *dev)
670{
671 return virtio_device_restore_priv(dev, restore: true);
672}
673EXPORT_SYMBOL_GPL(virtio_device_restore);
674#endif
675
676int virtio_device_reset_prepare(struct virtio_device *dev)
677{
678 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
679 int ret;
680
681 if (!drv || !drv->reset_prepare)
682 return -EOPNOTSUPP;
683
684 virtio_config_core_disable(dev);
685
686 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
687
688 ret = drv->reset_prepare(dev);
689 if (ret) {
690 virtio_config_core_enable(dev);
691 return ret;
692 }
693
694 return 0;
695}
696EXPORT_SYMBOL_GPL(virtio_device_reset_prepare);
697
698int virtio_device_reset_done(struct virtio_device *dev)
699{
700 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
701
702 if (!drv || !drv->reset_done)
703 return -EOPNOTSUPP;
704
705 return virtio_device_restore_priv(dev, restore: false);
706}
707EXPORT_SYMBOL_GPL(virtio_device_reset_done);
708
709static int virtio_init(void)
710{
711 BUILD_BUG_ON(offsetof(struct virtio_device, features) !=
712 offsetof(struct virtio_device, features_array[0]));
713
714 if (bus_register(bus: &virtio_bus) != 0)
715 panic(fmt: "virtio bus registration failed");
716 virtio_debug_init();
717 return 0;
718}
719
720static void __exit virtio_exit(void)
721{
722 virtio_debug_exit();
723 bus_unregister(bus: &virtio_bus);
724 ida_destroy(ida: &virtio_index_ida);
725}
726core_initcall(virtio_init);
727module_exit(virtio_exit);
728
729MODULE_DESCRIPTION("Virtio core interface");
730MODULE_LICENSE("GPL");
731

source code of linux/drivers/virtio/virtio.c