drivers/virtio/virtio.c

   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. */
  12 static DEFINE_IDA(virtio_index_ida);
  13
  14 static 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, "0x%04x\n", dev->id.device);
  19 }
  20 static DEVICE_ATTR_RO(device);
  21
  22 static 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, "0x%04x\n", dev->id.vendor);
  27 }
  28 static DEVICE_ATTR_RO(vendor);
  29
  30 static 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, "0x%08x\n", dev->config->get_status(dev));
  35 }
  36 static DEVICE_ATTR_RO(status);
  37
  38 static 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, "virtio:d%08Xv%08X\n",
  43                        dev->id.device, dev->id.vendor);
  44 }
  45 static DEVICE_ATTR_RO(modalias);
  46
  47 static 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 < sizeof(dev->features)*8; i++)
  57                 len += sysfs_emit_at(buf, len, "%c",
  58                                __virtio_test_bit(dev, i) ? '1' : '0');
  59         len += sysfs_emit_at(buf, len, "\n");
  60         return len;
  61 }
  62 static DEVICE_ATTR_RO(features);
  63
  64 static 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 };
  72 ATTRIBUTE_GROUPS(virtio_dev);
  73
  74 static 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(). */
  85 static 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, &ids[i]))
  94                         return 1;
  95         return 0;
  96 }
  97
  98 static 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, "MODALIAS=virtio:d%08Xv%08X",
 103                               dev->id.device, dev->id.vendor);
 104 }
 105
 106 void 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 }
 124 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 125
 126 static 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
 138 void 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(&dev->config_lock, flags);
 145 }
 146 EXPORT_SYMBOL_GPL(virtio_config_changed);
 147
 148 /**
 149  * virtio_config_driver_disable - disable config change reporting by drivers
 150  * @dev: the device to reset
 151  *
 152  * This is only allowed to be called by a driver and disabling can't
 153  * be nested.
 154  */
 155 void virtio_config_driver_disable(struct virtio_device *dev)
 156 {
 157         spin_lock_irq(&dev->config_lock);
 158         dev->config_driver_disabled = true;
 159         spin_unlock_irq(&dev->config_lock);
 160 }
 161 EXPORT_SYMBOL_GPL(virtio_config_driver_disable);
 162
 163 /**
 164  * virtio_config_driver_enable - enable config change reporting by drivers
 165  * @dev: the device to reset
 166  *
 167  * This is only allowed to be called by a driver and enabling can't
 168  * be nested.
 169  */
 170 void virtio_config_driver_enable(struct virtio_device *dev)
 171 {
 172         spin_lock_irq(&dev->config_lock);
 173         dev->config_driver_disabled = false;
 174         if (dev->config_change_pending)
 175                 __virtio_config_changed(dev);
 176         spin_unlock_irq(&dev->config_lock);
 177 }
 178 EXPORT_SYMBOL_GPL(virtio_config_driver_enable);
 179
 180 static void virtio_config_core_disable(struct virtio_device *dev)
 181 {
 182         spin_lock_irq(&dev->config_lock);
 183         dev->config_core_enabled = false;
 184         spin_unlock_irq(&dev->config_lock);
 185 }
 186
 187 static void virtio_config_core_enable(struct virtio_device *dev)
 188 {
 189         spin_lock_irq(&dev->config_lock);
 190         dev->config_core_enabled = true;
 191         if (dev->config_change_pending)
 192                 __virtio_config_changed(dev);
 193         spin_unlock_irq(&dev->config_lock);
 194 }
 195
 196 void 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 }
 201 EXPORT_SYMBOL_GPL(virtio_add_status);
 202
 203 /* Do some validation, then set FEATURES_OK */
 204 static 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(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(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(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  * */
 253 void 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 }
 268 EXPORT_SYMBOL_GPL(virtio_reset_device);
 269
 270 static 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;
 276         u64 driver_features;
 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         device_features = dev->config->get_features(dev);
 284
 285         /* Figure out what features the driver supports. */
 286         driver_features = 0;
 287         for (i = 0; i < drv->feature_table_size; i++) {
 288                 unsigned int f = drv->feature_table[i];
 289                 BUG_ON(f >= 64);
 290                 driver_features |= (1ULL << 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                         BUG_ON(f >= 64);
 299                         driver_features_legacy |= (1ULL << f);
 300                 }
 301         } else {
 302                 driver_features_legacy = driver_features;
 303         }
 304
 305         if (device_features & (1ULL << VIRTIO_F_VERSION_1))
 306                 dev->features = driver_features & device_features;
 307         else
 308                 dev->features = driver_features_legacy & device_features;
 309
 310         /* When debugging, user may filter some features by hand. */
 311         virtio_debug_device_filter_features(dev);
 312
 313         /* Transport features always preserved to pass to finalize_features. */
 314         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 315                 if (device_features & (1ULL << i))
 316                         __virtio_set_bit(dev, i);
 317
 318         err = dev->config->finalize_features(dev);
 319         if (err)
 320                 goto err;
 321
 322         if (drv->validate) {
 323                 u64 features = dev->features;
 324
 325                 err = drv->validate(dev);
 326                 if (err)
 327                         goto err;
 328
 329                 /* Did validation change any features? Then write them again. */
 330                 if (features != dev->features) {
 331                         err = dev->config->finalize_features(dev);
 332                         if (err)
 333                                 goto err;
 334                 }
 335         }
 336
 337         err = virtio_features_ok(dev);
 338         if (err)
 339                 goto err;
 340
 341         err = drv->probe(dev);
 342         if (err)
 343                 goto err;
 344
 345         /* If probe didn't do it, mark device DRIVER_OK ourselves. */
 346         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 347                 virtio_device_ready(dev);
 348
 349         if (drv->scan)
 350                 drv->scan(dev);
 351
 352         virtio_config_core_enable(dev);
 353
 354         return 0;
 355
 356 err:
 357         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 358         return err;
 359
 360 }
 361
 362 static void virtio_dev_remove(struct device *_d)
 363 {
 364         struct virtio_device *dev = dev_to_virtio(_d);
 365         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 366
 367         virtio_config_core_disable(dev);
 368
 369         drv->remove(dev);
 370
 371         /* Driver should have reset device. */
 372         WARN_ON_ONCE(dev->config->get_status(dev));
 373
 374         /* Acknowledge the device's existence again. */
 375         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 376
 377         of_node_put(dev->dev.of_node);
 378 }
 379
 380 static const struct bus_type virtio_bus = {
 381         .name  = "virtio",
 382         .match = virtio_dev_match,
 383         .dev_groups = virtio_dev_groups,
 384         .uevent = virtio_uevent,
 385         .probe = virtio_dev_probe,
 386         .remove = virtio_dev_remove,
 387 };
 388
 389 int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
 390 {
 391         /* Catch this early. */
 392         BUG_ON(driver->feature_table_size && !driver->feature_table);
 393         driver->driver.bus = &virtio_bus;
 394         driver->driver.owner = owner;
 395
 396         return driver_register(&driver->driver);
 397 }
 398 EXPORT_SYMBOL_GPL(__register_virtio_driver);
 399
 400 void unregister_virtio_driver(struct virtio_driver *driver)
 401 {
 402         driver_unregister(&driver->driver);
 403 }
 404 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 405
 406 static int virtio_device_of_init(struct virtio_device *dev)
 407 {
 408         struct device_node *np, *pnode = dev_of_node(dev->dev.parent);
 409         char compat[] = "virtio,deviceXXXXXXXX";
 410         int ret, count;
 411
 412         if (!pnode)
 413                 return 0;
 414
 415         count = of_get_available_child_count(pnode);
 416         if (!count)
 417                 return 0;
 418
 419         /* There can be only 1 child node */
 420         if (WARN_ON(count > 1))
 421                 return -EINVAL;
 422
 423         np = of_get_next_available_child(pnode, NULL);
 424         if (WARN_ON(!np))
 425                 return -ENODEV;
 426
 427         ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device);
 428         BUG_ON(ret >= sizeof(compat));
 429
 430         /*
 431          * On powerpc/pseries virtio devices are PCI devices so PCI
 432          * vendor/device ids play the role of the "compatible" property.
 433          * Simply don't init of_node in this case.
 434          */
 435         if (!of_device_is_compatible(np, compat)) {
 436                 ret = 0;
 437                 goto out;
 438         }
 439
 440         dev->dev.of_node = np;
 441         return 0;
 442
 443 out:
 444         of_node_put(np);
 445         return ret;
 446 }
 447
 448 /**
 449  * register_virtio_device - register virtio device
 450  * @dev        : virtio device to be registered
 451  *
 452  * On error, the caller must call put_device on &@dev->dev (and not kfree),
 453  * as another code path may have obtained a reference to @dev.
 454  *
 455  * Returns: 0 on suceess, -error on failure
 456  */
 457 int register_virtio_device(struct virtio_device *dev)
 458 {
 459         int err;
 460
 461         dev->dev.bus = &virtio_bus;
 462         device_initialize(&dev->dev);
 463
 464         /* Assign a unique device index and hence name. */
 465         err = ida_alloc(&virtio_index_ida, GFP_KERNEL);
 466         if (err < 0)
 467                 goto out;
 468
 469         dev->index = err;
 470         err = dev_set_name(&dev->dev, "virtio%u", dev->index);
 471         if (err)
 472                 goto out_ida_remove;
 473
 474         err = virtio_device_of_init(dev);
 475         if (err)
 476                 goto out_ida_remove;
 477
 478         spin_lock_init(&dev->config_lock);
 479         dev->config_core_enabled = false;
 480         dev->config_change_pending = false;
 481
 482         INIT_LIST_HEAD(&dev->vqs);
 483         spin_lock_init(&dev->vqs_list_lock);
 484
 485         /* We always start by resetting the device, in case a previous
 486          * driver messed it up.  This also tests that code path a little. */
 487         virtio_reset_device(dev);
 488
 489         /* Acknowledge that we've seen the device. */
 490         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 491
 492         virtio_debug_device_init(dev);
 493
 494         /*
 495          * device_add() causes the bus infrastructure to look for a matching
 496          * driver.
 497          */
 498         err = device_add(&dev->dev);
 499         if (err)
 500                 goto out_of_node_put;
 501
 502         return 0;
 503
 504 out_of_node_put:
 505         of_node_put(dev->dev.of_node);
 506 out_ida_remove:
 507         ida_free(&virtio_index_ida, dev->index);
 508 out:
 509         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 510         return err;
 511 }
 512 EXPORT_SYMBOL_GPL(register_virtio_device);
 513
 514 bool is_virtio_device(struct device *dev)
 515 {
 516         return dev->bus == &virtio_bus;
 517 }
 518 EXPORT_SYMBOL_GPL(is_virtio_device);
 519
 520 void unregister_virtio_device(struct virtio_device *dev)
 521 {
 522         int index = dev->index; /* save for after device release */
 523
 524         device_unregister(&dev->dev);
 525         virtio_debug_device_exit(dev);
 526         ida_free(&virtio_index_ida, index);
 527 }
 528 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 529
 530 #ifdef CONFIG_PM_SLEEP
 531 int virtio_device_freeze(struct virtio_device *dev)
 532 {
 533         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 534         int ret;
 535
 536         virtio_config_core_disable(dev);
 537
 538         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 539
 540         if (drv && drv->freeze) {
 541                 ret = drv->freeze(dev);
 542                 if (ret) {
 543                         virtio_config_core_enable(dev);
 544                         return ret;
 545                 }
 546         }
 547
 548         return 0;
 549 }
 550 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 551
 552 int virtio_device_restore(struct virtio_device *dev)
 553 {
 554         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 555         int ret;
 556
 557         /* We always start by resetting the device, in case a previous
 558          * driver messed it up. */
 559         virtio_reset_device(dev);
 560
 561         /* Acknowledge that we've seen the device. */
 562         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 563
 564         /* Maybe driver failed before freeze.
 565          * Restore the failed status, for debugging. */
 566         if (dev->failed)
 567                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 568
 569         if (!drv)
 570                 return 0;
 571
 572         /* We have a driver! */
 573         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 574
 575         ret = dev->config->finalize_features(dev);
 576         if (ret)
 577                 goto err;
 578
 579         ret = virtio_features_ok(dev);
 580         if (ret)
 581                 goto err;
 582
 583         if (drv->restore) {
 584                 ret = drv->restore(dev);
 585                 if (ret)
 586                         goto err;
 587         }
 588
 589         /* If restore didn't do it, mark device DRIVER_OK ourselves. */
 590         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 591                 virtio_device_ready(dev);
 592
 593         virtio_config_core_enable(dev);
 594
 595         return 0;
 596
 597 err:
 598         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 599         return ret;
 600 }
 601 EXPORT_SYMBOL_GPL(virtio_device_restore);
 602 #endif
 603
 604 static int virtio_init(void)
 605 {
 606         if (bus_register(&virtio_bus) != 0)
 607                 panic("virtio bus registration failed");
 608         virtio_debug_init();
 609         return 0;
 610 }
 611
 612 static void __exit virtio_exit(void)
 613 {
 614         virtio_debug_exit();
 615         bus_unregister(&virtio_bus);
 616         ida_destroy(&virtio_index_ida);
 617 }
 618 core_initcall(virtio_init);
 619 module_exit(virtio_exit);
 620
 621 MODULE_DESCRIPTION("Virtio core interface");
 622 MODULE_LICENSE("GPL");