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/module.h>
   6 #include <linux/idr.h>
   7 #include <linux/of.h>
   8 #include <uapi/linux/virtio_ids.h>
   9
  10 /* Unique numbering for virtio devices. */
  11 static DEFINE_IDA(virtio_index_ida);
  12
  13 static ssize_t device_show(struct device *_d,
  14                            struct device_attribute *attr, char *buf)
  15 {
  16         struct virtio_device *dev = dev_to_virtio(_d);
  17         return sprintf(buf, "0x%04x\n", dev->id.device);
  18 }
  19 static DEVICE_ATTR_RO(device);
  20
  21 static ssize_t vendor_show(struct device *_d,
  22                            struct device_attribute *attr, char *buf)
  23 {
  24         struct virtio_device *dev = dev_to_virtio(_d);
  25         return sprintf(buf, "0x%04x\n", dev->id.vendor);
  26 }
  27 static DEVICE_ATTR_RO(vendor);
  28
  29 static ssize_t status_show(struct device *_d,
  30                            struct device_attribute *attr, char *buf)
  31 {
  32         struct virtio_device *dev = dev_to_virtio(_d);
  33         return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
  34 }
  35 static DEVICE_ATTR_RO(status);
  36
  37 static ssize_t modalias_show(struct device *_d,
  38                              struct device_attribute *attr, char *buf)
  39 {
  40         struct virtio_device *dev = dev_to_virtio(_d);
  41         return sprintf(buf, "virtio:d%08Xv%08X\n",
  42                        dev->id.device, dev->id.vendor);
  43 }
  44 static DEVICE_ATTR_RO(modalias);
  45
  46 static ssize_t features_show(struct device *_d,
  47                              struct device_attribute *attr, char *buf)
  48 {
  49         struct virtio_device *dev = dev_to_virtio(_d);
  50         unsigned int i;
  51         ssize_t len = 0;
  52
  53         /* We actually represent this as a bitstring, as it could be
  54          * arbitrary length in future. */
  55         for (i = 0; i < sizeof(dev->features)*8; i++)
  56                 len += sprintf(buf+len, "%c",
  57                                __virtio_test_bit(dev, i) ? '1' : '0');
  58         len += sprintf(buf+len, "\n");
  59         return len;
  60 }
  61 static DEVICE_ATTR_RO(features);
  62
  63 static struct attribute *virtio_dev_attrs[] = {
  64         &dev_attr_device.attr,
  65         &dev_attr_vendor.attr,
  66         &dev_attr_status.attr,
  67         &dev_attr_modalias.attr,
  68         &dev_attr_features.attr,
  69         NULL,
  70 };
  71 ATTRIBUTE_GROUPS(virtio_dev);
  72
  73 static inline int virtio_id_match(const struct virtio_device *dev,
  74                                   const struct virtio_device_id *id)
  75 {
  76         if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
  77                 return 0;
  78
  79         return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
  80 }
  81
  82 /* This looks through all the IDs a driver claims to support.  If any of them
  83  * match, we return 1 and the kernel will call virtio_dev_probe(). */
  84 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  85 {
  86         unsigned int i;
  87         struct virtio_device *dev = dev_to_virtio(_dv);
  88         const struct virtio_device_id *ids;
  89
  90         ids = drv_to_virtio(_dr)->id_table;
  91         for (i = 0; ids[i].device; i++)
  92                 if (virtio_id_match(dev, &ids[i]))
  93                         return 1;
  94         return 0;
  95 }
  96
  97 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  98 {
  99         struct virtio_device *dev = dev_to_virtio(_dv);
 100
 101         return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
 102                               dev->id.device, dev->id.vendor);
 103 }
 104
 105 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 106                                          unsigned int fbit)
 107 {
 108         unsigned int i;
 109         struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 110
 111         for (i = 0; i < drv->feature_table_size; i++)
 112                 if (drv->feature_table[i] == fbit)
 113                         return;
 114
 115         if (drv->feature_table_legacy) {
 116                 for (i = 0; i < drv->feature_table_size_legacy; i++)
 117                         if (drv->feature_table_legacy[i] == fbit)
 118                                 return;
 119         }
 120
 121         BUG();
 122 }
 123 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 124
 125 static void __virtio_config_changed(struct virtio_device *dev)
 126 {
 127         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 128
 129         if (!dev->config_enabled)
 130                 dev->config_change_pending = true;
 131         else if (drv && drv->config_changed)
 132                 drv->config_changed(dev);
 133 }
 134
 135 void virtio_config_changed(struct virtio_device *dev)
 136 {
 137         unsigned long flags;
 138
 139         spin_lock_irqsave(&dev->config_lock, flags);
 140         __virtio_config_changed(dev);
 141         spin_unlock_irqrestore(&dev->config_lock, flags);
 142 }
 143 EXPORT_SYMBOL_GPL(virtio_config_changed);
 144
 145 static void virtio_config_disable(struct virtio_device *dev)
 146 {
 147         spin_lock_irq(&dev->config_lock);
 148         dev->config_enabled = false;
 149         spin_unlock_irq(&dev->config_lock);
 150 }
 151
 152 static void virtio_config_enable(struct virtio_device *dev)
 153 {
 154         spin_lock_irq(&dev->config_lock);
 155         dev->config_enabled = true;
 156         if (dev->config_change_pending)
 157                 __virtio_config_changed(dev);
 158         dev->config_change_pending = false;
 159         spin_unlock_irq(&dev->config_lock);
 160 }
 161
 162 void virtio_add_status(struct virtio_device *dev, unsigned int status)
 163 {
 164         might_sleep();
 165         dev->config->set_status(dev, dev->config->get_status(dev) | status);
 166 }
 167 EXPORT_SYMBOL_GPL(virtio_add_status);
 168
 169 int virtio_finalize_features(struct virtio_device *dev)
 170 {
 171         int ret = dev->config->finalize_features(dev);
 172         unsigned status;
 173
 174         might_sleep();
 175         if (ret)
 176                 return ret;
 177
 178         ret = arch_has_restricted_virtio_memory_access();
 179         if (ret) {
 180                 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
 181                         dev_warn(&dev->dev,
 182                                  "device must provide VIRTIO_F_VERSION_1\n");
 183                         return -ENODEV;
 184                 }
 185
 186                 if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) {
 187                         dev_warn(&dev->dev,
 188                                  "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
 189                         return -ENODEV;
 190                 }
 191         }
 192
 193         if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 194                 return 0;
 195
 196         virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 197         status = dev->config->get_status(dev);
 198         if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 199                 dev_err(&dev->dev, "virtio: device refuses features: %x\n",
 200                         status);
 201                 return -ENODEV;
 202         }
 203         return 0;
 204 }
 205 EXPORT_SYMBOL_GPL(virtio_finalize_features);
 206
 207 static int virtio_dev_probe(struct device *_d)
 208 {
 209         int err, i;
 210         struct virtio_device *dev = dev_to_virtio(_d);
 211         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 212         u64 device_features;
 213         u64 driver_features;
 214         u64 driver_features_legacy;
 215
 216         /* We have a driver! */
 217         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 218
 219         /* Figure out what features the device supports. */
 220         device_features = dev->config->get_features(dev);
 221
 222         /* Figure out what features the driver supports. */
 223         driver_features = 0;
 224         for (i = 0; i < drv->feature_table_size; i++) {
 225                 unsigned int f = drv->feature_table[i];
 226                 BUG_ON(f >= 64);
 227                 driver_features |= (1ULL << f);
 228         }
 229
 230         /* Some drivers have a separate feature table for virtio v1.0 */
 231         if (drv->feature_table_legacy) {
 232                 driver_features_legacy = 0;
 233                 for (i = 0; i < drv->feature_table_size_legacy; i++) {
 234                         unsigned int f = drv->feature_table_legacy[i];
 235                         BUG_ON(f >= 64);
 236                         driver_features_legacy |= (1ULL << f);
 237                 }
 238         } else {
 239                 driver_features_legacy = driver_features;
 240         }
 241
 242         /*
 243          * Some devices detect legacy solely via F_VERSION_1. Write
 244          * F_VERSION_1 to force LE config space accesses before FEATURES_OK for
 245          * these when needed.
 246          */
 247         if (drv->validate && !virtio_legacy_is_little_endian()
 248                           && device_features & BIT_ULL(VIRTIO_F_VERSION_1)) {
 249                 dev->features = BIT_ULL(VIRTIO_F_VERSION_1);
 250                 dev->config->finalize_features(dev);
 251         }
 252
 253         if (device_features & (1ULL << VIRTIO_F_VERSION_1))
 254                 dev->features = driver_features & device_features;
 255         else
 256                 dev->features = driver_features_legacy & device_features;
 257
 258         /* Transport features always preserved to pass to finalize_features. */
 259         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 260                 if (device_features & (1ULL << i))
 261                         __virtio_set_bit(dev, i);
 262
 263         if (drv->validate) {
 264                 err = drv->validate(dev);
 265                 if (err)
 266                         goto err;
 267         }
 268
 269         err = virtio_finalize_features(dev);
 270         if (err)
 271                 goto err;
 272
 273         err = drv->probe(dev);
 274         if (err)
 275                 goto err;
 276
 277         /* If probe didn't do it, mark device DRIVER_OK ourselves. */
 278         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 279                 virtio_device_ready(dev);
 280
 281         if (drv->scan)
 282                 drv->scan(dev);
 283
 284         virtio_config_enable(dev);
 285
 286         return 0;
 287 err:
 288         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 289         return err;
 290
 291 }
 292
 293 static void virtio_dev_remove(struct device *_d)
 294 {
 295         struct virtio_device *dev = dev_to_virtio(_d);
 296         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 297
 298         virtio_config_disable(dev);
 299
 300         drv->remove(dev);
 301
 302         /* Driver should have reset device. */
 303         WARN_ON_ONCE(dev->config->get_status(dev));
 304
 305         /* Acknowledge the device's existence again. */
 306         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 307
 308         of_node_put(dev->dev.of_node);
 309 }
 310
 311 static struct bus_type virtio_bus = {
 312         .name  = "virtio",
 313         .match = virtio_dev_match,
 314         .dev_groups = virtio_dev_groups,
 315         .uevent = virtio_uevent,
 316         .probe = virtio_dev_probe,
 317         .remove = virtio_dev_remove,
 318 };
 319
 320 int register_virtio_driver(struct virtio_driver *driver)
 321 {
 322         /* Catch this early. */
 323         BUG_ON(driver->feature_table_size && !driver->feature_table);
 324         driver->driver.bus = &virtio_bus;
 325         return driver_register(&driver->driver);
 326 }
 327 EXPORT_SYMBOL_GPL(register_virtio_driver);
 328
 329 void unregister_virtio_driver(struct virtio_driver *driver)
 330 {
 331         driver_unregister(&driver->driver);
 332 }
 333 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 334
 335 static int virtio_device_of_init(struct virtio_device *dev)
 336 {
 337         struct device_node *np, *pnode = dev_of_node(dev->dev.parent);
 338         char compat[] = "virtio,deviceXXXXXXXX";
 339         int ret, count;
 340
 341         if (!pnode)
 342                 return 0;
 343
 344         count = of_get_available_child_count(pnode);
 345         if (!count)
 346                 return 0;
 347
 348         /* There can be only 1 child node */
 349         if (WARN_ON(count > 1))
 350                 return -EINVAL;
 351
 352         np = of_get_next_available_child(pnode, NULL);
 353         if (WARN_ON(!np))
 354                 return -ENODEV;
 355
 356         ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device);
 357         BUG_ON(ret >= sizeof(compat));
 358
 359         /*
 360          * On powerpc/pseries virtio devices are PCI devices so PCI
 361          * vendor/device ids play the role of the "compatible" property.
 362          * Simply don't init of_node in this case.
 363          */
 364         if (!of_device_is_compatible(np, compat)) {
 365                 ret = 0;
 366                 goto out;
 367         }
 368
 369         dev->dev.of_node = np;
 370         return 0;
 371
 372 out:
 373         of_node_put(np);
 374         return ret;
 375 }
 376
 377 /**
 378  * register_virtio_device - register virtio device
 379  * @dev        : virtio device to be registered
 380  *
 381  * On error, the caller must call put_device on &@dev->dev (and not kfree),
 382  * as another code path may have obtained a reference to @dev.
 383  *
 384  * Returns: 0 on suceess, -error on failure
 385  */
 386 int register_virtio_device(struct virtio_device *dev)
 387 {
 388         int err;
 389
 390         dev->dev.bus = &virtio_bus;
 391         device_initialize(&dev->dev);
 392
 393         /* Assign a unique device index and hence name. */
 394         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 395         if (err < 0)
 396                 goto out;
 397
 398         dev->index = err;
 399         dev_set_name(&dev->dev, "virtio%u", dev->index);
 400
 401         err = virtio_device_of_init(dev);
 402         if (err)
 403                 goto out_ida_remove;
 404
 405         spin_lock_init(&dev->config_lock);
 406         dev->config_enabled = false;
 407         dev->config_change_pending = false;
 408
 409         /* We always start by resetting the device, in case a previous
 410          * driver messed it up.  This also tests that code path a little. */
 411         dev->config->reset(dev);
 412
 413         /* Acknowledge that we've seen the device. */
 414         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 415
 416         INIT_LIST_HEAD(&dev->vqs);
 417         spin_lock_init(&dev->vqs_list_lock);
 418
 419         /*
 420          * device_add() causes the bus infrastructure to look for a matching
 421          * driver.
 422          */
 423         err = device_add(&dev->dev);
 424         if (err)
 425                 goto out_of_node_put;
 426
 427         return 0;
 428
 429 out_of_node_put:
 430         of_node_put(dev->dev.of_node);
 431 out_ida_remove:
 432         ida_simple_remove(&virtio_index_ida, dev->index);
 433 out:
 434         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 435         return err;
 436 }
 437 EXPORT_SYMBOL_GPL(register_virtio_device);
 438
 439 bool is_virtio_device(struct device *dev)
 440 {
 441         return dev->bus == &virtio_bus;
 442 }
 443 EXPORT_SYMBOL_GPL(is_virtio_device);
 444
 445 void unregister_virtio_device(struct virtio_device *dev)
 446 {
 447         int index = dev->index; /* save for after device release */
 448
 449         device_unregister(&dev->dev);
 450         ida_simple_remove(&virtio_index_ida, index);
 451 }
 452 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 453
 454 #ifdef CONFIG_PM_SLEEP
 455 int virtio_device_freeze(struct virtio_device *dev)
 456 {
 457         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 458
 459         virtio_config_disable(dev);
 460
 461         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 462
 463         if (drv && drv->freeze)
 464                 return drv->freeze(dev);
 465
 466         return 0;
 467 }
 468 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 469
 470 int virtio_device_restore(struct virtio_device *dev)
 471 {
 472         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 473         int ret;
 474
 475         /* We always start by resetting the device, in case a previous
 476          * driver messed it up. */
 477         dev->config->reset(dev);
 478
 479         /* Acknowledge that we've seen the device. */
 480         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 481
 482         /* Maybe driver failed before freeze.
 483          * Restore the failed status, for debugging. */
 484         if (dev->failed)
 485                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 486
 487         if (!drv)
 488                 return 0;
 489
 490         /* We have a driver! */
 491         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 492
 493         ret = virtio_finalize_features(dev);
 494         if (ret)
 495                 goto err;
 496
 497         if (drv->restore) {
 498                 ret = drv->restore(dev);
 499                 if (ret)
 500                         goto err;
 501         }
 502
 503         /* Finally, tell the device we're all set */
 504         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 505
 506         virtio_config_enable(dev);
 507
 508         return 0;
 509
 510 err:
 511         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 512         return ret;
 513 }
 514 EXPORT_SYMBOL_GPL(virtio_device_restore);
 515 #endif
 516
 517 static int virtio_init(void)
 518 {
 519         if (bus_register(&virtio_bus) != 0)
 520                 panic("virtio bus registration failed");
 521         return 0;
 522 }
 523
 524 static void __exit virtio_exit(void)
 525 {
 526         bus_unregister(&virtio_bus);
 527         ida_destroy(&virtio_index_ida);
 528 }
 529 core_initcall(virtio_init);
 530 module_exit(virtio_exit);
 531
 532 MODULE_LICENSE("GPL");