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         if (device_features & (1ULL << VIRTIO_F_VERSION_1))
 243                 dev->features = driver_features & device_features;
 244         else
 245                 dev->features = driver_features_legacy & device_features;
 246
 247         /* Transport features always preserved to pass to finalize_features. */
 248         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 249                 if (device_features & (1ULL << i))
 250                         __virtio_set_bit(dev, i);
 251
 252         if (drv->validate) {
 253                 err = drv->validate(dev);
 254                 if (err)
 255                         goto err;
 256         }
 257
 258         err = virtio_finalize_features(dev);
 259         if (err)
 260                 goto err;
 261
 262         err = drv->probe(dev);
 263         if (err)
 264                 goto err;
 265
 266         /* If probe didn't do it, mark device DRIVER_OK ourselves. */
 267         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 268                 virtio_device_ready(dev);
 269
 270         if (drv->scan)
 271                 drv->scan(dev);
 272
 273         virtio_config_enable(dev);
 274
 275         return 0;
 276 err:
 277         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 278         return err;
 279
 280 }
 281
 282 static void virtio_dev_remove(struct device *_d)
 283 {
 284         struct virtio_device *dev = dev_to_virtio(_d);
 285         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 286
 287         virtio_config_disable(dev);
 288
 289         drv->remove(dev);
 290
 291         /* Driver should have reset device. */
 292         WARN_ON_ONCE(dev->config->get_status(dev));
 293
 294         /* Acknowledge the device's existence again. */
 295         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 296
 297         of_node_put(dev->dev.of_node);
 298 }
 299
 300 static struct bus_type virtio_bus = {
 301         .name  = "virtio",
 302         .match = virtio_dev_match,
 303         .dev_groups = virtio_dev_groups,
 304         .uevent = virtio_uevent,
 305         .probe = virtio_dev_probe,
 306         .remove = virtio_dev_remove,
 307 };
 308
 309 int register_virtio_driver(struct virtio_driver *driver)
 310 {
 311         /* Catch this early. */
 312         BUG_ON(driver->feature_table_size && !driver->feature_table);
 313         driver->driver.bus = &virtio_bus;
 314         return driver_register(&driver->driver);
 315 }
 316 EXPORT_SYMBOL_GPL(register_virtio_driver);
 317
 318 void unregister_virtio_driver(struct virtio_driver *driver)
 319 {
 320         driver_unregister(&driver->driver);
 321 }
 322 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 323
 324 static int virtio_device_of_init(struct virtio_device *dev)
 325 {
 326         struct device_node *np, *pnode = dev_of_node(dev->dev.parent);
 327         char compat[] = "virtio,deviceXXXXXXXX";
 328         int ret, count;
 329
 330         if (!pnode)
 331                 return 0;
 332
 333         count = of_get_available_child_count(pnode);
 334         if (!count)
 335                 return 0;
 336
 337         /* There can be only 1 child node */
 338         if (WARN_ON(count > 1))
 339                 return -EINVAL;
 340
 341         np = of_get_next_available_child(pnode, NULL);
 342         if (WARN_ON(!np))
 343                 return -ENODEV;
 344
 345         ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device);
 346         BUG_ON(ret >= sizeof(compat));
 347
 348         if (!of_device_is_compatible(np, compat)) {
 349                 ret = -EINVAL;
 350                 goto out;
 351         }
 352
 353         dev->dev.of_node = np;
 354         return 0;
 355
 356 out:
 357         of_node_put(np);
 358         return ret;
 359 }
 360
 361 /**
 362  * register_virtio_device - register virtio device
 363  * @dev        : virtio device to be registered
 364  *
 365  * On error, the caller must call put_device on &@dev->dev (and not kfree),
 366  * as another code path may have obtained a reference to @dev.
 367  *
 368  * Returns: 0 on suceess, -error on failure
 369  */
 370 int register_virtio_device(struct virtio_device *dev)
 371 {
 372         int err;
 373
 374         dev->dev.bus = &virtio_bus;
 375         device_initialize(&dev->dev);
 376
 377         /* Assign a unique device index and hence name. */
 378         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 379         if (err < 0)
 380                 goto out;
 381
 382         dev->index = err;
 383         dev_set_name(&dev->dev, "virtio%u", dev->index);
 384
 385         err = virtio_device_of_init(dev);
 386         if (err)
 387                 goto out_ida_remove;
 388
 389         spin_lock_init(&dev->config_lock);
 390         dev->config_enabled = false;
 391         dev->config_change_pending = false;
 392
 393         /* We always start by resetting the device, in case a previous
 394          * driver messed it up.  This also tests that code path a little. */
 395         dev->config->reset(dev);
 396
 397         /* Acknowledge that we've seen the device. */
 398         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 399
 400         INIT_LIST_HEAD(&dev->vqs);
 401         spin_lock_init(&dev->vqs_list_lock);
 402
 403         /*
 404          * device_add() causes the bus infrastructure to look for a matching
 405          * driver.
 406          */
 407         err = device_add(&dev->dev);
 408         if (err)
 409                 goto out_of_node_put;
 410
 411         return 0;
 412
 413 out_of_node_put:
 414         of_node_put(dev->dev.of_node);
 415 out_ida_remove:
 416         ida_simple_remove(&virtio_index_ida, dev->index);
 417 out:
 418         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 419         return err;
 420 }
 421 EXPORT_SYMBOL_GPL(register_virtio_device);
 422
 423 bool is_virtio_device(struct device *dev)
 424 {
 425         return dev->bus == &virtio_bus;
 426 }
 427 EXPORT_SYMBOL_GPL(is_virtio_device);
 428
 429 void unregister_virtio_device(struct virtio_device *dev)
 430 {
 431         int index = dev->index; /* save for after device release */
 432
 433         device_unregister(&dev->dev);
 434         ida_simple_remove(&virtio_index_ida, index);
 435 }
 436 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 437
 438 #ifdef CONFIG_PM_SLEEP
 439 int virtio_device_freeze(struct virtio_device *dev)
 440 {
 441         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 442
 443         virtio_config_disable(dev);
 444
 445         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 446
 447         if (drv && drv->freeze)
 448                 return drv->freeze(dev);
 449
 450         return 0;
 451 }
 452 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 453
 454 int virtio_device_restore(struct virtio_device *dev)
 455 {
 456         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 457         int ret;
 458
 459         /* We always start by resetting the device, in case a previous
 460          * driver messed it up. */
 461         dev->config->reset(dev);
 462
 463         /* Acknowledge that we've seen the device. */
 464         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 465
 466         /* Maybe driver failed before freeze.
 467          * Restore the failed status, for debugging. */
 468         if (dev->failed)
 469                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 470
 471         if (!drv)
 472                 return 0;
 473
 474         /* We have a driver! */
 475         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 476
 477         ret = virtio_finalize_features(dev);
 478         if (ret)
 479                 goto err;
 480
 481         if (drv->restore) {
 482                 ret = drv->restore(dev);
 483                 if (ret)
 484                         goto err;
 485         }
 486
 487         /* Finally, tell the device we're all set */
 488         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 489
 490         virtio_config_enable(dev);
 491
 492         return 0;
 493
 494 err:
 495         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 496         return ret;
 497 }
 498 EXPORT_SYMBOL_GPL(virtio_device_restore);
 499 #endif
 500
 501 static int virtio_init(void)
 502 {
 503         if (bus_register(&virtio_bus) != 0)
 504                 panic("virtio bus registration failed");
 505         return 0;
 506 }
 507
 508 static void __exit virtio_exit(void)
 509 {
 510         bus_unregister(&virtio_bus);
 511         ida_destroy(&virtio_index_ida);
 512 }
 513 core_initcall(virtio_init);
 514 module_exit(virtio_exit);
 515
 516 MODULE_LICENSE("GPL");