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