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 static 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
 151 static void virtio_config_enable(struct virtio_device *dev)
 152 {
 153         spin_lock_irq(&dev->config_lock);
 154         dev->config_enabled = true;
 155         if (dev->config_change_pending)
 156                 __virtio_config_changed(dev);
 157         dev->config_change_pending = false;
 158         spin_unlock_irq(&dev->config_lock);
 159 }
 160
 161 void virtio_add_status(struct virtio_device *dev, unsigned int status)
 162 {
 163         might_sleep();
 164         dev->config->set_status(dev, dev->config->get_status(dev) | status);
 165 }
 166 EXPORT_SYMBOL_GPL(virtio_add_status);
 167
 168 int virtio_finalize_features(struct virtio_device *dev)
 169 {
 170         int ret = dev->config->finalize_features(dev);
 171         unsigned status;
 172
 173         might_sleep();
 174         if (ret)
 175                 return ret;
 176
 177         ret = arch_has_restricted_virtio_memory_access();
 178         if (ret) {
 179                 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
 180                         dev_warn(&dev->dev,
 181                                  "device must provide VIRTIO_F_VERSION_1\n");
 182                         return -ENODEV;
 183                 }
 184
 185                 if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) {
 186                         dev_warn(&dev->dev,
 187                                  "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
 188                         return -ENODEV;
 189                 }
 190         }
 191
 192         if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 193                 return 0;
 194
 195         virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 196         status = dev->config->get_status(dev);
 197         if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 198                 dev_err(&dev->dev, "virtio: device refuses features: %x\n",
 199                         status);
 200                 return -ENODEV;
 201         }
 202         return 0;
 203 }
 204 EXPORT_SYMBOL_GPL(virtio_finalize_features);
 205
 206 static int virtio_dev_probe(struct device *_d)
 207 {
 208         int err, i;
 209         struct virtio_device *dev = dev_to_virtio(_d);
 210         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 211         u64 device_features;
 212         u64 driver_features;
 213         u64 driver_features_legacy;
 214
 215         /* We have a driver! */
 216         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 217
 218         /* Figure out what features the device supports. */
 219         device_features = dev->config->get_features(dev);
 220
 221         /* Figure out what features the driver supports. */
 222         driver_features = 0;
 223         for (i = 0; i < drv->feature_table_size; i++) {
 224                 unsigned int f = drv->feature_table[i];
 225                 BUG_ON(f >= 64);
 226                 driver_features |= (1ULL << f);
 227         }
 228
 229         /* Some drivers have a separate feature table for virtio v1.0 */
 230         if (drv->feature_table_legacy) {
 231                 driver_features_legacy = 0;
 232                 for (i = 0; i < drv->feature_table_size_legacy; i++) {
 233                         unsigned int f = drv->feature_table_legacy[i];
 234                         BUG_ON(f >= 64);
 235                         driver_features_legacy |= (1ULL << f);
 236                 }
 237         } else {
 238                 driver_features_legacy = driver_features;
 239         }
 240
 241         if (device_features & (1ULL << VIRTIO_F_VERSION_1))
 242                 dev->features = driver_features & device_features;
 243         else
 244                 dev->features = driver_features_legacy & device_features;
 245
 246         /* Transport features always preserved to pass to finalize_features. */
 247         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 248                 if (device_features & (1ULL << i))
 249                         __virtio_set_bit(dev, i);
 250
 251         if (drv->validate) {
 252                 err = drv->validate(dev);
 253                 if (err)
 254                         goto err;
 255         }
 256
 257         err = virtio_finalize_features(dev);
 258         if (err)
 259                 goto err;
 260
 261         err = drv->probe(dev);
 262         if (err)
 263                 goto err;
 264
 265         /* If probe didn't do it, mark device DRIVER_OK ourselves. */
 266         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 267                 virtio_device_ready(dev);
 268
 269         if (drv->scan)
 270                 drv->scan(dev);
 271
 272         virtio_config_enable(dev);
 273
 274         return 0;
 275 err:
 276         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 277         return err;
 278
 279 }
 280
 281 static int virtio_dev_remove(struct device *_d)
 282 {
 283         struct virtio_device *dev = dev_to_virtio(_d);
 284         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 285
 286         virtio_config_disable(dev);
 287
 288         drv->remove(dev);
 289
 290         /* Driver should have reset device. */
 291         WARN_ON_ONCE(dev->config->get_status(dev));
 292
 293         /* Acknowledge the device's existence again. */
 294         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 295         return 0;
 296 }
 297
 298 static struct bus_type virtio_bus = {
 299         .name  = "virtio",
 300         .match = virtio_dev_match,
 301         .dev_groups = virtio_dev_groups,
 302         .uevent = virtio_uevent,
 303         .probe = virtio_dev_probe,
 304         .remove = virtio_dev_remove,
 305 };
 306
 307 int register_virtio_driver(struct virtio_driver *driver)
 308 {
 309         /* Catch this early. */
 310         BUG_ON(driver->feature_table_size && !driver->feature_table);
 311         driver->driver.bus = &virtio_bus;
 312         return driver_register(&driver->driver);
 313 }
 314 EXPORT_SYMBOL_GPL(register_virtio_driver);
 315
 316 void unregister_virtio_driver(struct virtio_driver *driver)
 317 {
 318         driver_unregister(&driver->driver);
 319 }
 320 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 321
 322 /**
 323  * register_virtio_device - register virtio device
 324  * @dev        : virtio device to be registered
 325  *
 326  * On error, the caller must call put_device on &@dev->dev (and not kfree),
 327  * as another code path may have obtained a reference to @dev.
 328  *
 329  * Returns: 0 on suceess, -error on failure
 330  */
 331 int register_virtio_device(struct virtio_device *dev)
 332 {
 333         int err;
 334
 335         dev->dev.bus = &virtio_bus;
 336         device_initialize(&dev->dev);
 337
 338         /* Assign a unique device index and hence name. */
 339         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 340         if (err < 0)
 341                 goto out;
 342
 343         dev->index = err;
 344         dev_set_name(&dev->dev, "virtio%u", dev->index);
 345
 346         spin_lock_init(&dev->config_lock);
 347         dev->config_enabled = false;
 348         dev->config_change_pending = false;
 349
 350         /* We always start by resetting the device, in case a previous
 351          * driver messed it up.  This also tests that code path a little. */
 352         dev->config->reset(dev);
 353
 354         /* Acknowledge that we've seen the device. */
 355         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 356
 357         INIT_LIST_HEAD(&dev->vqs);
 358
 359         /*
 360          * device_add() causes the bus infrastructure to look for a matching
 361          * driver.
 362          */
 363         err = device_add(&dev->dev);
 364         if (err)
 365                 ida_simple_remove(&virtio_index_ida, dev->index);
 366 out:
 367         if (err)
 368                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 369         return err;
 370 }
 371 EXPORT_SYMBOL_GPL(register_virtio_device);
 372
 373 bool is_virtio_device(struct device *dev)
 374 {
 375         return dev->bus == &virtio_bus;
 376 }
 377 EXPORT_SYMBOL_GPL(is_virtio_device);
 378
 379 void unregister_virtio_device(struct virtio_device *dev)
 380 {
 381         int index = dev->index; /* save for after device release */
 382
 383         device_unregister(&dev->dev);
 384         ida_simple_remove(&virtio_index_ida, index);
 385 }
 386 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 387
 388 #ifdef CONFIG_PM_SLEEP
 389 int virtio_device_freeze(struct virtio_device *dev)
 390 {
 391         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 392
 393         virtio_config_disable(dev);
 394
 395         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 396
 397         if (drv && drv->freeze)
 398                 return drv->freeze(dev);
 399
 400         return 0;
 401 }
 402 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 403
 404 int virtio_device_restore(struct virtio_device *dev)
 405 {
 406         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 407         int ret;
 408
 409         /* We always start by resetting the device, in case a previous
 410          * driver messed it up. */
 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         /* Maybe driver failed before freeze.
 417          * Restore the failed status, for debugging. */
 418         if (dev->failed)
 419                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 420
 421         if (!drv)
 422                 return 0;
 423
 424         /* We have a driver! */
 425         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 426
 427         ret = virtio_finalize_features(dev);
 428         if (ret)
 429                 goto err;
 430
 431         if (drv->restore) {
 432                 ret = drv->restore(dev);
 433                 if (ret)
 434                         goto err;
 435         }
 436
 437         /* Finally, tell the device we're all set */
 438         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 439
 440         virtio_config_enable(dev);
 441
 442         return 0;
 443
 444 err:
 445         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 446         return ret;
 447 }
 448 EXPORT_SYMBOL_GPL(virtio_device_restore);
 449 #endif
 450
 451 static int virtio_init(void)
 452 {
 453         if (bus_register(&virtio_bus) != 0)
 454                 panic("virtio bus registration failed");
 455         return 0;
 456 }
 457
 458 static void __exit virtio_exit(void)
 459 {
 460         bus_unregister(&virtio_bus);
 461         ida_destroy(&virtio_index_ida);
 462 }
 463 core_initcall(virtio_init);
 464 module_exit(virtio_exit);
 465
 466 MODULE_LICENSE("GPL");