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         if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 180                 return 0;
 181
 182         virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 183         status = dev->config->get_status(dev);
 184         if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 185                 dev_err(&dev->dev, "virtio: device refuses features: %x\n",
 186                         status);
 187                 return -ENODEV;
 188         }
 189         return 0;
 190 }
 191 EXPORT_SYMBOL_GPL(virtio_finalize_features);
 192
 193 static int virtio_dev_probe(struct device *_d)
 194 {
 195         int err, i;
 196         struct virtio_device *dev = dev_to_virtio(_d);
 197         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 198         u64 device_features;
 199         u64 driver_features;
 200         u64 driver_features_legacy;
 201
 202         /* We have a driver! */
 203         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 204
 205         /* Figure out what features the device supports. */
 206         device_features = dev->config->get_features(dev);
 207
 208         /* Figure out what features the driver supports. */
 209         driver_features = 0;
 210         for (i = 0; i < drv->feature_table_size; i++) {
 211                 unsigned int f = drv->feature_table[i];
 212                 BUG_ON(f >= 64);
 213                 driver_features |= (1ULL << f);
 214         }
 215
 216         /* Some drivers have a separate feature table for virtio v1.0 */
 217         if (drv->feature_table_legacy) {
 218                 driver_features_legacy = 0;
 219                 for (i = 0; i < drv->feature_table_size_legacy; i++) {
 220                         unsigned int f = drv->feature_table_legacy[i];
 221                         BUG_ON(f >= 64);
 222                         driver_features_legacy |= (1ULL << f);
 223                 }
 224         } else {
 225                 driver_features_legacy = driver_features;
 226         }
 227
 228         if (device_features & (1ULL << VIRTIO_F_VERSION_1))
 229                 dev->features = driver_features & device_features;
 230         else
 231                 dev->features = driver_features_legacy & device_features;
 232
 233         /* Transport features always preserved to pass to finalize_features. */
 234         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 235                 if (device_features & (1ULL << i))
 236                         __virtio_set_bit(dev, i);
 237
 238         if (drv->validate) {
 239                 err = drv->validate(dev);
 240                 if (err)
 241                         goto err;
 242         }
 243
 244         err = virtio_finalize_features(dev);
 245         if (err)
 246                 goto err;
 247
 248         err = drv->probe(dev);
 249         if (err)
 250                 goto err;
 251
 252         /* If probe didn't do it, mark device DRIVER_OK ourselves. */
 253         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 254                 virtio_device_ready(dev);
 255
 256         if (drv->scan)
 257                 drv->scan(dev);
 258
 259         virtio_config_enable(dev);
 260
 261         return 0;
 262 err:
 263         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 264         return err;
 265
 266 }
 267
 268 static int virtio_dev_remove(struct device *_d)
 269 {
 270         struct virtio_device *dev = dev_to_virtio(_d);
 271         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 272
 273         virtio_config_disable(dev);
 274
 275         drv->remove(dev);
 276
 277         /* Driver should have reset device. */
 278         WARN_ON_ONCE(dev->config->get_status(dev));
 279
 280         /* Acknowledge the device's existence again. */
 281         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 282         return 0;
 283 }
 284
 285 static struct bus_type virtio_bus = {
 286         .name  = "virtio",
 287         .match = virtio_dev_match,
 288         .dev_groups = virtio_dev_groups,
 289         .uevent = virtio_uevent,
 290         .probe = virtio_dev_probe,
 291         .remove = virtio_dev_remove,
 292 };
 293
 294 int register_virtio_driver(struct virtio_driver *driver)
 295 {
 296         /* Catch this early. */
 297         BUG_ON(driver->feature_table_size && !driver->feature_table);
 298         driver->driver.bus = &virtio_bus;
 299         return driver_register(&driver->driver);
 300 }
 301 EXPORT_SYMBOL_GPL(register_virtio_driver);
 302
 303 void unregister_virtio_driver(struct virtio_driver *driver)
 304 {
 305         driver_unregister(&driver->driver);
 306 }
 307 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 308
 309 /**
 310  * register_virtio_device - register virtio device
 311  * @dev        : virtio device to be registered
 312  *
 313  * On error, the caller must call put_device on &@dev->dev (and not kfree),
 314  * as another code path may have obtained a reference to @dev.
 315  *
 316  * Returns: 0 on suceess, -error on failure
 317  */
 318 int register_virtio_device(struct virtio_device *dev)
 319 {
 320         int err;
 321
 322         dev->dev.bus = &virtio_bus;
 323         device_initialize(&dev->dev);
 324
 325         /* Assign a unique device index and hence name. */
 326         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 327         if (err < 0)
 328                 goto out;
 329
 330         dev->index = err;
 331         dev_set_name(&dev->dev, "virtio%u", dev->index);
 332
 333         spin_lock_init(&dev->config_lock);
 334         dev->config_enabled = false;
 335         dev->config_change_pending = false;
 336
 337         /* We always start by resetting the device, in case a previous
 338          * driver messed it up.  This also tests that code path a little. */
 339         dev->config->reset(dev);
 340
 341         /* Acknowledge that we've seen the device. */
 342         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 343
 344         INIT_LIST_HEAD(&dev->vqs);
 345
 346         /*
 347          * device_add() causes the bus infrastructure to look for a matching
 348          * driver.
 349          */
 350         err = device_add(&dev->dev);
 351         if (err)
 352                 ida_simple_remove(&virtio_index_ida, dev->index);
 353 out:
 354         if (err)
 355                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 356         return err;
 357 }
 358 EXPORT_SYMBOL_GPL(register_virtio_device);
 359
 360 void unregister_virtio_device(struct virtio_device *dev)
 361 {
 362         int index = dev->index; /* save for after device release */
 363
 364         device_unregister(&dev->dev);
 365         ida_simple_remove(&virtio_index_ida, index);
 366 }
 367 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 368
 369 #ifdef CONFIG_PM_SLEEP
 370 int virtio_device_freeze(struct virtio_device *dev)
 371 {
 372         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 373
 374         virtio_config_disable(dev);
 375
 376         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 377
 378         if (drv && drv->freeze)
 379                 return drv->freeze(dev);
 380
 381         return 0;
 382 }
 383 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 384
 385 int virtio_device_restore(struct virtio_device *dev)
 386 {
 387         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 388         int ret;
 389
 390         /* We always start by resetting the device, in case a previous
 391          * driver messed it up. */
 392         dev->config->reset(dev);
 393
 394         /* Acknowledge that we've seen the device. */
 395         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 396
 397         /* Maybe driver failed before freeze.
 398          * Restore the failed status, for debugging. */
 399         if (dev->failed)
 400                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 401
 402         if (!drv)
 403                 return 0;
 404
 405         /* We have a driver! */
 406         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 407
 408         ret = virtio_finalize_features(dev);
 409         if (ret)
 410                 goto err;
 411
 412         if (drv->restore) {
 413                 ret = drv->restore(dev);
 414                 if (ret)
 415                         goto err;
 416         }
 417
 418         /* Finally, tell the device we're all set */
 419         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 420
 421         virtio_config_enable(dev);
 422
 423         return 0;
 424
 425 err:
 426         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 427         return ret;
 428 }
 429 EXPORT_SYMBOL_GPL(virtio_device_restore);
 430 #endif
 431
 432 static int virtio_init(void)
 433 {
 434         if (bus_register(&virtio_bus) != 0)
 435                 panic("virtio bus registration failed");
 436         return 0;
 437 }
 438
 439 static void __exit virtio_exit(void)
 440 {
 441         bus_unregister(&virtio_bus);
 442         ida_destroy(&virtio_index_ida);
 443 }
 444 core_initcall(virtio_init);
 445 module_exit(virtio_exit);
 446
 447 MODULE_LICENSE("GPL");