drivers/virtio/virtio.c

   1 #include <linux/virtio.h>
   2 #include <linux/spinlock.h>
   3 #include <linux/virtio_config.h>
   4 #include <linux/module.h>
   5 #include <linux/idr.h>
   6 #include <uapi/linux/virtio_ids.h>
   7
   8 /* Unique numbering for virtio devices. */
   9 static DEFINE_IDA(virtio_index_ida);
  10
  11 static ssize_t device_show(struct device *_d,
  12                            struct device_attribute *attr, char *buf)
  13 {
  14         struct virtio_device *dev = dev_to_virtio(_d);
  15         return sprintf(buf, "0x%04x\n", dev->id.device);
  16 }
  17 static DEVICE_ATTR_RO(device);
  18
  19 static ssize_t vendor_show(struct device *_d,
  20                            struct device_attribute *attr, char *buf)
  21 {
  22         struct virtio_device *dev = dev_to_virtio(_d);
  23         return sprintf(buf, "0x%04x\n", dev->id.vendor);
  24 }
  25 static DEVICE_ATTR_RO(vendor);
  26
  27 static ssize_t status_show(struct device *_d,
  28                            struct device_attribute *attr, char *buf)
  29 {
  30         struct virtio_device *dev = dev_to_virtio(_d);
  31         return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
  32 }
  33 static DEVICE_ATTR_RO(status);
  34
  35 static ssize_t modalias_show(struct device *_d,
  36                              struct device_attribute *attr, char *buf)
  37 {
  38         struct virtio_device *dev = dev_to_virtio(_d);
  39         return sprintf(buf, "virtio:d%08Xv%08X\n",
  40                        dev->id.device, dev->id.vendor);
  41 }
  42 static DEVICE_ATTR_RO(modalias);
  43
  44 static ssize_t features_show(struct device *_d,
  45                              struct device_attribute *attr, char *buf)
  46 {
  47         struct virtio_device *dev = dev_to_virtio(_d);
  48         unsigned int i;
  49         ssize_t len = 0;
  50
  51         /* We actually represent this as a bitstring, as it could be
  52          * arbitrary length in future. */
  53         for (i = 0; i < sizeof(dev->features)*8; i++)
  54                 len += sprintf(buf+len, "%c",
  55                                __virtio_test_bit(dev, i) ? '1' : '0');
  56         len += sprintf(buf+len, "\n");
  57         return len;
  58 }
  59 static DEVICE_ATTR_RO(features);
  60
  61 static struct attribute *virtio_dev_attrs[] = {
  62         &dev_attr_device.attr,
  63         &dev_attr_vendor.attr,
  64         &dev_attr_status.attr,
  65         &dev_attr_modalias.attr,
  66         &dev_attr_features.attr,
  67         NULL,
  68 };
  69 ATTRIBUTE_GROUPS(virtio_dev);
  70
  71 static inline int virtio_id_match(const struct virtio_device *dev,
  72                                   const struct virtio_device_id *id)
  73 {
  74         if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
  75                 return 0;
  76
  77         return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
  78 }
  79
  80 /* This looks through all the IDs a driver claims to support.  If any of them
  81  * match, we return 1 and the kernel will call virtio_dev_probe(). */
  82 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  83 {
  84         unsigned int i;
  85         struct virtio_device *dev = dev_to_virtio(_dv);
  86         const struct virtio_device_id *ids;
  87
  88         ids = drv_to_virtio(_dr)->id_table;
  89         for (i = 0; ids[i].device; i++)
  90                 if (virtio_id_match(dev, &ids[i]))
  91                         return 1;
  92         return 0;
  93 }
  94
  95 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  96 {
  97         struct virtio_device *dev = dev_to_virtio(_dv);
  98
  99         return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
 100                               dev->id.device, dev->id.vendor);
 101 }
 102
 103 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 104                                          unsigned int fbit)
 105 {
 106         unsigned int i;
 107         struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 108
 109         for (i = 0; i < drv->feature_table_size; i++)
 110                 if (drv->feature_table[i] == fbit)
 111                         return;
 112
 113         if (drv->feature_table_legacy) {
 114                 for (i = 0; i < drv->feature_table_size_legacy; i++)
 115                         if (drv->feature_table_legacy[i] == fbit)
 116                                 return;
 117         }
 118
 119         BUG();
 120 }
 121 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 122
 123 static void __virtio_config_changed(struct virtio_device *dev)
 124 {
 125         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 126
 127         if (!dev->config_enabled)
 128                 dev->config_change_pending = true;
 129         else if (drv && drv->config_changed)
 130                 drv->config_changed(dev);
 131 }
 132
 133 void virtio_config_changed(struct virtio_device *dev)
 134 {
 135         unsigned long flags;
 136
 137         spin_lock_irqsave(&dev->config_lock, flags);
 138         __virtio_config_changed(dev);
 139         spin_unlock_irqrestore(&dev->config_lock, flags);
 140 }
 141 EXPORT_SYMBOL_GPL(virtio_config_changed);
 142
 143 void virtio_config_disable(struct virtio_device *dev)
 144 {
 145         spin_lock_irq(&dev->config_lock);
 146         dev->config_enabled = false;
 147         spin_unlock_irq(&dev->config_lock);
 148 }
 149 EXPORT_SYMBOL_GPL(virtio_config_disable);
 150
 151 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 EXPORT_SYMBOL_GPL(virtio_config_enable);
 161
 162 void virtio_add_status(struct virtio_device *dev, unsigned int status)
 163 {
 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         if (ret)
 174                 return ret;
 175
 176         if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 177                 return 0;
 178
 179         virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 180         status = dev->config->get_status(dev);
 181         if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 182                 dev_err(&dev->dev, "virtio: device refuses features: %x\n",
 183                         status);
 184                 return -ENODEV;
 185         }
 186         return 0;
 187 }
 188 EXPORT_SYMBOL_GPL(virtio_finalize_features);
 189
 190 static int virtio_dev_probe(struct device *_d)
 191 {
 192         int err, i;
 193         struct virtio_device *dev = dev_to_virtio(_d);
 194         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 195         u64 device_features;
 196         u64 driver_features;
 197         u64 driver_features_legacy;
 198
 199         /* We have a driver! */
 200         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 201
 202         /* Figure out what features the device supports. */
 203         device_features = dev->config->get_features(dev);
 204
 205         /* Figure out what features the driver supports. */
 206         driver_features = 0;
 207         for (i = 0; i < drv->feature_table_size; i++) {
 208                 unsigned int f = drv->feature_table[i];
 209                 BUG_ON(f >= 64);
 210                 driver_features |= (1ULL << f);
 211         }
 212
 213         /* Some drivers have a separate feature table for virtio v1.0 */
 214         if (drv->feature_table_legacy) {
 215                 driver_features_legacy = 0;
 216                 for (i = 0; i < drv->feature_table_size_legacy; i++) {
 217                         unsigned int f = drv->feature_table_legacy[i];
 218                         BUG_ON(f >= 64);
 219                         driver_features_legacy |= (1ULL << f);
 220                 }
 221         } else {
 222                 driver_features_legacy = driver_features;
 223         }
 224
 225         if (device_features & (1ULL << VIRTIO_F_VERSION_1))
 226                 dev->features = driver_features & device_features;
 227         else
 228                 dev->features = driver_features_legacy & device_features;
 229
 230         /* Transport features always preserved to pass to finalize_features. */
 231         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 232                 if (device_features & (1ULL << i))
 233                         __virtio_set_bit(dev, i);
 234
 235         err = virtio_finalize_features(dev);
 236         if (err)
 237                 goto err;
 238
 239         err = drv->probe(dev);
 240         if (err)
 241                 goto err;
 242
 243         /* If probe didn't do it, mark device DRIVER_OK ourselves. */
 244         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 245                 virtio_device_ready(dev);
 246
 247         if (drv->scan)
 248                 drv->scan(dev);
 249
 250         virtio_config_enable(dev);
 251
 252         return 0;
 253 err:
 254         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 255         return err;
 256
 257 }
 258
 259 static int virtio_dev_remove(struct device *_d)
 260 {
 261         struct virtio_device *dev = dev_to_virtio(_d);
 262         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 263
 264         virtio_config_disable(dev);
 265
 266         drv->remove(dev);
 267
 268         /* Driver should have reset device. */
 269         WARN_ON_ONCE(dev->config->get_status(dev));
 270
 271         /* Acknowledge the device's existence again. */
 272         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 273         return 0;
 274 }
 275
 276 static struct bus_type virtio_bus = {
 277         .name  = "virtio",
 278         .match = virtio_dev_match,
 279         .dev_groups = virtio_dev_groups,
 280         .uevent = virtio_uevent,
 281         .probe = virtio_dev_probe,
 282         .remove = virtio_dev_remove,
 283 };
 284
 285 int register_virtio_driver(struct virtio_driver *driver)
 286 {
 287         /* Catch this early. */
 288         BUG_ON(driver->feature_table_size && !driver->feature_table);
 289         driver->driver.bus = &virtio_bus;
 290         return driver_register(&driver->driver);
 291 }
 292 EXPORT_SYMBOL_GPL(register_virtio_driver);
 293
 294 void unregister_virtio_driver(struct virtio_driver *driver)
 295 {
 296         driver_unregister(&driver->driver);
 297 }
 298 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 299
 300 int register_virtio_device(struct virtio_device *dev)
 301 {
 302         int err;
 303
 304         dev->dev.bus = &virtio_bus;
 305
 306         /* Assign a unique device index and hence name. */
 307         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 308         if (err < 0)
 309                 goto out;
 310
 311         dev->index = err;
 312         dev_set_name(&dev->dev, "virtio%u", dev->index);
 313
 314         spin_lock_init(&dev->config_lock);
 315         dev->config_enabled = false;
 316         dev->config_change_pending = false;
 317
 318         /* We always start by resetting the device, in case a previous
 319          * driver messed it up.  This also tests that code path a little. */
 320         dev->config->reset(dev);
 321
 322         /* Acknowledge that we've seen the device. */
 323         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 324
 325         INIT_LIST_HEAD(&dev->vqs);
 326
 327         /* device_register() causes the bus infrastructure to look for a
 328          * matching driver. */
 329         err = device_register(&dev->dev);
 330 out:
 331         if (err)
 332                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 333         return err;
 334 }
 335 EXPORT_SYMBOL_GPL(register_virtio_device);
 336
 337 void unregister_virtio_device(struct virtio_device *dev)
 338 {
 339         int index = dev->index; /* save for after device release */
 340
 341         device_unregister(&dev->dev);
 342         ida_simple_remove(&virtio_index_ida, index);
 343 }
 344 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 345
 346 #ifdef CONFIG_PM_SLEEP
 347 int virtio_device_freeze(struct virtio_device *dev)
 348 {
 349         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 350
 351         virtio_config_disable(dev);
 352
 353         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 354
 355         if (drv && drv->freeze)
 356                 return drv->freeze(dev);
 357
 358         return 0;
 359 }
 360 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 361
 362 int virtio_device_restore(struct virtio_device *dev)
 363 {
 364         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 365         int ret;
 366
 367         /* We always start by resetting the device, in case a previous
 368          * driver messed it up. */
 369         dev->config->reset(dev);
 370
 371         /* Acknowledge that we've seen the device. */
 372         virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 373
 374         /* Maybe driver failed before freeze.
 375          * Restore the failed status, for debugging. */
 376         if (dev->failed)
 377                 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 378
 379         if (!drv)
 380                 return 0;
 381
 382         /* We have a driver! */
 383         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 384
 385         ret = virtio_finalize_features(dev);
 386         if (ret)
 387                 goto err;
 388
 389         if (drv->restore) {
 390                 ret = drv->restore(dev);
 391                 if (ret)
 392                         goto err;
 393         }
 394
 395         /* Finally, tell the device we're all set */
 396         virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 397
 398         virtio_config_enable(dev);
 399
 400         return 0;
 401
 402 err:
 403         virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 404         return ret;
 405 }
 406 EXPORT_SYMBOL_GPL(virtio_device_restore);
 407 #endif
 408
 409 static int virtio_init(void)
 410 {
 411         if (bus_register(&virtio_bus) != 0)
 412                 panic("virtio bus registration failed");
 413         return 0;
 414 }
 415
 416 static void __exit virtio_exit(void)
 417 {
 418         bus_unregister(&virtio_bus);
 419         ida_destroy(&virtio_index_ida);
 420 }
 421 core_initcall(virtio_init);
 422 module_exit(virtio_exit);
 423
 424 MODULE_LICENSE("GPL");