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 static void add_status(struct virtio_device *dev, unsigned status)
 104 {
 105         dev->config->set_status(dev, dev->config->get_status(dev) | status);
 106 }
 107
 108 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 109                                          unsigned int fbit)
 110 {
 111         unsigned int i;
 112         struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 113
 114         for (i = 0; i < drv->feature_table_size; i++)
 115                 if (drv->feature_table[i] == fbit)
 116                         return;
 117
 118         if (drv->feature_table_legacy) {
 119                 for (i = 0; i < drv->feature_table_size_legacy; i++)
 120                         if (drv->feature_table_legacy[i] == fbit)
 121                                 return;
 122         }
 123
 124         BUG();
 125 }
 126 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 127
 128 static void __virtio_config_changed(struct virtio_device *dev)
 129 {
 130         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 131
 132         if (!dev->config_enabled)
 133                 dev->config_change_pending = true;
 134         else if (drv && drv->config_changed)
 135                 drv->config_changed(dev);
 136 }
 137
 138 void virtio_config_changed(struct virtio_device *dev)
 139 {
 140         unsigned long flags;
 141
 142         spin_lock_irqsave(&dev->config_lock, flags);
 143         __virtio_config_changed(dev);
 144         spin_unlock_irqrestore(&dev->config_lock, flags);
 145 }
 146 EXPORT_SYMBOL_GPL(virtio_config_changed);
 147
 148 static void virtio_config_disable(struct virtio_device *dev)
 149 {
 150         spin_lock_irq(&dev->config_lock);
 151         dev->config_enabled = false;
 152         spin_unlock_irq(&dev->config_lock);
 153 }
 154
 155 static void virtio_config_enable(struct virtio_device *dev)
 156 {
 157         spin_lock_irq(&dev->config_lock);
 158         dev->config_enabled = true;
 159         if (dev->config_change_pending)
 160                 __virtio_config_changed(dev);
 161         dev->config_change_pending = false;
 162         spin_unlock_irq(&dev->config_lock);
 163 }
 164
 165 static int virtio_finalize_features(struct virtio_device *dev)
 166 {
 167         int ret = dev->config->finalize_features(dev);
 168         unsigned status;
 169
 170         if (ret)
 171                 return ret;
 172
 173         if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 174                 return 0;
 175
 176         add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 177         status = dev->config->get_status(dev);
 178         if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 179                 dev_err(&dev->dev, "virtio: device refuses features: %x\n",
 180                         status);
 181                 return -ENODEV;
 182         }
 183         return 0;
 184 }
 185
 186 static int virtio_dev_probe(struct device *_d)
 187 {
 188         int err, i;
 189         struct virtio_device *dev = dev_to_virtio(_d);
 190         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 191         u64 device_features;
 192         u64 driver_features;
 193         u64 driver_features_legacy;
 194
 195         /* We have a driver! */
 196         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 197
 198         /* Figure out what features the device supports. */
 199         device_features = dev->config->get_features(dev);
 200
 201         /* Figure out what features the driver supports. */
 202         driver_features = 0;
 203         for (i = 0; i < drv->feature_table_size; i++) {
 204                 unsigned int f = drv->feature_table[i];
 205                 BUG_ON(f >= 64);
 206                 driver_features |= (1ULL << f);
 207         }
 208
 209         /* Some drivers have a separate feature table for virtio v1.0 */
 210         if (drv->feature_table_legacy) {
 211                 driver_features_legacy = 0;
 212                 for (i = 0; i < drv->feature_table_size_legacy; i++) {
 213                         unsigned int f = drv->feature_table_legacy[i];
 214                         BUG_ON(f >= 64);
 215                         driver_features_legacy |= (1ULL << f);
 216                 }
 217         } else {
 218                 driver_features_legacy = driver_features;
 219         }
 220
 221         if (device_features & (1ULL << VIRTIO_F_VERSION_1))
 222                 dev->features = driver_features & device_features;
 223         else
 224                 dev->features = driver_features_legacy & device_features;
 225
 226         /* Transport features always preserved to pass to finalize_features. */
 227         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 228                 if (device_features & (1ULL << i))
 229                         __virtio_set_bit(dev, i);
 230
 231         err = virtio_finalize_features(dev);
 232         if (err)
 233                 goto err;
 234
 235         err = drv->probe(dev);
 236         if (err)
 237                 goto err;
 238
 239         /* If probe didn't do it, mark device DRIVER_OK ourselves. */
 240         if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
 241                 virtio_device_ready(dev);
 242
 243         if (drv->scan)
 244                 drv->scan(dev);
 245
 246         virtio_config_enable(dev);
 247
 248         return 0;
 249 err:
 250         add_status(dev, VIRTIO_CONFIG_S_FAILED);
 251         return err;
 252
 253 }
 254
 255 static int virtio_dev_remove(struct device *_d)
 256 {
 257         struct virtio_device *dev = dev_to_virtio(_d);
 258         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 259
 260         virtio_config_disable(dev);
 261
 262         drv->remove(dev);
 263
 264         /* Driver should have reset device. */
 265         WARN_ON_ONCE(dev->config->get_status(dev));
 266
 267         /* Acknowledge the device's existence again. */
 268         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 269         return 0;
 270 }
 271
 272 static struct bus_type virtio_bus = {
 273         .name  = "virtio",
 274         .match = virtio_dev_match,
 275         .dev_groups = virtio_dev_groups,
 276         .uevent = virtio_uevent,
 277         .probe = virtio_dev_probe,
 278         .remove = virtio_dev_remove,
 279 };
 280
 281 int register_virtio_driver(struct virtio_driver *driver)
 282 {
 283         /* Catch this early. */
 284         BUG_ON(driver->feature_table_size && !driver->feature_table);
 285         driver->driver.bus = &virtio_bus;
 286         return driver_register(&driver->driver);
 287 }
 288 EXPORT_SYMBOL_GPL(register_virtio_driver);
 289
 290 void unregister_virtio_driver(struct virtio_driver *driver)
 291 {
 292         driver_unregister(&driver->driver);
 293 }
 294 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 295
 296 int register_virtio_device(struct virtio_device *dev)
 297 {
 298         int err;
 299
 300         dev->dev.bus = &virtio_bus;
 301
 302         /* Assign a unique device index and hence name. */
 303         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 304         if (err < 0)
 305                 goto out;
 306
 307         dev->index = err;
 308         dev_set_name(&dev->dev, "virtio%u", dev->index);
 309
 310         spin_lock_init(&dev->config_lock);
 311         dev->config_enabled = false;
 312         dev->config_change_pending = false;
 313
 314         /* We always start by resetting the device, in case a previous
 315          * driver messed it up.  This also tests that code path a little. */
 316         dev->config->reset(dev);
 317
 318         /* Acknowledge that we've seen the device. */
 319         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 320
 321         INIT_LIST_HEAD(&dev->vqs);
 322
 323         /* device_register() causes the bus infrastructure to look for a
 324          * matching driver. */
 325         err = device_register(&dev->dev);
 326 out:
 327         if (err)
 328                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 329         return err;
 330 }
 331 EXPORT_SYMBOL_GPL(register_virtio_device);
 332
 333 void unregister_virtio_device(struct virtio_device *dev)
 334 {
 335         int index = dev->index; /* save for after device release */
 336
 337         device_unregister(&dev->dev);
 338         ida_simple_remove(&virtio_index_ida, index);
 339 }
 340 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 341
 342 #ifdef CONFIG_PM_SLEEP
 343 int virtio_device_freeze(struct virtio_device *dev)
 344 {
 345         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 346
 347         virtio_config_disable(dev);
 348
 349         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 350
 351         if (drv && drv->freeze)
 352                 return drv->freeze(dev);
 353
 354         return 0;
 355 }
 356 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 357
 358 int virtio_device_restore(struct virtio_device *dev)
 359 {
 360         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 361         int ret;
 362
 363         /* We always start by resetting the device, in case a previous
 364          * driver messed it up. */
 365         dev->config->reset(dev);
 366
 367         /* Acknowledge that we've seen the device. */
 368         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 369
 370         /* Maybe driver failed before freeze.
 371          * Restore the failed status, for debugging. */
 372         if (dev->failed)
 373                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 374
 375         if (!drv)
 376                 return 0;
 377
 378         /* We have a driver! */
 379         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 380
 381         ret = virtio_finalize_features(dev);
 382         if (ret)
 383                 goto err;
 384
 385         if (drv->restore) {
 386                 ret = drv->restore(dev);
 387                 if (ret)
 388                         goto err;
 389         }
 390
 391         /* Finally, tell the device we're all set */
 392         add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 393
 394         virtio_config_enable(dev);
 395
 396         return 0;
 397
 398 err:
 399         add_status(dev, VIRTIO_CONFIG_S_FAILED);
 400         return ret;
 401 }
 402 EXPORT_SYMBOL_GPL(virtio_device_restore);
 403 #endif
 404
 405 static int virtio_init(void)
 406 {
 407         if (bus_register(&virtio_bus) != 0)
 408                 panic("virtio bus registration failed");
 409         return 0;
 410 }
 411
 412 static void __exit virtio_exit(void)
 413 {
 414         bus_unregister(&virtio_bus);
 415         ida_destroy(&virtio_index_ida);
 416 }
 417 core_initcall(virtio_init);
 418 module_exit(virtio_exit);
 419
 420 MODULE_LICENSE("GPL");