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
   7 /* Unique numbering for virtio devices. */
   8 static DEFINE_IDA(virtio_index_ida);
   9
  10 static ssize_t device_show(struct device *_d,
  11                            struct device_attribute *attr, char *buf)
  12 {
  13         struct virtio_device *dev = dev_to_virtio(_d);
  14         return sprintf(buf, "0x%04x\n", dev->id.device);
  15 }
  16 static DEVICE_ATTR_RO(device);
  17
  18 static ssize_t vendor_show(struct device *_d,
  19                            struct device_attribute *attr, char *buf)
  20 {
  21         struct virtio_device *dev = dev_to_virtio(_d);
  22         return sprintf(buf, "0x%04x\n", dev->id.vendor);
  23 }
  24 static DEVICE_ATTR_RO(vendor);
  25
  26 static ssize_t status_show(struct device *_d,
  27                            struct device_attribute *attr, char *buf)
  28 {
  29         struct virtio_device *dev = dev_to_virtio(_d);
  30         return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
  31 }
  32 static DEVICE_ATTR_RO(status);
  33
  34 static ssize_t modalias_show(struct device *_d,
  35                              struct device_attribute *attr, char *buf)
  36 {
  37         struct virtio_device *dev = dev_to_virtio(_d);
  38         return sprintf(buf, "virtio:d%08Xv%08X\n",
  39                        dev->id.device, dev->id.vendor);
  40 }
  41 static DEVICE_ATTR_RO(modalias);
  42
  43 static ssize_t features_show(struct device *_d,
  44                              struct device_attribute *attr, char *buf)
  45 {
  46         struct virtio_device *dev = dev_to_virtio(_d);
  47         unsigned int i;
  48         ssize_t len = 0;
  49
  50         /* We actually represent this as a bitstring, as it could be
  51          * arbitrary length in future. */
  52         for (i = 0; i < sizeof(dev->features)*8; i++)
  53                 len += sprintf(buf+len, "%c",
  54                                __virtio_test_bit(dev, i) ? '1' : '0');
  55         len += sprintf(buf+len, "\n");
  56         return len;
  57 }
  58 static DEVICE_ATTR_RO(features);
  59
  60 static struct attribute *virtio_dev_attrs[] = {
  61         &dev_attr_device.attr,
  62         &dev_attr_vendor.attr,
  63         &dev_attr_status.attr,
  64         &dev_attr_modalias.attr,
  65         &dev_attr_features.attr,
  66         NULL,
  67 };
  68 ATTRIBUTE_GROUPS(virtio_dev);
  69
  70 static inline int virtio_id_match(const struct virtio_device *dev,
  71                                   const struct virtio_device_id *id)
  72 {
  73         if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
  74                 return 0;
  75
  76         return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
  77 }
  78
  79 /* This looks through all the IDs a driver claims to support.  If any of them
  80  * match, we return 1 and the kernel will call virtio_dev_probe(). */
  81 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  82 {
  83         unsigned int i;
  84         struct virtio_device *dev = dev_to_virtio(_dv);
  85         const struct virtio_device_id *ids;
  86
  87         ids = drv_to_virtio(_dr)->id_table;
  88         for (i = 0; ids[i].device; i++)
  89                 if (virtio_id_match(dev, &ids[i]))
  90                         return 1;
  91         return 0;
  92 }
  93
  94 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  95 {
  96         struct virtio_device *dev = dev_to_virtio(_dv);
  97
  98         return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
  99                               dev->id.device, dev->id.vendor);
 100 }
 101
 102 static void add_status(struct virtio_device *dev, unsigned status)
 103 {
 104         dev->config->set_status(dev, dev->config->get_status(dev) | status);
 105 }
 106
 107 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 108                                          unsigned int fbit)
 109 {
 110         unsigned int i;
 111         struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 112
 113         for (i = 0; i < drv->feature_table_size; i++)
 114                 if (drv->feature_table[i] == fbit)
 115                         return;
 116
 117         if (drv->feature_table_legacy) {
 118                 for (i = 0; i < drv->feature_table_size_legacy; i++)
 119                         if (drv->feature_table_legacy[i] == fbit)
 120                                 return;
 121         }
 122
 123         BUG();
 124 }
 125 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 126
 127 static void __virtio_config_changed(struct virtio_device *dev)
 128 {
 129         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 130
 131         if (!dev->config_enabled)
 132                 dev->config_change_pending = true;
 133         else if (drv && drv->config_changed)
 134                 drv->config_changed(dev);
 135 }
 136
 137 void virtio_config_changed(struct virtio_device *dev)
 138 {
 139         unsigned long flags;
 140
 141         spin_lock_irqsave(&dev->config_lock, flags);
 142         __virtio_config_changed(dev);
 143         spin_unlock_irqrestore(&dev->config_lock, flags);
 144 }
 145 EXPORT_SYMBOL_GPL(virtio_config_changed);
 146
 147 static void virtio_config_disable(struct virtio_device *dev)
 148 {
 149         spin_lock_irq(&dev->config_lock);
 150         dev->config_enabled = false;
 151         spin_unlock_irq(&dev->config_lock);
 152 }
 153
 154 static void virtio_config_enable(struct virtio_device *dev)
 155 {
 156         spin_lock_irq(&dev->config_lock);
 157         dev->config_enabled = true;
 158         if (dev->config_change_pending)
 159                 __virtio_config_changed(dev);
 160         dev->config_change_pending = false;
 161         spin_unlock_irq(&dev->config_lock);
 162 }
 163
 164 static int virtio_dev_probe(struct device *_d)
 165 {
 166         int err, i;
 167         struct virtio_device *dev = dev_to_virtio(_d);
 168         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 169         u64 device_features;
 170         u64 driver_features;
 171         u64 driver_features_legacy;
 172         unsigned status;
 173
 174         /* We have a driver! */
 175         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 176
 177         /* Figure out what features the device supports. */
 178         device_features = dev->config->get_features(dev);
 179
 180         /* Figure out what features the driver supports. */
 181         driver_features = 0;
 182         for (i = 0; i < drv->feature_table_size; i++) {
 183                 unsigned int f = drv->feature_table[i];
 184                 BUG_ON(f >= 64);
 185                 driver_features |= (1ULL << f);
 186         }
 187
 188         /* Some drivers have a separate feature table for virtio v1.0 */
 189         if (drv->feature_table_legacy) {
 190                 driver_features_legacy = 0;
 191                 for (i = 0; i < drv->feature_table_size_legacy; i++) {
 192                         unsigned int f = drv->feature_table_legacy[i];
 193                         BUG_ON(f >= 64);
 194                         driver_features_legacy |= (1ULL << f);
 195                 }
 196         } else {
 197                 driver_features_legacy = driver_features;
 198         }
 199
 200         if (driver_features & device_features & (1ULL << VIRTIO_F_VERSION_1))
 201                 dev->features = driver_features & device_features;
 202         else
 203                 dev->features = driver_features_legacy & device_features;
 204
 205         /* Transport features always preserved to pass to finalize_features. */
 206         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 207                 if (device_features & (1ULL << i))
 208                         __virtio_set_bit(dev, i);
 209
 210         dev->config->finalize_features(dev);
 211
 212         if (virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
 213                 add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 214                 status = dev->config->get_status(dev);
 215                 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 216                         dev_err(_d, "virtio: device refuses features: %x\n",
 217                                status);
 218                         err = -ENODEV;
 219                         goto err;
 220                 }
 221         }
 222
 223         err = drv->probe(dev);
 224         if (err)
 225                 goto err;
 226
 227         add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 228         if (drv->scan)
 229                 drv->scan(dev);
 230
 231         virtio_config_enable(dev);
 232
 233         return 0;
 234 err:
 235         add_status(dev, VIRTIO_CONFIG_S_FAILED);
 236         return err;
 237
 238 }
 239
 240 static int virtio_dev_remove(struct device *_d)
 241 {
 242         struct virtio_device *dev = dev_to_virtio(_d);
 243         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 244
 245         virtio_config_disable(dev);
 246
 247         drv->remove(dev);
 248
 249         /* Driver should have reset device. */
 250         WARN_ON_ONCE(dev->config->get_status(dev));
 251
 252         /* Acknowledge the device's existence again. */
 253         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 254         return 0;
 255 }
 256
 257 static struct bus_type virtio_bus = {
 258         .name  = "virtio",
 259         .match = virtio_dev_match,
 260         .dev_groups = virtio_dev_groups,
 261         .uevent = virtio_uevent,
 262         .probe = virtio_dev_probe,
 263         .remove = virtio_dev_remove,
 264 };
 265
 266 int register_virtio_driver(struct virtio_driver *driver)
 267 {
 268         /* Catch this early. */
 269         BUG_ON(driver->feature_table_size && !driver->feature_table);
 270         driver->driver.bus = &virtio_bus;
 271         return driver_register(&driver->driver);
 272 }
 273 EXPORT_SYMBOL_GPL(register_virtio_driver);
 274
 275 void unregister_virtio_driver(struct virtio_driver *driver)
 276 {
 277         driver_unregister(&driver->driver);
 278 }
 279 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 280
 281 int register_virtio_device(struct virtio_device *dev)
 282 {
 283         int err;
 284
 285         dev->dev.bus = &virtio_bus;
 286
 287         /* Assign a unique device index and hence name. */
 288         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 289         if (err < 0)
 290                 goto out;
 291
 292         dev->index = err;
 293         dev_set_name(&dev->dev, "virtio%u", dev->index);
 294
 295         spin_lock_init(&dev->config_lock);
 296         dev->config_enabled = false;
 297         dev->config_change_pending = false;
 298
 299         /* We always start by resetting the device, in case a previous
 300          * driver messed it up.  This also tests that code path a little. */
 301         dev->config->reset(dev);
 302
 303         /* Acknowledge that we've seen the device. */
 304         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 305
 306         INIT_LIST_HEAD(&dev->vqs);
 307
 308         /* device_register() causes the bus infrastructure to look for a
 309          * matching driver. */
 310         err = device_register(&dev->dev);
 311 out:
 312         if (err)
 313                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 314         return err;
 315 }
 316 EXPORT_SYMBOL_GPL(register_virtio_device);
 317
 318 void unregister_virtio_device(struct virtio_device *dev)
 319 {
 320         int index = dev->index; /* save for after device release */
 321
 322         device_unregister(&dev->dev);
 323         ida_simple_remove(&virtio_index_ida, index);
 324 }
 325 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 326
 327 #ifdef CONFIG_PM_SLEEP
 328 int virtio_device_freeze(struct virtio_device *dev)
 329 {
 330         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 331
 332         virtio_config_disable(dev);
 333
 334         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 335
 336         if (drv && drv->freeze)
 337                 return drv->freeze(dev);
 338
 339         return 0;
 340 }
 341 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 342
 343 int virtio_device_restore(struct virtio_device *dev)
 344 {
 345         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 346
 347         /* We always start by resetting the device, in case a previous
 348          * driver messed it up. */
 349         dev->config->reset(dev);
 350
 351         /* Acknowledge that we've seen the device. */
 352         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 353
 354         /* Maybe driver failed before freeze.
 355          * Restore the failed status, for debugging. */
 356         if (dev->failed)
 357                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 358
 359         if (!drv)
 360                 return 0;
 361
 362         /* We have a driver! */
 363         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 364
 365         dev->config->finalize_features(dev);
 366
 367         if (drv->restore) {
 368                 int ret = drv->restore(dev);
 369                 if (ret) {
 370                         add_status(dev, VIRTIO_CONFIG_S_FAILED);
 371                         return ret;
 372                 }
 373         }
 374
 375         /* Finally, tell the device we're all set */
 376         add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 377
 378         virtio_config_enable(dev);
 379
 380         return 0;
 381 }
 382 EXPORT_SYMBOL_GPL(virtio_device_restore);
 383 #endif
 384
 385 static int virtio_init(void)
 386 {
 387         if (bus_register(&virtio_bus) != 0)
 388                 panic("virtio bus registration failed");
 389         return 0;
 390 }
 391
 392 static void __exit virtio_exit(void)
 393 {
 394         bus_unregister(&virtio_bus);
 395 }
 396 core_initcall(virtio_init);
 397 module_exit(virtio_exit);
 398
 399 MODULE_LICENSE("GPL");