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_dev_probe(struct device *_d) 166 { 167 int err, i; 168 struct virtio_device *dev = dev_to_virtio(_d); 169 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 170 u64 device_features; 171 u64 driver_features; 172 u64 driver_features_legacy; 173 unsigned status; 174 175 /* We have a driver! */ 176 add_status(dev, VIRTIO_CONFIG_S_DRIVER); 177 178 /* Figure out what features the device supports. */ 179 device_features = dev->config->get_features(dev); 180 181 /* Figure out what features the driver supports. */ 182 driver_features = 0; 183 for (i = 0; i < drv->feature_table_size; i++) { 184 unsigned int f = drv->feature_table[i]; 185 BUG_ON(f >= 64); 186 driver_features |= (1ULL << f); 187 } 188 189 /* Some drivers have a separate feature table for virtio v1.0 */ 190 if (drv->feature_table_legacy) { 191 driver_features_legacy = 0; 192 for (i = 0; i < drv->feature_table_size_legacy; i++) { 193 unsigned int f = drv->feature_table_legacy[i]; 194 BUG_ON(f >= 64); 195 driver_features_legacy |= (1ULL << f); 196 } 197 } else { 198 driver_features_legacy = driver_features; 199 } 200 201 if (device_features & (1ULL << VIRTIO_F_VERSION_1)) 202 dev->features = driver_features & device_features; 203 else 204 dev->features = driver_features_legacy & device_features; 205 206 /* Transport features always preserved to pass to finalize_features. */ 207 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) 208 if (device_features & (1ULL << i)) 209 __virtio_set_bit(dev, i); 210 211 err = dev->config->finalize_features(dev); 212 if (err) 213 goto err; 214 215 if (virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { 216 add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK); 217 status = dev->config->get_status(dev); 218 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) { 219 dev_err(_d, "virtio: device refuses features: %x\n", 220 status); 221 err = -ENODEV; 222 goto err; 223 } 224 } 225 226 err = drv->probe(dev); 227 if (err) 228 goto err; 229 230 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); 231 if (drv->scan) 232 drv->scan(dev); 233 234 virtio_config_enable(dev); 235 236 return 0; 237 err: 238 add_status(dev, VIRTIO_CONFIG_S_FAILED); 239 return err; 240 241 } 242 243 static int virtio_dev_remove(struct device *_d) 244 { 245 struct virtio_device *dev = dev_to_virtio(_d); 246 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 247 248 virtio_config_disable(dev); 249 250 drv->remove(dev); 251 252 /* Driver should have reset device. */ 253 WARN_ON_ONCE(dev->config->get_status(dev)); 254 255 /* Acknowledge the device's existence again. */ 256 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 257 return 0; 258 } 259 260 static struct bus_type virtio_bus = { 261 .name = "virtio", 262 .match = virtio_dev_match, 263 .dev_groups = virtio_dev_groups, 264 .uevent = virtio_uevent, 265 .probe = virtio_dev_probe, 266 .remove = virtio_dev_remove, 267 }; 268 269 bool virtio_device_is_legacy_only(struct virtio_device_id id) 270 { 271 return id.device == VIRTIO_ID_BALLOON; 272 } 273 EXPORT_SYMBOL_GPL(virtio_device_is_legacy_only); 274 275 int register_virtio_driver(struct virtio_driver *driver) 276 { 277 /* Catch this early. */ 278 BUG_ON(driver->feature_table_size && !driver->feature_table); 279 driver->driver.bus = &virtio_bus; 280 return driver_register(&driver->driver); 281 } 282 EXPORT_SYMBOL_GPL(register_virtio_driver); 283 284 void unregister_virtio_driver(struct virtio_driver *driver) 285 { 286 driver_unregister(&driver->driver); 287 } 288 EXPORT_SYMBOL_GPL(unregister_virtio_driver); 289 290 int register_virtio_device(struct virtio_device *dev) 291 { 292 int err; 293 294 dev->dev.bus = &virtio_bus; 295 296 /* Assign a unique device index and hence name. */ 297 err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL); 298 if (err < 0) 299 goto out; 300 301 dev->index = err; 302 dev_set_name(&dev->dev, "virtio%u", dev->index); 303 304 spin_lock_init(&dev->config_lock); 305 dev->config_enabled = false; 306 dev->config_change_pending = false; 307 308 /* We always start by resetting the device, in case a previous 309 * driver messed it up. This also tests that code path a little. */ 310 dev->config->reset(dev); 311 312 /* Acknowledge that we've seen the device. */ 313 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 314 315 INIT_LIST_HEAD(&dev->vqs); 316 317 /* device_register() causes the bus infrastructure to look for a 318 * matching driver. */ 319 err = device_register(&dev->dev); 320 out: 321 if (err) 322 add_status(dev, VIRTIO_CONFIG_S_FAILED); 323 return err; 324 } 325 EXPORT_SYMBOL_GPL(register_virtio_device); 326 327 void unregister_virtio_device(struct virtio_device *dev) 328 { 329 int index = dev->index; /* save for after device release */ 330 331 device_unregister(&dev->dev); 332 ida_simple_remove(&virtio_index_ida, index); 333 } 334 EXPORT_SYMBOL_GPL(unregister_virtio_device); 335 336 #ifdef CONFIG_PM_SLEEP 337 int virtio_device_freeze(struct virtio_device *dev) 338 { 339 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 340 341 virtio_config_disable(dev); 342 343 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; 344 345 if (drv && drv->freeze) 346 return drv->freeze(dev); 347 348 return 0; 349 } 350 EXPORT_SYMBOL_GPL(virtio_device_freeze); 351 352 int virtio_device_restore(struct virtio_device *dev) 353 { 354 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 355 int ret; 356 357 /* We always start by resetting the device, in case a previous 358 * driver messed it up. */ 359 dev->config->reset(dev); 360 361 /* Acknowledge that we've seen the device. */ 362 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 363 364 /* Maybe driver failed before freeze. 365 * Restore the failed status, for debugging. */ 366 if (dev->failed) 367 add_status(dev, VIRTIO_CONFIG_S_FAILED); 368 369 if (!drv) 370 return 0; 371 372 /* We have a driver! */ 373 add_status(dev, VIRTIO_CONFIG_S_DRIVER); 374 375 ret = dev->config->finalize_features(dev); 376 if (ret) 377 goto err; 378 379 if (drv->restore) { 380 ret = drv->restore(dev); 381 if (ret) 382 goto err; 383 } 384 385 /* Finally, tell the device we're all set */ 386 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); 387 388 virtio_config_enable(dev); 389 390 return 0; 391 392 err: 393 add_status(dev, VIRTIO_CONFIG_S_FAILED); 394 return ret; 395 } 396 EXPORT_SYMBOL_GPL(virtio_device_restore); 397 #endif 398 399 static int virtio_init(void) 400 { 401 if (bus_register(&virtio_bus) != 0) 402 panic("virtio bus registration failed"); 403 return 0; 404 } 405 406 static void __exit virtio_exit(void) 407 { 408 bus_unregister(&virtio_bus); 409 } 410 core_initcall(virtio_init); 411 module_exit(virtio_exit); 412 413 MODULE_LICENSE("GPL"); 414