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 } 416 core_initcall(virtio_init); 417 module_exit(virtio_exit); 418 419 MODULE_LICENSE("GPL"); 420