1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/virtio.h> 3 #include <linux/spinlock.h> 4 #include <linux/virtio_config.h> 5 #include <linux/module.h> 6 #include <linux/idr.h> 7 #include <uapi/linux/virtio_ids.h> 8 9 /* Unique numbering for virtio devices. */ 10 static DEFINE_IDA(virtio_index_ida); 11 12 static ssize_t device_show(struct device *_d, 13 struct device_attribute *attr, char *buf) 14 { 15 struct virtio_device *dev = dev_to_virtio(_d); 16 return sprintf(buf, "0x%04x\n", dev->id.device); 17 } 18 static DEVICE_ATTR_RO(device); 19 20 static ssize_t vendor_show(struct device *_d, 21 struct device_attribute *attr, char *buf) 22 { 23 struct virtio_device *dev = dev_to_virtio(_d); 24 return sprintf(buf, "0x%04x\n", dev->id.vendor); 25 } 26 static DEVICE_ATTR_RO(vendor); 27 28 static ssize_t status_show(struct device *_d, 29 struct device_attribute *attr, char *buf) 30 { 31 struct virtio_device *dev = dev_to_virtio(_d); 32 return sprintf(buf, "0x%08x\n", dev->config->get_status(dev)); 33 } 34 static DEVICE_ATTR_RO(status); 35 36 static ssize_t modalias_show(struct device *_d, 37 struct device_attribute *attr, char *buf) 38 { 39 struct virtio_device *dev = dev_to_virtio(_d); 40 return sprintf(buf, "virtio:d%08Xv%08X\n", 41 dev->id.device, dev->id.vendor); 42 } 43 static DEVICE_ATTR_RO(modalias); 44 45 static ssize_t features_show(struct device *_d, 46 struct device_attribute *attr, char *buf) 47 { 48 struct virtio_device *dev = dev_to_virtio(_d); 49 unsigned int i; 50 ssize_t len = 0; 51 52 /* We actually represent this as a bitstring, as it could be 53 * arbitrary length in future. */ 54 for (i = 0; i < sizeof(dev->features)*8; i++) 55 len += sprintf(buf+len, "%c", 56 __virtio_test_bit(dev, i) ? '1' : '0'); 57 len += sprintf(buf+len, "\n"); 58 return len; 59 } 60 static DEVICE_ATTR_RO(features); 61 62 static struct attribute *virtio_dev_attrs[] = { 63 &dev_attr_device.attr, 64 &dev_attr_vendor.attr, 65 &dev_attr_status.attr, 66 &dev_attr_modalias.attr, 67 &dev_attr_features.attr, 68 NULL, 69 }; 70 ATTRIBUTE_GROUPS(virtio_dev); 71 72 static inline int virtio_id_match(const struct virtio_device *dev, 73 const struct virtio_device_id *id) 74 { 75 if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID) 76 return 0; 77 78 return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor; 79 } 80 81 /* This looks through all the IDs a driver claims to support. If any of them 82 * match, we return 1 and the kernel will call virtio_dev_probe(). */ 83 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr) 84 { 85 unsigned int i; 86 struct virtio_device *dev = dev_to_virtio(_dv); 87 const struct virtio_device_id *ids; 88 89 ids = drv_to_virtio(_dr)->id_table; 90 for (i = 0; ids[i].device; i++) 91 if (virtio_id_match(dev, &ids[i])) 92 return 1; 93 return 0; 94 } 95 96 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env) 97 { 98 struct virtio_device *dev = dev_to_virtio(_dv); 99 100 return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X", 101 dev->id.device, dev->id.vendor); 102 } 103 104 void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 105 unsigned int fbit) 106 { 107 unsigned int i; 108 struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver); 109 110 for (i = 0; i < drv->feature_table_size; i++) 111 if (drv->feature_table[i] == fbit) 112 return; 113 114 if (drv->feature_table_legacy) { 115 for (i = 0; i < drv->feature_table_size_legacy; i++) 116 if (drv->feature_table_legacy[i] == fbit) 117 return; 118 } 119 120 BUG(); 121 } 122 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature); 123 124 static void __virtio_config_changed(struct virtio_device *dev) 125 { 126 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 127 128 if (!dev->config_enabled) 129 dev->config_change_pending = true; 130 else if (drv && drv->config_changed) 131 drv->config_changed(dev); 132 } 133 134 void virtio_config_changed(struct virtio_device *dev) 135 { 136 unsigned long flags; 137 138 spin_lock_irqsave(&dev->config_lock, flags); 139 __virtio_config_changed(dev); 140 spin_unlock_irqrestore(&dev->config_lock, flags); 141 } 142 EXPORT_SYMBOL_GPL(virtio_config_changed); 143 144 void virtio_config_disable(struct virtio_device *dev) 145 { 146 spin_lock_irq(&dev->config_lock); 147 dev->config_enabled = false; 148 spin_unlock_irq(&dev->config_lock); 149 } 150 EXPORT_SYMBOL_GPL(virtio_config_disable); 151 152 void virtio_config_enable(struct virtio_device *dev) 153 { 154 spin_lock_irq(&dev->config_lock); 155 dev->config_enabled = true; 156 if (dev->config_change_pending) 157 __virtio_config_changed(dev); 158 dev->config_change_pending = false; 159 spin_unlock_irq(&dev->config_lock); 160 } 161 EXPORT_SYMBOL_GPL(virtio_config_enable); 162 163 void virtio_add_status(struct virtio_device *dev, unsigned int status) 164 { 165 might_sleep(); 166 dev->config->set_status(dev, dev->config->get_status(dev) | status); 167 } 168 EXPORT_SYMBOL_GPL(virtio_add_status); 169 170 int virtio_finalize_features(struct virtio_device *dev) 171 { 172 int ret = dev->config->finalize_features(dev); 173 unsigned status; 174 175 might_sleep(); 176 if (ret) 177 return ret; 178 179 ret = arch_has_restricted_virtio_memory_access(); 180 if (ret) { 181 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { 182 dev_warn(&dev->dev, 183 "device must provide VIRTIO_F_VERSION_1\n"); 184 return -ENODEV; 185 } 186 187 if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) { 188 dev_warn(&dev->dev, 189 "device must provide VIRTIO_F_ACCESS_PLATFORM\n"); 190 return -ENODEV; 191 } 192 } 193 194 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) 195 return 0; 196 197 virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK); 198 status = dev->config->get_status(dev); 199 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) { 200 dev_err(&dev->dev, "virtio: device refuses features: %x\n", 201 status); 202 return -ENODEV; 203 } 204 return 0; 205 } 206 EXPORT_SYMBOL_GPL(virtio_finalize_features); 207 208 static int virtio_dev_probe(struct device *_d) 209 { 210 int err, i; 211 struct virtio_device *dev = dev_to_virtio(_d); 212 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 213 u64 device_features; 214 u64 driver_features; 215 u64 driver_features_legacy; 216 217 /* We have a driver! */ 218 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 219 220 /* Figure out what features the device supports. */ 221 device_features = dev->config->get_features(dev); 222 223 /* Figure out what features the driver supports. */ 224 driver_features = 0; 225 for (i = 0; i < drv->feature_table_size; i++) { 226 unsigned int f = drv->feature_table[i]; 227 BUG_ON(f >= 64); 228 driver_features |= (1ULL << f); 229 } 230 231 /* Some drivers have a separate feature table for virtio v1.0 */ 232 if (drv->feature_table_legacy) { 233 driver_features_legacy = 0; 234 for (i = 0; i < drv->feature_table_size_legacy; i++) { 235 unsigned int f = drv->feature_table_legacy[i]; 236 BUG_ON(f >= 64); 237 driver_features_legacy |= (1ULL << f); 238 } 239 } else { 240 driver_features_legacy = driver_features; 241 } 242 243 if (device_features & (1ULL << VIRTIO_F_VERSION_1)) 244 dev->features = driver_features & device_features; 245 else 246 dev->features = driver_features_legacy & device_features; 247 248 /* Transport features always preserved to pass to finalize_features. */ 249 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) 250 if (device_features & (1ULL << i)) 251 __virtio_set_bit(dev, i); 252 253 if (drv->validate) { 254 err = drv->validate(dev); 255 if (err) 256 goto err; 257 } 258 259 err = virtio_finalize_features(dev); 260 if (err) 261 goto err; 262 263 err = drv->probe(dev); 264 if (err) 265 goto err; 266 267 /* If probe didn't do it, mark device DRIVER_OK ourselves. */ 268 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK)) 269 virtio_device_ready(dev); 270 271 if (drv->scan) 272 drv->scan(dev); 273 274 virtio_config_enable(dev); 275 276 return 0; 277 err: 278 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 279 return err; 280 281 } 282 283 static int virtio_dev_remove(struct device *_d) 284 { 285 struct virtio_device *dev = dev_to_virtio(_d); 286 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 287 288 virtio_config_disable(dev); 289 290 drv->remove(dev); 291 292 /* Driver should have reset device. */ 293 WARN_ON_ONCE(dev->config->get_status(dev)); 294 295 /* Acknowledge the device's existence again. */ 296 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 297 return 0; 298 } 299 300 static struct bus_type virtio_bus = { 301 .name = "virtio", 302 .match = virtio_dev_match, 303 .dev_groups = virtio_dev_groups, 304 .uevent = virtio_uevent, 305 .probe = virtio_dev_probe, 306 .remove = virtio_dev_remove, 307 }; 308 309 int register_virtio_driver(struct virtio_driver *driver) 310 { 311 /* Catch this early. */ 312 BUG_ON(driver->feature_table_size && !driver->feature_table); 313 driver->driver.bus = &virtio_bus; 314 return driver_register(&driver->driver); 315 } 316 EXPORT_SYMBOL_GPL(register_virtio_driver); 317 318 void unregister_virtio_driver(struct virtio_driver *driver) 319 { 320 driver_unregister(&driver->driver); 321 } 322 EXPORT_SYMBOL_GPL(unregister_virtio_driver); 323 324 /** 325 * register_virtio_device - register virtio device 326 * @dev : virtio device to be registered 327 * 328 * On error, the caller must call put_device on &@dev->dev (and not kfree), 329 * as another code path may have obtained a reference to @dev. 330 * 331 * Returns: 0 on suceess, -error on failure 332 */ 333 int register_virtio_device(struct virtio_device *dev) 334 { 335 int err; 336 337 dev->dev.bus = &virtio_bus; 338 device_initialize(&dev->dev); 339 340 /* Assign a unique device index and hence name. */ 341 err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL); 342 if (err < 0) 343 goto out; 344 345 dev->index = err; 346 dev_set_name(&dev->dev, "virtio%u", dev->index); 347 348 spin_lock_init(&dev->config_lock); 349 dev->config_enabled = false; 350 dev->config_change_pending = false; 351 352 /* We always start by resetting the device, in case a previous 353 * driver messed it up. This also tests that code path a little. */ 354 dev->config->reset(dev); 355 356 /* Acknowledge that we've seen the device. */ 357 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 358 359 INIT_LIST_HEAD(&dev->vqs); 360 361 /* 362 * device_add() causes the bus infrastructure to look for a matching 363 * driver. 364 */ 365 err = device_add(&dev->dev); 366 if (err) 367 ida_simple_remove(&virtio_index_ida, dev->index); 368 out: 369 if (err) 370 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 371 return err; 372 } 373 EXPORT_SYMBOL_GPL(register_virtio_device); 374 375 bool is_virtio_device(struct device *dev) 376 { 377 return dev->bus == &virtio_bus; 378 } 379 EXPORT_SYMBOL_GPL(is_virtio_device); 380 381 void unregister_virtio_device(struct virtio_device *dev) 382 { 383 int index = dev->index; /* save for after device release */ 384 385 device_unregister(&dev->dev); 386 ida_simple_remove(&virtio_index_ida, index); 387 } 388 EXPORT_SYMBOL_GPL(unregister_virtio_device); 389 390 #ifdef CONFIG_PM_SLEEP 391 int virtio_device_freeze(struct virtio_device *dev) 392 { 393 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 394 395 virtio_config_disable(dev); 396 397 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; 398 399 if (drv && drv->freeze) 400 return drv->freeze(dev); 401 402 return 0; 403 } 404 EXPORT_SYMBOL_GPL(virtio_device_freeze); 405 406 int virtio_device_restore(struct virtio_device *dev) 407 { 408 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 409 int ret; 410 411 /* We always start by resetting the device, in case a previous 412 * driver messed it up. */ 413 dev->config->reset(dev); 414 415 /* Acknowledge that we've seen the device. */ 416 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 417 418 /* Maybe driver failed before freeze. 419 * Restore the failed status, for debugging. */ 420 if (dev->failed) 421 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 422 423 if (!drv) 424 return 0; 425 426 /* We have a driver! */ 427 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 428 429 ret = virtio_finalize_features(dev); 430 if (ret) 431 goto err; 432 433 if (drv->restore) { 434 ret = drv->restore(dev); 435 if (ret) 436 goto err; 437 } 438 439 /* Finally, tell the device we're all set */ 440 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); 441 442 virtio_config_enable(dev); 443 444 return 0; 445 446 err: 447 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 448 return ret; 449 } 450 EXPORT_SYMBOL_GPL(virtio_device_restore); 451 #endif 452 453 static int virtio_init(void) 454 { 455 if (bus_register(&virtio_bus) != 0) 456 panic("virtio bus registration failed"); 457 return 0; 458 } 459 460 static void __exit virtio_exit(void) 461 { 462 bus_unregister(&virtio_bus); 463 ida_destroy(&virtio_index_ida); 464 } 465 core_initcall(virtio_init); 466 module_exit(virtio_exit); 467 468 MODULE_LICENSE("GPL"); 469