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 static 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 } 150 151 static void virtio_config_enable(struct virtio_device *dev) 152 { 153 spin_lock_irq(&dev->config_lock); 154 dev->config_enabled = true; 155 if (dev->config_change_pending) 156 __virtio_config_changed(dev); 157 dev->config_change_pending = false; 158 spin_unlock_irq(&dev->config_lock); 159 } 160 161 void virtio_add_status(struct virtio_device *dev, unsigned int status) 162 { 163 might_sleep(); 164 dev->config->set_status(dev, dev->config->get_status(dev) | status); 165 } 166 EXPORT_SYMBOL_GPL(virtio_add_status); 167 168 int virtio_finalize_features(struct virtio_device *dev) 169 { 170 int ret = dev->config->finalize_features(dev); 171 unsigned status; 172 173 might_sleep(); 174 if (ret) 175 return ret; 176 177 ret = arch_has_restricted_virtio_memory_access(); 178 if (ret) { 179 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { 180 dev_warn(&dev->dev, 181 "device must provide VIRTIO_F_VERSION_1\n"); 182 return -ENODEV; 183 } 184 185 if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) { 186 dev_warn(&dev->dev, 187 "device must provide VIRTIO_F_ACCESS_PLATFORM\n"); 188 return -ENODEV; 189 } 190 } 191 192 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) 193 return 0; 194 195 virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK); 196 status = dev->config->get_status(dev); 197 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) { 198 dev_err(&dev->dev, "virtio: device refuses features: %x\n", 199 status); 200 return -ENODEV; 201 } 202 return 0; 203 } 204 EXPORT_SYMBOL_GPL(virtio_finalize_features); 205 206 static int virtio_dev_probe(struct device *_d) 207 { 208 int err, i; 209 struct virtio_device *dev = dev_to_virtio(_d); 210 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 211 u64 device_features; 212 u64 driver_features; 213 u64 driver_features_legacy; 214 215 /* We have a driver! */ 216 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 217 218 /* Figure out what features the device supports. */ 219 device_features = dev->config->get_features(dev); 220 221 /* Figure out what features the driver supports. */ 222 driver_features = 0; 223 for (i = 0; i < drv->feature_table_size; i++) { 224 unsigned int f = drv->feature_table[i]; 225 BUG_ON(f >= 64); 226 driver_features |= (1ULL << f); 227 } 228 229 /* Some drivers have a separate feature table for virtio v1.0 */ 230 if (drv->feature_table_legacy) { 231 driver_features_legacy = 0; 232 for (i = 0; i < drv->feature_table_size_legacy; i++) { 233 unsigned int f = drv->feature_table_legacy[i]; 234 BUG_ON(f >= 64); 235 driver_features_legacy |= (1ULL << f); 236 } 237 } else { 238 driver_features_legacy = driver_features; 239 } 240 241 if (device_features & (1ULL << VIRTIO_F_VERSION_1)) 242 dev->features = driver_features & device_features; 243 else 244 dev->features = driver_features_legacy & device_features; 245 246 /* Transport features always preserved to pass to finalize_features. */ 247 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) 248 if (device_features & (1ULL << i)) 249 __virtio_set_bit(dev, i); 250 251 if (drv->validate) { 252 err = drv->validate(dev); 253 if (err) 254 goto err; 255 } 256 257 err = virtio_finalize_features(dev); 258 if (err) 259 goto err; 260 261 err = drv->probe(dev); 262 if (err) 263 goto err; 264 265 /* If probe didn't do it, mark device DRIVER_OK ourselves. */ 266 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK)) 267 virtio_device_ready(dev); 268 269 if (drv->scan) 270 drv->scan(dev); 271 272 virtio_config_enable(dev); 273 274 return 0; 275 err: 276 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 277 return err; 278 279 } 280 281 static int virtio_dev_remove(struct device *_d) 282 { 283 struct virtio_device *dev = dev_to_virtio(_d); 284 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 285 286 virtio_config_disable(dev); 287 288 drv->remove(dev); 289 290 /* Driver should have reset device. */ 291 WARN_ON_ONCE(dev->config->get_status(dev)); 292 293 /* Acknowledge the device's existence again. */ 294 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 295 return 0; 296 } 297 298 static struct bus_type virtio_bus = { 299 .name = "virtio", 300 .match = virtio_dev_match, 301 .dev_groups = virtio_dev_groups, 302 .uevent = virtio_uevent, 303 .probe = virtio_dev_probe, 304 .remove = virtio_dev_remove, 305 }; 306 307 int register_virtio_driver(struct virtio_driver *driver) 308 { 309 /* Catch this early. */ 310 BUG_ON(driver->feature_table_size && !driver->feature_table); 311 driver->driver.bus = &virtio_bus; 312 return driver_register(&driver->driver); 313 } 314 EXPORT_SYMBOL_GPL(register_virtio_driver); 315 316 void unregister_virtio_driver(struct virtio_driver *driver) 317 { 318 driver_unregister(&driver->driver); 319 } 320 EXPORT_SYMBOL_GPL(unregister_virtio_driver); 321 322 /** 323 * register_virtio_device - register virtio device 324 * @dev : virtio device to be registered 325 * 326 * On error, the caller must call put_device on &@dev->dev (and not kfree), 327 * as another code path may have obtained a reference to @dev. 328 * 329 * Returns: 0 on suceess, -error on failure 330 */ 331 int register_virtio_device(struct virtio_device *dev) 332 { 333 int err; 334 335 dev->dev.bus = &virtio_bus; 336 device_initialize(&dev->dev); 337 338 /* Assign a unique device index and hence name. */ 339 err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL); 340 if (err < 0) 341 goto out; 342 343 dev->index = err; 344 dev_set_name(&dev->dev, "virtio%u", dev->index); 345 346 spin_lock_init(&dev->config_lock); 347 dev->config_enabled = false; 348 dev->config_change_pending = false; 349 350 /* We always start by resetting the device, in case a previous 351 * driver messed it up. This also tests that code path a little. */ 352 dev->config->reset(dev); 353 354 /* Acknowledge that we've seen the device. */ 355 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 356 357 INIT_LIST_HEAD(&dev->vqs); 358 359 /* 360 * device_add() causes the bus infrastructure to look for a matching 361 * driver. 362 */ 363 err = device_add(&dev->dev); 364 if (err) 365 ida_simple_remove(&virtio_index_ida, dev->index); 366 out: 367 if (err) 368 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 369 return err; 370 } 371 EXPORT_SYMBOL_GPL(register_virtio_device); 372 373 bool is_virtio_device(struct device *dev) 374 { 375 return dev->bus == &virtio_bus; 376 } 377 EXPORT_SYMBOL_GPL(is_virtio_device); 378 379 void unregister_virtio_device(struct virtio_device *dev) 380 { 381 int index = dev->index; /* save for after device release */ 382 383 device_unregister(&dev->dev); 384 ida_simple_remove(&virtio_index_ida, index); 385 } 386 EXPORT_SYMBOL_GPL(unregister_virtio_device); 387 388 #ifdef CONFIG_PM_SLEEP 389 int virtio_device_freeze(struct virtio_device *dev) 390 { 391 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 392 393 virtio_config_disable(dev); 394 395 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; 396 397 if (drv && drv->freeze) 398 return drv->freeze(dev); 399 400 return 0; 401 } 402 EXPORT_SYMBOL_GPL(virtio_device_freeze); 403 404 int virtio_device_restore(struct virtio_device *dev) 405 { 406 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 407 int ret; 408 409 /* We always start by resetting the device, in case a previous 410 * driver messed it up. */ 411 dev->config->reset(dev); 412 413 /* Acknowledge that we've seen the device. */ 414 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 415 416 /* Maybe driver failed before freeze. 417 * Restore the failed status, for debugging. */ 418 if (dev->failed) 419 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 420 421 if (!drv) 422 return 0; 423 424 /* We have a driver! */ 425 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 426 427 ret = virtio_finalize_features(dev); 428 if (ret) 429 goto err; 430 431 if (drv->restore) { 432 ret = drv->restore(dev); 433 if (ret) 434 goto err; 435 } 436 437 /* Finally, tell the device we're all set */ 438 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); 439 440 virtio_config_enable(dev); 441 442 return 0; 443 444 err: 445 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 446 return ret; 447 } 448 EXPORT_SYMBOL_GPL(virtio_device_restore); 449 #endif 450 451 static int virtio_init(void) 452 { 453 if (bus_register(&virtio_bus) != 0) 454 panic("virtio bus registration failed"); 455 return 0; 456 } 457 458 static void __exit virtio_exit(void) 459 { 460 bus_unregister(&virtio_bus); 461 ida_destroy(&virtio_index_ida); 462 } 463 core_initcall(virtio_init); 464 module_exit(virtio_exit); 465 466 MODULE_LICENSE("GPL"); 467