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 <linux/of.h> 8 #include <uapi/linux/virtio_ids.h> 9 10 /* Unique numbering for virtio devices. */ 11 static DEFINE_IDA(virtio_index_ida); 12 13 static ssize_t device_show(struct device *_d, 14 struct device_attribute *attr, char *buf) 15 { 16 struct virtio_device *dev = dev_to_virtio(_d); 17 return sprintf(buf, "0x%04x\n", dev->id.device); 18 } 19 static DEVICE_ATTR_RO(device); 20 21 static ssize_t vendor_show(struct device *_d, 22 struct device_attribute *attr, char *buf) 23 { 24 struct virtio_device *dev = dev_to_virtio(_d); 25 return sprintf(buf, "0x%04x\n", dev->id.vendor); 26 } 27 static DEVICE_ATTR_RO(vendor); 28 29 static ssize_t status_show(struct device *_d, 30 struct device_attribute *attr, char *buf) 31 { 32 struct virtio_device *dev = dev_to_virtio(_d); 33 return sprintf(buf, "0x%08x\n", dev->config->get_status(dev)); 34 } 35 static DEVICE_ATTR_RO(status); 36 37 static ssize_t modalias_show(struct device *_d, 38 struct device_attribute *attr, char *buf) 39 { 40 struct virtio_device *dev = dev_to_virtio(_d); 41 return sprintf(buf, "virtio:d%08Xv%08X\n", 42 dev->id.device, dev->id.vendor); 43 } 44 static DEVICE_ATTR_RO(modalias); 45 46 static ssize_t features_show(struct device *_d, 47 struct device_attribute *attr, char *buf) 48 { 49 struct virtio_device *dev = dev_to_virtio(_d); 50 unsigned int i; 51 ssize_t len = 0; 52 53 /* We actually represent this as a bitstring, as it could be 54 * arbitrary length in future. */ 55 for (i = 0; i < sizeof(dev->features)*8; i++) 56 len += sprintf(buf+len, "%c", 57 __virtio_test_bit(dev, i) ? '1' : '0'); 58 len += sprintf(buf+len, "\n"); 59 return len; 60 } 61 static DEVICE_ATTR_RO(features); 62 63 static struct attribute *virtio_dev_attrs[] = { 64 &dev_attr_device.attr, 65 &dev_attr_vendor.attr, 66 &dev_attr_status.attr, 67 &dev_attr_modalias.attr, 68 &dev_attr_features.attr, 69 NULL, 70 }; 71 ATTRIBUTE_GROUPS(virtio_dev); 72 73 static inline int virtio_id_match(const struct virtio_device *dev, 74 const struct virtio_device_id *id) 75 { 76 if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID) 77 return 0; 78 79 return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor; 80 } 81 82 /* This looks through all the IDs a driver claims to support. If any of them 83 * match, we return 1 and the kernel will call virtio_dev_probe(). */ 84 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr) 85 { 86 unsigned int i; 87 struct virtio_device *dev = dev_to_virtio(_dv); 88 const struct virtio_device_id *ids; 89 90 ids = drv_to_virtio(_dr)->id_table; 91 for (i = 0; ids[i].device; i++) 92 if (virtio_id_match(dev, &ids[i])) 93 return 1; 94 return 0; 95 } 96 97 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env) 98 { 99 struct virtio_device *dev = dev_to_virtio(_dv); 100 101 return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X", 102 dev->id.device, dev->id.vendor); 103 } 104 105 void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 106 unsigned int fbit) 107 { 108 unsigned int i; 109 struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver); 110 111 for (i = 0; i < drv->feature_table_size; i++) 112 if (drv->feature_table[i] == fbit) 113 return; 114 115 if (drv->feature_table_legacy) { 116 for (i = 0; i < drv->feature_table_size_legacy; i++) 117 if (drv->feature_table_legacy[i] == fbit) 118 return; 119 } 120 121 BUG(); 122 } 123 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature); 124 125 static void __virtio_config_changed(struct virtio_device *dev) 126 { 127 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 128 129 if (!dev->config_enabled) 130 dev->config_change_pending = true; 131 else if (drv && drv->config_changed) 132 drv->config_changed(dev); 133 } 134 135 void virtio_config_changed(struct virtio_device *dev) 136 { 137 unsigned long flags; 138 139 spin_lock_irqsave(&dev->config_lock, flags); 140 __virtio_config_changed(dev); 141 spin_unlock_irqrestore(&dev->config_lock, flags); 142 } 143 EXPORT_SYMBOL_GPL(virtio_config_changed); 144 145 static void virtio_config_disable(struct virtio_device *dev) 146 { 147 spin_lock_irq(&dev->config_lock); 148 dev->config_enabled = false; 149 spin_unlock_irq(&dev->config_lock); 150 } 151 152 static 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 } 161 162 void virtio_add_status(struct virtio_device *dev, unsigned int status) 163 { 164 might_sleep(); 165 dev->config->set_status(dev, dev->config->get_status(dev) | status); 166 } 167 EXPORT_SYMBOL_GPL(virtio_add_status); 168 169 int virtio_finalize_features(struct virtio_device *dev) 170 { 171 int ret = dev->config->finalize_features(dev); 172 unsigned status; 173 174 might_sleep(); 175 if (ret) 176 return ret; 177 178 ret = arch_has_restricted_virtio_memory_access(); 179 if (ret) { 180 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { 181 dev_warn(&dev->dev, 182 "device must provide VIRTIO_F_VERSION_1\n"); 183 return -ENODEV; 184 } 185 186 if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) { 187 dev_warn(&dev->dev, 188 "device must provide VIRTIO_F_ACCESS_PLATFORM\n"); 189 return -ENODEV; 190 } 191 } 192 193 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) 194 return 0; 195 196 virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK); 197 status = dev->config->get_status(dev); 198 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) { 199 dev_err(&dev->dev, "virtio: device refuses features: %x\n", 200 status); 201 return -ENODEV; 202 } 203 return 0; 204 } 205 EXPORT_SYMBOL_GPL(virtio_finalize_features); 206 207 static int virtio_dev_probe(struct device *_d) 208 { 209 int err, i; 210 struct virtio_device *dev = dev_to_virtio(_d); 211 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 212 u64 device_features; 213 u64 driver_features; 214 u64 driver_features_legacy; 215 216 /* We have a driver! */ 217 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 218 219 /* Figure out what features the device supports. */ 220 device_features = dev->config->get_features(dev); 221 222 /* Figure out what features the driver supports. */ 223 driver_features = 0; 224 for (i = 0; i < drv->feature_table_size; i++) { 225 unsigned int f = drv->feature_table[i]; 226 BUG_ON(f >= 64); 227 driver_features |= (1ULL << f); 228 } 229 230 /* Some drivers have a separate feature table for virtio v1.0 */ 231 if (drv->feature_table_legacy) { 232 driver_features_legacy = 0; 233 for (i = 0; i < drv->feature_table_size_legacy; i++) { 234 unsigned int f = drv->feature_table_legacy[i]; 235 BUG_ON(f >= 64); 236 driver_features_legacy |= (1ULL << f); 237 } 238 } else { 239 driver_features_legacy = driver_features; 240 } 241 242 if (device_features & (1ULL << VIRTIO_F_VERSION_1)) 243 dev->features = driver_features & device_features; 244 else 245 dev->features = driver_features_legacy & device_features; 246 247 /* Transport features always preserved to pass to finalize_features. */ 248 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) 249 if (device_features & (1ULL << i)) 250 __virtio_set_bit(dev, i); 251 252 if (drv->validate) { 253 err = drv->validate(dev); 254 if (err) 255 goto err; 256 } 257 258 err = virtio_finalize_features(dev); 259 if (err) 260 goto err; 261 262 err = drv->probe(dev); 263 if (err) 264 goto err; 265 266 /* If probe didn't do it, mark device DRIVER_OK ourselves. */ 267 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK)) 268 virtio_device_ready(dev); 269 270 if (drv->scan) 271 drv->scan(dev); 272 273 virtio_config_enable(dev); 274 275 return 0; 276 err: 277 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 278 return err; 279 280 } 281 282 static void virtio_dev_remove(struct device *_d) 283 { 284 struct virtio_device *dev = dev_to_virtio(_d); 285 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 286 287 virtio_config_disable(dev); 288 289 drv->remove(dev); 290 291 /* Driver should have reset device. */ 292 WARN_ON_ONCE(dev->config->get_status(dev)); 293 294 /* Acknowledge the device's existence again. */ 295 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 296 297 of_node_put(dev->dev.of_node); 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 static int virtio_device_of_init(struct virtio_device *dev) 325 { 326 struct device_node *np, *pnode = dev_of_node(dev->dev.parent); 327 char compat[] = "virtio,deviceXXXXXXXX"; 328 int ret, count; 329 330 if (!pnode) 331 return 0; 332 333 count = of_get_available_child_count(pnode); 334 if (!count) 335 return 0; 336 337 /* There can be only 1 child node */ 338 if (WARN_ON(count > 1)) 339 return -EINVAL; 340 341 np = of_get_next_available_child(pnode, NULL); 342 if (WARN_ON(!np)) 343 return -ENODEV; 344 345 ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device); 346 BUG_ON(ret >= sizeof(compat)); 347 348 if (!of_device_is_compatible(np, compat)) { 349 ret = -EINVAL; 350 goto out; 351 } 352 353 dev->dev.of_node = np; 354 return 0; 355 356 out: 357 of_node_put(np); 358 return ret; 359 } 360 361 /** 362 * register_virtio_device - register virtio device 363 * @dev : virtio device to be registered 364 * 365 * On error, the caller must call put_device on &@dev->dev (and not kfree), 366 * as another code path may have obtained a reference to @dev. 367 * 368 * Returns: 0 on suceess, -error on failure 369 */ 370 int register_virtio_device(struct virtio_device *dev) 371 { 372 int err; 373 374 dev->dev.bus = &virtio_bus; 375 device_initialize(&dev->dev); 376 377 /* Assign a unique device index and hence name. */ 378 err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL); 379 if (err < 0) 380 goto out; 381 382 dev->index = err; 383 dev_set_name(&dev->dev, "virtio%u", dev->index); 384 385 err = virtio_device_of_init(dev); 386 if (err) 387 goto out_ida_remove; 388 389 spin_lock_init(&dev->config_lock); 390 dev->config_enabled = false; 391 dev->config_change_pending = false; 392 393 /* We always start by resetting the device, in case a previous 394 * driver messed it up. This also tests that code path a little. */ 395 dev->config->reset(dev); 396 397 /* Acknowledge that we've seen the device. */ 398 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 399 400 INIT_LIST_HEAD(&dev->vqs); 401 spin_lock_init(&dev->vqs_list_lock); 402 403 /* 404 * device_add() causes the bus infrastructure to look for a matching 405 * driver. 406 */ 407 err = device_add(&dev->dev); 408 if (err) 409 goto out_of_node_put; 410 411 return 0; 412 413 out_of_node_put: 414 of_node_put(dev->dev.of_node); 415 out_ida_remove: 416 ida_simple_remove(&virtio_index_ida, dev->index); 417 out: 418 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 419 return err; 420 } 421 EXPORT_SYMBOL_GPL(register_virtio_device); 422 423 bool is_virtio_device(struct device *dev) 424 { 425 return dev->bus == &virtio_bus; 426 } 427 EXPORT_SYMBOL_GPL(is_virtio_device); 428 429 void unregister_virtio_device(struct virtio_device *dev) 430 { 431 int index = dev->index; /* save for after device release */ 432 433 device_unregister(&dev->dev); 434 ida_simple_remove(&virtio_index_ida, index); 435 } 436 EXPORT_SYMBOL_GPL(unregister_virtio_device); 437 438 #ifdef CONFIG_PM_SLEEP 439 int virtio_device_freeze(struct virtio_device *dev) 440 { 441 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 442 443 virtio_config_disable(dev); 444 445 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; 446 447 if (drv && drv->freeze) 448 return drv->freeze(dev); 449 450 return 0; 451 } 452 EXPORT_SYMBOL_GPL(virtio_device_freeze); 453 454 int virtio_device_restore(struct virtio_device *dev) 455 { 456 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 457 int ret; 458 459 /* We always start by resetting the device, in case a previous 460 * driver messed it up. */ 461 dev->config->reset(dev); 462 463 /* Acknowledge that we've seen the device. */ 464 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 465 466 /* Maybe driver failed before freeze. 467 * Restore the failed status, for debugging. */ 468 if (dev->failed) 469 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 470 471 if (!drv) 472 return 0; 473 474 /* We have a driver! */ 475 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 476 477 ret = virtio_finalize_features(dev); 478 if (ret) 479 goto err; 480 481 if (drv->restore) { 482 ret = drv->restore(dev); 483 if (ret) 484 goto err; 485 } 486 487 /* Finally, tell the device we're all set */ 488 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); 489 490 virtio_config_enable(dev); 491 492 return 0; 493 494 err: 495 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 496 return ret; 497 } 498 EXPORT_SYMBOL_GPL(virtio_device_restore); 499 #endif 500 501 static int virtio_init(void) 502 { 503 if (bus_register(&virtio_bus) != 0) 504 panic("virtio bus registration failed"); 505 return 0; 506 } 507 508 static void __exit virtio_exit(void) 509 { 510 bus_unregister(&virtio_bus); 511 ida_destroy(&virtio_index_ida); 512 } 513 core_initcall(virtio_init); 514 module_exit(virtio_exit); 515 516 MODULE_LICENSE("GPL"); 517