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 /* Do some validation, then set FEATURES_OK */ 170 static int virtio_features_ok(struct virtio_device *dev) 171 { 172 unsigned int status; 173 int ret; 174 175 might_sleep(); 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 } 204 205 /** 206 * virtio_reset_device - quiesce device for removal 207 * @dev: the device to reset 208 * 209 * Prevents device from sending interrupts and accessing memory. 210 * 211 * Generally used for cleanup during driver / device removal. 212 * 213 * Once this has been invoked, caller must ensure that 214 * virtqueue_notify / virtqueue_kick are not in progress. 215 * 216 * Note: this guarantees that vq callbacks are not in progress, however caller 217 * is responsible for preventing access from other contexts, such as a system 218 * call/workqueue/bh. Invoking virtio_break_device then flushing any such 219 * contexts is one way to handle that. 220 * */ 221 void virtio_reset_device(struct virtio_device *dev) 222 { 223 /* 224 * The below virtio_synchronize_cbs() guarantees that any 225 * interrupt for this line arriving after 226 * virtio_synchronize_vqs() has completed is guaranteed to see 227 * vq->broken as true. 228 */ 229 virtio_break_device(dev); 230 virtio_synchronize_cbs(dev); 231 232 dev->config->reset(dev); 233 } 234 EXPORT_SYMBOL_GPL(virtio_reset_device); 235 236 static int virtio_dev_probe(struct device *_d) 237 { 238 int err, i; 239 struct virtio_device *dev = dev_to_virtio(_d); 240 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 241 u64 device_features; 242 u64 driver_features; 243 u64 driver_features_legacy; 244 245 /* We have a driver! */ 246 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 247 248 /* Figure out what features the device supports. */ 249 device_features = dev->config->get_features(dev); 250 251 /* Figure out what features the driver supports. */ 252 driver_features = 0; 253 for (i = 0; i < drv->feature_table_size; i++) { 254 unsigned int f = drv->feature_table[i]; 255 BUG_ON(f >= 64); 256 driver_features |= (1ULL << f); 257 } 258 259 /* Some drivers have a separate feature table for virtio v1.0 */ 260 if (drv->feature_table_legacy) { 261 driver_features_legacy = 0; 262 for (i = 0; i < drv->feature_table_size_legacy; i++) { 263 unsigned int f = drv->feature_table_legacy[i]; 264 BUG_ON(f >= 64); 265 driver_features_legacy |= (1ULL << f); 266 } 267 } else { 268 driver_features_legacy = driver_features; 269 } 270 271 if (device_features & (1ULL << VIRTIO_F_VERSION_1)) 272 dev->features = driver_features & device_features; 273 else 274 dev->features = driver_features_legacy & device_features; 275 276 /* Transport features always preserved to pass to finalize_features. */ 277 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) 278 if (device_features & (1ULL << i)) 279 __virtio_set_bit(dev, i); 280 281 err = dev->config->finalize_features(dev); 282 if (err) 283 goto err; 284 285 if (drv->validate) { 286 u64 features = dev->features; 287 288 err = drv->validate(dev); 289 if (err) 290 goto err; 291 292 /* Did validation change any features? Then write them again. */ 293 if (features != dev->features) { 294 err = dev->config->finalize_features(dev); 295 if (err) 296 goto err; 297 } 298 } 299 300 err = virtio_features_ok(dev); 301 if (err) 302 goto err; 303 304 err = drv->probe(dev); 305 if (err) 306 goto err; 307 308 /* If probe didn't do it, mark device DRIVER_OK ourselves. */ 309 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK)) 310 virtio_device_ready(dev); 311 312 if (drv->scan) 313 drv->scan(dev); 314 315 virtio_config_enable(dev); 316 317 return 0; 318 err: 319 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 320 return err; 321 322 } 323 324 static void virtio_dev_remove(struct device *_d) 325 { 326 struct virtio_device *dev = dev_to_virtio(_d); 327 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 328 329 virtio_config_disable(dev); 330 331 drv->remove(dev); 332 333 /* Driver should have reset device. */ 334 WARN_ON_ONCE(dev->config->get_status(dev)); 335 336 /* Acknowledge the device's existence again. */ 337 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 338 339 of_node_put(dev->dev.of_node); 340 } 341 342 static struct bus_type virtio_bus = { 343 .name = "virtio", 344 .match = virtio_dev_match, 345 .dev_groups = virtio_dev_groups, 346 .uevent = virtio_uevent, 347 .probe = virtio_dev_probe, 348 .remove = virtio_dev_remove, 349 }; 350 351 int register_virtio_driver(struct virtio_driver *driver) 352 { 353 /* Catch this early. */ 354 BUG_ON(driver->feature_table_size && !driver->feature_table); 355 driver->driver.bus = &virtio_bus; 356 return driver_register(&driver->driver); 357 } 358 EXPORT_SYMBOL_GPL(register_virtio_driver); 359 360 void unregister_virtio_driver(struct virtio_driver *driver) 361 { 362 driver_unregister(&driver->driver); 363 } 364 EXPORT_SYMBOL_GPL(unregister_virtio_driver); 365 366 static int virtio_device_of_init(struct virtio_device *dev) 367 { 368 struct device_node *np, *pnode = dev_of_node(dev->dev.parent); 369 char compat[] = "virtio,deviceXXXXXXXX"; 370 int ret, count; 371 372 if (!pnode) 373 return 0; 374 375 count = of_get_available_child_count(pnode); 376 if (!count) 377 return 0; 378 379 /* There can be only 1 child node */ 380 if (WARN_ON(count > 1)) 381 return -EINVAL; 382 383 np = of_get_next_available_child(pnode, NULL); 384 if (WARN_ON(!np)) 385 return -ENODEV; 386 387 ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device); 388 BUG_ON(ret >= sizeof(compat)); 389 390 /* 391 * On powerpc/pseries virtio devices are PCI devices so PCI 392 * vendor/device ids play the role of the "compatible" property. 393 * Simply don't init of_node in this case. 394 */ 395 if (!of_device_is_compatible(np, compat)) { 396 ret = 0; 397 goto out; 398 } 399 400 dev->dev.of_node = np; 401 return 0; 402 403 out: 404 of_node_put(np); 405 return ret; 406 } 407 408 /** 409 * register_virtio_device - register virtio device 410 * @dev : virtio device to be registered 411 * 412 * On error, the caller must call put_device on &@dev->dev (and not kfree), 413 * as another code path may have obtained a reference to @dev. 414 * 415 * Returns: 0 on suceess, -error on failure 416 */ 417 int register_virtio_device(struct virtio_device *dev) 418 { 419 int err; 420 421 dev->dev.bus = &virtio_bus; 422 device_initialize(&dev->dev); 423 424 /* Assign a unique device index and hence name. */ 425 err = ida_alloc(&virtio_index_ida, GFP_KERNEL); 426 if (err < 0) 427 goto out; 428 429 dev->index = err; 430 dev_set_name(&dev->dev, "virtio%u", dev->index); 431 432 err = virtio_device_of_init(dev); 433 if (err) 434 goto out_ida_remove; 435 436 spin_lock_init(&dev->config_lock); 437 dev->config_enabled = false; 438 dev->config_change_pending = false; 439 440 INIT_LIST_HEAD(&dev->vqs); 441 spin_lock_init(&dev->vqs_list_lock); 442 443 /* We always start by resetting the device, in case a previous 444 * driver messed it up. This also tests that code path a little. */ 445 virtio_reset_device(dev); 446 447 /* Acknowledge that we've seen the device. */ 448 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 449 450 /* 451 * device_add() causes the bus infrastructure to look for a matching 452 * driver. 453 */ 454 err = device_add(&dev->dev); 455 if (err) 456 goto out_of_node_put; 457 458 return 0; 459 460 out_of_node_put: 461 of_node_put(dev->dev.of_node); 462 out_ida_remove: 463 ida_free(&virtio_index_ida, dev->index); 464 out: 465 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 466 return err; 467 } 468 EXPORT_SYMBOL_GPL(register_virtio_device); 469 470 bool is_virtio_device(struct device *dev) 471 { 472 return dev->bus == &virtio_bus; 473 } 474 EXPORT_SYMBOL_GPL(is_virtio_device); 475 476 void unregister_virtio_device(struct virtio_device *dev) 477 { 478 int index = dev->index; /* save for after device release */ 479 480 device_unregister(&dev->dev); 481 ida_free(&virtio_index_ida, index); 482 } 483 EXPORT_SYMBOL_GPL(unregister_virtio_device); 484 485 #ifdef CONFIG_PM_SLEEP 486 int virtio_device_freeze(struct virtio_device *dev) 487 { 488 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 489 490 virtio_config_disable(dev); 491 492 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; 493 494 if (drv && drv->freeze) 495 return drv->freeze(dev); 496 497 return 0; 498 } 499 EXPORT_SYMBOL_GPL(virtio_device_freeze); 500 501 int virtio_device_restore(struct virtio_device *dev) 502 { 503 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 504 int ret; 505 506 /* We always start by resetting the device, in case a previous 507 * driver messed it up. */ 508 virtio_reset_device(dev); 509 510 /* Acknowledge that we've seen the device. */ 511 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 512 513 /* Maybe driver failed before freeze. 514 * Restore the failed status, for debugging. */ 515 if (dev->failed) 516 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 517 518 if (!drv) 519 return 0; 520 521 /* We have a driver! */ 522 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 523 524 ret = dev->config->finalize_features(dev); 525 if (ret) 526 goto err; 527 528 ret = virtio_features_ok(dev); 529 if (ret) 530 goto err; 531 532 if (drv->restore) { 533 ret = drv->restore(dev); 534 if (ret) 535 goto err; 536 } 537 538 /* If restore didn't do it, mark device DRIVER_OK ourselves. */ 539 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK)) 540 virtio_device_ready(dev); 541 542 virtio_config_enable(dev); 543 544 return 0; 545 546 err: 547 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 548 return ret; 549 } 550 EXPORT_SYMBOL_GPL(virtio_device_restore); 551 #endif 552 553 static int virtio_init(void) 554 { 555 if (bus_register(&virtio_bus) != 0) 556 panic("virtio bus registration failed"); 557 return 0; 558 } 559 560 static void __exit virtio_exit(void) 561 { 562 bus_unregister(&virtio_bus); 563 ida_destroy(&virtio_index_ida); 564 } 565 core_initcall(virtio_init); 566 module_exit(virtio_exit); 567 568 MODULE_LICENSE("GPL"); 569