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/virtio_anchor.h> 6 #include <linux/module.h> 7 #include <linux/idr.h> 8 #include <linux/of.h> 9 #include <uapi/linux/virtio_ids.h> 10 11 /* Unique numbering for virtio devices. */ 12 static DEFINE_IDA(virtio_index_ida); 13 14 static ssize_t device_show(struct device *_d, 15 struct device_attribute *attr, char *buf) 16 { 17 struct virtio_device *dev = dev_to_virtio(_d); 18 return sprintf(buf, "0x%04x\n", dev->id.device); 19 } 20 static DEVICE_ATTR_RO(device); 21 22 static ssize_t vendor_show(struct device *_d, 23 struct device_attribute *attr, char *buf) 24 { 25 struct virtio_device *dev = dev_to_virtio(_d); 26 return sprintf(buf, "0x%04x\n", dev->id.vendor); 27 } 28 static DEVICE_ATTR_RO(vendor); 29 30 static ssize_t status_show(struct device *_d, 31 struct device_attribute *attr, char *buf) 32 { 33 struct virtio_device *dev = dev_to_virtio(_d); 34 return sprintf(buf, "0x%08x\n", dev->config->get_status(dev)); 35 } 36 static DEVICE_ATTR_RO(status); 37 38 static ssize_t modalias_show(struct device *_d, 39 struct device_attribute *attr, char *buf) 40 { 41 struct virtio_device *dev = dev_to_virtio(_d); 42 return sprintf(buf, "virtio:d%08Xv%08X\n", 43 dev->id.device, dev->id.vendor); 44 } 45 static DEVICE_ATTR_RO(modalias); 46 47 static ssize_t features_show(struct device *_d, 48 struct device_attribute *attr, char *buf) 49 { 50 struct virtio_device *dev = dev_to_virtio(_d); 51 unsigned int i; 52 ssize_t len = 0; 53 54 /* We actually represent this as a bitstring, as it could be 55 * arbitrary length in future. */ 56 for (i = 0; i < sizeof(dev->features)*8; i++) 57 len += sprintf(buf+len, "%c", 58 __virtio_test_bit(dev, i) ? '1' : '0'); 59 len += sprintf(buf+len, "\n"); 60 return len; 61 } 62 static DEVICE_ATTR_RO(features); 63 64 static struct attribute *virtio_dev_attrs[] = { 65 &dev_attr_device.attr, 66 &dev_attr_vendor.attr, 67 &dev_attr_status.attr, 68 &dev_attr_modalias.attr, 69 &dev_attr_features.attr, 70 NULL, 71 }; 72 ATTRIBUTE_GROUPS(virtio_dev); 73 74 static inline int virtio_id_match(const struct virtio_device *dev, 75 const struct virtio_device_id *id) 76 { 77 if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID) 78 return 0; 79 80 return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor; 81 } 82 83 /* This looks through all the IDs a driver claims to support. If any of them 84 * match, we return 1 and the kernel will call virtio_dev_probe(). */ 85 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr) 86 { 87 unsigned int i; 88 struct virtio_device *dev = dev_to_virtio(_dv); 89 const struct virtio_device_id *ids; 90 91 ids = drv_to_virtio(_dr)->id_table; 92 for (i = 0; ids[i].device; i++) 93 if (virtio_id_match(dev, &ids[i])) 94 return 1; 95 return 0; 96 } 97 98 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env) 99 { 100 struct virtio_device *dev = dev_to_virtio(_dv); 101 102 return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X", 103 dev->id.device, dev->id.vendor); 104 } 105 106 void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 107 unsigned int fbit) 108 { 109 unsigned int i; 110 struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver); 111 112 for (i = 0; i < drv->feature_table_size; i++) 113 if (drv->feature_table[i] == fbit) 114 return; 115 116 if (drv->feature_table_legacy) { 117 for (i = 0; i < drv->feature_table_size_legacy; i++) 118 if (drv->feature_table_legacy[i] == fbit) 119 return; 120 } 121 122 BUG(); 123 } 124 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature); 125 126 static void __virtio_config_changed(struct virtio_device *dev) 127 { 128 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 129 130 if (!dev->config_enabled) 131 dev->config_change_pending = true; 132 else if (drv && drv->config_changed) 133 drv->config_changed(dev); 134 } 135 136 void virtio_config_changed(struct virtio_device *dev) 137 { 138 unsigned long flags; 139 140 spin_lock_irqsave(&dev->config_lock, flags); 141 __virtio_config_changed(dev); 142 spin_unlock_irqrestore(&dev->config_lock, flags); 143 } 144 EXPORT_SYMBOL_GPL(virtio_config_changed); 145 146 static void virtio_config_disable(struct virtio_device *dev) 147 { 148 spin_lock_irq(&dev->config_lock); 149 dev->config_enabled = false; 150 spin_unlock_irq(&dev->config_lock); 151 } 152 153 static void virtio_config_enable(struct virtio_device *dev) 154 { 155 spin_lock_irq(&dev->config_lock); 156 dev->config_enabled = true; 157 if (dev->config_change_pending) 158 __virtio_config_changed(dev); 159 dev->config_change_pending = false; 160 spin_unlock_irq(&dev->config_lock); 161 } 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 /* Do some validation, then set FEATURES_OK */ 171 static int virtio_features_ok(struct virtio_device *dev) 172 { 173 unsigned int status; 174 175 might_sleep(); 176 177 if (virtio_check_mem_acc_cb(dev)) { 178 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { 179 dev_warn(&dev->dev, 180 "device must provide VIRTIO_F_VERSION_1\n"); 181 return -ENODEV; 182 } 183 184 if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) { 185 dev_warn(&dev->dev, 186 "device must provide VIRTIO_F_ACCESS_PLATFORM\n"); 187 return -ENODEV; 188 } 189 } 190 191 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) 192 return 0; 193 194 virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK); 195 status = dev->config->get_status(dev); 196 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) { 197 dev_err(&dev->dev, "virtio: device refuses features: %x\n", 198 status); 199 return -ENODEV; 200 } 201 return 0; 202 } 203 204 /** 205 * virtio_reset_device - quiesce device for removal 206 * @dev: the device to reset 207 * 208 * Prevents device from sending interrupts and accessing memory. 209 * 210 * Generally used for cleanup during driver / device removal. 211 * 212 * Once this has been invoked, caller must ensure that 213 * virtqueue_notify / virtqueue_kick are not in progress. 214 * 215 * Note: this guarantees that vq callbacks are not in progress, however caller 216 * is responsible for preventing access from other contexts, such as a system 217 * call/workqueue/bh. Invoking virtio_break_device then flushing any such 218 * contexts is one way to handle that. 219 * */ 220 void virtio_reset_device(struct virtio_device *dev) 221 { 222 #ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION 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 #endif 232 233 dev->config->reset(dev); 234 } 235 EXPORT_SYMBOL_GPL(virtio_reset_device); 236 237 static int virtio_dev_probe(struct device *_d) 238 { 239 int err, i; 240 struct virtio_device *dev = dev_to_virtio(_d); 241 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 242 u64 device_features; 243 u64 driver_features; 244 u64 driver_features_legacy; 245 246 /* We have a driver! */ 247 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 248 249 /* Figure out what features the device supports. */ 250 device_features = dev->config->get_features(dev); 251 252 /* Figure out what features the driver supports. */ 253 driver_features = 0; 254 for (i = 0; i < drv->feature_table_size; i++) { 255 unsigned int f = drv->feature_table[i]; 256 BUG_ON(f >= 64); 257 driver_features |= (1ULL << f); 258 } 259 260 /* Some drivers have a separate feature table for virtio v1.0 */ 261 if (drv->feature_table_legacy) { 262 driver_features_legacy = 0; 263 for (i = 0; i < drv->feature_table_size_legacy; i++) { 264 unsigned int f = drv->feature_table_legacy[i]; 265 BUG_ON(f >= 64); 266 driver_features_legacy |= (1ULL << f); 267 } 268 } else { 269 driver_features_legacy = driver_features; 270 } 271 272 if (device_features & (1ULL << VIRTIO_F_VERSION_1)) 273 dev->features = driver_features & device_features; 274 else 275 dev->features = driver_features_legacy & device_features; 276 277 /* Transport features always preserved to pass to finalize_features. */ 278 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) 279 if (device_features & (1ULL << i)) 280 __virtio_set_bit(dev, i); 281 282 err = dev->config->finalize_features(dev); 283 if (err) 284 goto err; 285 286 if (drv->validate) { 287 u64 features = dev->features; 288 289 err = drv->validate(dev); 290 if (err) 291 goto err; 292 293 /* Did validation change any features? Then write them again. */ 294 if (features != dev->features) { 295 err = dev->config->finalize_features(dev); 296 if (err) 297 goto err; 298 } 299 } 300 301 err = virtio_features_ok(dev); 302 if (err) 303 goto err; 304 305 err = drv->probe(dev); 306 if (err) 307 goto err; 308 309 /* If probe didn't do it, mark device DRIVER_OK ourselves. */ 310 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK)) 311 virtio_device_ready(dev); 312 313 if (drv->scan) 314 drv->scan(dev); 315 316 virtio_config_enable(dev); 317 318 return 0; 319 err: 320 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 321 return err; 322 323 } 324 325 static void virtio_dev_remove(struct device *_d) 326 { 327 struct virtio_device *dev = dev_to_virtio(_d); 328 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 329 330 virtio_config_disable(dev); 331 332 drv->remove(dev); 333 334 /* Driver should have reset device. */ 335 WARN_ON_ONCE(dev->config->get_status(dev)); 336 337 /* Acknowledge the device's existence again. */ 338 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 339 340 of_node_put(dev->dev.of_node); 341 } 342 343 static struct bus_type virtio_bus = { 344 .name = "virtio", 345 .match = virtio_dev_match, 346 .dev_groups = virtio_dev_groups, 347 .uevent = virtio_uevent, 348 .probe = virtio_dev_probe, 349 .remove = virtio_dev_remove, 350 }; 351 352 int register_virtio_driver(struct virtio_driver *driver) 353 { 354 /* Catch this early. */ 355 BUG_ON(driver->feature_table_size && !driver->feature_table); 356 driver->driver.bus = &virtio_bus; 357 return driver_register(&driver->driver); 358 } 359 EXPORT_SYMBOL_GPL(register_virtio_driver); 360 361 void unregister_virtio_driver(struct virtio_driver *driver) 362 { 363 driver_unregister(&driver->driver); 364 } 365 EXPORT_SYMBOL_GPL(unregister_virtio_driver); 366 367 static int virtio_device_of_init(struct virtio_device *dev) 368 { 369 struct device_node *np, *pnode = dev_of_node(dev->dev.parent); 370 char compat[] = "virtio,deviceXXXXXXXX"; 371 int ret, count; 372 373 if (!pnode) 374 return 0; 375 376 count = of_get_available_child_count(pnode); 377 if (!count) 378 return 0; 379 380 /* There can be only 1 child node */ 381 if (WARN_ON(count > 1)) 382 return -EINVAL; 383 384 np = of_get_next_available_child(pnode, NULL); 385 if (WARN_ON(!np)) 386 return -ENODEV; 387 388 ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device); 389 BUG_ON(ret >= sizeof(compat)); 390 391 /* 392 * On powerpc/pseries virtio devices are PCI devices so PCI 393 * vendor/device ids play the role of the "compatible" property. 394 * Simply don't init of_node in this case. 395 */ 396 if (!of_device_is_compatible(np, compat)) { 397 ret = 0; 398 goto out; 399 } 400 401 dev->dev.of_node = np; 402 return 0; 403 404 out: 405 of_node_put(np); 406 return ret; 407 } 408 409 /** 410 * register_virtio_device - register virtio device 411 * @dev : virtio device to be registered 412 * 413 * On error, the caller must call put_device on &@dev->dev (and not kfree), 414 * as another code path may have obtained a reference to @dev. 415 * 416 * Returns: 0 on suceess, -error on failure 417 */ 418 int register_virtio_device(struct virtio_device *dev) 419 { 420 int err; 421 422 dev->dev.bus = &virtio_bus; 423 device_initialize(&dev->dev); 424 425 /* Assign a unique device index and hence name. */ 426 err = ida_alloc(&virtio_index_ida, GFP_KERNEL); 427 if (err < 0) 428 goto out; 429 430 dev->index = err; 431 err = dev_set_name(&dev->dev, "virtio%u", dev->index); 432 if (err) 433 goto out_ida_remove; 434 435 err = virtio_device_of_init(dev); 436 if (err) 437 goto out_ida_remove; 438 439 spin_lock_init(&dev->config_lock); 440 dev->config_enabled = false; 441 dev->config_change_pending = false; 442 443 INIT_LIST_HEAD(&dev->vqs); 444 spin_lock_init(&dev->vqs_list_lock); 445 446 /* We always start by resetting the device, in case a previous 447 * driver messed it up. This also tests that code path a little. */ 448 virtio_reset_device(dev); 449 450 /* Acknowledge that we've seen the device. */ 451 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 452 453 /* 454 * device_add() causes the bus infrastructure to look for a matching 455 * driver. 456 */ 457 err = device_add(&dev->dev); 458 if (err) 459 goto out_of_node_put; 460 461 return 0; 462 463 out_of_node_put: 464 of_node_put(dev->dev.of_node); 465 out_ida_remove: 466 ida_free(&virtio_index_ida, dev->index); 467 out: 468 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 469 return err; 470 } 471 EXPORT_SYMBOL_GPL(register_virtio_device); 472 473 bool is_virtio_device(struct device *dev) 474 { 475 return dev->bus == &virtio_bus; 476 } 477 EXPORT_SYMBOL_GPL(is_virtio_device); 478 479 void unregister_virtio_device(struct virtio_device *dev) 480 { 481 int index = dev->index; /* save for after device release */ 482 483 device_unregister(&dev->dev); 484 ida_free(&virtio_index_ida, index); 485 } 486 EXPORT_SYMBOL_GPL(unregister_virtio_device); 487 488 #ifdef CONFIG_PM_SLEEP 489 int virtio_device_freeze(struct virtio_device *dev) 490 { 491 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 492 493 virtio_config_disable(dev); 494 495 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; 496 497 if (drv && drv->freeze) 498 return drv->freeze(dev); 499 500 return 0; 501 } 502 EXPORT_SYMBOL_GPL(virtio_device_freeze); 503 504 int virtio_device_restore(struct virtio_device *dev) 505 { 506 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); 507 int ret; 508 509 /* We always start by resetting the device, in case a previous 510 * driver messed it up. */ 511 virtio_reset_device(dev); 512 513 /* Acknowledge that we've seen the device. */ 514 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 515 516 /* Maybe driver failed before freeze. 517 * Restore the failed status, for debugging. */ 518 if (dev->failed) 519 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 520 521 if (!drv) 522 return 0; 523 524 /* We have a driver! */ 525 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); 526 527 ret = dev->config->finalize_features(dev); 528 if (ret) 529 goto err; 530 531 ret = virtio_features_ok(dev); 532 if (ret) 533 goto err; 534 535 if (drv->restore) { 536 ret = drv->restore(dev); 537 if (ret) 538 goto err; 539 } 540 541 /* If restore didn't do it, mark device DRIVER_OK ourselves. */ 542 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK)) 543 virtio_device_ready(dev); 544 545 virtio_config_enable(dev); 546 547 return 0; 548 549 err: 550 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); 551 return ret; 552 } 553 EXPORT_SYMBOL_GPL(virtio_device_restore); 554 #endif 555 556 static int virtio_init(void) 557 { 558 if (bus_register(&virtio_bus) != 0) 559 panic("virtio bus registration failed"); 560 return 0; 561 } 562 563 static void __exit virtio_exit(void) 564 { 565 bus_unregister(&virtio_bus); 566 ida_destroy(&virtio_index_ida); 567 } 568 core_initcall(virtio_init); 569 module_exit(virtio_exit); 570 571 MODULE_LICENSE("GPL"); 572