1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Mediated device Core Driver 4 * 5 * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved. 6 * Author: Neo Jia <[email protected]> 7 * Kirti Wankhede <[email protected]> 8 */ 9 10 #include <linux/module.h> 11 #include <linux/device.h> 12 #include <linux/slab.h> 13 #include <linux/uuid.h> 14 #include <linux/sysfs.h> 15 #include <linux/mdev.h> 16 17 #include "mdev_private.h" 18 19 #define DRIVER_VERSION "0.1" 20 #define DRIVER_AUTHOR "NVIDIA Corporation" 21 #define DRIVER_DESC "Mediated device Core Driver" 22 23 static LIST_HEAD(parent_list); 24 static DEFINE_MUTEX(parent_list_lock); 25 static struct class_compat *mdev_bus_compat_class; 26 27 static LIST_HEAD(mdev_list); 28 static DEFINE_MUTEX(mdev_list_lock); 29 30 struct device *mdev_parent_dev(struct mdev_device *mdev) 31 { 32 return mdev->parent->dev; 33 } 34 EXPORT_SYMBOL(mdev_parent_dev); 35 36 /* Should be called holding parent_list_lock */ 37 static struct mdev_parent *__find_parent_device(struct device *dev) 38 { 39 struct mdev_parent *parent; 40 41 list_for_each_entry(parent, &parent_list, next) { 42 if (parent->dev == dev) 43 return parent; 44 } 45 return NULL; 46 } 47 48 static void mdev_release_parent(struct kref *kref) 49 { 50 struct mdev_parent *parent = container_of(kref, struct mdev_parent, 51 ref); 52 struct device *dev = parent->dev; 53 54 kfree(parent); 55 put_device(dev); 56 } 57 58 static struct mdev_parent *mdev_get_parent(struct mdev_parent *parent) 59 { 60 if (parent) 61 kref_get(&parent->ref); 62 63 return parent; 64 } 65 66 static void mdev_put_parent(struct mdev_parent *parent) 67 { 68 if (parent) 69 kref_put(&parent->ref, mdev_release_parent); 70 } 71 72 /* Caller must hold parent unreg_sem read or write lock */ 73 static void mdev_device_remove_common(struct mdev_device *mdev) 74 { 75 struct mdev_parent *parent; 76 int ret; 77 78 mdev_remove_sysfs_files(mdev); 79 device_del(&mdev->dev); 80 parent = mdev->parent; 81 lockdep_assert_held(&parent->unreg_sem); 82 ret = parent->ops->remove(mdev); 83 if (ret) 84 dev_err(&mdev->dev, "Remove failed: err=%d\n", ret); 85 86 /* Balances with device_initialize() */ 87 put_device(&mdev->dev); 88 mdev_put_parent(parent); 89 } 90 91 static int mdev_device_remove_cb(struct device *dev, void *data) 92 { 93 struct mdev_device *mdev = mdev_from_dev(dev); 94 95 if (mdev) 96 mdev_device_remove_common(mdev); 97 return 0; 98 } 99 100 /* 101 * mdev_register_device : Register a device 102 * @dev: device structure representing parent device. 103 * @ops: Parent device operation structure to be registered. 104 * 105 * Add device to list of registered parent devices. 106 * Returns a negative value on error, otherwise 0. 107 */ 108 int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops) 109 { 110 int ret; 111 struct mdev_parent *parent; 112 char *env_string = "MDEV_STATE=registered"; 113 char *envp[] = { env_string, NULL }; 114 115 /* check for mandatory ops */ 116 if (!ops || !ops->create || !ops->remove || !ops->supported_type_groups) 117 return -EINVAL; 118 119 dev = get_device(dev); 120 if (!dev) 121 return -EINVAL; 122 123 /* Not mandatory, but its absence could be a problem */ 124 if (!ops->request) 125 dev_info(dev, "Driver cannot be asked to release device\n"); 126 127 mutex_lock(&parent_list_lock); 128 129 /* Check for duplicate */ 130 parent = __find_parent_device(dev); 131 if (parent) { 132 parent = NULL; 133 ret = -EEXIST; 134 goto add_dev_err; 135 } 136 137 parent = kzalloc(sizeof(*parent), GFP_KERNEL); 138 if (!parent) { 139 ret = -ENOMEM; 140 goto add_dev_err; 141 } 142 143 kref_init(&parent->ref); 144 init_rwsem(&parent->unreg_sem); 145 146 parent->dev = dev; 147 parent->ops = ops; 148 149 if (!mdev_bus_compat_class) { 150 mdev_bus_compat_class = class_compat_register("mdev_bus"); 151 if (!mdev_bus_compat_class) { 152 ret = -ENOMEM; 153 goto add_dev_err; 154 } 155 } 156 157 ret = parent_create_sysfs_files(parent); 158 if (ret) 159 goto add_dev_err; 160 161 ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL); 162 if (ret) 163 dev_warn(dev, "Failed to create compatibility class link\n"); 164 165 list_add(&parent->next, &parent_list); 166 mutex_unlock(&parent_list_lock); 167 168 dev_info(dev, "MDEV: Registered\n"); 169 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); 170 171 return 0; 172 173 add_dev_err: 174 mutex_unlock(&parent_list_lock); 175 if (parent) 176 mdev_put_parent(parent); 177 else 178 put_device(dev); 179 return ret; 180 } 181 EXPORT_SYMBOL(mdev_register_device); 182 183 /* 184 * mdev_unregister_device : Unregister a parent device 185 * @dev: device structure representing parent device. 186 * 187 * Remove device from list of registered parent devices. Give a chance to free 188 * existing mediated devices for given device. 189 */ 190 191 void mdev_unregister_device(struct device *dev) 192 { 193 struct mdev_parent *parent; 194 char *env_string = "MDEV_STATE=unregistered"; 195 char *envp[] = { env_string, NULL }; 196 197 mutex_lock(&parent_list_lock); 198 parent = __find_parent_device(dev); 199 200 if (!parent) { 201 mutex_unlock(&parent_list_lock); 202 return; 203 } 204 dev_info(dev, "MDEV: Unregistering\n"); 205 206 list_del(&parent->next); 207 mutex_unlock(&parent_list_lock); 208 209 down_write(&parent->unreg_sem); 210 211 class_compat_remove_link(mdev_bus_compat_class, dev, NULL); 212 213 device_for_each_child(dev, NULL, mdev_device_remove_cb); 214 215 parent_remove_sysfs_files(parent); 216 up_write(&parent->unreg_sem); 217 218 mdev_put_parent(parent); 219 220 /* We still have the caller's reference to use for the uevent */ 221 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); 222 } 223 EXPORT_SYMBOL(mdev_unregister_device); 224 225 static void mdev_device_free(struct mdev_device *mdev) 226 { 227 mutex_lock(&mdev_list_lock); 228 list_del(&mdev->next); 229 mutex_unlock(&mdev_list_lock); 230 231 dev_dbg(&mdev->dev, "MDEV: destroying\n"); 232 kfree(mdev); 233 } 234 235 static void mdev_device_release(struct device *dev) 236 { 237 struct mdev_device *mdev = to_mdev_device(dev); 238 239 mdev_device_free(mdev); 240 } 241 242 int mdev_device_create(struct mdev_type *type, const guid_t *uuid) 243 { 244 int ret; 245 struct mdev_device *mdev, *tmp; 246 struct mdev_parent *parent; 247 248 parent = mdev_get_parent(type->parent); 249 if (!parent) 250 return -EINVAL; 251 252 mutex_lock(&mdev_list_lock); 253 254 /* Check for duplicate */ 255 list_for_each_entry(tmp, &mdev_list, next) { 256 if (guid_equal(&tmp->uuid, uuid)) { 257 mutex_unlock(&mdev_list_lock); 258 ret = -EEXIST; 259 goto mdev_fail; 260 } 261 } 262 263 mdev = kzalloc(sizeof(*mdev), GFP_KERNEL); 264 if (!mdev) { 265 mutex_unlock(&mdev_list_lock); 266 ret = -ENOMEM; 267 goto mdev_fail; 268 } 269 270 guid_copy(&mdev->uuid, uuid); 271 list_add(&mdev->next, &mdev_list); 272 mutex_unlock(&mdev_list_lock); 273 274 mdev->parent = parent; 275 276 /* Check if parent unregistration has started */ 277 if (!down_read_trylock(&parent->unreg_sem)) { 278 mdev_device_free(mdev); 279 ret = -ENODEV; 280 goto mdev_fail; 281 } 282 283 device_initialize(&mdev->dev); 284 mdev->dev.parent = parent->dev; 285 mdev->dev.bus = &mdev_bus_type; 286 mdev->dev.release = mdev_device_release; 287 dev_set_name(&mdev->dev, "%pUl", uuid); 288 mdev->dev.groups = parent->ops->mdev_attr_groups; 289 mdev->type = type; 290 291 ret = parent->ops->create(&type->kobj, mdev); 292 if (ret) 293 goto ops_create_fail; 294 295 ret = device_add(&mdev->dev); 296 if (ret) 297 goto add_fail; 298 299 ret = mdev_create_sysfs_files(mdev); 300 if (ret) 301 goto sysfs_fail; 302 303 mdev->active = true; 304 dev_dbg(&mdev->dev, "MDEV: created\n"); 305 up_read(&parent->unreg_sem); 306 307 return 0; 308 309 sysfs_fail: 310 device_del(&mdev->dev); 311 add_fail: 312 parent->ops->remove(mdev); 313 ops_create_fail: 314 up_read(&parent->unreg_sem); 315 put_device(&mdev->dev); 316 mdev_fail: 317 mdev_put_parent(parent); 318 return ret; 319 } 320 321 int mdev_device_remove(struct mdev_device *mdev) 322 { 323 struct mdev_device *tmp; 324 struct mdev_parent *parent; 325 326 mutex_lock(&mdev_list_lock); 327 list_for_each_entry(tmp, &mdev_list, next) { 328 if (tmp == mdev) 329 break; 330 } 331 332 if (tmp != mdev) { 333 mutex_unlock(&mdev_list_lock); 334 return -ENODEV; 335 } 336 337 if (!mdev->active) { 338 mutex_unlock(&mdev_list_lock); 339 return -EAGAIN; 340 } 341 342 mdev->active = false; 343 mutex_unlock(&mdev_list_lock); 344 345 parent = mdev->parent; 346 /* Check if parent unregistration has started */ 347 if (!down_read_trylock(&parent->unreg_sem)) 348 return -ENODEV; 349 350 mdev_device_remove_common(mdev); 351 up_read(&parent->unreg_sem); 352 return 0; 353 } 354 355 static int __init mdev_init(void) 356 { 357 return mdev_bus_register(); 358 } 359 360 static void __exit mdev_exit(void) 361 { 362 if (mdev_bus_compat_class) 363 class_compat_unregister(mdev_bus_compat_class); 364 365 mdev_bus_unregister(); 366 } 367 368 module_init(mdev_init) 369 module_exit(mdev_exit) 370 371 MODULE_VERSION(DRIVER_VERSION); 372 MODULE_LICENSE("GPL v2"); 373 MODULE_AUTHOR(DRIVER_AUTHOR); 374 MODULE_DESCRIPTION(DRIVER_DESC); 375 MODULE_SOFTDEP("post: vfio_mdev"); 376