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 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 /* Caller must hold parent unreg_sem read or write lock */ 59 static void mdev_device_remove_common(struct mdev_device *mdev) 60 { 61 struct mdev_parent *parent; 62 int ret; 63 64 mdev_remove_sysfs_files(mdev); 65 device_del(&mdev->dev); 66 parent = mdev->parent; 67 lockdep_assert_held(&parent->unreg_sem); 68 ret = parent->ops->remove(mdev); 69 if (ret) 70 dev_err(&mdev->dev, "Remove failed: err=%d\n", ret); 71 72 /* Balances with device_initialize() */ 73 put_device(&mdev->dev); 74 } 75 76 static int mdev_device_remove_cb(struct device *dev, void *data) 77 { 78 struct mdev_device *mdev = mdev_from_dev(dev); 79 80 if (mdev) 81 mdev_device_remove_common(mdev); 82 return 0; 83 } 84 85 /* 86 * mdev_register_device : Register a device 87 * @dev: device structure representing parent device. 88 * @ops: Parent device operation structure to be registered. 89 * 90 * Add device to list of registered parent devices. 91 * Returns a negative value on error, otherwise 0. 92 */ 93 int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops) 94 { 95 int ret; 96 struct mdev_parent *parent; 97 char *env_string = "MDEV_STATE=registered"; 98 char *envp[] = { env_string, NULL }; 99 100 /* check for mandatory ops */ 101 if (!ops || !ops->create || !ops->remove || !ops->supported_type_groups) 102 return -EINVAL; 103 104 dev = get_device(dev); 105 if (!dev) 106 return -EINVAL; 107 108 /* Not mandatory, but its absence could be a problem */ 109 if (!ops->request) 110 dev_info(dev, "Driver cannot be asked to release device\n"); 111 112 mutex_lock(&parent_list_lock); 113 114 /* Check for duplicate */ 115 parent = __find_parent_device(dev); 116 if (parent) { 117 parent = NULL; 118 ret = -EEXIST; 119 goto add_dev_err; 120 } 121 122 parent = kzalloc(sizeof(*parent), GFP_KERNEL); 123 if (!parent) { 124 ret = -ENOMEM; 125 goto add_dev_err; 126 } 127 128 kref_init(&parent->ref); 129 init_rwsem(&parent->unreg_sem); 130 131 parent->dev = dev; 132 parent->ops = ops; 133 134 if (!mdev_bus_compat_class) { 135 mdev_bus_compat_class = class_compat_register("mdev_bus"); 136 if (!mdev_bus_compat_class) { 137 ret = -ENOMEM; 138 goto add_dev_err; 139 } 140 } 141 142 ret = parent_create_sysfs_files(parent); 143 if (ret) 144 goto add_dev_err; 145 146 ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL); 147 if (ret) 148 dev_warn(dev, "Failed to create compatibility class link\n"); 149 150 list_add(&parent->next, &parent_list); 151 mutex_unlock(&parent_list_lock); 152 153 dev_info(dev, "MDEV: Registered\n"); 154 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); 155 156 return 0; 157 158 add_dev_err: 159 mutex_unlock(&parent_list_lock); 160 if (parent) 161 mdev_put_parent(parent); 162 else 163 put_device(dev); 164 return ret; 165 } 166 EXPORT_SYMBOL(mdev_register_device); 167 168 /* 169 * mdev_unregister_device : Unregister a parent device 170 * @dev: device structure representing parent device. 171 * 172 * Remove device from list of registered parent devices. Give a chance to free 173 * existing mediated devices for given device. 174 */ 175 176 void mdev_unregister_device(struct device *dev) 177 { 178 struct mdev_parent *parent; 179 char *env_string = "MDEV_STATE=unregistered"; 180 char *envp[] = { env_string, NULL }; 181 182 mutex_lock(&parent_list_lock); 183 parent = __find_parent_device(dev); 184 185 if (!parent) { 186 mutex_unlock(&parent_list_lock); 187 return; 188 } 189 dev_info(dev, "MDEV: Unregistering\n"); 190 191 list_del(&parent->next); 192 mutex_unlock(&parent_list_lock); 193 194 down_write(&parent->unreg_sem); 195 196 class_compat_remove_link(mdev_bus_compat_class, dev, NULL); 197 198 device_for_each_child(dev, NULL, mdev_device_remove_cb); 199 200 parent_remove_sysfs_files(parent); 201 up_write(&parent->unreg_sem); 202 203 mdev_put_parent(parent); 204 205 /* We still have the caller's reference to use for the uevent */ 206 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); 207 } 208 EXPORT_SYMBOL(mdev_unregister_device); 209 210 static void mdev_device_release(struct device *dev) 211 { 212 struct mdev_device *mdev = to_mdev_device(dev); 213 214 /* Pairs with the get in mdev_device_create() */ 215 mdev_put_parent(mdev->parent); 216 217 mutex_lock(&mdev_list_lock); 218 list_del(&mdev->next); 219 mutex_unlock(&mdev_list_lock); 220 221 dev_dbg(&mdev->dev, "MDEV: destroying\n"); 222 kfree(mdev); 223 } 224 225 int mdev_device_create(struct mdev_type *type, const guid_t *uuid) 226 { 227 int ret; 228 struct mdev_device *mdev, *tmp; 229 struct mdev_parent *parent = type->parent; 230 231 mutex_lock(&mdev_list_lock); 232 233 /* Check for duplicate */ 234 list_for_each_entry(tmp, &mdev_list, next) { 235 if (guid_equal(&tmp->uuid, uuid)) { 236 mutex_unlock(&mdev_list_lock); 237 return -EEXIST; 238 } 239 } 240 241 mdev = kzalloc(sizeof(*mdev), GFP_KERNEL); 242 if (!mdev) { 243 mutex_unlock(&mdev_list_lock); 244 return -ENOMEM; 245 } 246 247 device_initialize(&mdev->dev); 248 mdev->dev.parent = parent->dev; 249 mdev->dev.bus = &mdev_bus_type; 250 mdev->dev.release = mdev_device_release; 251 mdev->dev.groups = parent->ops->mdev_attr_groups; 252 mdev->type = type; 253 mdev->parent = parent; 254 /* Pairs with the put in mdev_device_release() */ 255 mdev_get_parent(parent); 256 257 guid_copy(&mdev->uuid, uuid); 258 list_add(&mdev->next, &mdev_list); 259 mutex_unlock(&mdev_list_lock); 260 261 ret = dev_set_name(&mdev->dev, "%pUl", uuid); 262 if (ret) 263 goto out_put_device; 264 265 /* Check if parent unregistration has started */ 266 if (!down_read_trylock(&parent->unreg_sem)) { 267 ret = -ENODEV; 268 goto out_put_device; 269 } 270 271 ret = parent->ops->create(&type->kobj, mdev); 272 if (ret) 273 goto out_unlock; 274 275 ret = device_add(&mdev->dev); 276 if (ret) 277 goto out_remove; 278 279 ret = mdev_create_sysfs_files(mdev); 280 if (ret) 281 goto out_del; 282 283 mdev->active = true; 284 dev_dbg(&mdev->dev, "MDEV: created\n"); 285 up_read(&parent->unreg_sem); 286 287 return 0; 288 289 out_del: 290 device_del(&mdev->dev); 291 out_remove: 292 parent->ops->remove(mdev); 293 out_unlock: 294 up_read(&parent->unreg_sem); 295 out_put_device: 296 put_device(&mdev->dev); 297 return ret; 298 } 299 300 int mdev_device_remove(struct mdev_device *mdev) 301 { 302 struct mdev_device *tmp; 303 struct mdev_parent *parent; 304 305 mutex_lock(&mdev_list_lock); 306 list_for_each_entry(tmp, &mdev_list, next) { 307 if (tmp == mdev) 308 break; 309 } 310 311 if (tmp != mdev) { 312 mutex_unlock(&mdev_list_lock); 313 return -ENODEV; 314 } 315 316 if (!mdev->active) { 317 mutex_unlock(&mdev_list_lock); 318 return -EAGAIN; 319 } 320 321 mdev->active = false; 322 mutex_unlock(&mdev_list_lock); 323 324 parent = mdev->parent; 325 /* Check if parent unregistration has started */ 326 if (!down_read_trylock(&parent->unreg_sem)) 327 return -ENODEV; 328 329 mdev_device_remove_common(mdev); 330 up_read(&parent->unreg_sem); 331 return 0; 332 } 333 334 static int __init mdev_init(void) 335 { 336 return mdev_bus_register(); 337 } 338 339 static void __exit mdev_exit(void) 340 { 341 if (mdev_bus_compat_class) 342 class_compat_unregister(mdev_bus_compat_class); 343 344 mdev_bus_unregister(); 345 } 346 347 module_init(mdev_init) 348 module_exit(mdev_exit) 349 350 MODULE_VERSION(DRIVER_VERSION); 351 MODULE_LICENSE("GPL v2"); 352 MODULE_AUTHOR(DRIVER_AUTHOR); 353 MODULE_DESCRIPTION(DRIVER_DESC); 354 MODULE_SOFTDEP("post: vfio_mdev"); 355