linux/drivers/vfio/mdev/mdev_core.c
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   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 <cjia@nvidia.com>
   7 *             Kirti Wankhede <kwankhede@nvidia.com>
   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
  23static LIST_HEAD(parent_list);
  24static DEFINE_MUTEX(parent_list_lock);
  25static struct class_compat *mdev_bus_compat_class;
  26
  27static LIST_HEAD(mdev_list);
  28static DEFINE_MUTEX(mdev_list_lock);
  29
  30struct device *mdev_parent_dev(struct mdev_device *mdev)
  31{
  32        return mdev->type->parent->dev;
  33}
  34EXPORT_SYMBOL(mdev_parent_dev);
  35
  36/*
  37 * Return the index in supported_type_groups that this mdev_device was created
  38 * from.
  39 */
  40unsigned int mdev_get_type_group_id(struct mdev_device *mdev)
  41{
  42        return mdev->type->type_group_id;
  43}
  44EXPORT_SYMBOL(mdev_get_type_group_id);
  45
  46/*
  47 * Used in mdev_type_attribute sysfs functions to return the index in the
  48 * supported_type_groups that the sysfs is called from.
  49 */
  50unsigned int mtype_get_type_group_id(struct mdev_type *mtype)
  51{
  52        return mtype->type_group_id;
  53}
  54EXPORT_SYMBOL(mtype_get_type_group_id);
  55
  56/*
  57 * Used in mdev_type_attribute sysfs functions to return the parent struct
  58 * device
  59 */
  60struct device *mtype_get_parent_dev(struct mdev_type *mtype)
  61{
  62        return mtype->parent->dev;
  63}
  64EXPORT_SYMBOL(mtype_get_parent_dev);
  65
  66/* Should be called holding parent_list_lock */
  67static struct mdev_parent *__find_parent_device(struct device *dev)
  68{
  69        struct mdev_parent *parent;
  70
  71        list_for_each_entry(parent, &parent_list, next) {
  72                if (parent->dev == dev)
  73                        return parent;
  74        }
  75        return NULL;
  76}
  77
  78void mdev_release_parent(struct kref *kref)
  79{
  80        struct mdev_parent *parent = container_of(kref, struct mdev_parent,
  81                                                  ref);
  82        struct device *dev = parent->dev;
  83
  84        kfree(parent);
  85        put_device(dev);
  86}
  87
  88/* Caller must hold parent unreg_sem read or write lock */
  89static void mdev_device_remove_common(struct mdev_device *mdev)
  90{
  91        struct mdev_parent *parent = mdev->type->parent;
  92        int ret;
  93
  94        mdev_remove_sysfs_files(mdev);
  95        device_del(&mdev->dev);
  96        lockdep_assert_held(&parent->unreg_sem);
  97        ret = parent->ops->remove(mdev);
  98        if (ret)
  99                dev_err(&mdev->dev, "Remove failed: err=%d\n", ret);
 100
 101        /* Balances with device_initialize() */
 102        put_device(&mdev->dev);
 103}
 104
 105static int mdev_device_remove_cb(struct device *dev, void *data)
 106{
 107        struct mdev_device *mdev = mdev_from_dev(dev);
 108
 109        if (mdev)
 110                mdev_device_remove_common(mdev);
 111        return 0;
 112}
 113
 114/*
 115 * mdev_register_device : Register a device
 116 * @dev: device structure representing parent device.
 117 * @ops: Parent device operation structure to be registered.
 118 *
 119 * Add device to list of registered parent devices.
 120 * Returns a negative value on error, otherwise 0.
 121 */
 122int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
 123{
 124        int ret;
 125        struct mdev_parent *parent;
 126        char *env_string = "MDEV_STATE=registered";
 127        char *envp[] = { env_string, NULL };
 128
 129        /* check for mandatory ops */
 130        if (!ops || !ops->create || !ops->remove || !ops->supported_type_groups)
 131                return -EINVAL;
 132
 133        dev = get_device(dev);
 134        if (!dev)
 135                return -EINVAL;
 136
 137        /* Not mandatory, but its absence could be a problem */
 138        if (!ops->request)
 139                dev_info(dev, "Driver cannot be asked to release device\n");
 140
 141        mutex_lock(&parent_list_lock);
 142
 143        /* Check for duplicate */
 144        parent = __find_parent_device(dev);
 145        if (parent) {
 146                parent = NULL;
 147                ret = -EEXIST;
 148                goto add_dev_err;
 149        }
 150
 151        parent = kzalloc(sizeof(*parent), GFP_KERNEL);
 152        if (!parent) {
 153                ret = -ENOMEM;
 154                goto add_dev_err;
 155        }
 156
 157        kref_init(&parent->ref);
 158        init_rwsem(&parent->unreg_sem);
 159
 160        parent->dev = dev;
 161        parent->ops = ops;
 162
 163        if (!mdev_bus_compat_class) {
 164                mdev_bus_compat_class = class_compat_register("mdev_bus");
 165                if (!mdev_bus_compat_class) {
 166                        ret = -ENOMEM;
 167                        goto add_dev_err;
 168                }
 169        }
 170
 171        ret = parent_create_sysfs_files(parent);
 172        if (ret)
 173                goto add_dev_err;
 174
 175        ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL);
 176        if (ret)
 177                dev_warn(dev, "Failed to create compatibility class link\n");
 178
 179        list_add(&parent->next, &parent_list);
 180        mutex_unlock(&parent_list_lock);
 181
 182        dev_info(dev, "MDEV: Registered\n");
 183        kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
 184
 185        return 0;
 186
 187add_dev_err:
 188        mutex_unlock(&parent_list_lock);
 189        if (parent)
 190                mdev_put_parent(parent);
 191        else
 192                put_device(dev);
 193        return ret;
 194}
 195EXPORT_SYMBOL(mdev_register_device);
 196
 197/*
 198 * mdev_unregister_device : Unregister a parent device
 199 * @dev: device structure representing parent device.
 200 *
 201 * Remove device from list of registered parent devices. Give a chance to free
 202 * existing mediated devices for given device.
 203 */
 204
 205void mdev_unregister_device(struct device *dev)
 206{
 207        struct mdev_parent *parent;
 208        char *env_string = "MDEV_STATE=unregistered";
 209        char *envp[] = { env_string, NULL };
 210
 211        mutex_lock(&parent_list_lock);
 212        parent = __find_parent_device(dev);
 213
 214        if (!parent) {
 215                mutex_unlock(&parent_list_lock);
 216                return;
 217        }
 218        dev_info(dev, "MDEV: Unregistering\n");
 219
 220        list_del(&parent->next);
 221        mutex_unlock(&parent_list_lock);
 222
 223        down_write(&parent->unreg_sem);
 224
 225        class_compat_remove_link(mdev_bus_compat_class, dev, NULL);
 226
 227        device_for_each_child(dev, NULL, mdev_device_remove_cb);
 228
 229        parent_remove_sysfs_files(parent);
 230        up_write(&parent->unreg_sem);
 231
 232        mdev_put_parent(parent);
 233
 234        /* We still have the caller's reference to use for the uevent */
 235        kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
 236}
 237EXPORT_SYMBOL(mdev_unregister_device);
 238
 239static void mdev_device_release(struct device *dev)
 240{
 241        struct mdev_device *mdev = to_mdev_device(dev);
 242
 243        /* Pairs with the get in mdev_device_create() */
 244        kobject_put(&mdev->type->kobj);
 245
 246        mutex_lock(&mdev_list_lock);
 247        list_del(&mdev->next);
 248        mutex_unlock(&mdev_list_lock);
 249
 250        dev_dbg(&mdev->dev, "MDEV: destroying\n");
 251        kfree(mdev);
 252}
 253
 254int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
 255{
 256        int ret;
 257        struct mdev_device *mdev, *tmp;
 258        struct mdev_parent *parent = type->parent;
 259
 260        mutex_lock(&mdev_list_lock);
 261
 262        /* Check for duplicate */
 263        list_for_each_entry(tmp, &mdev_list, next) {
 264                if (guid_equal(&tmp->uuid, uuid)) {
 265                        mutex_unlock(&mdev_list_lock);
 266                        return -EEXIST;
 267                }
 268        }
 269
 270        mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
 271        if (!mdev) {
 272                mutex_unlock(&mdev_list_lock);
 273                return -ENOMEM;
 274        }
 275
 276        device_initialize(&mdev->dev);
 277        mdev->dev.parent  = parent->dev;
 278        mdev->dev.bus = &mdev_bus_type;
 279        mdev->dev.release = mdev_device_release;
 280        mdev->dev.groups = parent->ops->mdev_attr_groups;
 281        mdev->type = type;
 282        /* Pairs with the put in mdev_device_release() */
 283        kobject_get(&type->kobj);
 284
 285        guid_copy(&mdev->uuid, uuid);
 286        list_add(&mdev->next, &mdev_list);
 287        mutex_unlock(&mdev_list_lock);
 288
 289        ret = dev_set_name(&mdev->dev, "%pUl", uuid);
 290        if (ret)
 291                goto out_put_device;
 292
 293        /* Check if parent unregistration has started */
 294        if (!down_read_trylock(&parent->unreg_sem)) {
 295                ret = -ENODEV;
 296                goto out_put_device;
 297        }
 298
 299        ret = parent->ops->create(mdev);
 300        if (ret)
 301                goto out_unlock;
 302
 303        ret = device_add(&mdev->dev);
 304        if (ret)
 305                goto out_remove;
 306
 307        ret = mdev_create_sysfs_files(mdev);
 308        if (ret)
 309                goto out_del;
 310
 311        mdev->active = true;
 312        dev_dbg(&mdev->dev, "MDEV: created\n");
 313        up_read(&parent->unreg_sem);
 314
 315        return 0;
 316
 317out_del:
 318        device_del(&mdev->dev);
 319out_remove:
 320        parent->ops->remove(mdev);
 321out_unlock:
 322        up_read(&parent->unreg_sem);
 323out_put_device:
 324        put_device(&mdev->dev);
 325        return ret;
 326}
 327
 328int mdev_device_remove(struct mdev_device *mdev)
 329{
 330        struct mdev_device *tmp;
 331        struct mdev_parent *parent = mdev->type->parent;
 332
 333        mutex_lock(&mdev_list_lock);
 334        list_for_each_entry(tmp, &mdev_list, next) {
 335                if (tmp == mdev)
 336                        break;
 337        }
 338
 339        if (tmp != mdev) {
 340                mutex_unlock(&mdev_list_lock);
 341                return -ENODEV;
 342        }
 343
 344        if (!mdev->active) {
 345                mutex_unlock(&mdev_list_lock);
 346                return -EAGAIN;
 347        }
 348
 349        mdev->active = false;
 350        mutex_unlock(&mdev_list_lock);
 351
 352        /* Check if parent unregistration has started */
 353        if (!down_read_trylock(&parent->unreg_sem))
 354                return -ENODEV;
 355
 356        mdev_device_remove_common(mdev);
 357        up_read(&parent->unreg_sem);
 358        return 0;
 359}
 360
 361static int __init mdev_init(void)
 362{
 363        return mdev_bus_register();
 364}
 365
 366static void __exit mdev_exit(void)
 367{
 368        if (mdev_bus_compat_class)
 369                class_compat_unregister(mdev_bus_compat_class);
 370
 371        mdev_bus_unregister();
 372}
 373
 374module_init(mdev_init)
 375module_exit(mdev_exit)
 376
 377MODULE_VERSION(DRIVER_VERSION);
 378MODULE_LICENSE("GPL v2");
 379MODULE_AUTHOR(DRIVER_AUTHOR);
 380MODULE_DESCRIPTION(DRIVER_DESC);
 381MODULE_SOFTDEP("post: vfio_mdev");
 382