drivers/vfio/group.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * VFIO core
   4  *
   5  * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
   6  *     Author: Alex Williamson <alex.williamson@redhat.com>
   7  *
   8  * Derived from original vfio:
   9  * Copyright 2010 Cisco Systems, Inc.  All rights reserved.
  10  * Author: Tom Lyon, pugs@cisco.com
  11  */
  12
  13 #include <linux/vfio.h>
  14 #include <linux/iommufd.h>
  15 #include <linux/anon_inodes.h>
  16 #include "vfio.h"
  17
  18 static struct vfio {
  19         struct class                    *class;
  20         struct list_head                group_list;
  21         struct mutex                    group_lock; /* locks group_list */
  22         struct ida                      group_ida;
  23         dev_t                           group_devt;
  24 } vfio;
  25
  26 static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
  27                                                      char *buf)
  28 {
  29         struct vfio_device *it, *device = ERR_PTR(-ENODEV);
  30
  31         mutex_lock(&group->device_lock);
  32         list_for_each_entry(it, &group->device_list, group_next) {
  33                 int ret;
  34
  35                 if (it->ops->match) {
  36                         ret = it->ops->match(it, buf);
  37                         if (ret < 0) {
  38                                 device = ERR_PTR(ret);
  39                                 break;
  40                         }
  41                 } else {
  42                         ret = !strcmp(dev_name(it->dev), buf);
  43                 }
  44
  45                 if (ret && vfio_device_try_get_registration(it)) {
  46                         device = it;
  47                         break;
  48                 }
  49         }
  50         mutex_unlock(&group->device_lock);
  51
  52         return device;
  53 }
  54
  55 /*
  56  * VFIO Group fd, /dev/vfio/$GROUP
  57  */
  58 static bool vfio_group_has_iommu(struct vfio_group *group)
  59 {
  60         lockdep_assert_held(&group->group_lock);
  61         /*
  62          * There can only be users if there is a container, and if there is a
  63          * container there must be users.
  64          */
  65         WARN_ON(!group->container != !group->container_users);
  66
  67         return group->container || group->iommufd;
  68 }
  69
  70 /*
  71  * VFIO_GROUP_UNSET_CONTAINER should fail if there are other users or
  72  * if there was no container to unset.  Since the ioctl is called on
  73  * the group, we know that still exists, therefore the only valid
  74  * transition here is 1->0.
  75  */
  76 static int vfio_group_ioctl_unset_container(struct vfio_group *group)
  77 {
  78         int ret = 0;
  79
  80         mutex_lock(&group->group_lock);
  81         if (!vfio_group_has_iommu(group)) {
  82                 ret = -EINVAL;
  83                 goto out_unlock;
  84         }
  85         if (group->container) {
  86                 if (group->container_users != 1) {
  87                         ret = -EBUSY;
  88                         goto out_unlock;
  89                 }
  90                 vfio_group_detach_container(group);
  91         }
  92         if (group->iommufd) {
  93                 iommufd_ctx_put(group->iommufd);
  94                 group->iommufd = NULL;
  95         }
  96
  97 out_unlock:
  98         mutex_unlock(&group->group_lock);
  99         return ret;
 100 }
 101
 102 static int vfio_group_ioctl_set_container(struct vfio_group *group,
 103                                           int __user *arg)
 104 {
 105         struct vfio_container *container;
 106         struct iommufd_ctx *iommufd;
 107         struct fd f;
 108         int ret;
 109         int fd;
 110
 111         if (get_user(fd, arg))
 112                 return -EFAULT;
 113
 114         f = fdget(fd);
 115         if (!fd_file(f))
 116                 return -EBADF;
 117
 118         mutex_lock(&group->group_lock);
 119         if (vfio_group_has_iommu(group)) {
 120                 ret = -EINVAL;
 121                 goto out_unlock;
 122         }
 123         if (!group->iommu_group) {
 124                 ret = -ENODEV;
 125                 goto out_unlock;
 126         }
 127
 128         container = vfio_container_from_file(fd_file(f));
 129         if (container) {
 130                 ret = vfio_container_attach_group(container, group);
 131                 goto out_unlock;
 132         }
 133
 134         iommufd = iommufd_ctx_from_file(fd_file(f));
 135         if (!IS_ERR(iommufd)) {
 136                 if (IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
 137                     group->type == VFIO_NO_IOMMU)
 138                         ret = iommufd_vfio_compat_set_no_iommu(iommufd);
 139                 else
 140                         ret = iommufd_vfio_compat_ioas_create(iommufd);
 141
 142                 if (ret) {
 143                         iommufd_ctx_put(iommufd);
 144                         goto out_unlock;
 145                 }
 146
 147                 group->iommufd = iommufd;
 148                 goto out_unlock;
 149         }
 150
 151         /* The FD passed is not recognized. */
 152         ret = -EBADFD;
 153
 154 out_unlock:
 155         mutex_unlock(&group->group_lock);
 156         fdput(f);
 157         return ret;
 158 }
 159
 160 static void vfio_device_group_get_kvm_safe(struct vfio_device *device)
 161 {
 162         spin_lock(&device->group->kvm_ref_lock);
 163         vfio_device_get_kvm_safe(device, device->group->kvm);
 164         spin_unlock(&device->group->kvm_ref_lock);
 165 }
 166
 167 static int vfio_df_group_open(struct vfio_device_file *df)
 168 {
 169         struct vfio_device *device = df->device;
 170         int ret;
 171
 172         mutex_lock(&device->group->group_lock);
 173         if (!vfio_group_has_iommu(device->group)) {
 174                 ret = -EINVAL;
 175                 goto out_unlock;
 176         }
 177
 178         mutex_lock(&device->dev_set->lock);
 179
 180         /*
 181          * Before the first device open, get the KVM pointer currently
 182          * associated with the group (if there is one) and obtain a reference
 183          * now that will be held until the open_count reaches 0 again.  Save
 184          * the pointer in the device for use by drivers.
 185          */
 186         if (device->open_count == 0)
 187                 vfio_device_group_get_kvm_safe(device);
 188
 189         df->iommufd = device->group->iommufd;
 190         if (df->iommufd && vfio_device_is_noiommu(device) && device->open_count == 0) {
 191                 /*
 192                  * Require no compat ioas to be assigned to proceed.  The basic
 193                  * statement is that the user cannot have done something that
 194                  * implies they expected translation to exist
 195                  */
 196                 if (!capable(CAP_SYS_RAWIO) ||
 197                     vfio_iommufd_device_has_compat_ioas(device, df->iommufd))
 198                         ret = -EPERM;
 199                 else
 200                         ret = 0;
 201                 goto out_put_kvm;
 202         }
 203
 204         ret = vfio_df_open(df);
 205         if (ret)
 206                 goto out_put_kvm;
 207
 208         if (df->iommufd && device->open_count == 1) {
 209                 ret = vfio_iommufd_compat_attach_ioas(device, df->iommufd);
 210                 if (ret)
 211                         goto out_close_device;
 212         }
 213
 214         /*
 215          * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
 216          * read/write/mmap and vfio_file_has_device_access()
 217          */
 218         smp_store_release(&df->access_granted, true);
 219
 220         mutex_unlock(&device->dev_set->lock);
 221         mutex_unlock(&device->group->group_lock);
 222         return 0;
 223
 224 out_close_device:
 225         vfio_df_close(df);
 226 out_put_kvm:
 227         df->iommufd = NULL;
 228         if (device->open_count == 0)
 229                 vfio_device_put_kvm(device);
 230         mutex_unlock(&device->dev_set->lock);
 231 out_unlock:
 232         mutex_unlock(&device->group->group_lock);
 233         return ret;
 234 }
 235
 236 void vfio_df_group_close(struct vfio_device_file *df)
 237 {
 238         struct vfio_device *device = df->device;
 239
 240         mutex_lock(&device->group->group_lock);
 241         mutex_lock(&device->dev_set->lock);
 242
 243         vfio_df_close(df);
 244         df->iommufd = NULL;
 245
 246         if (device->open_count == 0)
 247                 vfio_device_put_kvm(device);
 248
 249         mutex_unlock(&device->dev_set->lock);
 250         mutex_unlock(&device->group->group_lock);
 251 }
 252
 253 static struct file *vfio_device_open_file(struct vfio_device *device)
 254 {
 255         struct vfio_device_file *df;
 256         struct file *filep;
 257         int ret;
 258
 259         df = vfio_allocate_device_file(device);
 260         if (IS_ERR(df)) {
 261                 ret = PTR_ERR(df);
 262                 goto err_out;
 263         }
 264
 265         df->group = device->group;
 266
 267         ret = vfio_df_group_open(df);
 268         if (ret)
 269                 goto err_free;
 270
 271         /*
 272          * We can't use anon_inode_getfd() because we need to modify
 273          * the f_mode flags directly to allow more than just ioctls
 274          */
 275         filep = anon_inode_getfile("[vfio-device]", &vfio_device_fops,
 276                                    df, O_RDWR);
 277         if (IS_ERR(filep)) {
 278                 ret = PTR_ERR(filep);
 279                 goto err_close_device;
 280         }
 281
 282         /*
 283          * TODO: add an anon_inode interface to do this.
 284          * Appears to be missing by lack of need rather than
 285          * explicitly prevented.  Now there's need.
 286          */
 287         filep->f_mode |= (FMODE_PREAD | FMODE_PWRITE);
 288
 289         /*
 290          * Use the pseudo fs inode on the device to link all mmaps
 291          * to the same address space, allowing us to unmap all vmas
 292          * associated to this device using unmap_mapping_range().
 293          */
 294         filep->f_mapping = device->inode->i_mapping;
 295
 296         if (device->group->type == VFIO_NO_IOMMU)
 297                 dev_warn(device->dev, "vfio-noiommu device opened by user "
 298                          "(%s:%d)\n", current->comm, task_pid_nr(current));
 299         /*
 300          * On success the ref of device is moved to the file and
 301          * put in vfio_device_fops_release()
 302          */
 303         return filep;
 304
 305 err_close_device:
 306         vfio_df_group_close(df);
 307 err_free:
 308         kfree(df);
 309 err_out:
 310         return ERR_PTR(ret);
 311 }
 312
 313 static int vfio_group_ioctl_get_device_fd(struct vfio_group *group,
 314                                           char __user *arg)
 315 {
 316         struct vfio_device *device;
 317         struct file *filep;
 318         char *buf;
 319         int fdno;
 320         int ret;
 321
 322         buf = strndup_user(arg, PAGE_SIZE);
 323         if (IS_ERR(buf))
 324                 return PTR_ERR(buf);
 325
 326         device = vfio_device_get_from_name(group, buf);
 327         kfree(buf);
 328         if (IS_ERR(device))
 329                 return PTR_ERR(device);
 330
 331         fdno = get_unused_fd_flags(O_CLOEXEC);
 332         if (fdno < 0) {
 333                 ret = fdno;
 334                 goto err_put_device;
 335         }
 336
 337         filep = vfio_device_open_file(device);
 338         if (IS_ERR(filep)) {
 339                 ret = PTR_ERR(filep);
 340                 goto err_put_fdno;
 341         }
 342
 343         fd_install(fdno, filep);
 344         return fdno;
 345
 346 err_put_fdno:
 347         put_unused_fd(fdno);
 348 err_put_device:
 349         vfio_device_put_registration(device);
 350         return ret;
 351 }
 352
 353 static int vfio_group_ioctl_get_status(struct vfio_group *group,
 354                                        struct vfio_group_status __user *arg)
 355 {
 356         unsigned long minsz = offsetofend(struct vfio_group_status, flags);
 357         struct vfio_group_status status;
 358
 359         if (copy_from_user(&status, arg, minsz))
 360                 return -EFAULT;
 361
 362         if (status.argsz < minsz)
 363                 return -EINVAL;
 364
 365         status.flags = 0;
 366
 367         mutex_lock(&group->group_lock);
 368         if (!group->iommu_group) {
 369                 mutex_unlock(&group->group_lock);
 370                 return -ENODEV;
 371         }
 372
 373         /*
 374          * With the container FD the iommu_group_claim_dma_owner() is done
 375          * during SET_CONTAINER but for IOMMFD this is done during
 376          * VFIO_GROUP_GET_DEVICE_FD. Meaning that with iommufd
 377          * VFIO_GROUP_FLAGS_VIABLE could be set but GET_DEVICE_FD will fail due
 378          * to viability.
 379          */
 380         if (vfio_group_has_iommu(group))
 381                 status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET |
 382                                 VFIO_GROUP_FLAGS_VIABLE;
 383         else if (!iommu_group_dma_owner_claimed(group->iommu_group))
 384                 status.flags |= VFIO_GROUP_FLAGS_VIABLE;
 385         mutex_unlock(&group->group_lock);
 386
 387         if (copy_to_user(arg, &status, minsz))
 388                 return -EFAULT;
 389         return 0;
 390 }
 391
 392 static long vfio_group_fops_unl_ioctl(struct file *filep,
 393                                       unsigned int cmd, unsigned long arg)
 394 {
 395         struct vfio_group *group = filep->private_data;
 396         void __user *uarg = (void __user *)arg;
 397
 398         switch (cmd) {
 399         case VFIO_GROUP_GET_DEVICE_FD:
 400                 return vfio_group_ioctl_get_device_fd(group, uarg);
 401         case VFIO_GROUP_GET_STATUS:
 402                 return vfio_group_ioctl_get_status(group, uarg);
 403         case VFIO_GROUP_SET_CONTAINER:
 404                 return vfio_group_ioctl_set_container(group, uarg);
 405         case VFIO_GROUP_UNSET_CONTAINER:
 406                 return vfio_group_ioctl_unset_container(group);
 407         default:
 408                 return -ENOTTY;
 409         }
 410 }
 411
 412 int vfio_device_block_group(struct vfio_device *device)
 413 {
 414         struct vfio_group *group = device->group;
 415         int ret = 0;
 416
 417         mutex_lock(&group->group_lock);
 418         if (group->opened_file) {
 419                 ret = -EBUSY;
 420                 goto out_unlock;
 421         }
 422
 423         group->cdev_device_open_cnt++;
 424
 425 out_unlock:
 426         mutex_unlock(&group->group_lock);
 427         return ret;
 428 }
 429
 430 void vfio_device_unblock_group(struct vfio_device *device)
 431 {
 432         struct vfio_group *group = device->group;
 433
 434         mutex_lock(&group->group_lock);
 435         group->cdev_device_open_cnt--;
 436         mutex_unlock(&group->group_lock);
 437 }
 438
 439 static int vfio_group_fops_open(struct inode *inode, struct file *filep)
 440 {
 441         struct vfio_group *group =
 442                 container_of(inode->i_cdev, struct vfio_group, cdev);
 443         int ret;
 444
 445         mutex_lock(&group->group_lock);
 446
 447         /*
 448          * drivers can be zero if this races with vfio_device_remove_group(), it
 449          * will be stable at 0 under the group rwsem
 450          */
 451         if (refcount_read(&group->drivers) == 0) {
 452                 ret = -ENODEV;
 453                 goto out_unlock;
 454         }
 455
 456         if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO)) {
 457                 ret = -EPERM;
 458                 goto out_unlock;
 459         }
 460
 461         if (group->cdev_device_open_cnt) {
 462                 ret = -EBUSY;
 463                 goto out_unlock;
 464         }
 465
 466         /*
 467          * Do we need multiple instances of the group open?  Seems not.
 468          */
 469         if (group->opened_file) {
 470                 ret = -EBUSY;
 471                 goto out_unlock;
 472         }
 473         group->opened_file = filep;
 474         filep->private_data = group;
 475         ret = 0;
 476 out_unlock:
 477         mutex_unlock(&group->group_lock);
 478         return ret;
 479 }
 480
 481 static int vfio_group_fops_release(struct inode *inode, struct file *filep)
 482 {
 483         struct vfio_group *group = filep->private_data;
 484
 485         filep->private_data = NULL;
 486
 487         mutex_lock(&group->group_lock);
 488         /*
 489          * Device FDs hold a group file reference, therefore the group release
 490          * is only called when there are no open devices.
 491          */
 492         WARN_ON(group->notifier.head);
 493         if (group->container)
 494                 vfio_group_detach_container(group);
 495         if (group->iommufd) {
 496                 iommufd_ctx_put(group->iommufd);
 497                 group->iommufd = NULL;
 498         }
 499         group->opened_file = NULL;
 500         mutex_unlock(&group->group_lock);
 501         return 0;
 502 }
 503
 504 static const struct file_operations vfio_group_fops = {
 505         .owner          = THIS_MODULE,
 506         .unlocked_ioctl = vfio_group_fops_unl_ioctl,
 507         .compat_ioctl   = compat_ptr_ioctl,
 508         .open           = vfio_group_fops_open,
 509         .release        = vfio_group_fops_release,
 510 };
 511
 512 /*
 513  * Group objects - create, release, get, put, search
 514  */
 515 static struct vfio_group *
 516 vfio_group_find_from_iommu(struct iommu_group *iommu_group)
 517 {
 518         struct vfio_group *group;
 519
 520         lockdep_assert_held(&vfio.group_lock);
 521
 522         /*
 523          * group->iommu_group from the vfio.group_list cannot be NULL
 524          * under the vfio.group_lock.
 525          */
 526         list_for_each_entry(group, &vfio.group_list, vfio_next) {
 527                 if (group->iommu_group == iommu_group)
 528                         return group;
 529         }
 530         return NULL;
 531 }
 532
 533 static void vfio_group_release(struct device *dev)
 534 {
 535         struct vfio_group *group = container_of(dev, struct vfio_group, dev);
 536
 537         mutex_destroy(&group->device_lock);
 538         mutex_destroy(&group->group_lock);
 539         WARN_ON(group->iommu_group);
 540         WARN_ON(group->cdev_device_open_cnt);
 541         ida_free(&vfio.group_ida, MINOR(group->dev.devt));
 542         kfree(group);
 543 }
 544
 545 static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group,
 546                                            enum vfio_group_type type)
 547 {
 548         struct vfio_group *group;
 549         int minor;
 550
 551         group = kzalloc(sizeof(*group), GFP_KERNEL);
 552         if (!group)
 553                 return ERR_PTR(-ENOMEM);
 554
 555         minor = ida_alloc_max(&vfio.group_ida, MINORMASK, GFP_KERNEL);
 556         if (minor < 0) {
 557                 kfree(group);
 558                 return ERR_PTR(minor);
 559         }
 560
 561         device_initialize(&group->dev);
 562         group->dev.devt = MKDEV(MAJOR(vfio.group_devt), minor);
 563         group->dev.class = vfio.class;
 564         group->dev.release = vfio_group_release;
 565         cdev_init(&group->cdev, &vfio_group_fops);
 566         group->cdev.owner = THIS_MODULE;
 567
 568         refcount_set(&group->drivers, 1);
 569         mutex_init(&group->group_lock);
 570         spin_lock_init(&group->kvm_ref_lock);
 571         INIT_LIST_HEAD(&group->device_list);
 572         mutex_init(&group->device_lock);
 573         group->iommu_group = iommu_group;
 574         /* put in vfio_group_release() */
 575         iommu_group_ref_get(iommu_group);
 576         group->type = type;
 577         BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);
 578
 579         return group;
 580 }
 581
 582 static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
 583                 enum vfio_group_type type)
 584 {
 585         struct vfio_group *group;
 586         struct vfio_group *ret;
 587         int err;
 588
 589         lockdep_assert_held(&vfio.group_lock);
 590
 591         group = vfio_group_alloc(iommu_group, type);
 592         if (IS_ERR(group))
 593                 return group;
 594
 595         err = dev_set_name(&group->dev, "%s%d",
 596                            group->type == VFIO_NO_IOMMU ? "noiommu-" : "",
 597                            iommu_group_id(iommu_group));
 598         if (err) {
 599                 ret = ERR_PTR(err);
 600                 goto err_put;
 601         }
 602
 603         err = cdev_device_add(&group->cdev, &group->dev);
 604         if (err) {
 605                 ret = ERR_PTR(err);
 606                 goto err_put;
 607         }
 608
 609         list_add(&group->vfio_next, &vfio.group_list);
 610
 611         return group;
 612
 613 err_put:
 614         put_device(&group->dev);
 615         return ret;
 616 }
 617
 618 static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
 619                 enum vfio_group_type type)
 620 {
 621         struct iommu_group *iommu_group;
 622         struct vfio_group *group;
 623         int ret;
 624
 625         iommu_group = iommu_group_alloc();
 626         if (IS_ERR(iommu_group))
 627                 return ERR_CAST(iommu_group);
 628
 629         ret = iommu_group_set_name(iommu_group, "vfio-noiommu");
 630         if (ret)
 631                 goto out_put_group;
 632         ret = iommu_group_add_device(iommu_group, dev);
 633         if (ret)
 634                 goto out_put_group;
 635
 636         mutex_lock(&vfio.group_lock);
 637         group = vfio_create_group(iommu_group, type);
 638         mutex_unlock(&vfio.group_lock);
 639         if (IS_ERR(group)) {
 640                 ret = PTR_ERR(group);
 641                 goto out_remove_device;
 642         }
 643         iommu_group_put(iommu_group);
 644         return group;
 645
 646 out_remove_device:
 647         iommu_group_remove_device(dev);
 648 out_put_group:
 649         iommu_group_put(iommu_group);
 650         return ERR_PTR(ret);
 651 }
 652
 653 static bool vfio_group_has_device(struct vfio_group *group, struct device *dev)
 654 {
 655         struct vfio_device *device;
 656
 657         mutex_lock(&group->device_lock);
 658         list_for_each_entry(device, &group->device_list, group_next) {
 659                 if (device->dev == dev) {
 660                         mutex_unlock(&group->device_lock);
 661                         return true;
 662                 }
 663         }
 664         mutex_unlock(&group->device_lock);
 665         return false;
 666 }
 667
 668 static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
 669 {
 670         struct iommu_group *iommu_group;
 671         struct vfio_group *group;
 672
 673         iommu_group = iommu_group_get(dev);
 674         if (!iommu_group && vfio_noiommu) {
 675                 /*
 676                  * With noiommu enabled, create an IOMMU group for devices that
 677                  * don't already have one, implying no IOMMU hardware/driver
 678                  * exists.  Taint the kernel because we're about to give a DMA
 679                  * capable device to a user without IOMMU protection.
 680                  */
 681                 group = vfio_noiommu_group_alloc(dev, VFIO_NO_IOMMU);
 682                 if (!IS_ERR(group)) {
 683                         add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 684                         dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
 685                 }
 686                 return group;
 687         }
 688
 689         if (!iommu_group)
 690                 return ERR_PTR(-EINVAL);
 691
 692         mutex_lock(&vfio.group_lock);
 693         group = vfio_group_find_from_iommu(iommu_group);
 694         if (group) {
 695                 if (WARN_ON(vfio_group_has_device(group, dev)))
 696                         group = ERR_PTR(-EINVAL);
 697                 else
 698                         refcount_inc(&group->drivers);
 699         } else {
 700                 group = vfio_create_group(iommu_group, VFIO_IOMMU);
 701         }
 702         mutex_unlock(&vfio.group_lock);
 703
 704         /* The vfio_group holds a reference to the iommu_group */
 705         iommu_group_put(iommu_group);
 706         return group;
 707 }
 708
 709 int vfio_device_set_group(struct vfio_device *device,
 710                           enum vfio_group_type type)
 711 {
 712         struct vfio_group *group;
 713
 714         if (type == VFIO_IOMMU)
 715                 group = vfio_group_find_or_alloc(device->dev);
 716         else
 717                 group = vfio_noiommu_group_alloc(device->dev, type);
 718
 719         if (IS_ERR(group))
 720                 return PTR_ERR(group);
 721
 722         /* Our reference on group is moved to the device */
 723         device->group = group;
 724         return 0;
 725 }
 726
 727 void vfio_device_remove_group(struct vfio_device *device)
 728 {
 729         struct vfio_group *group = device->group;
 730         struct iommu_group *iommu_group;
 731
 732         if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)
 733                 iommu_group_remove_device(device->dev);
 734
 735         /* Pairs with vfio_create_group() / vfio_group_get_from_iommu() */
 736         if (!refcount_dec_and_mutex_lock(&group->drivers, &vfio.group_lock))
 737                 return;
 738         list_del(&group->vfio_next);
 739
 740         /*
 741          * We could concurrently probe another driver in the group that might
 742          * race vfio_device_remove_group() with vfio_get_group(), so we have to
 743          * ensure that the sysfs is all cleaned up under lock otherwise the
 744          * cdev_device_add() will fail due to the name aready existing.
 745          */
 746         cdev_device_del(&group->cdev, &group->dev);
 747
 748         mutex_lock(&group->group_lock);
 749         /*
 750          * These data structures all have paired operations that can only be
 751          * undone when the caller holds a live reference on the device. Since
 752          * all pairs must be undone these WARN_ON's indicate some caller did not
 753          * properly hold the group reference.
 754          */
 755         WARN_ON(!list_empty(&group->device_list));
 756         WARN_ON(group->notifier.head);
 757
 758         /*
 759          * Revoke all users of group->iommu_group. At this point we know there
 760          * are no devices active because we are unplugging the last one. Setting
 761          * iommu_group to NULL blocks all new users.
 762          */
 763         if (group->container)
 764                 vfio_group_detach_container(group);
 765         iommu_group = group->iommu_group;
 766         group->iommu_group = NULL;
 767         mutex_unlock(&group->group_lock);
 768         mutex_unlock(&vfio.group_lock);
 769
 770         iommu_group_put(iommu_group);
 771         put_device(&group->dev);
 772 }
 773
 774 void vfio_device_group_register(struct vfio_device *device)
 775 {
 776         mutex_lock(&device->group->device_lock);
 777         list_add(&device->group_next, &device->group->device_list);
 778         mutex_unlock(&device->group->device_lock);
 779 }
 780
 781 void vfio_device_group_unregister(struct vfio_device *device)
 782 {
 783         mutex_lock(&device->group->device_lock);
 784         list_del(&device->group_next);
 785         mutex_unlock(&device->group->device_lock);
 786 }
 787
 788 int vfio_device_group_use_iommu(struct vfio_device *device)
 789 {
 790         struct vfio_group *group = device->group;
 791         int ret = 0;
 792
 793         lockdep_assert_held(&group->group_lock);
 794
 795         if (WARN_ON(!group->container))
 796                 return -EINVAL;
 797
 798         ret = vfio_group_use_container(group);
 799         if (ret)
 800                 return ret;
 801         vfio_device_container_register(device);
 802         return 0;
 803 }
 804
 805 void vfio_device_group_unuse_iommu(struct vfio_device *device)
 806 {
 807         struct vfio_group *group = device->group;
 808
 809         lockdep_assert_held(&group->group_lock);
 810
 811         if (WARN_ON(!group->container))
 812                 return;
 813
 814         vfio_device_container_unregister(device);
 815         vfio_group_unuse_container(group);
 816 }
 817
 818 bool vfio_device_has_container(struct vfio_device *device)
 819 {
 820         return device->group->container;
 821 }
 822
 823 struct vfio_group *vfio_group_from_file(struct file *file)
 824 {
 825         struct vfio_group *group = file->private_data;
 826
 827         if (file->f_op != &vfio_group_fops)
 828                 return NULL;
 829         return group;
 830 }
 831
 832 /**
 833  * vfio_file_iommu_group - Return the struct iommu_group for the vfio group file
 834  * @file: VFIO group file
 835  *
 836  * The returned iommu_group is valid as long as a ref is held on the file. This
 837  * returns a reference on the group. This function is deprecated, only the SPAPR
 838  * path in kvm should call it.
 839  */
 840 struct iommu_group *vfio_file_iommu_group(struct file *file)
 841 {
 842         struct vfio_group *group = vfio_group_from_file(file);
 843         struct iommu_group *iommu_group = NULL;
 844
 845         if (!IS_ENABLED(CONFIG_SPAPR_TCE_IOMMU))
 846                 return NULL;
 847
 848         if (!group)
 849                 return NULL;
 850
 851         mutex_lock(&group->group_lock);
 852         if (group->iommu_group) {
 853                 iommu_group = group->iommu_group;
 854                 iommu_group_ref_get(iommu_group);
 855         }
 856         mutex_unlock(&group->group_lock);
 857         return iommu_group;
 858 }
 859 EXPORT_SYMBOL_GPL(vfio_file_iommu_group);
 860
 861 /**
 862  * vfio_file_is_group - True if the file is a vfio group file
 863  * @file: VFIO group file
 864  */
 865 bool vfio_file_is_group(struct file *file)
 866 {
 867         return vfio_group_from_file(file);
 868 }
 869 EXPORT_SYMBOL_GPL(vfio_file_is_group);
 870
 871 bool vfio_group_enforced_coherent(struct vfio_group *group)
 872 {
 873         struct vfio_device *device;
 874         bool ret = true;
 875
 876         /*
 877          * If the device does not have IOMMU_CAP_ENFORCE_CACHE_COHERENCY then
 878          * any domain later attached to it will also not support it. If the cap
 879          * is set then the iommu_domain eventually attached to the device/group
 880          * must use a domain with enforce_cache_coherency().
 881          */
 882         mutex_lock(&group->device_lock);
 883         list_for_each_entry(device, &group->device_list, group_next) {
 884                 if (!device_iommu_capable(device->dev,
 885                                           IOMMU_CAP_ENFORCE_CACHE_COHERENCY)) {
 886                         ret = false;
 887                         break;
 888                 }
 889         }
 890         mutex_unlock(&group->device_lock);
 891         return ret;
 892 }
 893
 894 void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
 895 {
 896         spin_lock(&group->kvm_ref_lock);
 897         group->kvm = kvm;
 898         spin_unlock(&group->kvm_ref_lock);
 899 }
 900
 901 /**
 902  * vfio_file_has_dev - True if the VFIO file is a handle for device
 903  * @file: VFIO file to check
 904  * @device: Device that must be part of the file
 905  *
 906  * Returns true if given file has permission to manipulate the given device.
 907  */
 908 bool vfio_file_has_dev(struct file *file, struct vfio_device *device)
 909 {
 910         struct vfio_group *group = vfio_group_from_file(file);
 911
 912         if (!group)
 913                 return false;
 914
 915         return group == device->group;
 916 }
 917 EXPORT_SYMBOL_GPL(vfio_file_has_dev);
 918
 919 static char *vfio_devnode(const struct device *dev, umode_t *mode)
 920 {
 921         return kasprintf(GFP_KERNEL, "vfio/%s", dev_name(dev));
 922 }
 923
 924 int __init vfio_group_init(void)
 925 {
 926         int ret;
 927
 928         ida_init(&vfio.group_ida);
 929         mutex_init(&vfio.group_lock);
 930         INIT_LIST_HEAD(&vfio.group_list);
 931
 932         ret = vfio_container_init();
 933         if (ret)
 934                 return ret;
 935
 936         /* /dev/vfio/$GROUP */
 937         vfio.class = class_create("vfio");
 938         if (IS_ERR(vfio.class)) {
 939                 ret = PTR_ERR(vfio.class);
 940                 goto err_group_class;
 941         }
 942
 943         vfio.class->devnode = vfio_devnode;
 944
 945         ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK + 1, "vfio");
 946         if (ret)
 947                 goto err_alloc_chrdev;
 948         return 0;
 949
 950 err_alloc_chrdev:
 951         class_destroy(vfio.class);
 952         vfio.class = NULL;
 953 err_group_class:
 954         vfio_container_cleanup();
 955         return ret;
 956 }
 957
 958 void vfio_group_cleanup(void)
 959 {
 960         WARN_ON(!list_empty(&vfio.group_list));
 961         ida_destroy(&vfio.group_ida);
 962         unregister_chrdev_region(vfio.group_devt, MINORMASK + 1);
 963         class_destroy(vfio.class);
 964         vfio.class = NULL;
 965         vfio_container_cleanup();
 966 }