virt/kvm/vfio.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * VFIO-KVM bridge pseudo device
   4  *
   5  * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
   6  *     Author: Alex Williamson <alex.williamson@redhat.com>
   7  */
   8
   9 #include <linux/errno.h>
  10 #include <linux/file.h>
  11 #include <linux/kvm_host.h>
  12 #include <linux/list.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/slab.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/vfio.h>
  18 #include "vfio.h"
  19
  20 #ifdef CONFIG_SPAPR_TCE_IOMMU
  21 #include <asm/kvm_ppc.h>
  22 #endif
  23
  24 struct kvm_vfio_group {
  25         struct list_head node;
  26         struct vfio_group *vfio_group;
  27 };
  28
  29 struct kvm_vfio {
  30         struct list_head group_list;
  31         struct mutex lock;
  32         bool noncoherent;
  33 };
  34
  35 static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
  36 {
  37         struct vfio_group *vfio_group;
  38         struct vfio_group *(*fn)(struct file *);
  39
  40         fn = symbol_get(vfio_group_get_external_user);
  41         if (!fn)
  42                 return ERR_PTR(-EINVAL);
  43
  44         vfio_group = fn(filep);
  45
  46         symbol_put(vfio_group_get_external_user);
  47
  48         return vfio_group;
  49 }
  50
  51 static bool kvm_vfio_external_group_match_file(struct vfio_group *group,
  52                                                struct file *filep)
  53 {
  54         bool ret, (*fn)(struct vfio_group *, struct file *);
  55
  56         fn = symbol_get(vfio_external_group_match_file);
  57         if (!fn)
  58                 return false;
  59
  60         ret = fn(group, filep);
  61
  62         symbol_put(vfio_external_group_match_file);
  63
  64         return ret;
  65 }
  66
  67 static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
  68 {
  69         void (*fn)(struct vfio_group *);
  70
  71         fn = symbol_get(vfio_group_put_external_user);
  72         if (!fn)
  73                 return;
  74
  75         fn(vfio_group);
  76
  77         symbol_put(vfio_group_put_external_user);
  78 }
  79
  80 static void kvm_vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
  81 {
  82         void (*fn)(struct vfio_group *, struct kvm *);
  83
  84         fn = symbol_get(vfio_group_set_kvm);
  85         if (!fn)
  86                 return;
  87
  88         fn(group, kvm);
  89
  90         symbol_put(vfio_group_set_kvm);
  91 }
  92
  93 static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
  94 {
  95         long (*fn)(struct vfio_group *, unsigned long);
  96         long ret;
  97
  98         fn = symbol_get(vfio_external_check_extension);
  99         if (!fn)
 100                 return false;
 101
 102         ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
 103
 104         symbol_put(vfio_external_check_extension);
 105
 106         return ret > 0;
 107 }
 108
 109 #ifdef CONFIG_SPAPR_TCE_IOMMU
 110 static int kvm_vfio_external_user_iommu_id(struct vfio_group *vfio_group)
 111 {
 112         int (*fn)(struct vfio_group *);
 113         int ret = -EINVAL;
 114
 115         fn = symbol_get(vfio_external_user_iommu_id);
 116         if (!fn)
 117                 return ret;
 118
 119         ret = fn(vfio_group);
 120
 121         symbol_put(vfio_external_user_iommu_id);
 122
 123         return ret;
 124 }
 125
 126 static struct iommu_group *kvm_vfio_group_get_iommu_group(
 127                 struct vfio_group *group)
 128 {
 129         int group_id = kvm_vfio_external_user_iommu_id(group);
 130
 131         if (group_id < 0)
 132                 return NULL;
 133
 134         return iommu_group_get_by_id(group_id);
 135 }
 136
 137 static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
 138                 struct vfio_group *vfio_group)
 139 {
 140         struct iommu_group *grp = kvm_vfio_group_get_iommu_group(vfio_group);
 141
 142         if (WARN_ON_ONCE(!grp))
 143                 return;
 144
 145         kvm_spapr_tce_release_iommu_group(kvm, grp);
 146         iommu_group_put(grp);
 147 }
 148 #endif
 149
 150 /*
 151  * Groups can use the same or different IOMMU domains.  If the same then
 152  * adding a new group may change the coherency of groups we've previously
 153  * been told about.  We don't want to care about any of that so we retest
 154  * each group and bail as soon as we find one that's noncoherent.  This
 155  * means we only ever [un]register_noncoherent_dma once for the whole device.
 156  */
 157 static void kvm_vfio_update_coherency(struct kvm_device *dev)
 158 {
 159         struct kvm_vfio *kv = dev->private;
 160         bool noncoherent = false;
 161         struct kvm_vfio_group *kvg;
 162
 163         mutex_lock(&kv->lock);
 164
 165         list_for_each_entry(kvg, &kv->group_list, node) {
 166                 if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
 167                         noncoherent = true;
 168                         break;
 169                 }
 170         }
 171
 172         if (noncoherent != kv->noncoherent) {
 173                 kv->noncoherent = noncoherent;
 174
 175                 if (kv->noncoherent)
 176                         kvm_arch_register_noncoherent_dma(dev->kvm);
 177                 else
 178                         kvm_arch_unregister_noncoherent_dma(dev->kvm);
 179         }
 180
 181         mutex_unlock(&kv->lock);
 182 }
 183
 184 static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 185 {
 186         struct kvm_vfio *kv = dev->private;
 187         struct vfio_group *vfio_group;
 188         struct kvm_vfio_group *kvg;
 189         int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
 190         struct fd f;
 191         int32_t fd;
 192         int ret;
 193
 194         switch (attr) {
 195         case KVM_DEV_VFIO_GROUP_ADD:
 196                 if (get_user(fd, argp))
 197                         return -EFAULT;
 198
 199                 f = fdget(fd);
 200                 if (!f.file)
 201                         return -EBADF;
 202
 203                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 204                 fdput(f);
 205
 206                 if (IS_ERR(vfio_group))
 207                         return PTR_ERR(vfio_group);
 208
 209                 mutex_lock(&kv->lock);
 210
 211                 list_for_each_entry(kvg, &kv->group_list, node) {
 212                         if (kvg->vfio_group == vfio_group) {
 213                                 mutex_unlock(&kv->lock);
 214                                 kvm_vfio_group_put_external_user(vfio_group);
 215                                 return -EEXIST;
 216                         }
 217                 }
 218
 219                 kvg = kzalloc(sizeof(*kvg), GFP_KERNEL_ACCOUNT);
 220                 if (!kvg) {
 221                         mutex_unlock(&kv->lock);
 222                         kvm_vfio_group_put_external_user(vfio_group);
 223                         return -ENOMEM;
 224                 }
 225
 226                 list_add_tail(&kvg->node, &kv->group_list);
 227                 kvg->vfio_group = vfio_group;
 228
 229                 kvm_arch_start_assignment(dev->kvm);
 230
 231                 mutex_unlock(&kv->lock);
 232
 233                 kvm_vfio_group_set_kvm(vfio_group, dev->kvm);
 234
 235                 kvm_vfio_update_coherency(dev);
 236
 237                 return 0;
 238
 239         case KVM_DEV_VFIO_GROUP_DEL:
 240                 if (get_user(fd, argp))
 241                         return -EFAULT;
 242
 243                 f = fdget(fd);
 244                 if (!f.file)
 245                         return -EBADF;
 246
 247                 ret = -ENOENT;
 248
 249                 mutex_lock(&kv->lock);
 250
 251                 list_for_each_entry(kvg, &kv->group_list, node) {
 252                         if (!kvm_vfio_external_group_match_file(kvg->vfio_group,
 253                                                                 f.file))
 254                                 continue;
 255
 256                         list_del(&kvg->node);
 257                         kvm_arch_end_assignment(dev->kvm);
 258 #ifdef CONFIG_SPAPR_TCE_IOMMU
 259                         kvm_spapr_tce_release_vfio_group(dev->kvm,
 260                                                          kvg->vfio_group);
 261 #endif
 262                         kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 263                         kvm_vfio_group_put_external_user(kvg->vfio_group);
 264                         kfree(kvg);
 265                         ret = 0;
 266                         break;
 267                 }
 268
 269                 mutex_unlock(&kv->lock);
 270
 271                 fdput(f);
 272
 273                 kvm_vfio_update_coherency(dev);
 274
 275                 return ret;
 276
 277 #ifdef CONFIG_SPAPR_TCE_IOMMU
 278         case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: {
 279                 struct kvm_vfio_spapr_tce param;
 280                 struct kvm_vfio *kv = dev->private;
 281                 struct vfio_group *vfio_group;
 282                 struct kvm_vfio_group *kvg;
 283                 struct fd f;
 284                 struct iommu_group *grp;
 285
 286                 if (copy_from_user(&param, (void __user *)arg,
 287                                 sizeof(struct kvm_vfio_spapr_tce)))
 288                         return -EFAULT;
 289
 290                 f = fdget(param.groupfd);
 291                 if (!f.file)
 292                         return -EBADF;
 293
 294                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 295                 fdput(f);
 296
 297                 if (IS_ERR(vfio_group))
 298                         return PTR_ERR(vfio_group);
 299
 300                 grp = kvm_vfio_group_get_iommu_group(vfio_group);
 301                 if (WARN_ON_ONCE(!grp)) {
 302                         kvm_vfio_group_put_external_user(vfio_group);
 303                         return -EIO;
 304                 }
 305
 306                 ret = -ENOENT;
 307
 308                 mutex_lock(&kv->lock);
 309
 310                 list_for_each_entry(kvg, &kv->group_list, node) {
 311                         if (kvg->vfio_group != vfio_group)
 312                                 continue;
 313
 314                         ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
 315                                         param.tablefd, grp);
 316                         break;
 317                 }
 318
 319                 mutex_unlock(&kv->lock);
 320
 321                 iommu_group_put(grp);
 322                 kvm_vfio_group_put_external_user(vfio_group);
 323
 324                 return ret;
 325         }
 326 #endif /* CONFIG_SPAPR_TCE_IOMMU */
 327         }
 328
 329         return -ENXIO;
 330 }
 331
 332 static int kvm_vfio_set_attr(struct kvm_device *dev,
 333                              struct kvm_device_attr *attr)
 334 {
 335         switch (attr->group) {
 336         case KVM_DEV_VFIO_GROUP:
 337                 return kvm_vfio_set_group(dev, attr->attr, attr->addr);
 338         }
 339
 340         return -ENXIO;
 341 }
 342
 343 static int kvm_vfio_has_attr(struct kvm_device *dev,
 344                              struct kvm_device_attr *attr)
 345 {
 346         switch (attr->group) {
 347         case KVM_DEV_VFIO_GROUP:
 348                 switch (attr->attr) {
 349                 case KVM_DEV_VFIO_GROUP_ADD:
 350                 case KVM_DEV_VFIO_GROUP_DEL:
 351 #ifdef CONFIG_SPAPR_TCE_IOMMU
 352                 case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
 353 #endif
 354                         return 0;
 355                 }
 356
 357                 break;
 358         }
 359
 360         return -ENXIO;
 361 }
 362
 363 static void kvm_vfio_destroy(struct kvm_device *dev)
 364 {
 365         struct kvm_vfio *kv = dev->private;
 366         struct kvm_vfio_group *kvg, *tmp;
 367
 368         list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
 369 #ifdef CONFIG_SPAPR_TCE_IOMMU
 370                 kvm_spapr_tce_release_vfio_group(dev->kvm, kvg->vfio_group);
 371 #endif
 372                 kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 373                 kvm_vfio_group_put_external_user(kvg->vfio_group);
 374                 list_del(&kvg->node);
 375                 kfree(kvg);
 376                 kvm_arch_end_assignment(dev->kvm);
 377         }
 378
 379         kvm_vfio_update_coherency(dev);
 380
 381         kfree(kv);
 382         kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
 383 }
 384
 385 static int kvm_vfio_create(struct kvm_device *dev, u32 type);
 386
 387 static struct kvm_device_ops kvm_vfio_ops = {
 388         .name = "kvm-vfio",
 389         .create = kvm_vfio_create,
 390         .destroy = kvm_vfio_destroy,
 391         .set_attr = kvm_vfio_set_attr,
 392         .has_attr = kvm_vfio_has_attr,
 393 };
 394
 395 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 396 {
 397         struct kvm_device *tmp;
 398         struct kvm_vfio *kv;
 399
 400         /* Only one VFIO "device" per VM */
 401         list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
 402                 if (tmp->ops == &kvm_vfio_ops)
 403                         return -EBUSY;
 404
 405         kv = kzalloc(sizeof(*kv), GFP_KERNEL_ACCOUNT);
 406         if (!kv)
 407                 return -ENOMEM;
 408
 409         INIT_LIST_HEAD(&kv->group_list);
 410         mutex_init(&kv->lock);
 411
 412         dev->private = kv;
 413
 414         return 0;
 415 }
 416
 417 int kvm_vfio_ops_init(void)
 418 {
 419         return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
 420 }
 421
 422 void kvm_vfio_ops_exit(void)
 423 {
 424         kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
 425 }