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_file {
  25         struct list_head node;
  26         struct file *file;
  27 #ifdef CONFIG_SPAPR_TCE_IOMMU
  28         struct iommu_group *iommu_group;
  29 #endif
  30 };
  31
  32 struct kvm_vfio {
  33         struct list_head file_list;
  34         struct mutex lock;
  35         bool noncoherent;
  36 };
  37
  38 static void kvm_vfio_file_set_kvm(struct file *file, struct kvm *kvm)
  39 {
  40         void (*fn)(struct file *file, struct kvm *kvm);
  41
  42         fn = symbol_get(vfio_file_set_kvm);
  43         if (!fn)
  44                 return;
  45
  46         fn(file, kvm);
  47
  48         symbol_put(vfio_file_set_kvm);
  49 }
  50
  51 static bool kvm_vfio_file_enforced_coherent(struct file *file)
  52 {
  53         bool (*fn)(struct file *file);
  54         bool ret;
  55
  56         fn = symbol_get(vfio_file_enforced_coherent);
  57         if (!fn)
  58                 return false;
  59
  60         ret = fn(file);
  61
  62         symbol_put(vfio_file_enforced_coherent);
  63
  64         return ret;
  65 }
  66
  67 static bool kvm_vfio_file_is_valid(struct file *file)
  68 {
  69         bool (*fn)(struct file *file);
  70         bool ret;
  71
  72         fn = symbol_get(vfio_file_is_valid);
  73         if (!fn)
  74                 return false;
  75
  76         ret = fn(file);
  77
  78         symbol_put(vfio_file_is_valid);
  79
  80         return ret;
  81 }
  82
  83 #ifdef CONFIG_SPAPR_TCE_IOMMU
  84 static struct iommu_group *kvm_vfio_file_iommu_group(struct file *file)
  85 {
  86         struct iommu_group *(*fn)(struct file *file);
  87         struct iommu_group *ret;
  88
  89         fn = symbol_get(vfio_file_iommu_group);
  90         if (!fn)
  91                 return NULL;
  92
  93         ret = fn(file);
  94
  95         symbol_put(vfio_file_iommu_group);
  96
  97         return ret;
  98 }
  99
 100 static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
 101                                              struct kvm_vfio_file *kvf)
 102 {
 103         if (WARN_ON_ONCE(!kvf->iommu_group))
 104                 return;
 105
 106         kvm_spapr_tce_release_iommu_group(kvm, kvf->iommu_group);
 107         iommu_group_put(kvf->iommu_group);
 108         kvf->iommu_group = NULL;
 109 }
 110 #endif
 111
 112 /*
 113  * Groups/devices can use the same or different IOMMU domains. If the same
 114  * then adding a new group/device may change the coherency of groups/devices
 115  * we've previously been told about. We don't want to care about any of
 116  * that so we retest each group/device and bail as soon as we find one that's
 117  * noncoherent.  This means we only ever [un]register_noncoherent_dma once
 118  * for the whole device.
 119  */
 120 static void kvm_vfio_update_coherency(struct kvm_device *dev)
 121 {
 122         struct kvm_vfio *kv = dev->private;
 123         bool noncoherent = false;
 124         struct kvm_vfio_file *kvf;
 125
 126         list_for_each_entry(kvf, &kv->file_list, node) {
 127                 if (!kvm_vfio_file_enforced_coherent(kvf->file)) {
 128                         noncoherent = true;
 129                         break;
 130                 }
 131         }
 132
 133         if (noncoherent != kv->noncoherent) {
 134                 kv->noncoherent = noncoherent;
 135
 136                 if (kv->noncoherent)
 137                         kvm_arch_register_noncoherent_dma(dev->kvm);
 138                 else
 139                         kvm_arch_unregister_noncoherent_dma(dev->kvm);
 140         }
 141 }
 142
 143 static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd)
 144 {
 145         struct kvm_vfio *kv = dev->private;
 146         struct kvm_vfio_file *kvf;
 147         struct file *filp;
 148         int ret = 0;
 149
 150         filp = fget(fd);
 151         if (!filp)
 152                 return -EBADF;
 153
 154         /* Ensure the FD is a vfio FD. */
 155         if (!kvm_vfio_file_is_valid(filp)) {
 156                 ret = -EINVAL;
 157                 goto out_fput;
 158         }
 159
 160         mutex_lock(&kv->lock);
 161
 162         list_for_each_entry(kvf, &kv->file_list, node) {
 163                 if (kvf->file == filp) {
 164                         ret = -EEXIST;
 165                         goto out_unlock;
 166                 }
 167         }
 168
 169         kvf = kzalloc(sizeof(*kvf), GFP_KERNEL_ACCOUNT);
 170         if (!kvf) {
 171                 ret = -ENOMEM;
 172                 goto out_unlock;
 173         }
 174
 175         kvf->file = get_file(filp);
 176         list_add_tail(&kvf->node, &kv->file_list);
 177
 178         kvm_arch_start_assignment(dev->kvm);
 179         kvm_vfio_file_set_kvm(kvf->file, dev->kvm);
 180         kvm_vfio_update_coherency(dev);
 181
 182 out_unlock:
 183         mutex_unlock(&kv->lock);
 184 out_fput:
 185         fput(filp);
 186         return ret;
 187 }
 188
 189 static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
 190 {
 191         struct kvm_vfio *kv = dev->private;
 192         struct kvm_vfio_file *kvf;
 193         CLASS(fd, f)(fd);
 194         int ret;
 195
 196         if (fd_empty(f))
 197                 return -EBADF;
 198
 199         ret = -ENOENT;
 200
 201         mutex_lock(&kv->lock);
 202
 203         list_for_each_entry(kvf, &kv->file_list, node) {
 204                 if (kvf->file != fd_file(f))
 205                         continue;
 206
 207                 list_del(&kvf->node);
 208                 kvm_arch_end_assignment(dev->kvm);
 209 #ifdef CONFIG_SPAPR_TCE_IOMMU
 210                 kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
 211 #endif
 212                 kvm_vfio_file_set_kvm(kvf->file, NULL);
 213                 fput(kvf->file);
 214                 kfree(kvf);
 215                 ret = 0;
 216                 break;
 217         }
 218
 219         kvm_vfio_update_coherency(dev);
 220
 221         mutex_unlock(&kv->lock);
 222         return ret;
 223 }
 224
 225 #ifdef CONFIG_SPAPR_TCE_IOMMU
 226 static int kvm_vfio_file_set_spapr_tce(struct kvm_device *dev,
 227                                        void __user *arg)
 228 {
 229         struct kvm_vfio_spapr_tce param;
 230         struct kvm_vfio *kv = dev->private;
 231         struct kvm_vfio_file *kvf;
 232         int ret;
 233
 234         if (copy_from_user(&param, arg, sizeof(struct kvm_vfio_spapr_tce)))
 235                 return -EFAULT;
 236
 237         CLASS(fd, f)(param.groupfd);
 238         if (fd_empty(f))
 239                 return -EBADF;
 240
 241         ret = -ENOENT;
 242
 243         mutex_lock(&kv->lock);
 244
 245         list_for_each_entry(kvf, &kv->file_list, node) {
 246                 if (kvf->file != fd_file(f))
 247                         continue;
 248
 249                 if (!kvf->iommu_group) {
 250                         kvf->iommu_group = kvm_vfio_file_iommu_group(kvf->file);
 251                         if (WARN_ON_ONCE(!kvf->iommu_group)) {
 252                                 ret = -EIO;
 253                                 goto err_fdput;
 254                         }
 255                 }
 256
 257                 ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
 258                                                        kvf->iommu_group);
 259                 break;
 260         }
 261
 262 err_fdput:
 263         mutex_unlock(&kv->lock);
 264         return ret;
 265 }
 266 #endif
 267
 268 static int kvm_vfio_set_file(struct kvm_device *dev, long attr,
 269                              void __user *arg)
 270 {
 271         int32_t __user *argp = arg;
 272         int32_t fd;
 273
 274         switch (attr) {
 275         case KVM_DEV_VFIO_FILE_ADD:
 276                 if (get_user(fd, argp))
 277                         return -EFAULT;
 278                 return kvm_vfio_file_add(dev, fd);
 279
 280         case KVM_DEV_VFIO_FILE_DEL:
 281                 if (get_user(fd, argp))
 282                         return -EFAULT;
 283                 return kvm_vfio_file_del(dev, fd);
 284
 285 #ifdef CONFIG_SPAPR_TCE_IOMMU
 286         case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
 287                 return kvm_vfio_file_set_spapr_tce(dev, arg);
 288 #endif
 289         }
 290
 291         return -ENXIO;
 292 }
 293
 294 static int kvm_vfio_set_attr(struct kvm_device *dev,
 295                              struct kvm_device_attr *attr)
 296 {
 297         switch (attr->group) {
 298         case KVM_DEV_VFIO_FILE:
 299                 return kvm_vfio_set_file(dev, attr->attr,
 300                                          u64_to_user_ptr(attr->addr));
 301         }
 302
 303         return -ENXIO;
 304 }
 305
 306 static int kvm_vfio_has_attr(struct kvm_device *dev,
 307                              struct kvm_device_attr *attr)
 308 {
 309         switch (attr->group) {
 310         case KVM_DEV_VFIO_FILE:
 311                 switch (attr->attr) {
 312                 case KVM_DEV_VFIO_FILE_ADD:
 313                 case KVM_DEV_VFIO_FILE_DEL:
 314 #ifdef CONFIG_SPAPR_TCE_IOMMU
 315                 case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
 316 #endif
 317                         return 0;
 318                 }
 319
 320                 break;
 321         }
 322
 323         return -ENXIO;
 324 }
 325
 326 static void kvm_vfio_release(struct kvm_device *dev)
 327 {
 328         struct kvm_vfio *kv = dev->private;
 329         struct kvm_vfio_file *kvf, *tmp;
 330
 331         list_for_each_entry_safe(kvf, tmp, &kv->file_list, node) {
 332 #ifdef CONFIG_SPAPR_TCE_IOMMU
 333                 kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
 334 #endif
 335                 kvm_vfio_file_set_kvm(kvf->file, NULL);
 336                 fput(kvf->file);
 337                 list_del(&kvf->node);
 338                 kfree(kvf);
 339                 kvm_arch_end_assignment(dev->kvm);
 340         }
 341
 342         kvm_vfio_update_coherency(dev);
 343
 344         kfree(kv);
 345         kfree(dev); /* alloc by kvm_ioctl_create_device, free by .release */
 346 }
 347
 348 static int kvm_vfio_create(struct kvm_device *dev, u32 type);
 349
 350 static const struct kvm_device_ops kvm_vfio_ops = {
 351         .name = "kvm-vfio",
 352         .create = kvm_vfio_create,
 353         .release = kvm_vfio_release,
 354         .set_attr = kvm_vfio_set_attr,
 355         .has_attr = kvm_vfio_has_attr,
 356 };
 357
 358 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 359 {
 360         struct kvm_device *tmp;
 361         struct kvm_vfio *kv;
 362
 363         lockdep_assert_held(&dev->kvm->lock);
 364
 365         /* Only one VFIO "device" per VM */
 366         list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
 367                 if (tmp->ops == &kvm_vfio_ops)
 368                         return -EBUSY;
 369
 370         kv = kzalloc(sizeof(*kv), GFP_KERNEL_ACCOUNT);
 371         if (!kv)
 372                 return -ENOMEM;
 373
 374         INIT_LIST_HEAD(&kv->file_list);
 375         mutex_init(&kv->lock);
 376
 377         dev->private = kv;
 378
 379         return 0;
 380 }
 381
 382 int kvm_vfio_ops_init(void)
 383 {
 384         return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
 385 }
 386
 387 void kvm_vfio_ops_exit(void)
 388 {
 389         kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
 390 }