virt/kvm/vfio.c

   1 /*
   2  * VFIO-KVM bridge pseudo device
   3  *
   4  * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
   5  *     Author: Alex Williamson <alex.williamson@redhat.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/errno.h>
  13 #include <linux/file.h>
  14 #include <linux/kvm_host.h>
  15 #include <linux/list.h>
  16 #include <linux/module.h>
  17 #include <linux/mutex.h>
  18 #include <linux/slab.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/vfio.h>
  21 #include "vfio.h"
  22
  23 struct kvm_vfio_group {
  24         struct list_head node;
  25         struct vfio_group *vfio_group;
  26 };
  27
  28 struct kvm_vfio {
  29         struct list_head group_list;
  30         struct mutex lock;
  31         bool noncoherent;
  32 };
  33
  34 static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
  35 {
  36         struct vfio_group *vfio_group;
  37         struct vfio_group *(*fn)(struct file *);
  38
  39         fn = symbol_get(vfio_group_get_external_user);
  40         if (!fn)
  41                 return ERR_PTR(-EINVAL);
  42
  43         vfio_group = fn(filep);
  44
  45         symbol_put(vfio_group_get_external_user);
  46
  47         return vfio_group;
  48 }
  49
  50 static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
  51 {
  52         void (*fn)(struct vfio_group *);
  53
  54         fn = symbol_get(vfio_group_put_external_user);
  55         if (!fn)
  56                 return;
  57
  58         fn(vfio_group);
  59
  60         symbol_put(vfio_group_put_external_user);
  61 }
  62
  63 static void kvm_vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
  64 {
  65         void (*fn)(struct vfio_group *, struct kvm *);
  66
  67         fn = symbol_get(vfio_group_set_kvm);
  68         if (!fn)
  69                 return;
  70
  71         fn(group, kvm);
  72
  73         symbol_put(vfio_group_set_kvm);
  74 }
  75
  76 static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
  77 {
  78         long (*fn)(struct vfio_group *, unsigned long);
  79         long ret;
  80
  81         fn = symbol_get(vfio_external_check_extension);
  82         if (!fn)
  83                 return false;
  84
  85         ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
  86
  87         symbol_put(vfio_external_check_extension);
  88
  89         return ret > 0;
  90 }
  91
  92 /*
  93  * Groups can use the same or different IOMMU domains.  If the same then
  94  * adding a new group may change the coherency of groups we've previously
  95  * been told about.  We don't want to care about any of that so we retest
  96  * each group and bail as soon as we find one that's noncoherent.  This
  97  * means we only ever [un]register_noncoherent_dma once for the whole device.
  98  */
  99 static void kvm_vfio_update_coherency(struct kvm_device *dev)
 100 {
 101         struct kvm_vfio *kv = dev->private;
 102         bool noncoherent = false;
 103         struct kvm_vfio_group *kvg;
 104
 105         mutex_lock(&kv->lock);
 106
 107         list_for_each_entry(kvg, &kv->group_list, node) {
 108                 if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
 109                         noncoherent = true;
 110                         break;
 111                 }
 112         }
 113
 114         if (noncoherent != kv->noncoherent) {
 115                 kv->noncoherent = noncoherent;
 116
 117                 if (kv->noncoherent)
 118                         kvm_arch_register_noncoherent_dma(dev->kvm);
 119                 else
 120                         kvm_arch_unregister_noncoherent_dma(dev->kvm);
 121         }
 122
 123         mutex_unlock(&kv->lock);
 124 }
 125
 126 static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 127 {
 128         struct kvm_vfio *kv = dev->private;
 129         struct vfio_group *vfio_group;
 130         struct kvm_vfio_group *kvg;
 131         int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
 132         struct fd f;
 133         int32_t fd;
 134         int ret;
 135
 136         switch (attr) {
 137         case KVM_DEV_VFIO_GROUP_ADD:
 138                 if (get_user(fd, argp))
 139                         return -EFAULT;
 140
 141                 f = fdget(fd);
 142                 if (!f.file)
 143                         return -EBADF;
 144
 145                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 146                 fdput(f);
 147
 148                 if (IS_ERR(vfio_group))
 149                         return PTR_ERR(vfio_group);
 150
 151                 mutex_lock(&kv->lock);
 152
 153                 list_for_each_entry(kvg, &kv->group_list, node) {
 154                         if (kvg->vfio_group == vfio_group) {
 155                                 mutex_unlock(&kv->lock);
 156                                 kvm_vfio_group_put_external_user(vfio_group);
 157                                 return -EEXIST;
 158                         }
 159                 }
 160
 161                 kvg = kzalloc(sizeof(*kvg), GFP_KERNEL);
 162                 if (!kvg) {
 163                         mutex_unlock(&kv->lock);
 164                         kvm_vfio_group_put_external_user(vfio_group);
 165                         return -ENOMEM;
 166                 }
 167
 168                 list_add_tail(&kvg->node, &kv->group_list);
 169                 kvg->vfio_group = vfio_group;
 170
 171                 kvm_arch_start_assignment(dev->kvm);
 172
 173                 mutex_unlock(&kv->lock);
 174
 175                 kvm_vfio_group_set_kvm(vfio_group, dev->kvm);
 176
 177                 kvm_vfio_update_coherency(dev);
 178
 179                 return 0;
 180
 181         case KVM_DEV_VFIO_GROUP_DEL:
 182                 if (get_user(fd, argp))
 183                         return -EFAULT;
 184
 185                 f = fdget(fd);
 186                 if (!f.file)
 187                         return -EBADF;
 188
 189                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 190                 fdput(f);
 191
 192                 if (IS_ERR(vfio_group))
 193                         return PTR_ERR(vfio_group);
 194
 195                 ret = -ENOENT;
 196
 197                 mutex_lock(&kv->lock);
 198
 199                 list_for_each_entry(kvg, &kv->group_list, node) {
 200                         if (kvg->vfio_group != vfio_group)
 201                                 continue;
 202
 203                         list_del(&kvg->node);
 204                         kvm_vfio_group_put_external_user(kvg->vfio_group);
 205                         kfree(kvg);
 206                         ret = 0;
 207                         break;
 208                 }
 209
 210                 kvm_arch_end_assignment(dev->kvm);
 211
 212                 mutex_unlock(&kv->lock);
 213
 214                 kvm_vfio_group_set_kvm(vfio_group, NULL);
 215
 216                 kvm_vfio_group_put_external_user(vfio_group);
 217
 218                 kvm_vfio_update_coherency(dev);
 219
 220                 return ret;
 221         }
 222
 223         return -ENXIO;
 224 }
 225
 226 static int kvm_vfio_set_attr(struct kvm_device *dev,
 227                              struct kvm_device_attr *attr)
 228 {
 229         switch (attr->group) {
 230         case KVM_DEV_VFIO_GROUP:
 231                 return kvm_vfio_set_group(dev, attr->attr, attr->addr);
 232         }
 233
 234         return -ENXIO;
 235 }
 236
 237 static int kvm_vfio_has_attr(struct kvm_device *dev,
 238                              struct kvm_device_attr *attr)
 239 {
 240         switch (attr->group) {
 241         case KVM_DEV_VFIO_GROUP:
 242                 switch (attr->attr) {
 243                 case KVM_DEV_VFIO_GROUP_ADD:
 244                 case KVM_DEV_VFIO_GROUP_DEL:
 245                         return 0;
 246                 }
 247
 248                 break;
 249         }
 250
 251         return -ENXIO;
 252 }
 253
 254 static void kvm_vfio_destroy(struct kvm_device *dev)
 255 {
 256         struct kvm_vfio *kv = dev->private;
 257         struct kvm_vfio_group *kvg, *tmp;
 258
 259         list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
 260                 kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 261                 kvm_vfio_group_put_external_user(kvg->vfio_group);
 262                 list_del(&kvg->node);
 263                 kfree(kvg);
 264                 kvm_arch_end_assignment(dev->kvm);
 265         }
 266
 267         kvm_vfio_update_coherency(dev);
 268
 269         kfree(kv);
 270         kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
 271 }
 272
 273 static int kvm_vfio_create(struct kvm_device *dev, u32 type);
 274
 275 static struct kvm_device_ops kvm_vfio_ops = {
 276         .name = "kvm-vfio",
 277         .create = kvm_vfio_create,
 278         .destroy = kvm_vfio_destroy,
 279         .set_attr = kvm_vfio_set_attr,
 280         .has_attr = kvm_vfio_has_attr,
 281 };
 282
 283 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 284 {
 285         struct kvm_device *tmp;
 286         struct kvm_vfio *kv;
 287
 288         /* Only one VFIO "device" per VM */
 289         list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
 290                 if (tmp->ops == &kvm_vfio_ops)
 291                         return -EBUSY;
 292
 293         kv = kzalloc(sizeof(*kv), GFP_KERNEL);
 294         if (!kv)
 295                 return -ENOMEM;
 296
 297         INIT_LIST_HEAD(&kv->group_list);
 298         mutex_init(&kv->lock);
 299
 300         dev->private = kv;
 301
 302         return 0;
 303 }
 304
 305 int kvm_vfio_ops_init(void)
 306 {
 307         return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
 308 }
 309
 310 void kvm_vfio_ops_exit(void)
 311 {
 312         kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
 313 }