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 bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
  64 {
  65         long (*fn)(struct vfio_group *, unsigned long);
  66         long ret;
  67
  68         fn = symbol_get(vfio_external_check_extension);
  69         if (!fn)
  70                 return false;
  71
  72         ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
  73
  74         symbol_put(vfio_external_check_extension);
  75
  76         return ret > 0;
  77 }
  78
  79 /*
  80  * Groups can use the same or different IOMMU domains.  If the same then
  81  * adding a new group may change the coherency of groups we've previously
  82  * been told about.  We don't want to care about any of that so we retest
  83  * each group and bail as soon as we find one that's noncoherent.  This
  84  * means we only ever [un]register_noncoherent_dma once for the whole device.
  85  */
  86 static void kvm_vfio_update_coherency(struct kvm_device *dev)
  87 {
  88         struct kvm_vfio *kv = dev->private;
  89         bool noncoherent = false;
  90         struct kvm_vfio_group *kvg;
  91
  92         mutex_lock(&kv->lock);
  93
  94         list_for_each_entry(kvg, &kv->group_list, node) {
  95                 if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
  96                         noncoherent = true;
  97                         break;
  98                 }
  99         }
 100
 101         if (noncoherent != kv->noncoherent) {
 102                 kv->noncoherent = noncoherent;
 103
 104                 if (kv->noncoherent)
 105                         kvm_arch_register_noncoherent_dma(dev->kvm);
 106                 else
 107                         kvm_arch_unregister_noncoherent_dma(dev->kvm);
 108         }
 109
 110         mutex_unlock(&kv->lock);
 111 }
 112
 113 static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 114 {
 115         struct kvm_vfio *kv = dev->private;
 116         struct vfio_group *vfio_group;
 117         struct kvm_vfio_group *kvg;
 118         int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
 119         struct fd f;
 120         int32_t fd;
 121         int ret;
 122
 123         switch (attr) {
 124         case KVM_DEV_VFIO_GROUP_ADD:
 125                 if (get_user(fd, argp))
 126                         return -EFAULT;
 127
 128                 f = fdget(fd);
 129                 if (!f.file)
 130                         return -EBADF;
 131
 132                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 133                 fdput(f);
 134
 135                 if (IS_ERR(vfio_group))
 136                         return PTR_ERR(vfio_group);
 137
 138                 mutex_lock(&kv->lock);
 139
 140                 list_for_each_entry(kvg, &kv->group_list, node) {
 141                         if (kvg->vfio_group == vfio_group) {
 142                                 mutex_unlock(&kv->lock);
 143                                 kvm_vfio_group_put_external_user(vfio_group);
 144                                 return -EEXIST;
 145                         }
 146                 }
 147
 148                 kvg = kzalloc(sizeof(*kvg), GFP_KERNEL);
 149                 if (!kvg) {
 150                         mutex_unlock(&kv->lock);
 151                         kvm_vfio_group_put_external_user(vfio_group);
 152                         return -ENOMEM;
 153                 }
 154
 155                 list_add_tail(&kvg->node, &kv->group_list);
 156                 kvg->vfio_group = vfio_group;
 157
 158                 mutex_unlock(&kv->lock);
 159
 160                 kvm_vfio_update_coherency(dev);
 161
 162                 return 0;
 163
 164         case KVM_DEV_VFIO_GROUP_DEL:
 165                 if (get_user(fd, argp))
 166                         return -EFAULT;
 167
 168                 f = fdget(fd);
 169                 if (!f.file)
 170                         return -EBADF;
 171
 172                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 173                 fdput(f);
 174
 175                 if (IS_ERR(vfio_group))
 176                         return PTR_ERR(vfio_group);
 177
 178                 ret = -ENOENT;
 179
 180                 mutex_lock(&kv->lock);
 181
 182                 list_for_each_entry(kvg, &kv->group_list, node) {
 183                         if (kvg->vfio_group != vfio_group)
 184                                 continue;
 185
 186                         list_del(&kvg->node);
 187                         kvm_vfio_group_put_external_user(kvg->vfio_group);
 188                         kfree(kvg);
 189                         ret = 0;
 190                         break;
 191                 }
 192
 193                 mutex_unlock(&kv->lock);
 194
 195                 kvm_vfio_group_put_external_user(vfio_group);
 196
 197                 kvm_vfio_update_coherency(dev);
 198
 199                 return ret;
 200         }
 201
 202         return -ENXIO;
 203 }
 204
 205 static int kvm_vfio_set_attr(struct kvm_device *dev,
 206                              struct kvm_device_attr *attr)
 207 {
 208         switch (attr->group) {
 209         case KVM_DEV_VFIO_GROUP:
 210                 return kvm_vfio_set_group(dev, attr->attr, attr->addr);
 211         }
 212
 213         return -ENXIO;
 214 }
 215
 216 static int kvm_vfio_has_attr(struct kvm_device *dev,
 217                              struct kvm_device_attr *attr)
 218 {
 219         switch (attr->group) {
 220         case KVM_DEV_VFIO_GROUP:
 221                 switch (attr->attr) {
 222                 case KVM_DEV_VFIO_GROUP_ADD:
 223                 case KVM_DEV_VFIO_GROUP_DEL:
 224                         return 0;
 225                 }
 226
 227                 break;
 228         }
 229
 230         return -ENXIO;
 231 }
 232
 233 static void kvm_vfio_destroy(struct kvm_device *dev)
 234 {
 235         struct kvm_vfio *kv = dev->private;
 236         struct kvm_vfio_group *kvg, *tmp;
 237
 238         list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
 239                 kvm_vfio_group_put_external_user(kvg->vfio_group);
 240                 list_del(&kvg->node);
 241                 kfree(kvg);
 242         }
 243
 244         kvm_vfio_update_coherency(dev);
 245
 246         kfree(kv);
 247         kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
 248 }
 249
 250 static int kvm_vfio_create(struct kvm_device *dev, u32 type);
 251
 252 static struct kvm_device_ops kvm_vfio_ops = {
 253         .name = "kvm-vfio",
 254         .create = kvm_vfio_create,
 255         .destroy = kvm_vfio_destroy,
 256         .set_attr = kvm_vfio_set_attr,
 257         .has_attr = kvm_vfio_has_attr,
 258 };
 259
 260 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 261 {
 262         struct kvm_device *tmp;
 263         struct kvm_vfio *kv;
 264
 265         /* Only one VFIO "device" per VM */
 266         list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
 267                 if (tmp->ops == &kvm_vfio_ops)
 268                         return -EBUSY;
 269
 270         kv = kzalloc(sizeof(*kv), GFP_KERNEL);
 271         if (!kv)
 272                 return -ENOMEM;
 273
 274         INIT_LIST_HEAD(&kv->group_list);
 275         mutex_init(&kv->lock);
 276
 277         dev->private = kv;
 278
 279         return 0;
 280 }
 281
 282 int kvm_vfio_ops_init(void)
 283 {
 284         return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
 285 }
 286
 287 void kvm_vfio_ops_exit(void)
 288 {
 289         kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
 290 }