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 bool kvm_vfio_external_group_match_file(struct vfio_group *group,
  51                                                struct file *filep)
  52 {
  53         bool ret, (*fn)(struct vfio_group *, struct file *);
  54
  55         fn = symbol_get(vfio_external_group_match_file);
  56         if (!fn)
  57                 return false;
  58
  59         ret = fn(group, filep);
  60
  61         symbol_put(vfio_external_group_match_file);
  62
  63         return ret;
  64 }
  65
  66 static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
  67 {
  68         void (*fn)(struct vfio_group *);
  69
  70         fn = symbol_get(vfio_group_put_external_user);
  71         if (!fn)
  72                 return;
  73
  74         fn(vfio_group);
  75
  76         symbol_put(vfio_group_put_external_user);
  77 }
  78
  79 static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
  80 {
  81         long (*fn)(struct vfio_group *, unsigned long);
  82         long ret;
  83
  84         fn = symbol_get(vfio_external_check_extension);
  85         if (!fn)
  86                 return false;
  87
  88         ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
  89
  90         symbol_put(vfio_external_check_extension);
  91
  92         return ret > 0;
  93 }
  94
  95 /*
  96  * Groups can use the same or different IOMMU domains.  If the same then
  97  * adding a new group may change the coherency of groups we've previously
  98  * been told about.  We don't want to care about any of that so we retest
  99  * each group and bail as soon as we find one that's noncoherent.  This
 100  * means we only ever [un]register_noncoherent_dma once for the whole device.
 101  */
 102 static void kvm_vfio_update_coherency(struct kvm_device *dev)
 103 {
 104         struct kvm_vfio *kv = dev->private;
 105         bool noncoherent = false;
 106         struct kvm_vfio_group *kvg;
 107
 108         mutex_lock(&kv->lock);
 109
 110         list_for_each_entry(kvg, &kv->group_list, node) {
 111                 if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
 112                         noncoherent = true;
 113                         break;
 114                 }
 115         }
 116
 117         if (noncoherent != kv->noncoherent) {
 118                 kv->noncoherent = noncoherent;
 119
 120                 if (kv->noncoherent)
 121                         kvm_arch_register_noncoherent_dma(dev->kvm);
 122                 else
 123                         kvm_arch_unregister_noncoherent_dma(dev->kvm);
 124         }
 125
 126         mutex_unlock(&kv->lock);
 127 }
 128
 129 static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 130 {
 131         struct kvm_vfio *kv = dev->private;
 132         struct vfio_group *vfio_group;
 133         struct kvm_vfio_group *kvg;
 134         int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
 135         struct fd f;
 136         int32_t fd;
 137         int ret;
 138
 139         switch (attr) {
 140         case KVM_DEV_VFIO_GROUP_ADD:
 141                 if (get_user(fd, argp))
 142                         return -EFAULT;
 143
 144                 f = fdget(fd);
 145                 if (!f.file)
 146                         return -EBADF;
 147
 148                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 149                 fdput(f);
 150
 151                 if (IS_ERR(vfio_group))
 152                         return PTR_ERR(vfio_group);
 153
 154                 mutex_lock(&kv->lock);
 155
 156                 list_for_each_entry(kvg, &kv->group_list, node) {
 157                         if (kvg->vfio_group == vfio_group) {
 158                                 mutex_unlock(&kv->lock);
 159                                 kvm_vfio_group_put_external_user(vfio_group);
 160                                 return -EEXIST;
 161                         }
 162                 }
 163
 164                 kvg = kzalloc(sizeof(*kvg), GFP_KERNEL);
 165                 if (!kvg) {
 166                         mutex_unlock(&kv->lock);
 167                         kvm_vfio_group_put_external_user(vfio_group);
 168                         return -ENOMEM;
 169                 }
 170
 171                 list_add_tail(&kvg->node, &kv->group_list);
 172                 kvg->vfio_group = vfio_group;
 173
 174                 kvm_arch_start_assignment(dev->kvm);
 175
 176                 mutex_unlock(&kv->lock);
 177
 178                 kvm_vfio_update_coherency(dev);
 179
 180                 return 0;
 181
 182         case KVM_DEV_VFIO_GROUP_DEL:
 183                 if (get_user(fd, argp))
 184                         return -EFAULT;
 185
 186                 f = fdget(fd);
 187                 if (!f.file)
 188                         return -EBADF;
 189
 190                 ret = -ENOENT;
 191
 192                 mutex_lock(&kv->lock);
 193
 194                 list_for_each_entry(kvg, &kv->group_list, node) {
 195                         if (!kvm_vfio_external_group_match_file(kvg->vfio_group,
 196                                                                 f.file))
 197                                 continue;
 198
 199                         list_del(&kvg->node);
 200                         kvm_vfio_group_put_external_user(kvg->vfio_group);
 201                         kfree(kvg);
 202                         ret = 0;
 203                         break;
 204                 }
 205
 206                 kvm_arch_end_assignment(dev->kvm);
 207
 208                 mutex_unlock(&kv->lock);
 209
 210                 fdput(f);
 211
 212                 kvm_vfio_update_coherency(dev);
 213
 214                 return ret;
 215         }
 216
 217         return -ENXIO;
 218 }
 219
 220 static int kvm_vfio_set_attr(struct kvm_device *dev,
 221                              struct kvm_device_attr *attr)
 222 {
 223         switch (attr->group) {
 224         case KVM_DEV_VFIO_GROUP:
 225                 return kvm_vfio_set_group(dev, attr->attr, attr->addr);
 226         }
 227
 228         return -ENXIO;
 229 }
 230
 231 static int kvm_vfio_has_attr(struct kvm_device *dev,
 232                              struct kvm_device_attr *attr)
 233 {
 234         switch (attr->group) {
 235         case KVM_DEV_VFIO_GROUP:
 236                 switch (attr->attr) {
 237                 case KVM_DEV_VFIO_GROUP_ADD:
 238                 case KVM_DEV_VFIO_GROUP_DEL:
 239                         return 0;
 240                 }
 241
 242                 break;
 243         }
 244
 245         return -ENXIO;
 246 }
 247
 248 static void kvm_vfio_destroy(struct kvm_device *dev)
 249 {
 250         struct kvm_vfio *kv = dev->private;
 251         struct kvm_vfio_group *kvg, *tmp;
 252
 253         list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
 254                 kvm_vfio_group_put_external_user(kvg->vfio_group);
 255                 list_del(&kvg->node);
 256                 kfree(kvg);
 257                 kvm_arch_end_assignment(dev->kvm);
 258         }
 259
 260         kvm_vfio_update_coherency(dev);
 261
 262         kfree(kv);
 263         kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
 264 }
 265
 266 static int kvm_vfio_create(struct kvm_device *dev, u32 type);
 267
 268 static struct kvm_device_ops kvm_vfio_ops = {
 269         .name = "kvm-vfio",
 270         .create = kvm_vfio_create,
 271         .destroy = kvm_vfio_destroy,
 272         .set_attr = kvm_vfio_set_attr,
 273         .has_attr = kvm_vfio_has_attr,
 274 };
 275
 276 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 277 {
 278         struct kvm_device *tmp;
 279         struct kvm_vfio *kv;
 280
 281         /* Only one VFIO "device" per VM */
 282         list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
 283                 if (tmp->ops == &kvm_vfio_ops)
 284                         return -EBUSY;
 285
 286         kv = kzalloc(sizeof(*kv), GFP_KERNEL);
 287         if (!kv)
 288                 return -ENOMEM;
 289
 290         INIT_LIST_HEAD(&kv->group_list);
 291         mutex_init(&kv->lock);
 292
 293         dev->private = kv;
 294
 295         return 0;
 296 }
 297
 298 int kvm_vfio_ops_init(void)
 299 {
 300         return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
 301 }
 302
 303 void kvm_vfio_ops_exit(void)
 304 {
 305         kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
 306 }