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
  22 struct kvm_vfio_group {
  23         struct list_head node;
  24         struct vfio_group *vfio_group;
  25 };
  26
  27 struct kvm_vfio {
  28         struct list_head group_list;
  29         struct mutex lock;
  30         bool noncoherent;
  31 };
  32
  33 static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
  34 {
  35         struct vfio_group *vfio_group;
  36         struct vfio_group *(*fn)(struct file *);
  37
  38         fn = symbol_get(vfio_group_get_external_user);
  39         if (!fn)
  40                 return ERR_PTR(-EINVAL);
  41
  42         vfio_group = fn(filep);
  43
  44         symbol_put(vfio_group_get_external_user);
  45
  46         return vfio_group;
  47 }
  48
  49 static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
  50 {
  51         void (*fn)(struct vfio_group *);
  52
  53         fn = symbol_get(vfio_group_put_external_user);
  54         if (!fn)
  55                 return;
  56
  57         fn(vfio_group);
  58
  59         symbol_put(vfio_group_put_external_user);
  60 }
  61
  62 static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
  63 {
  64         long (*fn)(struct vfio_group *, unsigned long);
  65         long ret;
  66
  67         fn = symbol_get(vfio_external_check_extension);
  68         if (!fn)
  69                 return false;
  70
  71         ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
  72
  73         symbol_put(vfio_external_check_extension);
  74
  75         return ret > 0;
  76 }
  77
  78 /*
  79  * Groups can use the same or different IOMMU domains.  If the same then
  80  * adding a new group may change the coherency of groups we've previously
  81  * been told about.  We don't want to care about any of that so we retest
  82  * each group and bail as soon as we find one that's noncoherent.  This
  83  * means we only ever [un]register_noncoherent_dma once for the whole device.
  84  */
  85 static void kvm_vfio_update_coherency(struct kvm_device *dev)
  86 {
  87         struct kvm_vfio *kv = dev->private;
  88         bool noncoherent = false;
  89         struct kvm_vfio_group *kvg;
  90
  91         mutex_lock(&kv->lock);
  92
  93         list_for_each_entry(kvg, &kv->group_list, node) {
  94                 if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
  95                         noncoherent = true;
  96                         break;
  97                 }
  98         }
  99
 100         if (noncoherent != kv->noncoherent) {
 101                 kv->noncoherent = noncoherent;
 102
 103                 if (kv->noncoherent)
 104                         kvm_arch_register_noncoherent_dma(dev->kvm);
 105                 else
 106                         kvm_arch_unregister_noncoherent_dma(dev->kvm);
 107         }
 108
 109         mutex_unlock(&kv->lock);
 110 }
 111
 112 static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 113 {
 114         struct kvm_vfio *kv = dev->private;
 115         struct vfio_group *vfio_group;
 116         struct kvm_vfio_group *kvg;
 117         int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
 118         struct fd f;
 119         int32_t fd;
 120         int ret;
 121
 122         switch (attr) {
 123         case KVM_DEV_VFIO_GROUP_ADD:
 124                 if (get_user(fd, argp))
 125                         return -EFAULT;
 126
 127                 f = fdget(fd);
 128                 if (!f.file)
 129                         return -EBADF;
 130
 131                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 132                 fdput(f);
 133
 134                 if (IS_ERR(vfio_group))
 135                         return PTR_ERR(vfio_group);
 136
 137                 mutex_lock(&kv->lock);
 138
 139                 list_for_each_entry(kvg, &kv->group_list, node) {
 140                         if (kvg->vfio_group == vfio_group) {
 141                                 mutex_unlock(&kv->lock);
 142                                 kvm_vfio_group_put_external_user(vfio_group);
 143                                 return -EEXIST;
 144                         }
 145                 }
 146
 147                 kvg = kzalloc(sizeof(*kvg), GFP_KERNEL);
 148                 if (!kvg) {
 149                         mutex_unlock(&kv->lock);
 150                         kvm_vfio_group_put_external_user(vfio_group);
 151                         return -ENOMEM;
 152                 }
 153
 154                 list_add_tail(&kvg->node, &kv->group_list);
 155                 kvg->vfio_group = vfio_group;
 156
 157                 mutex_unlock(&kv->lock);
 158
 159                 kvm_vfio_update_coherency(dev);
 160
 161                 return 0;
 162
 163         case KVM_DEV_VFIO_GROUP_DEL:
 164                 if (get_user(fd, argp))
 165                         return -EFAULT;
 166
 167                 f = fdget(fd);
 168                 if (!f.file)
 169                         return -EBADF;
 170
 171                 vfio_group = kvm_vfio_group_get_external_user(f.file);
 172                 fdput(f);
 173
 174                 if (IS_ERR(vfio_group))
 175                         return PTR_ERR(vfio_group);
 176
 177                 ret = -ENOENT;
 178
 179                 mutex_lock(&kv->lock);
 180
 181                 list_for_each_entry(kvg, &kv->group_list, node) {
 182                         if (kvg->vfio_group != vfio_group)
 183                                 continue;
 184
 185                         list_del(&kvg->node);
 186                         kvm_vfio_group_put_external_user(kvg->vfio_group);
 187                         kfree(kvg);
 188                         ret = 0;
 189                         break;
 190                 }
 191
 192                 mutex_unlock(&kv->lock);
 193
 194                 kvm_vfio_group_put_external_user(vfio_group);
 195
 196                 kvm_vfio_update_coherency(dev);
 197
 198                 return ret;
 199         }
 200
 201         return -ENXIO;
 202 }
 203
 204 static int kvm_vfio_set_attr(struct kvm_device *dev,
 205                              struct kvm_device_attr *attr)
 206 {
 207         switch (attr->group) {
 208         case KVM_DEV_VFIO_GROUP:
 209                 return kvm_vfio_set_group(dev, attr->attr, attr->addr);
 210         }
 211
 212         return -ENXIO;
 213 }
 214
 215 static int kvm_vfio_has_attr(struct kvm_device *dev,
 216                              struct kvm_device_attr *attr)
 217 {
 218         switch (attr->group) {
 219         case KVM_DEV_VFIO_GROUP:
 220                 switch (attr->attr) {
 221                 case KVM_DEV_VFIO_GROUP_ADD:
 222                 case KVM_DEV_VFIO_GROUP_DEL:
 223                         return 0;
 224                 }
 225
 226                 break;
 227         }
 228
 229         return -ENXIO;
 230 }
 231
 232 static void kvm_vfio_destroy(struct kvm_device *dev)
 233 {
 234         struct kvm_vfio *kv = dev->private;
 235         struct kvm_vfio_group *kvg, *tmp;
 236
 237         list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
 238                 kvm_vfio_group_put_external_user(kvg->vfio_group);
 239                 list_del(&kvg->node);
 240                 kfree(kvg);
 241         }
 242
 243         kvm_vfio_update_coherency(dev);
 244
 245         kfree(kv);
 246         kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
 247 }
 248
 249 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 250 {
 251         struct kvm_device *tmp;
 252         struct kvm_vfio *kv;
 253
 254         /* Only one VFIO "device" per VM */
 255         list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
 256                 if (tmp->ops == &kvm_vfio_ops)
 257                         return -EBUSY;
 258
 259         kv = kzalloc(sizeof(*kv), GFP_KERNEL);
 260         if (!kv)
 261                 return -ENOMEM;
 262
 263         INIT_LIST_HEAD(&kv->group_list);
 264         mutex_init(&kv->lock);
 265
 266         dev->private = kv;
 267
 268         return 0;
 269 }
 270
 271 struct kvm_device_ops kvm_vfio_ops = {
 272         .name = "kvm-vfio",
 273         .create = kvm_vfio_create,
 274         .destroy = kvm_vfio_destroy,
 275         .set_attr = kvm_vfio_set_attr,
 276         .has_attr = kvm_vfio_has_attr,
 277 };