virt/kvm/vfio.c - linux - Git at Google

 /*
  * VFIO-KVM bridge pseudo device
  *
  * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
  *     Author: Alex Williamson <alex.williamson@redhat.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/errno.h>
 #include <linux/file.h>
 #include <linux/kvm_host.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/vfio.h>
 #include "vfio.h"

 #ifdef CONFIG_SPAPR_TCE_IOMMU
 #include <asm/kvm_ppc.h>
 #endif

 struct kvm_vfio_group {
 	struct list_head node;
 	struct vfio_group *vfio_group;
 };

 struct kvm_vfio {
 	struct list_head group_list;
 	struct mutex lock;
 	bool noncoherent;
 };

 static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
 {
 	struct vfio_group *vfio_group;
 	struct vfio_group *(*fn)(struct file *);

 	fn = symbol_get(vfio_group_get_external_user);
 	if (!fn)
 		return ERR_PTR(-EINVAL);

 	vfio_group = fn(filep);

 	symbol_put(vfio_group_get_external_user);

 	return vfio_group;
 }

 static bool kvm_vfio_external_group_match_file(struct vfio_group *group,
 					       struct file *filep)
 {
 	bool ret, (*fn)(struct vfio_group *, struct file *);

 	fn = symbol_get(vfio_external_group_match_file);
 	if (!fn)
 		return false;

 	ret = fn(group, filep);

 	symbol_put(vfio_external_group_match_file);

 	return ret;
 }

 static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
 {
 	void (*fn)(struct vfio_group *);

 	fn = symbol_get(vfio_group_put_external_user);
 	if (!fn)
 		return;

 	fn(vfio_group);

 	symbol_put(vfio_group_put_external_user);
 }

 static void kvm_vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
 {
 	void (*fn)(struct vfio_group *, struct kvm *);

 	fn = symbol_get(vfio_group_set_kvm);
 	if (!fn)
 		return;

 	fn(group, kvm);

 	symbol_put(vfio_group_set_kvm);
 }

 static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
 {
 	long (*fn)(struct vfio_group *, unsigned long);
 	long ret;

 	fn = symbol_get(vfio_external_check_extension);
 	if (!fn)
 		return false;

 	ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);

 	symbol_put(vfio_external_check_extension);

 	return ret > 0;
 }

 #ifdef CONFIG_SPAPR_TCE_IOMMU
 static int kvm_vfio_external_user_iommu_id(struct vfio_group *vfio_group)
 {
 	int (*fn)(struct vfio_group *);
 	int ret = -EINVAL;

 	fn = symbol_get(vfio_external_user_iommu_id);
 	if (!fn)
 		return ret;

 	ret = fn(vfio_group);

 	symbol_put(vfio_external_user_iommu_id);

 	return ret;
 }

 static struct iommu_group *kvm_vfio_group_get_iommu_group(
 		struct vfio_group *group)
 {
 	int group_id = kvm_vfio_external_user_iommu_id(group);

 	if (group_id < 0)
 		return NULL;

 	return iommu_group_get_by_id(group_id);
 }

 static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
 		struct vfio_group *vfio_group)
 {
 	struct iommu_group *grp = kvm_vfio_group_get_iommu_group(vfio_group);

 	if (WARN_ON_ONCE(!grp))
 		return;

 	kvm_spapr_tce_release_iommu_group(kvm, grp);
 	iommu_group_put(grp);
 }
 #endif

 /*
  * Groups can use the same or different IOMMU domains.  If the same then
  * adding a new group may change the coherency of groups we've previously
  * been told about.  We don't want to care about any of that so we retest
  * each group and bail as soon as we find one that's noncoherent.  This
  * means we only ever [un]register_noncoherent_dma once for the whole device.
  */
 static void kvm_vfio_update_coherency(struct kvm_device *dev)
 {
 	struct kvm_vfio *kv = dev->private;
 	bool noncoherent = false;
 	struct kvm_vfio_group *kvg;

 	mutex_lock(&kv->lock);

 	list_for_each_entry(kvg, &kv->group_list, node) {
 		if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
 			noncoherent = true;
 			break;
 		}
 	}

 	if (noncoherent != kv->noncoherent) {
 		kv->noncoherent = noncoherent;

 		if (kv->noncoherent)
 			kvm_arch_register_noncoherent_dma(dev->kvm);
 		else
 			kvm_arch_unregister_noncoherent_dma(dev->kvm);
 	}

 	mutex_unlock(&kv->lock);
 }

 static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 {
 	struct kvm_vfio *kv = dev->private;
 	struct vfio_group *vfio_group;
 	struct kvm_vfio_group *kvg;
 	int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
 	struct fd f;
 	int32_t fd;
 	int ret;

 	switch (attr) {
 	case KVM_DEV_VFIO_GROUP_ADD:
 		if (get_user(fd, argp))
 			return -EFAULT;

 		f = fdget(fd);
 		if (!f.file)
 			return -EBADF;

 		vfio_group = kvm_vfio_group_get_external_user(f.file);
 		fdput(f);

 		if (IS_ERR(vfio_group))
 			return PTR_ERR(vfio_group);

 		mutex_lock(&kv->lock);

 		list_for_each_entry(kvg, &kv->group_list, node) {
 			if (kvg->vfio_group == vfio_group) {
 				mutex_unlock(&kv->lock);
 				kvm_vfio_group_put_external_user(vfio_group);
 				return -EEXIST;
 			}
 		}

 		kvg = kzalloc(sizeof(*kvg), GFP_KERNEL_ACCOUNT);
 		if (!kvg) {
 			mutex_unlock(&kv->lock);
 			kvm_vfio_group_put_external_user(vfio_group);
 			return -ENOMEM;
 		}

 		list_add_tail(&kvg->node, &kv->group_list);
 		kvg->vfio_group = vfio_group;

 		kvm_arch_start_assignment(dev->kvm);

 		mutex_unlock(&kv->lock);

 		kvm_vfio_group_set_kvm(vfio_group, dev->kvm);

 		kvm_vfio_update_coherency(dev);

 		return 0;

 	case KVM_DEV_VFIO_GROUP_DEL:
 		if (get_user(fd, argp))
 			return -EFAULT;

 		f = fdget(fd);
 		if (!f.file)
 			return -EBADF;

 		ret = -ENOENT;

 		mutex_lock(&kv->lock);

 		list_for_each_entry(kvg, &kv->group_list, node) {
 			if (!kvm_vfio_external_group_match_file(kvg->vfio_group,
 								f.file))
 				continue;

 			list_del(&kvg->node);
 			kvm_arch_end_assignment(dev->kvm);
 #ifdef CONFIG_SPAPR_TCE_IOMMU
 			kvm_spapr_tce_release_vfio_group(dev->kvm,
 							 kvg->vfio_group);
 #endif
 			kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 			kvm_vfio_group_put_external_user(kvg->vfio_group);
 			kfree(kvg);
 			ret = 0;
 			break;
 		}

 		mutex_unlock(&kv->lock);

 		fdput(f);

 		kvm_vfio_update_coherency(dev);

 		return ret;

 #ifdef CONFIG_SPAPR_TCE_IOMMU
 	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: {
 		struct kvm_vfio_spapr_tce param;
 		struct kvm_vfio *kv = dev->private;
 		struct vfio_group *vfio_group;
 		struct kvm_vfio_group *kvg;
 		struct fd f;
 		struct iommu_group *grp;

 		if (copy_from_user(&param, (void __user *)arg,
 				sizeof(struct kvm_vfio_spapr_tce)))
 			return -EFAULT;

 		f = fdget(param.groupfd);
 		if (!f.file)
 			return -EBADF;

 		vfio_group = kvm_vfio_group_get_external_user(f.file);
 		fdput(f);

 		if (IS_ERR(vfio_group))
 			return PTR_ERR(vfio_group);

 		grp = kvm_vfio_group_get_iommu_group(vfio_group);
 		if (WARN_ON_ONCE(!grp)) {
 			kvm_vfio_group_put_external_user(vfio_group);
 			return -EIO;
 		}

 		ret = -ENOENT;

 		mutex_lock(&kv->lock);

 		list_for_each_entry(kvg, &kv->group_list, node) {
 			if (kvg->vfio_group != vfio_group)
 				continue;

 			ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
 					param.tablefd, grp);
 			break;
 		}

 		mutex_unlock(&kv->lock);

 		iommu_group_put(grp);
 		kvm_vfio_group_put_external_user(vfio_group);

 		return ret;
 	}
 #endif /* CONFIG_SPAPR_TCE_IOMMU */
 	}

 	return -ENXIO;
 }

 static int kvm_vfio_set_attr(struct kvm_device *dev,
 			     struct kvm_device_attr *attr)
 {
 	switch (attr->group) {
 	case KVM_DEV_VFIO_GROUP:
 		return kvm_vfio_set_group(dev, attr->attr, attr->addr);
 	}

 	return -ENXIO;
 }

 static int kvm_vfio_has_attr(struct kvm_device *dev,
 			     struct kvm_device_attr *attr)
 {
 	switch (attr->group) {
 	case KVM_DEV_VFIO_GROUP:
 		switch (attr->attr) {
 		case KVM_DEV_VFIO_GROUP_ADD:
 		case KVM_DEV_VFIO_GROUP_DEL:
 #ifdef CONFIG_SPAPR_TCE_IOMMU
 		case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
 #endif
 			return 0;
 		}

 		break;
 	}

 	return -ENXIO;
 }

 static void kvm_vfio_destroy(struct kvm_device *dev)
 {
 	struct kvm_vfio *kv = dev->private;
 	struct kvm_vfio_group *kvg, *tmp;

 	list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
 #ifdef CONFIG_SPAPR_TCE_IOMMU
 		kvm_spapr_tce_release_vfio_group(dev->kvm, kvg->vfio_group);
 #endif
 		kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 		kvm_vfio_group_put_external_user(kvg->vfio_group);
 		list_del(&kvg->node);
 		kfree(kvg);
 		kvm_arch_end_assignment(dev->kvm);
 	}

 	kvm_vfio_update_coherency(dev);

 	kfree(kv);
 	kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
 }

 static int kvm_vfio_create(struct kvm_device *dev, u32 type);

 static struct kvm_device_ops kvm_vfio_ops = {
 	.name = "kvm-vfio",
 	.create = kvm_vfio_create,
 	.destroy = kvm_vfio_destroy,
 	.set_attr = kvm_vfio_set_attr,
 	.has_attr = kvm_vfio_has_attr,
 };

 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 {
 	struct kvm_device *tmp;
 	struct kvm_vfio *kv;

 	/* Only one VFIO "device" per VM */
 	list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
 		if (tmp->ops == &kvm_vfio_ops)
 			return -EBUSY;

 	kv = kzalloc(sizeof(*kv), GFP_KERNEL_ACCOUNT);
 	if (!kv)
 		return -ENOMEM;

 	INIT_LIST_HEAD(&kv->group_list);
 	mutex_init(&kv->lock);

 	dev->private = kv;

 	return 0;
 }

 int kvm_vfio_ops_init(void)
 {
 	return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
 }

 void kvm_vfio_ops_exit(void)
 {
 	kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
 }
	/*
	* VFIO-KVM bridge pseudo device
	*
	* Copyright (C) 2013 Red Hat, Inc. All rights reserved.
	* Author: Alex Williamson <alex.williamson@redhat.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/errno.h>
	#include <linux/file.h>
	#include <linux/kvm_host.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/slab.h>
	#include <linux/uaccess.h>
	#include <linux/vfio.h>
	#include "vfio.h"

	#ifdef CONFIG_SPAPR_TCE_IOMMU
	#include <asm/kvm_ppc.h>
	#endif

	struct kvm_vfio_group {
	struct list_head node;
	struct vfio_group *vfio_group;
	};

	struct kvm_vfio {
	struct list_head group_list;
	struct mutex lock;
	bool noncoherent;
	};

	static struct vfio_group kvm_vfio_group_get_external_user(struct file filep)
	{
	struct vfio_group *vfio_group;
	struct vfio_group (fn)(struct file *);

	fn = symbol_get(vfio_group_get_external_user);
	if (!fn)
	return ERR_PTR(-EINVAL);

	vfio_group = fn(filep);

	symbol_put(vfio_group_get_external_user);

	return vfio_group;
	}

	static bool kvm_vfio_external_group_match_file(struct vfio_group *group,
	struct file *filep)
	{
	bool ret, (fn)(struct vfio_group , struct file *);

	fn = symbol_get(vfio_external_group_match_file);
	if (!fn)
	return false;

	ret = fn(group, filep);

	symbol_put(vfio_external_group_match_file);

	return ret;
	}

	static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
	{
	void (fn)(struct vfio_group );

	fn = symbol_get(vfio_group_put_external_user);
	if (!fn)
	return;

	fn(vfio_group);

	symbol_put(vfio_group_put_external_user);
	}

	static void kvm_vfio_group_set_kvm(struct vfio_group group, struct kvm kvm)
	{
	void (fn)(struct vfio_group , struct kvm *);

	fn = symbol_get(vfio_group_set_kvm);
	if (!fn)
	return;

	fn(group, kvm);

	symbol_put(vfio_group_set_kvm);
	}

	static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
	{
	long (fn)(struct vfio_group , unsigned long);
	long ret;

	fn = symbol_get(vfio_external_check_extension);
	if (!fn)
	return false;

	ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);

	symbol_put(vfio_external_check_extension);

	return ret > 0;
	}

	#ifdef CONFIG_SPAPR_TCE_IOMMU
	static int kvm_vfio_external_user_iommu_id(struct vfio_group *vfio_group)
	{
	int (fn)(struct vfio_group );
	int ret = -EINVAL;

	fn = symbol_get(vfio_external_user_iommu_id);
	if (!fn)
	return ret;

	ret = fn(vfio_group);

	symbol_put(vfio_external_user_iommu_id);

	return ret;
	}

	static struct iommu_group *kvm_vfio_group_get_iommu_group(
	struct vfio_group *group)
	{
	int group_id = kvm_vfio_external_user_iommu_id(group);

	if (group_id < 0)
	return NULL;

	return iommu_group_get_by_id(group_id);
	}

	static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
	struct vfio_group *vfio_group)
	{
	struct iommu_group *grp = kvm_vfio_group_get_iommu_group(vfio_group);

	if (WARN_ON_ONCE(!grp))
	return;

	kvm_spapr_tce_release_iommu_group(kvm, grp);
	iommu_group_put(grp);
	}
	#endif

	/*
	* Groups can use the same or different IOMMU domains. If the same then
	* adding a new group may change the coherency of groups we've previously
	* been told about. We don't want to care about any of that so we retest
	* each group and bail as soon as we find one that's noncoherent. This
	* means we only ever [un]register_noncoherent_dma once for the whole device.
	*/
	static void kvm_vfio_update_coherency(struct kvm_device *dev)
	{
	struct kvm_vfio *kv = dev->private;
	bool noncoherent = false;
	struct kvm_vfio_group *kvg;

	mutex_lock(&kv->lock);

	list_for_each_entry(kvg, &kv->group_list, node) {
	if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
	noncoherent = true;
	break;
	}
	}

	if (noncoherent != kv->noncoherent) {
	kv->noncoherent = noncoherent;

	if (kv->noncoherent)
	kvm_arch_register_noncoherent_dma(dev->kvm);
	else
	kvm_arch_unregister_noncoherent_dma(dev->kvm);
	}

	mutex_unlock(&kv->lock);
	}

	static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
	{
	struct kvm_vfio *kv = dev->private;
	struct vfio_group *vfio_group;
	struct kvm_vfio_group *kvg;
	int32_t __user argp = (int32_t __user )(unsigned long)arg;
	struct fd f;
	int32_t fd;
	int ret;

	switch (attr) {
	case KVM_DEV_VFIO_GROUP_ADD:
	if (get_user(fd, argp))
	return -EFAULT;

	f = fdget(fd);
	if (!f.file)
	return -EBADF;

	vfio_group = kvm_vfio_group_get_external_user(f.file);
	fdput(f);

	if (IS_ERR(vfio_group))
	return PTR_ERR(vfio_group);

	mutex_lock(&kv->lock);

	list_for_each_entry(kvg, &kv->group_list, node) {
	if (kvg->vfio_group == vfio_group) {
	mutex_unlock(&kv->lock);
	kvm_vfio_group_put_external_user(vfio_group);
	return -EEXIST;
	}
	}

	kvg = kzalloc(sizeof(*kvg), GFP_KERNEL_ACCOUNT);
	if (!kvg) {
	mutex_unlock(&kv->lock);
	kvm_vfio_group_put_external_user(vfio_group);
	return -ENOMEM;
	}

	list_add_tail(&kvg->node, &kv->group_list);
	kvg->vfio_group = vfio_group;

	kvm_arch_start_assignment(dev->kvm);

	mutex_unlock(&kv->lock);

	kvm_vfio_group_set_kvm(vfio_group, dev->kvm);

	kvm_vfio_update_coherency(dev);

	return 0;

	case KVM_DEV_VFIO_GROUP_DEL:
	if (get_user(fd, argp))
	return -EFAULT;

	f = fdget(fd);
	if (!f.file)
	return -EBADF;

	ret = -ENOENT;

	mutex_lock(&kv->lock);

	list_for_each_entry(kvg, &kv->group_list, node) {
	if (!kvm_vfio_external_group_match_file(kvg->vfio_group,
	f.file))
	continue;

	list_del(&kvg->node);
	kvm_arch_end_assignment(dev->kvm);
	#ifdef CONFIG_SPAPR_TCE_IOMMU
	kvm_spapr_tce_release_vfio_group(dev->kvm,
	kvg->vfio_group);
	#endif
	kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
	kvm_vfio_group_put_external_user(kvg->vfio_group);
	kfree(kvg);
	ret = 0;
	break;
	}

	mutex_unlock(&kv->lock);

	fdput(f);

	kvm_vfio_update_coherency(dev);

	return ret;

	#ifdef CONFIG_SPAPR_TCE_IOMMU
	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: {
	struct kvm_vfio_spapr_tce param;
	struct kvm_vfio *kv = dev->private;
	struct vfio_group *vfio_group;
	struct kvm_vfio_group *kvg;
	struct fd f;
	struct iommu_group *grp;

	if (copy_from_user(&param, (void __user *)arg,
	sizeof(struct kvm_vfio_spapr_tce)))
	return -EFAULT;

	f = fdget(param.groupfd);
	if (!f.file)
	return -EBADF;

	vfio_group = kvm_vfio_group_get_external_user(f.file);
	fdput(f);

	if (IS_ERR(vfio_group))
	return PTR_ERR(vfio_group);

	grp = kvm_vfio_group_get_iommu_group(vfio_group);
	if (WARN_ON_ONCE(!grp)) {
	kvm_vfio_group_put_external_user(vfio_group);
	return -EIO;
	}

	ret = -ENOENT;

	mutex_lock(&kv->lock);

	list_for_each_entry(kvg, &kv->group_list, node) {
	if (kvg->vfio_group != vfio_group)
	continue;

	ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
	param.tablefd, grp);
	break;
	}

	mutex_unlock(&kv->lock);

	iommu_group_put(grp);
	kvm_vfio_group_put_external_user(vfio_group);

	return ret;
	}
	#endif /* CONFIG_SPAPR_TCE_IOMMU */
	}

	return -ENXIO;
	}

	static int kvm_vfio_set_attr(struct kvm_device *dev,
	struct kvm_device_attr *attr)
	{
	switch (attr->group) {
	case KVM_DEV_VFIO_GROUP:
	return kvm_vfio_set_group(dev, attr->attr, attr->addr);
	}

	return -ENXIO;
	}

	static int kvm_vfio_has_attr(struct kvm_device *dev,
	struct kvm_device_attr *attr)
	{
	switch (attr->group) {
	case KVM_DEV_VFIO_GROUP:
	switch (attr->attr) {
	case KVM_DEV_VFIO_GROUP_ADD:
	case KVM_DEV_VFIO_GROUP_DEL:
	#ifdef CONFIG_SPAPR_TCE_IOMMU
	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
	#endif
	return 0;
	}

	break;
	}

	return -ENXIO;
	}

	static void kvm_vfio_destroy(struct kvm_device *dev)
	{
	struct kvm_vfio *kv = dev->private;
	struct kvm_vfio_group kvg, tmp;

	list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
	#ifdef CONFIG_SPAPR_TCE_IOMMU
	kvm_spapr_tce_release_vfio_group(dev->kvm, kvg->vfio_group);
	#endif
	kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
	kvm_vfio_group_put_external_user(kvg->vfio_group);
	list_del(&kvg->node);
	kfree(kvg);
	kvm_arch_end_assignment(dev->kvm);
	}

	kvm_vfio_update_coherency(dev);

	kfree(kv);
	kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
	}

	static int kvm_vfio_create(struct kvm_device *dev, u32 type);

	static struct kvm_device_ops kvm_vfio_ops = {
	.name = "kvm-vfio",
	.create = kvm_vfio_create,
	.destroy = kvm_vfio_destroy,
	.set_attr = kvm_vfio_set_attr,
	.has_attr = kvm_vfio_has_attr,
	};

	static int kvm_vfio_create(struct kvm_device *dev, u32 type)
	{
	struct kvm_device *tmp;
	struct kvm_vfio *kv;

	/* Only one VFIO "device" per VM */
	list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
	if (tmp->ops == &kvm_vfio_ops)
	return -EBUSY;

	kv = kzalloc(sizeof(*kv), GFP_KERNEL_ACCOUNT);
	if (!kv)
	return -ENOMEM;

	INIT_LIST_HEAD(&kv->group_list);
	mutex_init(&kv->lock);

	dev->private = kv;

	return 0;
	}

	int kvm_vfio_ops_init(void)
	{
	return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
	}

	void kvm_vfio_ops_exit(void)
	{
	kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
	}