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/*
* 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>
struct kvm_vfio_group {
struct list_head node;
struct vfio_group *vfio_group;
};
struct kvm_vfio {
struct list_head group_list;
struct mutex lock;
};
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 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 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;
void __user *argp = (void __user *)arg;
struct fd f;
int32_t fd;
int ret;
switch (attr) {
case KVM_DEV_VFIO_GROUP_ADD:
if (get_user(fd, (int32_t __user *)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);
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;
mutex_unlock(&kv->lock);
return 0;
case KVM_DEV_VFIO_GROUP_DEL:
if (get_user(fd, (int32_t __user *)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);
ret = -ENOENT;
mutex_lock(&kv->lock);
list_for_each_entry(kvg, &kv->group_list, node) {
if (kvg->vfio_group != vfio_group)
continue;
list_del(&kvg->node);
kvm_vfio_group_put_external_user(kvg->vfio_group);
kfree(kvg);
ret = 0;
break;
}
mutex_unlock(&kv->lock);
kvm_vfio_group_put_external_user(vfio_group);
return ret;
}
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:
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) {
kvm_vfio_group_put_external_user(kvg->vfio_group);
list_del(&kvg->node);
kfree(kvg);
}
kfree(kv);
kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
}
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);
if (!kv)
return -ENOMEM;
INIT_LIST_HEAD(&kv->group_list);
mutex_init(&kv->lock);
dev->private = kv;
return 0;
}
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,
};
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