path: root/drivers/vfio/group.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * VFIO core
 *
 * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <alex.williamson@redhat.com>
 *
 * Derived from original vfio:
 * Copyright 2010 Cisco Systems, Inc.  All rights reserved.
 * Author: Tom Lyon, pugs@cisco.com
 */

#include <linux/vfio.h>
#include <linux/iommufd.h>
#include <linux/anon_inodes.h>
#include "vfio.h"

static struct vfio {
	struct class			*class;
	struct list_head		group_list;
	struct mutex			group_lock; /* locks group_list */
	struct ida			group_ida;
	dev_t				group_devt;
} vfio;

static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
						     char *buf)
{
	struct vfio_device *it, *device = ERR_PTR(-ENODEV);

	mutex_lock(&group->device_lock);
	list_for_each_entry(it, &group->device_list, group_next) {
		int ret;

		if (it->ops->match) {
			ret = it->ops->match(it, buf);
			if (ret < 0) {
				device = ERR_PTR(ret);
				break;
			}
		} else {
			ret = !strcmp(dev_name(it->dev), buf);
		}

		if (ret && vfio_device_try_get_registration(it)) {
			device = it;
			break;
		}
	}
	mutex_unlock(&group->device_lock);

	return device;
}

/*
 * VFIO Group fd, /dev/vfio/$GROUP
 */
static bool vfio_group_has_iommu(struct vfio_group *group)
{
	lockdep_assert_held(&group->group_lock);
	/*
	 * There can only be users if there is a container, and if there is a
	 * container there must be users.
	 */
	WARN_ON(!group->container != !group->container_users);

	return group->container || group->iommufd;
}

/*
 * VFIO_GROUP_UNSET_CONTAINER should fail if there are other users or
 * if there was no container to unset.  Since the ioctl is called on
 * the group, we know that still exists, therefore the only valid
 * transition here is 1->0.
 */
static int vfio_group_ioctl_unset_container(struct vfio_group *group)
{
	int ret = 0;

	mutex_lock(&group->group_lock);
	if (!vfio_group_has_iommu(group)) {
		ret = -EINVAL;
		goto out_unlock;
	}
	if (group->container) {
		if (group->container_users != 1) {
			ret = -EBUSY;
			goto out_unlock;
		}
		vfio_group_detach_container(group);
	}
	if (group->iommufd) {
		iommufd_ctx_put(group->iommufd);
		group->iommufd = NULL;
	}

out_unlock:
	mutex_unlock(&group->group_lock);
	return ret;
}

static int vfio_group_ioctl_set_container(struct vfio_group *group,
					  int __user *arg)
{
	struct vfio_container *container;
	struct iommufd_ctx *iommufd;
	int ret;
	int fd;

	if (get_user(fd, arg))
		return -EFAULT;

	CLASS(fd, f)(fd);
	if (fd_empty(f))
		return -EBADF;

	mutex_lock(&group->group_lock);
	if (vfio_group_has_iommu(group)) {
		ret = -EINVAL;
		goto out_unlock;
	}
	if (!group->iommu_group) {
		ret = -ENODEV;
		goto out_unlock;
	}

	container = vfio_container_from_file(fd_file(f));
	if (container) {
		ret = vfio_container_attach_group(container, group);
		goto out_unlock;
	}

	iommufd = iommufd_ctx_from_file(fd_file(f));
	if (!IS_ERR(iommufd)) {
		if (IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
		    group->type == VFIO_NO_IOMMU)
			ret = iommufd_vfio_compat_set_no_iommu(iommufd);
		else
			ret = iommufd_vfio_compat_ioas_create(iommufd);

		if (ret) {
			iommufd_ctx_put(iommufd);
			goto out_unlock;
		}

		group->iommufd = iommufd;
		goto out_unlock;
	}

	/* The FD passed is not recognized. */
	ret = -EBADFD;

out_unlock:
	mutex_unlock(&group->group_lock);
	return ret;
}

static void vfio_device_group_get_kvm_safe(struct vfio_device *device)
{
	spin_lock(&device->group->kvm_ref_lock);
	vfio_device_get_kvm_safe(device, device->group->kvm);
	spin_unlock(&device->group->kvm_ref_lock);
}

static int vfio_df_group_open(struct vfio_device_file *df)
{
	struct vfio_device *device = df->device;
	int ret;

	mutex_lock(&device->group->group_lock);
	if (!vfio_group_has_iommu(device->group)) {
		ret = -EINVAL;
		goto out_unlock