/*
* VFIO core
*
* Copyright (C) 2012 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.
*
* Derived from original vfio:
* Copyright 2010 Cisco Systems, Inc. All rights reserved.
* Author: Tom Lyon, pugs@cisco.com
*/
#include <linux/cdev.h>
#include <linux/compat.h>
#include <linux/device.h>
#include <linux/file.h>
#include <linux/anon_inodes.h>
#include <linux/fs.h>
#include <linux/idr.h>
#include <linux/iommu.h>
#include <linux/list.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>
#include <linux/wait.h>
#define DRIVER_VERSION "0.3"
#define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>"
#define DRIVER_DESC "VFIO - User Level meta-driver"
static struct vfio {
struct class *class;
struct list_head iommu_drivers_list;
struct mutex iommu_drivers_lock;
struct list_head group_list;
struct idr group_idr;
struct mutex group_lock;
struct cdev group_cdev;
dev_t group_devt;
wait_queue_head_t release_q;
} vfio;
struct vfio_iommu_driver {
const struct vfio_iommu_driver_ops *ops;
struct list_head vfio_next;
};
struct vfio_container {
struct kref kref;
struct list_head group_list;
struct rw_semaphore group_lock;
struct vfio_iommu_driver *iommu_driver;
void *iommu_data;
};
struct vfio_unbound_dev {
struct device *dev;
struct list_head unbound_next;
};
struct vfio_group {
struct kref kref;
int minor;
atomic_t container_users;
struct iommu_group *iommu_group;
struct vfio_container *container;
struct list_head device_list;
struct mutex device_lock;
struct device *dev;
struct notifier_block nb;
struct list_head vfio_next;
struct list_head container_next;
struct list_head unbound_list;
struct mutex unbound_lock;
atomic_t opened;
};
struct vfio_device {
struct kref kref;
struct device *dev;
const struct vfio_device_ops *ops;
struct vfio_group *group;
struct list_head group_next;
void *device_data;
};
/**
* IOMMU driver registration
*/
int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops)
{
struct vfio_iommu_driver *driver, *tmp;
driver = kzalloc(sizeof(*driver), GFP_KERNEL);
if (!driver)
return -ENOMEM;
driver->ops = ops;
mutex_lock(&vfio.iommu_drivers_lock);
/* Check for duplicates */
list_for_each_entry(tmp, &vfio.iommu_drivers_list, vfio_next) {
if (tmp->ops == ops) {
mutex_unlock(&vfio.iommu_drivers_lock);
kfree(driver);
return -EINVAL;
}
}
list_add(&driver->vfio_next, &vfio.iommu_drivers_list);
mutex_unlock(&vfio.iommu_drivers_lock);
return 0;
}
EXPORT_SYMBOL_GPL(vfio_register_iommu_driver);
void vfio_unregister_iommu_driver(const struct vfio_iommu_driver_ops *ops)
{
struct vfio_iommu_driver *driver;
mutex_lock(&vfio.iommu_drivers_lock);
list_for_each_entry(driver, &vfio.iommu_drivers_list, vfio_next) {
if (driver->ops == ops) {
list_del(&driver->vfio_next);
mutex_unlock(&vfio.iommu_drivers_lock);
kfree(driver);
return;
}
}
mutex_unlock(&vfio.iommu_drivers_lock);
}
EXPORT_SYMBOL_GPL(vfio_unregister_iommu_driver);
/**
* Group minor allocation/free - both called with vfio.group_lock held
*/
static int vfio_alloc_group_minor(struct vfio_group *group)
{
return idr_alloc(&vfio.group_idr, group, 0, MINORMASK + 1, GFP_KERNEL);
}
static void vfio_free_group_minor(int minor)
{
idr_remove(&vfio.group_idr, minor);
}
static int vfio_iommu_group_notifier(struct notifier_block *nb,
unsigned long action, void *data);
static void vfio_group_get(struct vfio_group *group);
/**
* Container objects - containers are created when /dev/vfio/vfio is
* opened, but their lifecycle extends until the last user is done, so
* it's freed via kref. Must support container/group/device being
* closed in any order.
*/
static void vfio_container_get(struct vfio_container *container)
{
kref_get(&container->kref);
}
static void vfio_container_release(struct kref *kref)
{
struct vfio_container *container;
container = container_of(kref, struct vfio_container, kref);
kfree(container);
}
static void vfio_container_put(struct vfio_container *container)
{
kref_put(&container->kref, vfio_container_release);
}
static void vfio_group_unlock_and_free(struct vfio_group *group)
{
mutex_unlock(&vfio.group_lock);
/*
* Unregister outside of lock. A spurious callback is harmless now
* that the group is no longer in vfio.group_list.
*/
iommu_group_unregister_notifier(group->iommu_group, &group->nb);
kfree(group);
}
/**
* Group objects - create, release, get, put, search
*/
static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
{
struct vfio_group *group, *tmp;
struct device *dev;
int ret, minor;
group = kzalloc(sizeof(*group), GFP_KERNEL);
if (!group)
return ERR_PTR(-ENOMEM);
kref_init(&group->kref);
INIT_LIST_HEAD(&group->device_list);
mutex_init(&group->device_lock);
INIT_LIST_HEAD(&group->unbound_list);
mutex_init(&group->unbound_lock);
atomic_set(&group->container_users, 0);
atomic_set(&group->opened, 0);
group->iommu_group = iommu_group;
group->nb.notifier_call = vfio_iommu_group_notifier;
/*
* blocking notifiers acquire a rwsem around registering and hold
* it around callback. Therefore, need to register outside of
* vfio.group_lock to avoid A-B/B-A contention. Our callback won't
* do anything unless it can find the group in vfio.group_list, so
* no harm in registering early.
*/
ret = iommu_group_register_notifier(iommu_group, &group->nb);
if (ret) {
kfree(group);
return ERR_PTR(ret);
}
mutex_lock(&vfio.group_lock);
/* Did we race creating this group? */
list_for_each_entry(tmp, &vfio.group_list, vfio_next) {
if (tmp->iommu_group == iommu_group) {
vfio_group_get(tmp);
vfio_group_unlock_and_free(group);
return tmp;
}
}
minor = vfio_alloc_group_minor(group);
if (minor < 0) {
vfio_group_unlock_and_free(group);
return ERR_PTR(minor);
}
dev = device_create(vfio.class, NULL,
MKDEV(MAJOR(vfio.group_devt), minor),
group, "%d", iommu_group_id(iommu_group));
if (IS_ERR(dev)) {
vfio_free_group_minor(minor);
vfio_group_unlock_and_free(group);
return (struct vfio_group *)dev; /* ERR_PTR */
}
group->minor = minor;
group->dev = dev;
list_add(&group->vfio_next, &vfio.group_list);
mutex_unlock(&vfio.group_lock);
return group;
}
/* called with vfio.group_lock held */
static void vfio_group_release(struct kref *kref)
{
struct vfio_group *group = container_of(kref, struct vfio_group, kref);
struct vfio_unbound_dev *unbound, *tmp;
struct iommu_group *iommu_group = group->iommu_group;
WARN_ON(!list_empty(&group->device_list));
list_for_each_entry_safe(unbound, tmp,
&group->unbound_list, unbound_next) {
list_del(&unbound->unbound_next);
kfree(unbound);
}
device_destroy(vfio.class, MKDEV(MAJOR(vfio.group_devt), group->minor));
list_del(&group->vfio_next);
vfio_free_group_minor(group->minor);
vfio_group_unlock_and_free(group);
iommu_group_put(iommu_group);
}
static void vfio_group_put(struct vfio_group *group)
{
kref_put_mutex(&group->kref, vfio_group_release, &vfio.group_lock);
}
/* Assume group_lock or group reference is held */
static void vfio_group_get(struct vfio_group *group)
{
kref_get(&group->kref);
}
/*
* Not really a try as we will sleep for mutex, but we need to make
* sure the group pointer is valid under lock and get a reference.
*/
static struct vfio_group *vfio_group_try_get(struct vfio_group *group)
{
struct vfio_group *target = group;
mutex_lock(&vfio.group_lock);
list_for_each_entry(group, &vfio.group_list, vfio_next) {
if (group == target) {
vfio_group_get(group);
mutex_unlock(&vfio.group_lock);
return group;
}
}
mutex_unlock(&vfio.group_lock);
return NULL;
}
static
struct vfio_group *vfio_group_get_from_iommu(struct iommu_group *iommu_group)
{
struct vfio_group *group;
mutex_lock(&vfio.group_lock);
list_for_each_entry(group, &vfio.group_list, vfio_next) {
if (group->iommu_group == iommu_group) {
vfio_group_get(group);
mutex_unlock(&vfio.group_lock);
return group;
}
}
mutex_unlock(&vfio.group_lock);
return NULL;
}
static struct vfio_group *vfio_group_get_from_minor(int minor)
{
struct vfio_group *group;
mutex_lock(&vfio.group_lock);
group = idr_find(&vfio.group_idr, minor);
if (!group) {
mutex_unlock(&vfio.group_lock);
return NULL;
}
vfio_group_get(group);
mutex_unlock(&vfio.group_lock);
return group;
}
/**
* Device objects - create, release, get, put, search
*/
static
struct vfio_device *vfio_group_create_device(struct vfio_group *group,
struct device *dev,
const struct vfio_device_ops *ops,
void *device_data)
{
struct vfio_device *device;
device = kzalloc(sizeof(*device), GFP_KERNEL);
if (!device)
return ERR_PTR(-ENOMEM);
kref_init(&device->kref);
device->dev = dev;
device->group = group;
device->ops = ops;
device->device_data = device_data;
dev_set_drvdata(dev, device);
/* No need to get group_lock, caller has group reference */
vfio_group_get(group);
mutex_lock(&group->device_lock);
list_add(&device->group_next, &group->device_list);
mutex_unlock(&group->device_lock);
return device;
}
static void vfio_device_release(struct kref *kref)
{
struct vfio_device *device = container_of(kref,
struct vfio_device, kref);
struct vfio_group *group = device->group;
list_del(&device->group_next);
mutex_unlock(&group->device_lock);
dev_set_drvdata(device->dev, NULL);
kfree(device);
/* vfio_del_group_dev may be waiting for this device */
wake_up(&vfio.release_q);
}
/* Device reference always implies a group reference */
void vfio_device_put(struct vfio_device *device)
{
struct vfio_group *group = device->group;
kref_put_mutex(&device->kref, vfio_device_release, &group->device_lock);
vfio_group_put(group);
}
EXPORT_SYMBOL_GPL(vfio_device_put);
static void vfio_device_get(struct vfio_device *device)
{
vfio_group_get(device->group);
kref_get(&device->kref);
}
static struct vfio_device *vfio_group_get_device(struct vfio_group *group,
struct device *dev)
{
struct vfio_device *device;
mutex_lock(&group->device_lock);
list_for_each_entry(device, &group->device_list, group_next) {
if (device->dev == dev) {
vfio_device_get(device);
mutex_unlock(&group->device_lock);
return device;
}
}
mutex_unlock(&group->device_lock);
return NULL;
}
/*
* Some drivers, like pci-stub, are only used to prevent other drivers from
* claiming a device and are therefore perfectly legitimate for a user owned
* group. The pci-stub driver has no dependencies on DMA or the IOVA mapping
* of the device, but it does prevent the user from having direct access to
* the device, which is useful in some circumstances.
*
* We also assume that we can include PCI interconnect devices, ie. bridges.
* IOMMU grouping on PCI necessitates that if we lack isolation on a bridge
* then all of the downstream devices will be part of the same IOMMU group as
* the bridge. Thus, if placing the bridge into the user owned IOVA space
* breaks anything, it only does so for user owned devices downstream. Note
* that error notification via MSI can be affected for platforms that handle
* MSI within the same IOVA space as DMA.
*/
static const char * const vfio_driver_whitelist[] = { "pci-stub" };
static bool vfio_dev_whitelisted(struct device *dev, struct device_driver *drv)
{
int i;
if (dev_is_pci(dev)) {
struct pci_dev *pdev = to_pci_dev(dev);
if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL)
return true;
}
for (i = 0; i < ARRAY_SIZE(vfio_driver_whitelist); i++) {
if (!strcmp(drv->name, vfio_driver_whitelist[i]))
return true;
}
return false;
}
/*
* A vfio group is viable for use by userspace if all devices are in
* one of the following states:
* - driver-less
* - bound to a vfio driver
* - bound to a whitelisted driver
* - a PCI interconnect device
*
* We use two methods to determine whether a device is bound to a vfio
* driver. The first is to test whether the device exists in the vfio
* group. The second is to test if the device exists on the group
* unbound_list, indicating it's in the middle of transitioning from
* a vfio driver to driver-less.
*/
static int vfio_dev_viable(struct device *dev, void *data)
{
struct vfio_group *group = data;
struct vfio_device *device;
struct device_driver *drv = ACCESS_ONCE(dev->driver);
struct vfio_unbound_dev *unbound;
int ret = -EINVAL;
mutex_lock(&group->unbound_lock);
list_for_each_entry(unbound, &group->unbound_list, unbound_next) {
if (dev == unbound->dev) {
ret = 0;
break;
}
}
mutex_unlock(&group->unbound_lock);
if (!ret || !drv || vfio_dev_whitelisted(dev, drv))
return 0;
device = vfio_group_get_device(group, dev);
if (device) {
vfio_device_put(device);
return 0;
}
return ret;
}
/**
* Async device support
*/
static int vfio_group_nb_add_dev(struct vfio_group *group, struct device *dev)
{
struct vfio_device *device;
/* Do we already know about it? We shouldn't */
device = vfio_group_get_device(group, dev);
if (WARN_ON_ONCE(device)) {
vfio_device_put(device);
return 0;
}
/* Nothing to do for idle groups */
if (!atomic_read(&group->container_users))
return 0;
/* TODO Prevent device auto probing */
WARN(1, "Device %s added to live group %d!\n", dev_name(dev),
iommu_group_id(group->iommu_group));
return 0;
}
static int vfio_group_nb_verify(struct vfio_group *group, struct device *dev)
{
/* We don't care what happens when the group isn't in use */
if (!atomic_read(&group->container_users))
return 0;
return vfio_dev_viable(dev, group);
}
static int vfio_iommu_group_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
struct vfio_group *group = container_of(nb, struct vfio_group, nb);
struct device *dev = data;
struct vfio_unbound_dev *unbound;
/*
* Need to go through a group_lock lookup to get a reference or we
* risk racing a group being removed. Ignore spurious notifies.
*/
group = vfio_group_try_get(group);
if (!group)
return NOTIFY_OK;
switch (action) {
case IOMMU_GROUP_NOTIFY_ADD_DEVICE:
vfio_group_nb_add_dev(group, dev);
break;
case IOMMU_GROUP_NOTIFY_DEL_DEVICE:
/*
* Nothing to do here. If the device is in use, then the
* vfio sub-driver should block the remove callback until
* it is unused. If the device is unused or attached to a
* stub driver, then it should be released and we don't
* care that it will be going away.
*/
break;
case IOMMU_GROUP_NOTIFY_BIND_DRIVER:
pr_debug("%s: Device %s, group %d binding to driver\n",
__func__, dev_name(dev),
iommu_group_id(group->iommu_group));
break;
case IOMMU_GROUP_NOTIFY_BOUND_DRIVER:
pr_debug("%s: Device %s, group %d bound to driver %s\n",
__func__, dev_name(dev),
iommu_group_id(group->iommu_group), dev->driver->name);
BUG_ON(vfio_group_nb_verify(group, dev));
break;
case IOMMU_GROUP_NOTIFY_UNBIND_DRIVER:
pr_debug("%s: Device %s, group %d unbinding from driver %s\n",
__func__, dev_name(dev),
iommu_group_id(group->iommu_group), dev->driver->name);
break;
case IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER:
pr_debug("%s: Device %s, group %d unbound from driver\n",
__func__, dev_name(dev),
iommu_group_id(group->iommu_group));
/*
* XXX An unbound device in a live group is ok, but we'd
* really like to avoid the above BUG_ON by preventing other
* drivers from binding to it. Once that occurs, we have to
* stop the system to maintain isolation. At a minimum, we'd
* want a toggle to disable driver auto probe for this device.
*/
mutex_lock(&group->unbound_lock);
list_for_each_entry(unbound,
&group->unbound_list, unbound_next) {
if (dev == unbound->dev) {
list_del(&unbound->unbound_next);
kfree(unbound);
break;
}
}
mutex_unlock(&group->unbound_lock);
break;
}
vfio_group_put(group);
return NOTIFY_OK;
}
/**
* VFIO driver API
*/
int vfio_add_group_dev(struct device *dev,
const struct vfio_device_ops *ops, void *device_data)
{
struct iommu_group *iommu_group;
struct vfio_group *group;
struct vfio_device *device;
iommu_group = iommu_group_get(dev);
if (!iommu_group)
return -EINVAL;
group = vfio_group_get_from_iommu(iommu_group);
if (!group) {
group = vfio_create_group(iommu_group);
if (IS_ERR(group)) {
iommu_group_put(iommu_group);
return PTR_ERR(group);
}
} else {
/*
* A found vfio_group already holds a reference to the
* iommu_group. A created vfio_group keeps the reference.
*/
iommu_group_put(iommu_group);
}
device = vfio_group_get_device(group, dev);
if (device) {
WARN(1, "Device %s already exists on group %d\n",
dev_name(dev), iommu_group_id(iommu_group));
vfio_device_put(device);
vfio_group_put(group);
return -EBUSY;
}
device = vfio_group_create_device(group, dev, ops, device_data);
if (IS_ERR(device)) {
vfio_group_put(group);
return PTR_ERR(device);
}
/*
* Drop all but the vfio_device reference. The vfio_device holds
* a reference to the vfio_group, which holds a reference to the
* iommu_group.
*/
vfio_group_put(group);
return 0;
}
EXPORT_SYMBOL_GPL(vfio_add_group_dev);
/**
* Get a reference to the vfio_device for a device. Even if the
* caller thinks they own the device, they could be racing with a
* release call path, so we can't trust drvdata for the shortcut.
* Go the long way around, from the iommu_group to the vfio_group
* to the vfio_device.
*/
struct vfio_device *vfio_device_get_from_dev(struct device *dev)
{
struct iommu_group *iommu_group;
struct vfio_group *group;
struct vfio_device *device;
iommu_group = iommu_group_get(dev);
if (!iommu_group)
return NULL;
group = vfio_group_get_from_iommu(iommu_group);
iommu_group_put(iommu_group);
if (!group)
return NULL;
device = vfio_group_get_device(group, dev);
vfio_group_put(group);
return device;
}
EXPORT_SYMBOL_GPL(vfio_device_get_from_dev);
static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
char *buf)
{
struct vfio_device *it, *device = NULL;
mutex_lock(&group->device_lock);
list_for_each_entry(it, &group->device_list, group_next) {
if (!strcmp(dev_name(it->dev), buf)) {
device = it;
vfio_device_get(device);
break;
}
}
mutex_unlock(&group->device_lock);
return device;
}
/*
* Caller must hold a reference to the vfio_device
*/
void *vfio_device_data(struct vfio_device *device)
{
return device->device_data;
}
EXPORT_SYMBOL_GPL(vfio_device_data);
/* Given a referenced group, check if it contains the device */
static bool vfio_dev_present(struct vfio_group *group, struct device *dev)
{
struct vfio_device *device;
device = vfio_group_get_device(group, dev);
if (!device)
return false;
vfio_device_put(device);
return true;
}
/*
* Decrement the device reference count and wait for the device to be
* removed. Open file descriptors for the device... */
void *vfio_del_group_dev(struct device *dev)
{
struct vfio_device *device = dev_get_drvdata(dev);
struct vfio_group *group = device->group;
void *device_data = device->device_data;
struct vfio_unbound_dev *unbound;
unsigned int i = 0;
long ret;
bool interrupted = false;
/*
* The group exists so long as we have a device reference. Get
* a group reference and use it to scan for the device going away.
*/
vfio_group_get(group);
/*
* When the device is removed from the group, the group suddenly
* becomes non-viable; the device has a driver (until the unbind
* completes), but it's not present in the group. This is bad news
* for any external users that need to re-acquire a group reference
* in order to match and release their existing reference. To
* solve this, we track such devices on the unbound_list to bridge
* the gap until they're fully unbound.
*/
unbound = kzalloc(sizeof(*unbound), GFP_KERNEL);
if (unbound) {
unbound->dev = dev;
mutex_lock(&group->unbound_lock);
list_add(&unbound->unbound_next, &group->unbound_list);
mutex_unlock(&group->unbound_lock);
}
WARN_ON(!unbound);
vfio_device_put(device);
/*
* If the device is still present in the group after the above
* 'put', then it is in use and we need to request it from the
* bus driver. The driver may in turn need to request the
* device from the user. We send the request on an arbitrary
* interval with counter to allow the driver to take escalating
* measures to release the device if it has the ability to do so.
*/
do {
device = vfio_group_get_device(group, dev);
if (!device)
break;
if (device->ops->request)
device->ops->request(device_data, i++);
vfio_device_put(device);
if (interrupted) {
ret = wait_event_timeout(vfio.release_q,
!vfio_dev_present(group, dev), HZ * 10);
} else {
ret = wait_event_interruptible_timeout(vfio.release_q,
!vfio_dev_present(group, dev), HZ * 10);
if (ret == -ERESTARTSYS) {
interrupted = true;
dev_warn(dev,
"Device is currently in use, task"
" \"%s\" (%d) "
"blocked until device is released",
current->comm, task_pid_nr(current));
}
}
} while (ret <= 0);
vfio_group_put(group);
return device_data;
}
EXPORT_SYMBOL_GPL(vfio_del_group_dev);
/**
* VFIO base fd, /dev/vfio/vfio
*/
static long vfio_ioctl_check_extension(struct vfio_container *container,
unsigned long arg)
{
struct vfio_iommu_driver *driver;
long ret = 0;
down_read(&container->group_lock);
driver = container->iommu_driver;
switch (arg) {
/* No base extensions yet */
default:
/*
* If no driver is set, poll all registered drivers for
* extensions and return the first positive result. If
* a driver is already set, further queries will be passed
* only to that driver.
*/
if (!driver) {
mutex_lock(&vfio.iommu_drivers_lock);
list_for_each_entry(driver, &vfio.iommu_drivers_list,
vfio_next) {
if (!try_module_get(driver->ops->owner))
continue;
ret = driver->ops->ioctl(NULL,
VFIO_CHECK_EXTENSION,
arg);
module_put(driver->ops->owner);
if (ret > 0)
break;
}
mutex_unlock(&vfio.iommu_drivers_lock);
} else
ret = driver->ops->ioctl(container->iommu_data,
VFIO_CHECK_EXTENSION, arg);
}
up_read(&container->group_lock);
return ret;
}
/* hold write lock on container->group_lock */
static int __vfio_container_attach_groups(struct vfio_container *container,
struct vfio_iommu_driver *driver,
void *data)
{
struct vfio_group *group;
int ret = -ENODEV;
list_for_each_entry(group, &container->group_list, container_next) {
ret = driver->ops->attach_group(data, group->iommu_group);
if (ret)
goto unwind;
}
return ret;
unwind:
list_for_each_entry_continue_reverse(group, &container->group_list,
container_next) {
driver->ops->detach_group(data, group->iommu_group);
}
return ret;
}
static long vfio_ioctl_set_iommu(struct vfio_container *container,
unsigned long arg)
{
struct vfio_iommu_driver *driver;
long ret = -ENODEV;
down_write(&container->group_lock);
/*
* The container is designed to be an unprivileged interface while
* the group can be assigned to specific users. Therefore, only by
* adding a group to a container does the user get the privilege of
* enabling the iommu, which may allocate finite resources. There
* is no unset_iommu, but by removing all the groups from a container,
* the container is deprivileged and returns to an unset state.
*/
if (list_empty(&container->group_list) || container->iommu_driver) {
up_write(&container->group_lock);
return -EINVAL;
}
mutex_lock(&vfio.iommu_drivers_lock);
list_for_each_entry(driver, &vfio.iommu_drivers_list, vfio_next) {
void *data;
if (!try_module_get(driver->ops->owner))
continue;
/*
* The arg magic for SET_IOMMU is the same as CHECK_EXTENSION,
* so test which iommu driver reported support for this
* extension and call open on them. We also pass them the
* magic, allowing a single driver to support multiple
* interfaces if they'd like.
*/
if (driver->ops->ioctl(NULL, VFIO_CHECK_EXTENSION, arg) <= 0) {
module_put(driver->ops->owner);
continue;
}
/* module reference holds the driver we're working on */
mutex_unlock(&vfio.iommu_drivers_lock);
data = driver->ops->open(arg);
if (IS_ERR(data)) {
ret = PTR_ERR(data);
module_put(driver->ops->owner);
goto skip_drivers_unlock;
}
ret = __vfio_container_attach_groups(container, driver, data);
if (!ret) {
container->iommu_driver = driver;
container->iommu_data = data;
} else {
driver->ops->release(data);
module_put(driver->ops->owner);
}
goto skip_drivers_unlock;
}
mutex_unlock(&vfio.iommu_drivers_lock);
skip_drivers_unlock:
up_write(&container->group_lock);
return ret;
}
static long vfio_fops_unl_ioctl(struct file *filep,
unsigned int cmd, unsigned long arg)
{
struct vfio_container *container = filep->private_data;
struct vfio_iommu_driver *driver;
void *data;
long ret = -EINVAL;
if (!container)
return ret;
switch (cmd) {
case VFIO_GET_API_VERSION:
ret = VFIO_API_VERSION;
break;
case VFIO_CHECK_EXTENSION:
ret = vfio_ioctl_check_extension(container, arg);
break;
case VFIO_SET_IOMMU:
ret = vfio_ioctl_set_iommu(container, arg);
break;
default:
down_read(&container->group_lock);
driver = container->iommu_driver;
data = container->iommu_data;
if (driver) /* passthrough all unrecognized ioctls */
ret = driver->ops->ioctl(data, cmd, arg);
up_read(&container->group_lock);
}
return ret;
}
#ifdef CONFIG_COMPAT
static long vfio_fops_compat_ioctl(struct file *filep,
unsigned int cmd, unsigned long arg)
{
arg = (unsigned long)compat_ptr(arg);
return vfio_fops_unl_ioctl(filep, cmd, arg);
}
#endif /* CONFIG_COMPAT */
static int vfio_fops_open(struct inode *inode, struct file *filep)
{
struct vfio_container *container;
container = kzalloc(sizeof(*container), GFP_KERNEL);
if (!container)
return -ENOMEM;
INIT_LIST_HEAD(&container->group_list);
init_rwsem(&container->group_lock);
kref_init(&container->kref);
filep->private_data = container;
return 0;
}
static int vfio_fops_release(struct inode *inode, struct file *filep)
{
struct vfio_container *container = filep->private_data;
filep->private_data = NULL;
vfio_container_put(container);
return 0;
}
/*
* Once an iommu driver is set, we optionally pass read/write/mmap
* on to the driver, allowing management interfaces beyond ioctl.
*/
static ssize_t vfio_fops_read(struct file *filep, char __user *buf,
size_t count, loff_t *ppos)
{
struct vfio_container *container = filep->private_data;
struct vfio_iommu_driver *driver;
ssize_t ret = -EINVAL;
down_read(&container->group_lock);
driver = container->iommu_driver;
if (likely(driver && driver->ops->read))
ret = driver->ops->read(container->iommu_data,
buf, count, ppos);
up_read(&container->group_lock);
return ret;
}
static ssize_t vfio_fops_write(struct file *filep, const char __user *buf,
size_t count, loff_t *ppos)
{
struct vfio_container *container = filep->private_data;
struct vfio_iommu_driver *driver;
ssize_t ret = -EINVAL;
down_read(&container->group_lock);
driver = container->iommu_driver;
if (likely(driver && driver->ops->write))
ret = driver->ops->write(container->iommu_data,
buf, count, ppos);
up_read(&container->group_lock);
return ret;
}
static int vfio_fops_mmap(struct file *filep, struct vm_area_struct *vma)
{
struct vfio_container *container = filep->private_data;
struct vfio_iommu_driver *driver;
int ret = -EINVAL;
down_read(&container->group_lock);
driver = container->iommu_driver;
if (likely(driver && driver->ops->mmap))
ret = driver->ops->mmap(container->iommu_data, vma);
up_read(&container->group_lock);
return ret;
}
static const struct file_operations vfio_fops = {
.owner = THIS_MODULE,
.open = vfio_fops_open,
.release = vfio_fops_release,
.read = vfio_fops_read,
.write = vfio_fops_write,
.unlocked_ioctl = vfio_fops_unl_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = vfio_fops_compat_ioctl,
#endif
.mmap = vfio_fops_mmap,
};
/**
* VFIO Group fd, /dev/vfio/$GROUP
*/
static void __vfio_group_unset_container(struct vfio_group *group)
{
struct vfio_container *container = group->container;
struct vfio_iommu_driver *driver;
down_write(&container->group_lock);
driver = container->iommu_driver;
if (driver)
driver->ops->detach_group(container->iommu_data,
group->iommu_group);
group->container = NULL;
list_del(&group->container_next);
/* Detaching the last group deprivileges a container, remove iommu */
if (driver && list_empty(&container->group_list)) {
driver->ops->release(container->iommu_data);
module_put(driver->ops->owner);
container->iommu_driver = NULL;
container->iommu_data = NULL;
}
up_write(&container->group_lock);
vfio_container_put(container);
}
/*
* 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_unset_container(struct vfio_group *group)
{
int users = atomic_cmpxchg(&group->container_users, 1, 0);
if (!users)
return -EINVAL;
if (users != 1)
return -EBUSY;
__vfio_group_unset_container(group);
return 0;
}
/*
* When removing container users, anything that removes the last user
* implicitly removes the group from the container. That is, if the
* group file descriptor is closed, as well as any device file descriptors,
* the group is free.
*/
static void vfio_group_try_dissolve_container(struct vfio_group *group)
{
if (0 == atomic_dec_if_positive(&group->container_users))
__vfio_group_unset_container(group);
}
static int vfio_group_set_container(struct vfio_group *group, int container_fd)
{
struct fd f;
struct vfio_container *container;
struct vfio_iommu_driver *driver;
int ret = 0;
if (atomic_read(&group->container_users))
return -EINVAL;
f = fdget(container_fd);
if (!f.file)
return -EBADF;
/* Sanity check, is this really our fd? */
if (f.file->f_op != &vfio_fops) {
fdput(f);
return -EINVAL;
}
container = f.file->private_data;
WARN_ON(!container); /* fget ensures we don't race vfio_release */
down_write(&container->group_lock);
driver = container->iommu_driver;
if (driver) {
ret = driver->ops->attach_group(container->iommu_data,
group->iommu_group);
if (ret)
goto unlock_out;
}
group->container = container;
list_add(&group->container_next, &container->group_list);
/* Get a reference on the container and mark a user within the group */
vfio_container_get(container);
atomic_inc(&group->container_users);
unlock_out:
up_write(&container->group_lock);
fdput(f);
return ret;
}
static bool vfio_group_viable(struct vfio_group *group)
{
return (iommu_group_for_each_dev(group->iommu_group,
group, vfio_dev_viable) == 0);
}
static const struct file_operations vfio_device_fops;
static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
{
struct vfio_device *device;
struct file *filep;
int ret;
if (0 == atomic_read(&group->container_users) ||
!group->container->iommu_driver || !vfio_group_viable(group))
return -EINVAL;
device = vfio_device_get_from_name(group, buf);
if (!device)
return -ENODEV;
ret = device->ops->open(device->device_data);
if (ret) {
vfio_device_put(device);
return ret;
}
/*
* We can't use anon_inode_getfd() because we need to modify
* the f_mode flags directly to allow more than just ioctls
*/
ret = get_unused_fd_flags(O_CLOEXEC);
if (ret < 0) {
device->ops->release(device->device_data);
vfio_device_put(device);
return ret;
}
filep = anon_inode_getfile("[vfio-device]", &vfio_device_fops,
device, O_RDWR);
if (IS_ERR(filep)) {
put_unused_fd(ret);
ret = PTR_ERR(filep);
device->ops->release(device->device_data);
vfio_device_put(device);
return ret;
}
/*
* TODO: add an anon_inode interface to do this.
* Appears to be missing by lack of need rather than
* explicitly prevented. Now there's need.
*/
filep->f_mode |= (FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
atomic_inc(&group->container_users);
fd_install(ret, filep);
return ret;
}
static long vfio_group_fops_unl_ioctl(struct file *filep,
unsigned int cmd, unsigned long arg)
{
struct vfio_group *group = filep->private_data;
long ret = -ENOTTY;
switch (cmd) {
case VFIO_GROUP_GET_STATUS:
{
struct vfio_group_status status;
unsigned long minsz;
minsz = offsetofend(struct vfio_group_status, flags);
if (copy_from_user(&status, (void __user *)arg, minsz))
return -EFAULT;
if (status.argsz < minsz)
return -EINVAL;
status.flags = 0;
if (vfio_group_viable(group))
status.flags |= VFIO_GROUP_FLAGS_VIABLE;
if (group->container)
status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET;
if (copy_to_user((void __user *)arg, &status, minsz))
return -EFAULT;
ret = 0;
break;
}
case VFIO_GROUP_SET_CONTAINER:
{
int fd;
if (get_user(fd, (int __user *)arg))
return -EFAULT;
if (fd < 0)
return -EINVAL;
ret = vfio_group_set_container(group, fd);
break;
}
case VFIO_GROUP_UNSET_CONTAINER:
ret = vfio_group_unset_container(group);
break;
case VFIO_GROUP_GET_DEVICE_FD:
{
char *buf;
buf = strndup_user((const char __user *)arg, PAGE_SIZE);
if (IS_ERR(buf))
return PTR_ERR(buf);
ret = vfio_group_get_device_fd(group, buf);
kfree(buf);
break;
}
}
return ret;
}
#ifdef CONFIG_COMPAT
static long vfio_group_fops_compat_ioctl(struct file *filep,
unsigned int cmd, unsigned long arg)
{
arg = (unsigned long)compat_ptr(arg);
return vfio_group_fops_unl_ioctl(filep, cmd, arg);
}
#endif /* CONFIG_COMPAT */
static int vfio_group_fops_open(struct inode *inode, struct file *filep)
{
struct vfio_group *group;
int opened;
group = vfio_group_get_from_minor(iminor(inode));
if (!group)
return -ENODEV;
/* Do we need multiple instances of the group open? Seems not. */
opened = atomic_cmpxchg(&group->opened, 0, 1);
if (opened) {
vfio_group_put(group);
return -EBUSY;
}
/* Is something still in use from a previous open? */
if (group->container) {
atomic_dec(&group->opened);
vfio_group_put(group);
return -EBUSY;
}
filep->private_data = group;
return 0;
}
static int vfio_group_fops_release(struct inode *inode, struct file *filep)
{
struct vfio_group *group = filep->private_data;
filep->private_data = NULL;
vfio_group_try_dissolve_container(group);
atomic_dec(&group->opened);
vfio_group_put(group);
return 0;
}
static const struct file_operations vfio_group_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = vfio_group_fops_unl_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = vfio_group_fops_compat_ioctl,
#endif
.open = vfio_group_fops_open,
.release = vfio_group_fops_release,
};
/**
* VFIO Device fd
*/
static int vfio_device_fops_release(struct inode *inode, struct file *filep)
{
struct vfio_device *device = filep->private_data;
device->ops->release(device->device_data);
vfio_group_try_dissolve_container(device->group);
vfio_device_put(device);
return 0;
}
static long vfio_device_fops_unl_ioctl(struct file *filep,
unsigned int cmd, unsigned long arg)
{
struct vfio_device *device = filep->private_data;
if (unlikely(!device->ops->ioctl))
return -EINVAL;
return device->ops->ioctl(device->device_data, cmd, arg);
}
static ssize_t vfio_device_fops_read(struct file *filep, char __user *buf,
size_t count, loff_t *ppos)
{
struct vfio_device *device = filep->private_data;
if (unlikely(!device->ops->read))
return -EINVAL;
return device->ops->read(device->device_data, buf, count, ppos);
}
static ssize_t vfio_device_fops_write(struct file *filep,
const char __user *buf,
size_t count, loff_t *ppos)
{
struct vfio_device *device = filep->private_data;
if (unlikely(!device->ops->write))
return -EINVAL;
return device->ops->write(device->device_data, buf, count, ppos);
}
static int vfio_device_fops_mmap(struct file *filep, struct vm_area_struct *vma)
{
struct vfio_device *device = filep->private_data;
if (unlikely(!device->ops->mmap))
return -EINVAL;
return device->ops->mmap(device->device_data, vma);
}
#ifdef CONFIG_COMPAT
static long vfio_device_fops_compat_ioctl(struct file *filep,
unsigned int cmd, unsigned long arg)
{
arg = (unsigned long)compat_ptr(arg);
return vfio_device_fops_unl_ioctl(filep, cmd, arg);
}
#endif /* CONFIG_COMPAT */
static const struct file_operations vfio_device_fops = {
.owner = THIS_MODULE,
.release = vfio_device_fops_release,
.read = vfio_device_fops_read,
.write = vfio_device_fops_write,
.unlocked_ioctl = vfio_device_fops_unl_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = vfio_device_fops_compat_ioctl,
#endif
.mmap = vfio_device_fops_mmap,
};
/**
* External user API, exported by symbols to be linked dynamically.
*
* The protocol includes:
* 1. do normal VFIO init operation:
* - opening a new container;
* - attaching group(s) to it;
* - setting an IOMMU driver for a container.
* When IOMMU is set for a container, all groups in it are
* considered ready to use by an external user.
*
* 2. User space passes a group fd to an external user.
* The external user calls vfio_group_get_external_user()
* to verify that:
* - the group is initialized;
* - IOMMU is set for it.
* If both checks passed, vfio_group_get_external_user()
* increments the container user counter to prevent
* the VFIO group from disposal before KVM exits.
*
* 3. The external user calls vfio_external_user_iommu_id()
* to know an IOMMU ID.
*
* 4. When the external KVM finishes, it calls
* vfio_group_put_external_user() to release the VFIO group.
* This call decrements the container user counter.
*/
struct vfio_group *vfio_group_get_external_user(struct file *filep)
{
struct vfio_group *group = filep->private_data;
if (filep->f_op != &vfio_group_fops)
return ERR_PTR(-EINVAL);
if (!atomic_inc_not_zero(&group->container_users))
return ERR_PTR(-EINVAL);
if (!group->container->iommu_driver ||
!vfio_group_viable(group)) {
atomic_dec(&group->container_users);
return ERR_PTR(-EINVAL);
}
vfio_group_get(group);
return group;
}
EXPORT_SYMBOL_GPL(vfio_group_get_external_user);
void vfio_group_put_external_user(struct vfio_group *group)
{
vfio_group_put(group);
vfio_group_try_dissolve_container(group);
}
EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
int vfio_external_user_iommu_id(struct vfio_group *group)
{
return iommu_group_id(group->iommu_group);
}
EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id);
long vfio_external_check_extension(struct vfio_group *group, unsigned long arg)
{
return vfio_ioctl_check_extension(group->container, arg);
}
EXPORT_SYMBOL_GPL(vfio_external_check_extension);
/**
* Module/class support
*/
static char *vfio_devnode(struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "vfio/%s", dev_name(dev));
}
static struct miscdevice vfio_dev = {
.minor = VFIO_MINOR,
.name = "vfio",
.fops = &vfio_fops,
.nodename = "vfio/vfio",
.mode = S_IRUGO | S_IWUGO,
};
static int __init vfio_init(void)
{
int ret;
idr_init(&vfio.group_idr);
mutex_init(&vfio.group_lock);
mutex_init(&vfio.iommu_drivers_lock);
INIT_LIST_HEAD(&vfio.group_list);
INIT_LIST_HEAD(&vfio.iommu_drivers_list);
init_waitqueue_head(&vfio.release_q);
ret = misc_register(&vfio_dev);
if (ret) {
pr_err("vfio: misc device register failed\n");
return ret;
}
/* /dev/vfio/$GROUP */
vfio.class = class_create(THIS_MODULE, "vfio");
if (IS_ERR(vfio.class)) {
ret = PTR_ERR(vfio.class);
goto err_class;
}
vfio.class->devnode = vfio_devnode;
ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK, "vfio");
if (ret)
goto err_alloc_chrdev;
cdev_init(&vfio.group_cdev, &vfio_group_fops);
ret = cdev_add(&vfio.group_cdev, vfio.group_devt, MINORMASK);
if (ret)
goto err_cdev_add;
pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
/*
* Attempt to load known iommu-drivers. This gives us a working
* environment without the user needing to explicitly load iommu
* drivers.
*/
request_module_nowait("vfio_iommu_type1");
request_module_nowait("vfio_iommu_spapr_tce");
return 0;
err_cdev_add:
unregister_chrdev_region(vfio.group_devt, MINORMASK);
err_alloc_chrdev:
class_destroy(vfio.class);
vfio.class = NULL;
err_class:
misc_deregister(&vfio_dev);
return ret;
}
static void __exit vfio_cleanup(void)
{
WARN_ON(!list_empty(&vfio.group_list));
idr_destroy(&vfio.group_idr);
cdev_del(&vfio.group_cdev);
unregister_chrdev_region(vfio.group_devt, MINORMASK);
class_destroy(vfio.class);
vfio.class = NULL;
misc_deregister(&vfio_dev);
}
module_init(vfio_init);
module_exit(vfio_cleanup);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_ALIAS_MISCDEV(VFIO_MINOR);
MODULE_ALIAS("devname:vfio/vfio");