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-rw-r--r--drivers/vfio/vfio.c1420
1 files changed, 1420 insertions, 0 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
new file mode 100644
index 000000000000..9591e2b509d7
--- /dev/null
+++ b/drivers/vfio/vfio.c
@@ -0,0 +1,1420 @@
+/*
+ * 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/module.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/slab.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;
+ struct device *dev;
+ dev_t devt;
+ struct cdev cdev;
+ 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 mutex group_lock;
+ struct vfio_iommu_driver *iommu_driver;
+ void *iommu_data;
+};
+
+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 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)
+{
+ int ret, minor;
+
+again:
+ if (unlikely(idr_pre_get(&vfio.group_idr, GFP_KERNEL) == 0))
+ return -ENOMEM;
+
+ /* index 0 is used by /dev/vfio/vfio */
+ ret = idr_get_new_above(&vfio.group_idr, group, 1, &minor);
+ if (ret == -EAGAIN)
+ goto again;
+ if (ret || minor > MINORMASK) {
+ if (minor > MINORMASK)
+ idr_remove(&vfio.group_idr, minor);
+ return -ENOSPC;
+ }
+
+ return minor;
+}
+
+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);
+}
+
+/**
+ * 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);
+ atomic_set(&group->container_users, 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);
+
+ minor = vfio_alloc_group_minor(group);
+ if (minor < 0) {
+ mutex_unlock(&vfio.group_lock);
+ kfree(group);
+ return ERR_PTR(minor);
+ }
+
+ /* 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_free_group_minor(minor);
+ mutex_unlock(&vfio.group_lock);
+ kfree(group);
+ return tmp;
+ }
+ }
+
+ dev = device_create(vfio.class, NULL, MKDEV(MAJOR(vfio.devt), minor),
+ group, "%d", iommu_group_id(iommu_group));
+ if (IS_ERR(dev)) {
+ vfio_free_group_minor(minor);
+ mutex_unlock(&vfio.group_lock);
+ kfree(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;
+}
+
+static void vfio_group_release(struct kref *kref)
+{
+ struct vfio_group *group = container_of(kref, struct vfio_group, kref);
+
+ WARN_ON(!list_empty(&group->device_list));
+
+ device_destroy(vfio.class, MKDEV(MAJOR(vfio.devt), group->minor));
+ list_del(&group->vfio_next);
+ vfio_free_group_minor(group->minor);
+
+ 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);
+}
+
+static void vfio_group_put(struct vfio_group *group)
+{
+ mutex_lock(&vfio.group_lock);
+ /*
+ * Release needs to unlock to unregister the notifier, so only
+ * unlock if not released.
+ */
+ if (!kref_put(&group->kref, vfio_group_release))
+ mutex_unlock(&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;
+ int ret;
+
+ 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;
+
+ ret = dev_set_drvdata(dev, device);
+ if (ret) {
+ kfree(device);
+ return ERR_PTR(ret);
+ }
+
+ /* 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;
+
+ mutex_lock(&group->device_lock);
+ 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 */
+static void vfio_device_put(struct vfio_device *device)
+{
+ kref_put(&device->kref, vfio_device_release);
+ vfio_group_put(device->group);
+}
+
+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;
+}
+
+/*
+ * Whitelist some drivers that we know are safe (no dma) or just sit on
+ * a device. It's not always practical to leave a device within a group
+ * driverless as it could get re-bound to something unsafe.
+ */
+static const char * const vfio_driver_whitelist[] = { "pci-stub" };
+
+static bool vfio_whitelisted_driver(struct device_driver *drv)
+{
+ int i;
+
+ 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 either
+ * driver-less or bound to a vfio or whitelisted driver. We test the
+ * latter by the existence of a struct vfio_device matching the dev.
+ */
+static int vfio_dev_viable(struct device *dev, void *data)
+{
+ struct vfio_group *group = data;
+ struct vfio_device *device;
+
+ if (!dev->driver || vfio_whitelisted_driver(dev->driver))
+ return 0;
+
+ device = vfio_group_get_device(group, dev);
+ if (device) {
+ vfio_device_put(device);
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+/**
+ * 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("Device %s added to live group %d!\n", dev_name(dev),
+ iommu_group_id(group->iommu_group));
+
+ return 0;
+}
+
+static int vfio_group_nb_del_dev(struct vfio_group *group, struct device *dev)
+{
+ struct vfio_device *device;
+
+ /*
+ * Expect to fall out here. If a device was in use, it would
+ * have been bound to a vfio sub-driver, which would have blocked
+ * in .remove at vfio_del_group_dev. Sanity check that we no
+ * longer track the device, so it's safe to remove.
+ */
+ device = vfio_group_get_device(group, dev);
+ if (likely(!device))
+ return 0;
+
+ WARN("Device %s removed from live group %d!\n", dev_name(dev),
+ iommu_group_id(group->iommu_group));
+
+ vfio_device_put(device);
+ 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;
+
+ /*
+ * Need to go through a group_lock lookup to get a reference or
+ * we risk racing a group being removed. Leave a WARN_ON for
+ * debuging, but if the group no longer exists, a spurious notify
+ * is harmless.
+ */
+ group = vfio_group_try_get(group);
+ if (WARN_ON(!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:
+ vfio_group_nb_del_dev(group, dev);
+ 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.
+ */
+ 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);
+ }
+ }
+
+ 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);
+ iommu_group_put(iommu_group);
+ return -EBUSY;
+ }
+
+ device = vfio_group_create_device(group, dev, ops, device_data);
+ if (IS_ERR(device)) {
+ vfio_group_put(group);
+ iommu_group_put(iommu_group);
+ return PTR_ERR(device);
+ }
+
+ /*
+ * Added device holds reference to iommu_group and vfio_device
+ * (which in turn holds reference to vfio_group). Drop extra
+ * group reference used while acquiring device.
+ */
+ vfio_group_put(group);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_add_group_dev);
+
+/* Test whether a struct device is present in our tracking */
+static bool vfio_dev_present(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 false;
+
+ group = vfio_group_get_from_iommu(iommu_group);
+ if (!group) {
+ iommu_group_put(iommu_group);
+ return false;
+ }
+
+ device = vfio_group_get_device(group, dev);
+ if (!device) {
+ vfio_group_put(group);
+ iommu_group_put(iommu_group);
+ return false;
+ }
+
+ vfio_device_put(device);
+ vfio_group_put(group);
+ iommu_group_put(iommu_group);
+ 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;
+ struct iommu_group *iommu_group = group->iommu_group;
+ void *device_data = device->device_data;
+
+ vfio_device_put(device);
+
+ /* TODO send a signal to encourage this to be released */
+ wait_event(vfio.release_q, !vfio_dev_present(dev));
+
+ iommu_group_put(iommu_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 = container->iommu_driver;
+ long ret = 0;
+
+ 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);
+ }
+
+ return ret;
+}
+
+/* hold 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;
+
+ mutex_lock(&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) {
+ mutex_unlock(&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:
+ mutex_unlock(&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;
+
+ driver = container->iommu_driver;
+ data = container->iommu_data;
+
+ 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:
+ if (driver) /* passthrough all unrecognized ioctls */
+ ret = driver->ops->ioctl(data, cmd, arg);
+ }
+
+ 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);
+ mutex_init(&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 = container->iommu_driver;
+
+ if (unlikely(!driver || !driver->ops->read))
+ return -EINVAL;
+
+ return driver->ops->read(container->iommu_data, buf, count, ppos);
+}
+
+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 = container->iommu_driver;
+
+ if (unlikely(!driver || !driver->ops->write))
+ return -EINVAL;
+
+ return driver->ops->write(container->iommu_data, buf, count, ppos);
+}
+
+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 = container->iommu_driver;
+
+ if (unlikely(!driver || !driver->ops->mmap))
+ return -EINVAL;
+
+ return driver->ops->mmap(container->iommu_data, vma);
+}
+
+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;
+
+ mutex_lock(&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;
+ }
+
+ mutex_unlock(&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 file *filep;
+ struct vfio_container *container;
+ struct vfio_iommu_driver *driver;
+ int ret = 0;
+
+ if (atomic_read(&group->container_users))
+ return -EINVAL;
+
+ filep = fget(container_fd);
+ if (!filep)
+ return -EBADF;
+
+ /* Sanity check, is this really our fd? */
+ if (filep->f_op != &vfio_fops) {
+ fput(filep);
+ return -EINVAL;
+ }
+
+ container = filep->private_data;
+ WARN_ON(!container); /* fget ensures we don't race vfio_release */
+
+ mutex_lock(&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:
+ mutex_unlock(&container->group_lock);
+ fput(filep);
+
+ 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 = -ENODEV;
+
+ if (0 == atomic_read(&group->container_users) ||
+ !group->container->iommu_driver || !vfio_group_viable(group))
+ return -EINVAL;
+
+ mutex_lock(&group->device_lock);
+ list_for_each_entry(device, &group->device_list, group_next) {
+ if (strcmp(dev_name(device->dev), buf))
+ continue;
+
+ ret = device->ops->open(device->device_data);
+ if (ret)
+ break;
+ /*
+ * 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();
+ if (ret < 0) {
+ device->ops->release(device->device_data);
+ break;
+ }
+
+ 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);
+ break;
+ }
+
+ /*
+ * 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);
+
+ fd_install(ret, filep);
+
+ vfio_device_get(device);
+ atomic_inc(&group->container_users);
+ break;
+ }
+ mutex_unlock(&group->device_lock);
+
+ 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;
+
+ group = vfio_group_get_from_minor(iminor(inode));
+ if (!group)
+ return -ENODEV;
+
+ if (group->container) {
+ 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);
+
+ 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,
+};
+
+/**
+ * Module/class support
+ */
+static char *vfio_devnode(struct device *dev, umode_t *mode)
+{
+ return kasprintf(GFP_KERNEL, "vfio/%s", dev_name(dev));
+}
+
+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);
+
+ 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.devt, 0, MINORMASK, "vfio");
+ if (ret)
+ goto err_base_chrdev;
+
+ cdev_init(&vfio.cdev, &vfio_fops);
+ ret = cdev_add(&vfio.cdev, vfio.devt, 1);
+ if (ret)
+ goto err_base_cdev;
+
+ vfio.dev = device_create(vfio.class, NULL, vfio.devt, NULL, "vfio");
+ if (IS_ERR(vfio.dev)) {
+ ret = PTR_ERR(vfio.dev);
+ goto err_base_dev;
+ }
+
+ /* /dev/vfio/$GROUP */
+ cdev_init(&vfio.group_cdev, &vfio_group_fops);
+ ret = cdev_add(&vfio.group_cdev,
+ MKDEV(MAJOR(vfio.devt), 1), MINORMASK - 1);
+ if (ret)
+ goto err_groups_cdev;
+
+ 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");
+
+ return 0;
+
+err_groups_cdev:
+ device_destroy(vfio.class, vfio.devt);
+err_base_dev:
+ cdev_del(&vfio.cdev);
+err_base_cdev:
+ unregister_chrdev_region(vfio.devt, MINORMASK);
+err_base_chrdev:
+ class_destroy(vfio.class);
+ vfio.class = NULL;
+err_class:
+ 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);
+ device_destroy(vfio.class, vfio.devt);
+ cdev_del(&vfio.cdev);
+ unregister_chrdev_region(vfio.devt, MINORMASK);
+ class_destroy(vfio.class);
+ vfio.class = NULL;
+}
+
+module_init(vfio_init);
+module_exit(vfio_cleanup);
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.