/* * 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/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; 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 rw_semaphore 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; 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) { /* index 0 is used by /dev/vfio/vfio */ return idr_alloc(&vfio.group_idr, group, 1, 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); 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); minor = vfio_alloc_group_minor(group); if (minor < 0) { vfio_group_unlock_and_free(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); vfio_group_unlock_and_free(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); 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); 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); vfio_group_unlock_and_free(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; 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; 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; } /* * 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", "pcieport" }; 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; struct device_driver *drv = ACCESS_ONCE(dev->driver); if (!drv || vfio_whitelisted_driver(drv)) 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_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. 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. */ 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); /** * Get a reference to the vfio_device for a device that is known to * be bound to a vfio driver. The driver implicitly holds a * vfio_device reference between vfio_add_group_dev and * vfio_del_group_dev. We can therefore use drvdata to increment * that reference from the struct device. This additional * reference must be released by calling vfio_device_put. */ struct vfio_device *vfio_device_get_from_dev(struct device *dev) { struct vfio_device *device = dev_get_drvdata(dev); vfio_device_get(device); return device; } EXPORT_SYMBOL_GPL(vfio_device_get_from_dev); /* * 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; struct iommu_group *iommu_group = group->iommu_group; void *device_data = device->device_data; /* * 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); vfio_device_put(device); /* TODO send a signal to encourage this to be released */ wait_event(vfio.release_q, !vfio_dev_present(group, dev)); vfio_group_put(group); 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; 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 = -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_flags(O_CLOEXEC); 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); vfio_device_get(device); atomic_inc(&group->container_users); fd_install(ret, filep); 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; 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); /** * Module/class support */ static char *vfio_devnode(struct device *dev, umode_t *mode) { if (mode && (MINOR(dev->devt) == 0)) *mode = S_IRUGO | S_IWUGO; 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"); request_module_nowait("vfio_iommu_spapr_tce"); 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);