X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=kernel%2Fdrivers%2Fvfio%2Fvfio.c;fp=kernel%2Fdrivers%2Fvfio%2Fvfio.c;h=e1278fe04b1e7ba16eddbece247c21620b6e8fb7;hb=9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00;hp=0000000000000000000000000000000000000000;hpb=98260f3884f4a202f9ca5eabed40b1354c489b29;p=kvmfornfv.git diff --git a/kernel/drivers/vfio/vfio.c b/kernel/drivers/vfio/vfio.c new file mode 100644 index 000000000..e1278fe04 --- /dev/null +++ b/kernel/drivers/vfio/vfio.c @@ -0,0 +1,1612 @@ +/* + * VFIO core + * + * Copyright (C) 2012 Red Hat, Inc. All rights reserved. + * Author: Alex Williamson + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define DRIVER_VERSION "0.3" +#define DRIVER_AUTHOR "Alex Williamson " +#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; +} + +/* + * 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 in + * one of the following states: + * - driver-less + * - bound to a vfio driver + * - bound to a whitelisted driver + * + * 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_whitelisted_driver(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("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 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; + 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 = -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); + +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");