vfio: Include No-IOMMU mode (03a76b60) · Commits · 戴 / test

drivers/vfio/Kconfig

+15 −0

Original line number	Diff line number	Diff line
		@@ -31,6 +31,21 @@ menuconfig VFIO

		If you don't know what to do here, say N.

		menuconfig VFIO_NOIOMMU
		bool "VFIO No-IOMMU support"
		depends on VFIO
		help
		VFIO is built on the ability to isolate devices using the IOMMU.
		Only with an IOMMU can userspace access to DMA capable devices be
		considered secure. VFIO No-IOMMU mode enables IOMMU groups for
		devices without IOMMU backing for the purpose of re-using the VFIO
		infrastructure in a non-secure mode. Use of this mode will result
		in an unsupportable kernel and will therefore taint the kernel.
		Device assignment to virtual machines is also not possible with
		this mode since there is no IOMMU to provide DMA translation.

		If you don't know what to do here, say N.

		source "drivers/vfio/pci/Kconfig"
		source "drivers/vfio/platform/Kconfig"
		source "virt/lib/Kconfig"

drivers/vfio/pci/vfio_pci.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -940,13 +940,13 @@ static int vfio_pci_probe(struct pci_dev pdev, const struct pci_device_id id)
		if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL)
		return -EINVAL;

		group = iommu_group_get(&pdev->dev);
		group = vfio_iommu_group_get(&pdev->dev);
		if (!group)
		return -EINVAL;

		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
		if (!vdev) {
		iommu_group_put(group);
		vfio_iommu_group_put(group, &pdev->dev);
		return -ENOMEM;
		}

		@@ -957,7 +957,7 @@ static int vfio_pci_probe(struct pci_dev pdev, const struct pci_device_id id)

		ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
		if (ret) {
		iommu_group_put(group);
		vfio_iommu_group_put(group, &pdev->dev);
		kfree(vdev);
		return ret;
		}
		@@ -993,7 +993,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)
		if (!vdev)
		return;

		iommu_group_put(pdev->dev.iommu_group);
		vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
		kfree(vdev);

		if (vfio_pci_is_vga(pdev)) {

drivers/vfio/vfio.c

+181 −3

Original line number	Diff line number	Diff line
		@@ -62,6 +62,7 @@ struct vfio_container {
		struct rw_semaphore group_lock;
		struct vfio_iommu_driver *iommu_driver;
		void *iommu_data;
		bool noiommu;
		};

		struct vfio_unbound_dev {
		@@ -84,6 +85,7 @@ struct vfio_group {
		struct list_head unbound_list;
		struct mutex unbound_lock;
		atomic_t opened;
		bool noiommu;
		};

		struct vfio_device {
		@@ -95,6 +97,128 @@ struct vfio_device {
		void *device_data;
		};

		#ifdef CONFIG_VFIO_NOIOMMU
		static bool noiommu __read_mostly;
		module_param_named(enable_unsafe_noiommu_mode,
		noiommu, bool, S_IRUGO \| S_IWUSR);
		MODULE_PARM_DESC(enable_unsafe_noiommu_mode, "Enable UNSAFE, no-IOMMU mode. This mode provides no device isolation, no DMA translation, no host kernel protection, cannot be used for device assignment to virtual machines, requires RAWIO permissions, and will taint the kernel. If you do not know what this is for, step away. (default: false)");
		#endif

		/*
		* vfio_iommu_group_{get,put} are only intended for VFIO bus driver probe
		* and remove functions, any use cases other than acquiring the first
		* reference for the purpose of calling vfio_add_group_dev() or removing
		* that symmetric reference after vfio_del_group_dev() should use the raw
		* iommu_group_{get,put} functions. In particular, vfio_iommu_group_put()
		* removes the device from the dummy group and cannot be nested.
		*/
		struct iommu_group vfio_iommu_group_get(struct device dev)
		{
		struct iommu_group *group;
		int __maybe_unused ret;

		group = iommu_group_get(dev);

		#ifdef CONFIG_VFIO_NOIOMMU
		/*
		* With noiommu enabled, an IOMMU group will be created for a device
		* that doesn't already have one and doesn't have an iommu_ops on their
		* bus. We use iommu_present() again in the main code to detect these
		* fake groups.
		*/
		if (group \|\| !noiommu \|\| iommu_present(dev->bus))
		return group;

		group = iommu_group_alloc();
		if (IS_ERR(group))
		return NULL;

		iommu_group_set_name(group, "vfio-noiommu");
		ret = iommu_group_add_device(group, dev);
		iommu_group_put(group);
		if (ret)
		return NULL;

		/*
		* Where to taint? At this point we've added an IOMMU group for a
		* device that is not backed by iommu_ops, therefore any iommu_
		* callback using iommu_ops can legitimately Oops. So, while we may
		* be about to give a DMA capable device to a user without IOMMU
		* protection, which is clearly taint-worthy, let's go ahead and do
		* it here.
		*/
		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
		dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
		#endif

		return group;
		}
		EXPORT_SYMBOL_GPL(vfio_iommu_group_get);

		void vfio_iommu_group_put(struct iommu_group group, struct device dev)
		{
		#ifdef CONFIG_VFIO_NOIOMMU
		if (!iommu_present(dev->bus))
		iommu_group_remove_device(dev);
		#endif

		iommu_group_put(group);
		}
		EXPORT_SYMBOL_GPL(vfio_iommu_group_put);

		#ifdef CONFIG_VFIO_NOIOMMU
		static void *vfio_noiommu_open(unsigned long arg)
		{
		if (arg != VFIO_NOIOMMU_IOMMU)
		return ERR_PTR(-EINVAL);
		if (!capable(CAP_SYS_RAWIO))
		return ERR_PTR(-EPERM);

		return NULL;
		}

		static void vfio_noiommu_release(void *iommu_data)
		{
		}

		static long vfio_noiommu_ioctl(void *iommu_data,
		unsigned int cmd, unsigned long arg)
		{
		if (cmd == VFIO_CHECK_EXTENSION)
		return noiommu && (arg == VFIO_NOIOMMU_IOMMU) ? 1 : 0;

		return -ENOTTY;
		}

		static int vfio_iommu_present(struct device dev, void unused)
		{
		return iommu_present(dev->bus) ? 1 : 0;
		}

		static int vfio_noiommu_attach_group(void *iommu_data,
		struct iommu_group *iommu_group)
		{
		return iommu_group_for_each_dev(iommu_group, NULL,
		vfio_iommu_present) ? -EINVAL : 0;
		}

		static void vfio_noiommu_detach_group(void *iommu_data,
		struct iommu_group *iommu_group)
		{
		}

		static const struct vfio_iommu_driver_ops vfio_noiommu_ops = {
		.name = "vfio-noiommu",
		.owner = THIS_MODULE,
		.open = vfio_noiommu_open,
		.release = vfio_noiommu_release,
		.ioctl = vfio_noiommu_ioctl,
		.attach_group = vfio_noiommu_attach_group,
		.detach_group = vfio_noiommu_detach_group,
		};
		#endif


		/**
		* IOMMU driver registration
		*/
		@@ -199,7 +323,8 @@ static void vfio_group_unlock_and_free(struct vfio_group *group)
		/**
		* Group objects - create, release, get, put, search
		*/
		static struct vfio_group vfio_create_group(struct iommu_group iommu_group)
		static struct vfio_group vfio_create_group(struct iommu_group iommu_group,
		bool iommu_present)
		{
		struct vfio_group group, tmp;
		struct device *dev;
		@@ -217,6 +342,7 @@ static struct vfio_group vfio_create_group(struct iommu_group iommu_group)
		atomic_set(&group->container_users, 0);
		atomic_set(&group->opened, 0);
		group->iommu_group = iommu_group;
		group->noiommu = !iommu_present;

		group->nb.notifier_call = vfio_iommu_group_notifier;

		@@ -252,7 +378,8 @@ static struct vfio_group vfio_create_group(struct iommu_group iommu_group)

		dev = device_create(vfio.class, NULL,
		MKDEV(MAJOR(vfio.group_devt), minor),
		group, "%d", iommu_group_id(iommu_group));
		group, "%s%d", group->noiommu ? "noiommu-" : "",
		iommu_group_id(iommu_group));
		if (IS_ERR(dev)) {
		vfio_free_group_minor(minor);
		vfio_group_unlock_and_free(group);
		@@ -640,7 +767,7 @@ int vfio_add_group_dev(struct device *dev,

		group = vfio_group_get_from_iommu(iommu_group);
		if (!group) {
		group = vfio_create_group(iommu_group);
		group = vfio_create_group(iommu_group, iommu_present(dev->bus));
		if (IS_ERR(group)) {
		iommu_group_put(iommu_group);
		return PTR_ERR(group);
		@@ -854,6 +981,14 @@ static long vfio_ioctl_check_extension(struct vfio_container *container,
		mutex_lock(&vfio.iommu_drivers_lock);
		list_for_each_entry(driver, &vfio.iommu_drivers_list,
		vfio_next) {

		#ifdef CONFIG_VFIO_NOIOMMU
		if (!list_empty(&container->group_list) &&
		(container->noiommu !=
		(driver->ops == &vfio_noiommu_ops)))
		continue;
		#endif

		if (!try_module_get(driver->ops->owner))
		continue;

		@@ -925,6 +1060,15 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container,
		list_for_each_entry(driver, &vfio.iommu_drivers_list, vfio_next) {
		void *data;

		#ifdef CONFIG_VFIO_NOIOMMU
		/*
		* Only noiommu containers can use vfio-noiommu and noiommu
		* containers can only use vfio-noiommu.
		*/
		if (container->noiommu != (driver->ops == &vfio_noiommu_ops))
		continue;
		#endif

		if (!try_module_get(driver->ops->owner))
		continue;

		@@ -1187,6 +1331,9 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
		if (atomic_read(&group->container_users))
		return -EINVAL;

		if (group->noiommu && !capable(CAP_SYS_RAWIO))
		return -EPERM;

		f = fdget(container_fd);
		if (!f.file)
		return -EBADF;
		@@ -1202,6 +1349,13 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)

		down_write(&container->group_lock);

		/* Real groups and fake groups cannot mix */
		if (!list_empty(&container->group_list) &&
		container->noiommu != group->noiommu) {
		ret = -EPERM;
		goto unlock_out;
		}

		driver = container->iommu_driver;
		if (driver) {
		ret = driver->ops->attach_group(container->iommu_data,
		@@ -1211,6 +1365,7 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
		}

		group->container = container;
		container->noiommu = group->noiommu;
		list_add(&group->container_next, &container->group_list);

		/* Get a reference on the container and mark a user within the group */
		@@ -1241,6 +1396,9 @@ static int vfio_group_get_device_fd(struct vfio_group group, char buf)
		!group->container->iommu_driver \|\| !vfio_group_viable(group))
		return -EINVAL;

		if (group->noiommu && !capable(CAP_SYS_RAWIO))
		return -EPERM;

		device = vfio_device_get_from_name(group, buf);
		if (!device)
		return -ENODEV;
		@@ -1283,6 +1441,10 @@ static int vfio_group_get_device_fd(struct vfio_group group, char buf)

		fd_install(ret, filep);

		if (group->noiommu)
		dev_warn(device->dev, "vfio-noiommu device opened by user "
		"(%s:%d)\n", current->comm, task_pid_nr(current));

		return ret;
		}

		@@ -1371,6 +1533,11 @@ static int vfio_group_fops_open(struct inode inode, struct file filep)
		if (!group)
		return -ENODEV;

		if (group->noiommu && !capable(CAP_SYS_RAWIO)) {
		vfio_group_put(group);
		return -EPERM;
		}

		/* Do we need multiple instances of the group open? Seems not. */
		opened = atomic_cmpxchg(&group->opened, 0, 1);
		if (opened) {
		@@ -1533,6 +1700,11 @@ struct vfio_group vfio_group_get_external_user(struct file filep)
		if (!atomic_inc_not_zero(&group->container_users))
		return ERR_PTR(-EINVAL);

		if (group->noiommu) {
		atomic_dec(&group->container_users);
		return ERR_PTR(-EPERM);
		}

		if (!group->container->iommu_driver \|\|
		!vfio_group_viable(group)) {
		atomic_dec(&group->container_users);
		@@ -1625,6 +1797,9 @@ static int __init vfio_init(void)
		request_module_nowait("vfio_iommu_type1");
		request_module_nowait("vfio_iommu_spapr_tce");

		#ifdef CONFIG_VFIO_NOIOMMU
		vfio_register_iommu_driver(&vfio_noiommu_ops);
		#endif
		return 0;

		err_cdev_add:
		@@ -1641,6 +1816,9 @@ static void __exit vfio_cleanup(void)
		{
		WARN_ON(!list_empty(&vfio.group_list));

		#ifdef CONFIG_VFIO_NOIOMMU
		vfio_unregister_iommu_driver(&vfio_noiommu_ops);
		#endif
		idr_destroy(&vfio.group_idr);
		cdev_del(&vfio.group_cdev);
		unregister_chrdev_region(vfio.group_devt, MINORMASK);

include/linux/vfio.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -44,6 +44,9 @@ struct vfio_device_ops {
		void (request)(void device_data, unsigned int count);
		};

		extern struct iommu_group vfio_iommu_group_get(struct device dev);
		extern void vfio_iommu_group_put(struct iommu_group group, struct device dev);

		extern int vfio_add_group_dev(struct device *dev,
		const struct vfio_device_ops *ops,
		void *device_data);

include/uapi/linux/vfio.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -38,6 +38,13 @@

		#define VFIO_SPAPR_TCE_v2_IOMMU 7

		/*
		* The No-IOMMU IOMMU offers no translation or isolation for devices and
		* supports no ioctls outside of VFIO_CHECK_EXTENSION. Use of VFIO's No-IOMMU
		* code will taint the host kernel and should be used with extreme caution.
		*/
		#define VFIO_NOIOMMU_IOMMU 8

		/*
		* The IOCTL interface is designed for extensibility by embedding the
		* structure length (argsz) and flags into structures passed between

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