Commit 3af91771 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Alex Williamson
Browse files

vfio: refactor noiommu group creation 



Split the actual noiommu group creation from vfio_iommu_group_get into a
new helper, and open code the rest of vfio_iommu_group_get in its only
caller.  This creates an entirely separate and clear code path for the
noiommu group creation.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-6-hch@lst.de


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 1362591f

drivers/vfio/vfio.c

+52 −52
Original line number Diff line number Diff line
@@ -169,50 +169,6 @@ static void vfio_release_device_set(struct vfio_device *device) 
	xa_unlock(&vfio_device_set_xa);

}



static 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 set iommudata simply to be able to identify these groups

	 * as special use and for reclamation later.

	 */

	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");

	iommu_group_set_iommudata(group, &noiommu, NULL);

	ret = iommu_group_add_device(group, dev);

	if (ret) {

		iommu_group_put(group);

		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;

}



#ifdef CONFIG_VFIO_NOIOMMU

static void *vfio_noiommu_open(unsigned long arg)

{
@@ -823,12 +779,61 @@ void vfio_uninit_group_dev(struct vfio_device *device) 
}

EXPORT_SYMBOL_GPL(vfio_uninit_group_dev);



struct vfio_group *vfio_group_find_or_alloc(struct device *dev)

#ifdef CONFIG_VFIO_NOIOMMU

static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev)

{

	struct iommu_group *iommu_group;

	struct vfio_group *group;

	int ret;



	iommu_group = iommu_group_alloc();

	if (IS_ERR(iommu_group))

		return ERR_CAST(iommu_group);



	iommu_group_set_name(iommu_group, "vfio-noiommu");

	iommu_group_set_iommudata(iommu_group, &noiommu, NULL);

	ret = iommu_group_add_device(iommu_group, dev);

	if (ret)

		goto out_put_group;



	group = vfio_create_group(iommu_group);

	if (IS_ERR(group)) {

		ret = PTR_ERR(group);

		goto out_remove_device;

	}



	return group;



out_remove_device:

	iommu_group_remove_device(dev);

out_put_group:

	iommu_group_put(iommu_group);

	return ERR_PTR(ret);

}

#endif



static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)

{

	struct iommu_group *iommu_group;

	struct vfio_group *group;



	iommu_group = vfio_iommu_group_get(dev);

	iommu_group = iommu_group_get(dev);

#ifdef CONFIG_VFIO_NOIOMMU

	if (!iommu_group && noiommu && !iommu_present(dev->bus)) {

		/*

		 * With noiommu enabled, create an IOMMU group for devices that

		 * don't already have one and don't have an iommu_ops on their

		 * bus.  Taint the kernel because we're about to give a DMA

		 * capable device to a user without IOMMU protection.

		 */

		group = vfio_noiommu_group_alloc(dev);

		if (!IS_ERR(group)) {

			add_taint(TAINT_USER, LOCKDEP_STILL_OK);

			dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");

		}

		return group;

	}

#endif

	if (!iommu_group)

		return ERR_PTR(-EINVAL);
@@ -840,14 +845,9 @@ struct vfio_group *vfio_group_find_or_alloc(struct device *dev) 
	/* a newly created vfio_group keeps the reference. */

	group = vfio_create_group(iommu_group);

	if (IS_ERR(group))

		goto out_remove;

		goto out_put;

	return group;



out_remove:

#ifdef CONFIG_VFIO_NOIOMMU

	if (iommu_group_get_iommudata(iommu_group) == &noiommu)

		iommu_group_remove_device(dev);

#endif

out_put:

	iommu_group_put(iommu_group);

	return group;