Patch "vfio/powerpc/spapr_tce: Enforce IOMMU type compatibility check" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

vfio/powerpc/spapr_tce: Enforce IOMMU type compatibility check

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
vfio-powerpc-spapr_tce-enforce-iommu-type-compatibility-check.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alexey Kardashevskiy <[email protected]>
Date: Fri, 24 Mar 2017 17:44:06 +1100
Subject: vfio/powerpc/spapr_tce: Enforce IOMMU type compatibility check

From: Alexey Kardashevskiy <[email protected]>

[ Upstream commit 1282ba7fc28dbc66c3f0e4aaafaaa228361d1ae5 ]

The existing SPAPR TCE driver advertises both VFIO_SPAPR_TCE_IOMMU and VFIO_SPAPR_TCE_v2_IOMMU types to the userspace and the userspace usually picks the v2.

Normally the userspace would create a container, attach an IOMMU group to it and only then set the IOMMU type (which would normally be v2).

However a specific IOMMU group may not support v2, in other words it may not implement set_window/unset_window/take_ownership/ release_ownership and such a group should not be attached to a v2 container.

This adds extra checks that a new group can do what the selected IOMMU type suggests. The userspace can then test the return value from ioctl(VFIO_SET_IOMMU, VFIO_SPAPR_TCE_v2_IOMMU) and try VFIO_SPAPR_TCE_IOMMU.

---
 drivers/vfio/vfio_iommu_spapr_tce.c |    8 ++++++++
 1 file changed, 8 insertions(+)

@@ -1332,8 +1332,16 @@ static int tce_iommu_attach_group(void *
 
 	if (!table_group->ops || !table_group->ops->take_ownership ||
 			!table_group->ops->release_ownership) {
+		if (container->v2) {
+			ret = -EPERM;
+			goto unlock_exit;
+		}
 		ret = tce_iommu_take_ownership(container, table_group);
 	} else {
+		if (!container->v2) {
+			ret = -EPERM;
+			goto unlock_exit;
+		}
 		ret = tce_iommu_take_ownership_ddw(container, table_group);
 		if (!tce_groups_attached(container) && !container->tables[0])
 			container->def_window_pending = true;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/vfio-spapr_tce-check-kzalloc-return-when-preregistering-memory.patch queue-4.9/vfio-powerpc-spapr_tce-enforce-iommu-type-compatibility-check.patch