linux-kernel - [PATCH AUTOSEL for 4.9 008/190] vfio/powerpc/spapr_tce: Enforce IOMMU type compatibility check

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Message-ID: <20180308045810.8041-8-alexander.levin@microsoft.com>
Date:   Thu, 8 Mar 2018 04:58:50 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Alexey Kardashevskiy <aik@...abs.ru>,
        Alex Williamson <alex.williamson@...hat.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 008/190] vfio/powerpc/spapr_tce: Enforce IOMMU
 type compatibility check

From: Alexey Kardashevskiy <aik@...abs.ru>

[ 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.

Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/vfio/vfio_iommu_spapr_tce.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 59b3f62a2d64..87ad0d72d8a9 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -1332,8 +1332,16 @@ static int tce_iommu_attach_group(void *iommu_data,
 
 	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;
-- 
2.14.1