[PATCH kernel] vfio/spapr_tce: Set window when adding additional groups to container

[Alexey Kardashevskiy]

If a container already has a group attached, attaching a new group
should just program already created IOMMU tables to the hardware via
the iommu_table_group_ops::set_window() callback.

However 6f01cc692 "vfio/spapr: Add a helper to create default DMA window"
did not just simplify the code but also removed the set_window() calls
in the case of attaching groups to a container which already has tables
so it broke VFIO PCI hotplug.

This reverts set_window() bits in tce_iommu_take_ownership_ddw().

Fixes: 6f01cc692
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
 drivers/vfio/vfio_iommu_spapr_tce.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c 
b/drivers/vfio/vfio_iommu_spapr_tce.c
index 7690e5bf3cf1..14c62a8495a2 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -1245,6 +1245,8 @@ static void tce_iommu_release_ownership_ddw(struct 
tce_container *container,
 static long tce_iommu_take_ownership_ddw(struct tce_container *container,
                struct iommu_table_group *table_group)
 {
+       long i, ret = 0;
+
        if (!table_group->ops->create_table || !table_group->ops->set_window ||
                        !table_group->ops->release_ownership) {
                WARN_ON_ONCE(1);
@@ -1253,7 +1255,26 @@ static long tce_iommu_take_ownership_ddw(struct 
tce_container *container,
 
        table_group->ops->take_ownership(table_group);
 
+       /* Set all windows to the new group */
+       for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
+               struct iommu_table *tbl = container->tables[i];
+               if (!tbl)
+                       continue;
+
+               ret = table_group->ops->set_window(table_group, i, tbl);
+               if (ret)
+                       goto release_exit;
+       }
+
        return 0;
+
+release_exit:
+       for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
+               table_group->ops->unset_window(table_group, i);
+
+       table_group->ops->release_ownership(table_group);
+
+       return ret;
 }
 
 static int tce_iommu_attach_group(void *iommu_data,
-- 
2.11.0