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vfio/spapr_tce: Skip unsetting already unset table

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VFIO TCE IOMMU v2 owns IOMMU tables. When we detach an IOMMU group from
a container, we need to unset these tables from the group which we do by
calling unset_window(). We also unset tables when removing a DMA window
via the VFIO_IOMMU_SPAPR_TCE_REMOVE ioctl.

The window removal checks if the table actually exists (hidden inside
tce_iommu_find_table()) but the group detaching does not so the user
may see duplicating messages:
pci 0009:03     : [PE# fd] Removing DMA window #0
pci 0009:03     : [PE# fd] Removing DMA window #1
pci 0009:03     : [PE# fd] Removing DMA window #0
pci 0009:03     : [PE# fd] Removing DMA window #1

At the moment this is not a problem as the second invocation
of unset_window() writes zeroes to the HW registers again and exits early
as there is no table.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alexey Kardashevskiy 2019-02-11 18:49:17 +11:00 committed by Alex Williamson
parent 3e4835f7d7
commit a390685589
1 changed files with 2 additions and 1 deletions
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3
drivers/vfio/vfio_iommu_spapr_tce.c
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@ -1235,7 +1235,8 @@ static void tce_iommu_release_ownership_ddw(struct tce_container *container,
}
for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
table_group->ops->unset_window(table_group, i);
if (container->tables[i])
table_group->ops->unset_window(table_group, i);
table_group->ops->release_ownership(table_group);
}