[PATCH 1/2] powerpc: iommu: Bring back table group release_ownership() call

[Shivaprasad G Bhat]

The commit 2ad56efa80db ("powerpc/iommu: Setup a default domain and
remove set_platform_dma_ops") refactored the code removing the
set_platform_dma_ops(). It missed out the table group
release_ownership() call which would have got called otherwise
during the guest shutdown via vfio_group_detach_container(). On
PPC64, this particular call actually sets up the 32-bit TCE table,
and enables the 64-bit DMA bypass etc. Now after guest shutdown,
the subsequent host driver (e.g megaraid-sas) probe post unbind
from vfio-pci fails like,

megaraid_sas 0031:01:00.0: Warning: IOMMU dma not supported: mask 
0x7fffffffffffffff, table unavailable
megaraid_sas 0031:01:00.0: Warning: IOMMU dma not supported: mask 0xffffffff, 
table unavailable
megaraid_sas 0031:01:00.0: Failed to set DMA mask
megaraid_sas 0031:01:00.0: Failed from megasas_init_fw 6539

The patch brings back the call to table_group release_ownership()
call when switching back to PLATFORM domain.

Fixes: 2ad56efa80db ("powerpc/iommu: Setup a default domain and remove 
set_platform_dma_ops")
Signed-off-by: Shivaprasad G Bhat <sb...@linux.ibm.com>
---
 arch/powerpc/kernel/iommu.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index ebe259bdd462..ac7df43fa7ef 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -1296,9 +1296,19 @@ spapr_tce_platform_iommu_attach_dev(struct iommu_domain 
*platform_domain,
        if (!grp)
                return -ENODEV;
 
-       table_group = iommu_group_get_iommudata(grp);
-       ret = table_group->ops->take_ownership(table_group);
-       iommu_group_put(grp);
+       if (platform_domain->type == IOMMU_DOMAIN_PLATFORM) {
+               ret = 0;
+               table_group = iommu_group_get_iommudata(grp);
+               /*
+                * The domain being set to PLATFORM from earlier
+                * BLOCKED. The table_group ownership has to be released.
+                */
+               table_group->ops->release_ownership(table_group);
+       } else if (platform_domain->type == IOMMU_DOMAIN_BLOCKED) {
+               table_group = iommu_group_get_iommudata(grp);
+               ret = table_group->ops->take_ownership(table_group);
+               iommu_group_put(grp);
+       }
 
        return ret;
 }