powerpc/pseries/iommu: Don't use dma_iommu_ops on secure guests

Secure guest memory is inacessible to devices so regular DMA isn't
possible.

In that case set devices' dma_map_ops to NULL so that the generic
DMA code path will use SWIOTLB to bounce buffers for DMA.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190820021326.6884-14-bauerman@linux.ibm.com

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index df7db33ca93b..6ba081dd61c9 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -36,6 +36,7 @@
 #include <asm/udbg.h>
 #include <asm/mmzone.h>
 #include <asm/plpar_wrappers.h>
+#include <asm/svm.h>
 
 #include "pseries.h"
 
@@ -1319,7 +1320,15 @@ void iommu_init_early_pSeries(void)
         of_reconfig_notifier_register(&iommu_reconfig_nb);
         register_memory_notifier(&iommu_mem_nb);
 
-        set_pci_dma_ops(&dma_iommu_ops);
+        /*
+         * Secure guest memory is inacessible to devices so regular DMA isn't
+         * possible.
+         *
+         * In that case keep devices' dma_map_ops as NULL so that the generic
+         * DMA code path will use SWIOTLB to bounce buffers for DMA.
+         */
+        if (!is_secure_guest())
+                set_pci_dma_ops(&dma_iommu_ops);
 }
 
 static int __init disable_multitce(char *str)