iommu: Add IOMMU index argument to translate method

Add an IOMMU index argument to the translate method of
IOMMUs. Since all of our current IOMMU implementations
support only a single IOMMU index, this has no effect
on the behaviour.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20180604152941.20374-4-peter.maydell@linaro.org
diff --git a/exec.c b/exec.c
index 1fa2cdb..ecdf192 100644
--- a/exec.c
+++ b/exec.c
@@ -501,8 +501,15 @@
     do {
         hwaddr addr = *xlat;
         IOMMUMemoryRegionClass *imrc = memory_region_get_iommu_class_nocheck(iommu_mr);
-        IOMMUTLBEntry iotlb = imrc->translate(iommu_mr, addr, is_write ?
-                                              IOMMU_WO : IOMMU_RO);
+        int iommu_idx = 0;
+        IOMMUTLBEntry iotlb;
+
+        if (imrc->attrs_to_index) {
+            iommu_idx = imrc->attrs_to_index(iommu_mr, attrs);
+        }
+
+        iotlb = imrc->translate(iommu_mr, addr, is_write ?
+                                IOMMU_WO : IOMMU_RO, iommu_idx);
 
         if (!(iotlb.perm & (1 << is_write))) {
             goto unassigned;