iommu: Add IOMMU index argument to notifier APIs

Add support for multiple IOMMU indexes to the IOMMU notifier APIs.
When initializing a notifier with iommu_notifier_init(), the caller
must pass the IOMMU index that it is interested in. When a change
happens, the IOMMU implementation must pass
memory_region_notify_iommu() the IOMMU index that has changed and
that notifiers must be called for.

IOMMUs which support only a single index don't need to change.
Callers which only really support working with IOMMUs with a single
index can use the result of passing MEMTXATTRS_UNSPECIFIED to
memory_region_iommu_attrs_to_index().

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: 20180604152941.20374-3-peter.maydell@linaro.org
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 8e57265..fb396cf 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -507,6 +507,7 @@
     if (memory_region_is_iommu(section->mr)) {
         VFIOGuestIOMMU *giommu;
         IOMMUMemoryRegion *iommu_mr = IOMMU_MEMORY_REGION(section->mr);
+        int iommu_idx;
 
         trace_vfio_listener_region_add_iommu(iova, end);
         /*
@@ -523,10 +524,13 @@
         llend = int128_add(int128_make64(section->offset_within_region),
                            section->size);
         llend = int128_sub(llend, int128_one());
+        iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
+                                                       MEMTXATTRS_UNSPECIFIED);
         iommu_notifier_init(&giommu->n, vfio_iommu_map_notify,
                             IOMMU_NOTIFIER_ALL,
                             section->offset_within_region,
-                            int128_get64(llend));
+                            int128_get64(llend),
+                            iommu_idx);
         QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
 
         memory_region_register_iommu_notifier(section->mr, &giommu->n);