VFIO needs to check VFIO_TYPE1_NESTING_IOMMU support with Kernel before
further using it. e.g. requires to check IOMMU UAPI version.

Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Yi Sun <yi.y.sun@linux.intel.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
---
 hw/vfio/common.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 5ca1148..be1a9e5 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1157,12 +1157,21 @@ static void vfio_put_address_space(VFIOAddressSpace *space)
 static int vfio_get_iommu_type(VFIOContainer *container,
                                Error **errp)
 {
-    int iommu_types[] = { VFIO_TYPE1v2_IOMMU, VFIO_TYPE1_IOMMU,
+    int iommu_types[] = { VFIO_TYPE1_NESTING_IOMMU,
+                          VFIO_TYPE1v2_IOMMU, VFIO_TYPE1_IOMMU,
                           VFIO_SPAPR_TCE_v2_IOMMU, VFIO_SPAPR_TCE_IOMMU };
-    int i;
+    int i, version;
 
     for (i = 0; i < ARRAY_SIZE(iommu_types); i++) {
         if (ioctl(container->fd, VFIO_CHECK_EXTENSION, iommu_types[i])) {
+            if (iommu_types[i] == VFIO_TYPE1_NESTING_IOMMU) {
+                version = ioctl(container->fd, VFIO_CHECK_EXTENSION,
+                                VFIO_NESTING_IOMMU_UAPI);
+                if (version < IOMMU_UAPI_VERSION) {
+                    info_report("IOMMU UAPI incompatible for nesting");
+                    continue;
+                }
+            }
             return iommu_types[i];
         }
     }
@@ -1278,6 +1287,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
     }
 
     switch (container->iommu_type) {
+    case VFIO_TYPE1_NESTING_IOMMU:
     case VFIO_TYPE1v2_IOMMU:
     case VFIO_TYPE1_IOMMU:
     {
-- 
2.7.4