diff --git a/backends/iommufd.c b/backends/iommufd.c
index c7e969d..84fefbc 100644
--- a/backends/iommufd.c
+++ b/backends/iommufd.c
@@ -230,6 +230,28 @@
     return true;
 }
 
+static int hiod_iommufd_get_cap(HostIOMMUDevice *hiod, int cap, Error **errp)
+{
+    HostIOMMUDeviceCaps *caps = &hiod->caps;
+
+    switch (cap) {
+    case HOST_IOMMU_DEVICE_CAP_IOMMU_TYPE:
+        return caps->type;
+    case HOST_IOMMU_DEVICE_CAP_AW_BITS:
+        return caps->aw_bits;
+    default:
+        error_setg(errp, "%s: unsupported capability %x", hiod->name, cap);
+        return -EINVAL;
+    }
+}
+
+static void hiod_iommufd_class_init(ObjectClass *oc, void *data)
+{
+    HostIOMMUDeviceClass *hioc = HOST_IOMMU_DEVICE_CLASS(oc);
+
+    hioc->get_cap = hiod_iommufd_get_cap;
+};
+
 static const TypeInfo types[] = {
     {
         .name = TYPE_IOMMUFD_BACKEND,
@@ -246,6 +268,7 @@
     }, {
         .name = TYPE_HOST_IOMMU_DEVICE_IOMMUFD,
         .parent = TYPE_HOST_IOMMU_DEVICE,
+        .class_init = hiod_iommufd_class_init,
         .abstract = true,
     }
 };