virtio-iommu: Add an assert check in translate routine

With address space switch supported, dma access translation only
happen after endpoint is attached to a non-bypass domain.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220613061010.2674054-4-zhenzhong.duan@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/virtio-iommu.c

@@ -865,6 +865,10 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
     qemu_rec_mutex_lock(&s->mutex);
 
     ep = g_tree_lookup(s->endpoints, GUINT_TO_POINTER(sid));
+
+    if (bypass_allowed)
+        assert(ep && ep->domain && !ep->domain->bypass);
+
     if (!ep) {
         if (!bypass_allowed) {
             error_report_once("%s sid=%d is not known!!", __func__, sid);