diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 1109a86532..67ffe6635e 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -568,7 +568,7 @@ int iommu_do_domctl(
 {
     int ret = -ENODEV;
 
-    if ( !is_iommu_enabled(d) )
+    if ( !(d ? is_iommu_enabled(d) : iommu_enabled) )
         return -EOPNOTSUPP;
 
 #ifdef CONFIG_HAS_PCI