diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 04b7f73e489b..3ea9bbaf77f1 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1681,10 +1681,10 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 	 * entry for first-level or pass-through translation modes should
 	 * be programmed with a domain id different from those used for
 	 * second-level or nested translation. We reserve a domain id for
-	 * this purpose.
+	 * this purpose. This domain id is also used for identity domain
+	 * in legacy mode.
 	 */
-	if (sm_supported(iommu))
-		set_bit(FLPT_DEFAULT_DID, iommu->domain_ids);
+	set_bit(FLPT_DEFAULT_DID, iommu->domain_ids);
 
 	return 0;
 }