diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index a7967ce..785675a 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -309,6 +309,7 @@
 	struct acpi_table_dmar *dmar;
 	struct acpi_dmar_header *entry_header;
 	int ret = 0;
+	int drhd_count = 0;
 
 	/*
 	 * Do it again, earlier dmar_tbl mapping could be mapped with
@@ -347,6 +348,7 @@
 
 		switch (entry_header->type) {
 		case ACPI_DMAR_TYPE_HARDWARE_UNIT:
+			drhd_count++;
 			ret = dmar_parse_one_drhd(entry_header);
 			break;
 		case ACPI_DMAR_TYPE_RESERVED_MEMORY:
@@ -371,6 +373,8 @@
 
 		entry_header = ((void *)entry_header + entry_header->length);
 	}
+	if (drhd_count == 0)
+		pr_warn(FW_BUG "No DRHD structure found in DMAR table\n");
 	return ret;
 }