diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 505fc04..80250e6 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -297,6 +297,14 @@
  ****************************************************************************/
 
 /*
+ * This function calculates the length of a given IVHD entry
+ */
+static inline int ivhd_entry_length(u8 *ivhd)
+{
+	return 0x04 << (*ivhd >> 6);
+}
+
+/*
  * This function reads the last device id the IOMMU has to handle from the PCI
  * capability header for this IOMMU
  */
@@ -340,7 +348,7 @@
 		default:
 			break;
 		}
-		p += 0x04 << (*p >> 6);
+		p += ivhd_entry_length(p);
 	}
 
 	WARN_ON(p != end);
@@ -641,7 +649,7 @@
 			break;
 		}
 
-		p += 0x04 << (e->type >> 6);
+		p += ivhd_entry_length(p);
 	}
 }