diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b56ee02d2514..f2e1e7fc0ffd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -294,7 +294,7 @@ and is between 256 and 4096 characters. It is defined in the file
 			Possible values are:
 			isolate - enable device isolation (each device, as far
 			          as possible, will get its own protection
-			          domain)
+			          domain) [default]
 			share - put every device behind one IOMMU into the
 				same protection domain
 			fullflush - enable flushing of IO/TLB entries when
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 838a2e1d5bb2..595edd2befc6 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -121,7 +121,7 @@ u16 amd_iommu_last_bdf;			/* largest PCI device id we have
 LIST_HEAD(amd_iommu_unity_map);		/* a list of required unity mappings
 					   we find in ACPI */
 unsigned amd_iommu_aperture_order = 26; /* size of aperture in power of 2 */
-int amd_iommu_isolate;			/* if 1, device isolation is enabled */
+int amd_iommu_isolate = 1;		/* if 1, device isolation is enabled */
 bool amd_iommu_unmap_flush;		/* if true, flush on every unmap */
 
 LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the