Merge tag 'iommu-fixes-v5.0-rc5' of git://git.kernel.org/pub/scm/linu…

…x/kernel/git/joro/iommu

Pull IOMMU fix from Joerg Roedel:
 "Intel decided to leave the newly added Scalable Mode Feature
  default-disabled for now. The patch here accomplishes that"

* tag 'iommu-fixes-v5.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/vt-d: Leave scalable mode default off

Documentation/admin-guide/kernel-parameters.txt

@@ -1696,12 +1696,11 @@
 			By default, super page will be supported if Intel IOMMU
 			has the capability. With this option, super page will
 			not be supported.
-		sm_off [Default Off]
-			By default, scalable mode will be supported if the
+		sm_on [Default Off]
+			By default, scalable mode will be disabled even if the
 			hardware advertises that it has support for the scalable
 			mode translation. With this option set, scalable mode
-			will not be used even on hardware which claims to support
-			it.
+			will be used on hardware which claims to support it.
 		tboot_noforce [Default Off]
 			Do not force the Intel IOMMU enabled under tboot.
 			By default, tboot will force Intel IOMMU on, which

drivers/iommu/intel-iommu.c

@@ -363,7 +363,7 @@ static int dmar_map_gfx = 1;
 static int dmar_forcedac;
 static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
-static int intel_iommu_sm = 1;
+static int intel_iommu_sm;
 static int iommu_identity_mapping;
 
 #define IDENTMAP_ALL		1
@@ -456,9 +456,9 @@ static int __init intel_iommu_setup(char *str)
 		} else if (!strncmp(str, "sp_off", 6)) {
 			pr_info("Disable supported super page\n");
 			intel_iommu_superpage = 0;
-		} else if (!strncmp(str, "sm_off", 6)) {
-			pr_info("Intel-IOMMU: disable scalable mode support\n");
-			intel_iommu_sm = 0;
+		} else if (!strncmp(str, "sm_on", 5)) {
+			pr_info("Intel-IOMMU: scalable mode supported\n");
+			intel_iommu_sm = 1;
 		} else if (!strncmp(str, "tboot_noforce", 13)) {
 			printk(KERN_INFO
 				"Intel-IOMMU: not forcing on after tboot. This could expose security risk for tboot\n");