Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[platform/kernel/linux-starfive.git] / drivers / iommu / Kconfig

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index eb1c8cd..e559e43 100644 (file)
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -360,6 +360,31 @@ config ARM_SMMU
          Say Y here if your SoC includes an IOMMU device implementing
          the ARM SMMU architecture.
 
+config ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT
+       bool "Default to disabling bypass on ARM SMMU v1 and v2"
+       depends on ARM_SMMU
+       default y
+       help
+         Say Y here to (by default) disable bypass streams such that
+         incoming transactions from devices that are not attached to
+         an iommu domain will report an abort back to the device and
+         will not be allowed to pass through the SMMU.
+
+         Any old kernels that existed before this KConfig was
+         introduced would default to _allowing_ bypass (AKA the
+         equivalent of NO for this config).  However the default for
+         this option is YES because the old behavior is insecure.
+
+         There are few reasons to allow unmatched stream bypass, and
+         even fewer good ones.  If saying YES here breaks your board
+         you should work on fixing your board.  This KConfig option
+         is expected to be removed in the future and we'll simply
+         hardcode the bypass disable in the code.
+
+         NOTE: the kernel command line parameter
+         'arm-smmu.disable_bypass' will continue to override this
+         config.
+
 config ARM_SMMU_V3
        bool "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
        depends on ARM64