[PATCH] iommu: Split out and tidy up Arm Kconfig
Robin Murphy
robin.murphy at arm.com
Thu Mar 20 07:21:28 PDT 2025
There are quite a lot of options for the Arm drivers, still all buried
in the top-level Kconfig. For ease of use and consistency with all the
other subdirectories, break these out into drivers/arm. For similar
clarity and self-consistency, also tweak the ARM_SMMU sub-options to use
"if" instead of "depends", to match ARM_SMMU_V3. Lastly also clean up
the slightly messy description of ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT as
highlighted by Geert - by now we really shouldn't need commentary on
v4.x kernel behaviour anyway - and downgrade it to EXPERT as the first
step in the 6-year-old threat to remove it entirely.
Cc: Geert Uytterhoeven <geert+renesas at glider.be>
Signed-off-by: Robin Murphy <robin.murphy at arm.com>
---
drivers/iommu/Kconfig | 157 +-------------------------------------
drivers/iommu/arm/Kconfig | 144 ++++++++++++++++++++++++++++++++++
2 files changed, 145 insertions(+), 156 deletions(-)
create mode 100644 drivers/iommu/arm/Kconfig
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index d935b59abb35..5ad3b7b8bfeb 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -193,6 +193,7 @@ config MSM_IOMMU
If unsure, say N here.
source "drivers/iommu/amd/Kconfig"
+source "drivers/iommu/arm/Kconfig"
source "drivers/iommu/intel/Kconfig"
source "drivers/iommu/iommufd/Kconfig"
source "drivers/iommu/riscv/Kconfig"
@@ -315,150 +316,6 @@ config APPLE_DART
Say Y here if you are using an Apple SoC.
-# ARM IOMMU support
-config ARM_SMMU
- tristate "ARM Ltd. System MMU (SMMU) Support"
- depends on ARM64 || ARM || COMPILE_TEST
- depends on !GENERIC_ATOMIC64 # for IOMMU_IO_PGTABLE_LPAE
- select IOMMU_API
- select IOMMU_IO_PGTABLE_LPAE
- select ARM_DMA_USE_IOMMU if ARM
- help
- Support for implementations of the ARM System MMU architecture
- versions 1 and 2.
-
- Say Y here if your SoC includes an IOMMU device implementing
- the ARM SMMU architecture.
-
-config ARM_SMMU_LEGACY_DT_BINDINGS
- bool "Support the legacy \"mmu-masters\" devicetree bindings"
- depends on ARM_SMMU=y && OF
- help
- Support for the badly designed and deprecated "mmu-masters"
- devicetree bindings. This allows some DMA masters to attach
- to the SMMU but does not provide any support via the DMA API.
- If you're lucky, you might be able to get VFIO up and running.
-
- If you say Y here then you'll make me very sad. Instead, say N
- and move your firmware to the utopian future that was 2016.
-
-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_MMU_500_CPRE_ERRATA
- bool "Enable errata workaround for CPRE in SMMU reset path"
- depends on ARM_SMMU
- default y
- help
- Say Y here (by default) to apply workaround to disable
- MMU-500's next-page prefetcher for sake of 4 known errata.
-
- Say N here only when it is sure that any errata related to
- prefetch enablement are not applicable on the platform.
- Refer silicon-errata.rst for info on errata IDs.
-
-config ARM_SMMU_QCOM
- def_tristate y
- depends on ARM_SMMU && ARCH_QCOM
- select QCOM_SCM
- help
- When running on a Qualcomm platform that has the custom variant
- of the ARM SMMU, this needs to be built into the SMMU driver.
-
-config ARM_SMMU_QCOM_DEBUG
- bool "ARM SMMU QCOM implementation defined debug support"
- depends on ARM_SMMU_QCOM=y
- help
- Support for implementation specific debug features in ARM SMMU
- hardware found in QTI platforms. This include support for
- the Translation Buffer Units (TBU) that can be used to obtain
- additional information when debugging memory management issues
- like context faults.
-
- Say Y here to enable debug for issues such as context faults
- or TLB sync timeouts which requires implementation defined
- register dumps.
-
-config ARM_SMMU_V3
- tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
- depends on ARM64
- select IOMMU_API
- select IOMMU_IO_PGTABLE_LPAE
- select GENERIC_MSI_IRQ
- select IOMMUFD_DRIVER if IOMMUFD
- help
- Support for implementations of the ARM System MMU architecture
- version 3 providing translation support to a PCIe root complex.
-
- Say Y here if your system includes an IOMMU device implementing
- the ARM SMMUv3 architecture.
-
-if ARM_SMMU_V3
-config ARM_SMMU_V3_SVA
- bool "Shared Virtual Addressing support for the ARM SMMUv3"
- select IOMMU_SVA
- select IOMMU_IOPF
- select MMU_NOTIFIER
- help
- Support for sharing process address spaces with devices using the
- SMMUv3.
-
- Say Y here if your system supports SVA extensions such as PCIe PASID
- and PRI.
-
-config ARM_SMMU_V3_IOMMUFD
- bool "Enable IOMMUFD features for ARM SMMUv3 (EXPERIMENTAL)"
- depends on IOMMUFD
- help
- Support for IOMMUFD features intended to support virtual machines
- with accelerated virtual IOMMUs.
-
- Say Y here if you are doing development and testing on this feature.
-
-config ARM_SMMU_V3_KUNIT_TEST
- tristate "KUnit tests for arm-smmu-v3 driver" if !KUNIT_ALL_TESTS
- depends on KUNIT
- depends on ARM_SMMU_V3_SVA
- default KUNIT_ALL_TESTS
- help
- Enable this option to unit-test arm-smmu-v3 driver functions.
-
- If unsure, say N.
-
-config TEGRA241_CMDQV
- bool "NVIDIA Tegra241 CMDQ-V extension support for ARM SMMUv3"
- depends on ACPI
- help
- Support for NVIDIA CMDQ-Virtualization extension for ARM SMMUv3. The
- CMDQ-V extension is similar to v3.3 ECMDQ for multi command queues
- support, except with virtualization capabilities.
-
- Say Y here if your system is NVIDIA Tegra241 (Grace) or it has the same
- CMDQ-V extension.
-endif
-
config S390_IOMMU
def_bool y if S390 && PCI
depends on S390 && PCI
@@ -495,18 +352,6 @@ config MTK_IOMMU_V1
if unsure, say N here.
-config QCOM_IOMMU
- # Note: iommu drivers cannot (yet?) be built as modules
- bool "Qualcomm IOMMU Support"
- depends on ARCH_QCOM || COMPILE_TEST
- depends on !GENERIC_ATOMIC64 # for IOMMU_IO_PGTABLE_LPAE
- select QCOM_SCM
- select IOMMU_API
- select IOMMU_IO_PGTABLE_LPAE
- select ARM_DMA_USE_IOMMU
- help
- Support for IOMMU on certain Qualcomm SoCs.
-
config HYPERV_IOMMU
bool "Hyper-V IRQ Handling"
depends on HYPERV && X86
diff --git a/drivers/iommu/arm/Kconfig b/drivers/iommu/arm/Kconfig
new file mode 100644
index 000000000000..ef42bbe07dbe
--- /dev/null
+++ b/drivers/iommu/arm/Kconfig
@@ -0,0 +1,144 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# ARM IOMMU support
+config ARM_SMMU
+ tristate "ARM Ltd. System MMU (SMMU) Support"
+ depends on ARM64 || ARM || COMPILE_TEST
+ depends on !GENERIC_ATOMIC64 # for IOMMU_IO_PGTABLE_LPAE
+ select IOMMU_API
+ select IOMMU_IO_PGTABLE_LPAE
+ select ARM_DMA_USE_IOMMU if ARM
+ help
+ Support for implementations of the ARM System MMU architecture
+ versions 1 and 2.
+
+ Say Y here if your SoC includes an IOMMU device implementing
+ the ARM SMMU architecture.
+
+if ARM_SMMU
+config ARM_SMMU_LEGACY_DT_BINDINGS
+ bool "Support the legacy \"mmu-masters\" devicetree bindings"
+ depends on ARM_SMMU=y && OF
+ help
+ Support for the badly designed and deprecated "mmu-masters"
+ devicetree bindings. This allows some DMA masters to attach
+ to the SMMU but does not provide any support via the DMA API.
+ If you're lucky, you might be able to get VFIO up and running.
+
+ If you say Y here then you'll make me very sad. Instead, say N
+ and move your firmware to the utopian future that was 2016.
+
+config ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT
+ bool "Disable unmatched stream bypass by default" if EXPERT
+ default y
+ help
+ If your firmware is broken and fails to describe StreamIDs which
+ Linux should know about in order to manage the SMMU correctly and
+ securely, and you don't want to boot with the 'arm-smmu.disable_bypass=0'
+ command line parameter, then as a last resort you can turn it off
+ by default here. But don't. This option may be removed at any time.
+
+ Note that 'arm-smmu.disable_bypass=1' will still take precedence.
+
+config ARM_SMMU_MMU_500_CPRE_ERRATA
+ bool "Enable errata workaround for CPRE in SMMU reset path"
+ default y
+ help
+ Say Y here (by default) to apply workaround to disable
+ MMU-500's next-page prefetcher for sake of 4 known errata.
+
+ Say N here only when it is sure that any errata related to
+ prefetch enablement are not applicable on the platform.
+ Refer silicon-errata.rst for info on errata IDs.
+
+config ARM_SMMU_QCOM
+ def_tristate y
+ depends on ARCH_QCOM
+ select QCOM_SCM
+ help
+ When running on a Qualcomm platform that has the custom variant
+ of the ARM SMMU, this needs to be built into the SMMU driver.
+
+config ARM_SMMU_QCOM_DEBUG
+ bool "ARM SMMU QCOM implementation defined debug support"
+ depends on ARM_SMMU_QCOM=y
+ help
+ Support for implementation specific debug features in ARM SMMU
+ hardware found in QTI platforms. This include support for
+ the Translation Buffer Units (TBU) that can be used to obtain
+ additional information when debugging memory management issues
+ like context faults.
+
+ Say Y here to enable debug for issues such as context faults
+ or TLB sync timeouts which requires implementation defined
+ register dumps.
+endif
+
+config ARM_SMMU_V3
+ tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
+ depends on ARM64
+ select IOMMU_API
+ select IOMMU_IO_PGTABLE_LPAE
+ select GENERIC_MSI_IRQ
+ select IOMMUFD_DRIVER if IOMMUFD
+ help
+ Support for implementations of the ARM System MMU architecture
+ version 3 providing translation support to a PCIe root complex.
+
+ Say Y here if your system includes an IOMMU device implementing
+ the ARM SMMUv3 architecture.
+
+if ARM_SMMU_V3
+config ARM_SMMU_V3_SVA
+ bool "Shared Virtual Addressing support for the ARM SMMUv3"
+ select IOMMU_SVA
+ select IOMMU_IOPF
+ select MMU_NOTIFIER
+ help
+ Support for sharing process address spaces with devices using the
+ SMMUv3.
+
+ Say Y here if your system supports SVA extensions such as PCIe PASID
+ and PRI.
+
+config ARM_SMMU_V3_IOMMUFD
+ bool "Enable IOMMUFD features for ARM SMMUv3 (EXPERIMENTAL)"
+ depends on IOMMUFD
+ help
+ Support for IOMMUFD features intended to support virtual machines
+ with accelerated virtual IOMMUs.
+
+ Say Y here if you are doing development and testing on this feature.
+
+config ARM_SMMU_V3_KUNIT_TEST
+ tristate "KUnit tests for arm-smmu-v3 driver" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ depends on ARM_SMMU_V3_SVA
+ default KUNIT_ALL_TESTS
+ help
+ Enable this option to unit-test arm-smmu-v3 driver functions.
+
+ If unsure, say N.
+
+config TEGRA241_CMDQV
+ bool "NVIDIA Tegra241 CMDQ-V extension support for ARM SMMUv3"
+ depends on ACPI
+ help
+ Support for NVIDIA CMDQ-Virtualization extension for ARM SMMUv3. The
+ CMDQ-V extension is similar to v3.3 ECMDQ for multi command queues
+ support, except with virtualization capabilities.
+
+ Say Y here if your system is NVIDIA Tegra241 (Grace) or it has the same
+ CMDQ-V extension.
+endif
+
+config QCOM_IOMMU
+ # Note: iommu drivers cannot (yet?) be built as modules
+ bool "Qualcomm IOMMU Support"
+ depends on ARCH_QCOM || COMPILE_TEST
+ depends on !GENERIC_ATOMIC64 # for IOMMU_IO_PGTABLE_LPAE
+ select QCOM_SCM
+ select IOMMU_API
+ select IOMMU_IO_PGTABLE_LPAE
+ select ARM_DMA_USE_IOMMU
+ help
+ Support for IOMMU on certain Qualcomm SoCs.
--
2.39.2.101.g768bb238c484.dirty
More information about the linux-arm-kernel
mailing list