On 2021/6/3 21:58, John Garry wrote:
> From: Zhen Lei <[email protected]>
>
> First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
> opportunity to set {lazy|strict} mode as default at build time. Then put
> the two config options in an choice, as they are mutually-exclusive.
>
> [jpg: Make choice between strict and lazy only (and not passthrough)]
> Signed-off-by: Zhen Lei <[email protected]>
> Signed-off-by: John Garry <[email protected]>
> ---
> drivers/iommu/Kconfig | 34 ++++++++++++++++++++++++++++++++++
> drivers/iommu/iommu.c | 3 ++-
> 2 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 1f111b399bca..12ef90256df8 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -90,6 +90,40 @@ config IOMMU_DEFAULT_PASSTHROUGH
>
> If unsure, say N here.
>
> +choice
> + prompt "IOMMU default DMA mode"
> + depends on IOMMU_API
config INTEL_IOMMU
depends on PCI_MSI && ACPI && (X86 || IA64)
config AMD_IOMMU
depends on X86_64 && PCI && ACPI && HAVE_CMPXCHG_DOUBLE
config ARM_SMMU_V3
depends on ARM64
"depends on ARM_SMMU_V3 || INTEL_IOMMU || AMD_IOMMU" may need to be added,
because it doesn't work on other platforms.
or "depends on X86 || IA64 || X86_64 || ARM64"
> +
> + default IOMMU_DEFAULT_STRICT
> + help
> + This option allows an IOMMU DMA mode to be chosen at build time, to
> + override the default DMA mode of each ARCH, removing the need to
> + pass in kernel parameters through command line. It is still possible
> + to provide ARCH-specific or common boot options to override this
> + option.
> +
> + If unsure, keep the default.
> +
> +config IOMMU_DEFAULT_LAZY
> + bool "lazy"
> + help
> + Support lazy mode, where for every IOMMU DMA unmap operation, the
> + flush operation of IOTLB and the free operation of IOVA are deferred.
> + They are only guaranteed to be done before the related IOVA will be
> + reused.
> +
> +config IOMMU_DEFAULT_STRICT
> + bool "strict"
> + help
> + For every IOMMU DMA unmap operation, the flush operation of IOTLB and
> + the free operation of IOVA are guaranteed to be done in the unmap
> + function.
> +
> + This mode is safer than the two above, but it maybe slower in some
> + high performace scenarios.
> +
> +endchoice
> +
> config OF_IOMMU
> def_bool y
> depends on OF && IOMMU_API
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 966426a96520..177b0dafc535 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -29,7 +29,8 @@ static struct kset *iommu_group_kset;
> static DEFINE_IDA(iommu_group_ida);
>
> static unsigned int iommu_def_domain_type __read_mostly;
> -static bool iommu_dma_strict __read_mostly = true;
> +static bool iommu_dma_strict __read_mostly =
> + IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
Currently, a maximum of 100 columns are allowed in a row.
> static u32 iommu_cmd_line __read_mostly;
>
> struct iommu_group {
>
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