From: Zhen Lei <thunder.leiz...@huawei.com> 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 <thunder.leiz...@huawei.com> Signed-off-by: John Garry <john.ga...@huawei.com> --- drivers/iommu/Kconfig | 38 ++++++++++++++++++++++++++++++++++++++ drivers/iommu/iommu.c | 3 ++- 2 files changed, 40 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 1f111b399bca..2a71347611d4 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -90,6 +90,44 @@ config IOMMU_DEFAULT_PASSTHROUGH If unsure, say N here. +choice + prompt "IOMMU default DMA mode" + depends on IOMMU_DMA + + 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_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. + +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. + + The isolation provided in this mode is not as secure as STRICT mode, + such that a vulnerable time window may be created between the DMA + unmap and the mapping finally being torn down in the IOMMU, where the + device can still access the system memory. However this mode may + provide better performance in high throughput scenarios, and is still + considerably more secure than passthrough mode or no IOMMU. + +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 cf58949cc2f3..ccbd5d4c1a50 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); static u32 iommu_cmd_line __read_mostly; struct iommu_group { -- 2.26.2 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu