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Subject[PATCH 1/1] iommu: Add config option to set lazy mode as default
Date
This allows the default behaviour to be controlled by a kernel config
option instead of changing the command line for the kernel to include
"iommu.strict=0" on ARM64 where this is desired.

This is similar to CONFIG_IOMMU_DEFAULT_PASSTHROUGH.

Note: At present, intel_iommu, amd_iommu and s390_iommu use lazy mode as
defalut, so there is no need to add code for them.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
drivers/iommu/Kconfig | 14 ++++++++++++++
drivers/iommu/iommu.c | 5 +++++
2 files changed, 19 insertions(+)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 6f07f3b21816c64..5ec9780f564eaf8 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -85,6 +85,20 @@ config IOMMU_DEFAULT_PASSTHROUGH

If unsure, say N here.

+config IOMMU_LAZY_MODE
+ bool "IOMMU use lazy mode to flush IOTLB and free IOVA"
+ depends on IOMMU_API
+ help
+ For every IOMMU 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. Removing the need to pass in iommu.strict=0
+ through command line on ARM64(Now, intel_iommu, amd_iommu, s390_iommu use
+ lazy mode as deault). If this is enabled, you can still disable with kernel
+ parameters, such as iommu.strict=1, intel_iommu=strict, amd_iommu=fullflush
+ or s390_iommu=strict depending on the architecture.
+
+ If unsure, say N here.
+
config OF_IOMMU
def_bool y
depends on OF && IOMMU_API
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 33a982e33716369..e307d70d1578b3b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -43,7 +43,12 @@
#else
static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA;
#endif
+
+#ifdef CONFIG_IOMMU_LAZY_MODE
+static bool iommu_dma_strict __read_mostly;
+#else
static bool iommu_dma_strict __read_mostly = true;
+#endif

struct iommu_callback_data {
const struct iommu_ops *ops;
--
1.8.3

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