To parallel the sysfs behaviour, extend the build-time configuration
for default domains to include the new type as well.
Signed-off-by: Robin Murphy <robin.mur...@arm.com>
---
This effectively replaces patch #3 of John's "iommu: Enhance IOMMU
default DMA mode build options" series.
---
drivers/iommu/Kconfig | 48 +++++++++++++++++++++++++++++++++++--------
drivers/iommu/iommu.c | 2 +-
2 files changed, 41 insertions(+), 9 deletions(-)
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 07b7c25cbed8..e3f7990046ae 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -79,16 +79,48 @@ config IOMMU_DEBUGFS
debug/iommu directory, and then populate a subdirectory with
entries as required.
-config IOMMU_DEFAULT_PASSTHROUGH
- bool "IOMMU passthrough by default"
+choice
+ prompt "Default IOMMU domain type"
depends on IOMMU_API
- help
- Enable passthrough by default, removing the need to pass in
- iommu.passthrough=on or iommu=pt through command line. If this
- is enabled, you can still disable with iommu.passthrough=off
- or iommu=nopt depending on the architecture.
+ default IOMMU_DEFAULT_DMA_LAZY if INTEL_IOMMU || AMD_IOMMU
+ default IOMMU_DEFAULT_DMA_STRICT
- If unsure, say N here.
+config IOMMU_DEFAULT_DMA_STRICT
+ bool "Translated - Strict"
+ help
+ Trusted devices use translation to restrict their access to only
+ DMA-mapped pages, with strict TLB invalidation on unmap. Equivalent
+ to passing "iommu.passthrough=0 iommu.strict=1" on the command line.
+
+ Untrusted devices always use this mode, with an additional layer of
+ bounce-buffering such that they cannot gain access to any unrelated
+ data within a mapped page.
+
+config IOMMU_DEFAULT_DMA_LAZY
+ bool "Translated - Lazy"
+ help
+ Trusted devices use translation to restrict their access to only
+ DMA-mapped pages, but with "lazy" batched TLB invalidation. This
+ mode allows higher performance with some IOMMUs due to reduced TLB
+ flushing, but at the cost of reduced isolation since devices may be
+ able to access memory for some time after it has been unmapped.
+ Equivalent to passing "iommu.passthrough=0 iommu.strict=0" on the
+ command line.
+
+ If this mode is not supported by the IOMMU driver, the effective
+ runtime default will fall back to IOMMU_DEFAULT_DMA_STRICT.
+
+config IOMMU_DEFAULT_PASSTHROUGH
+ bool "Passthrough"
+ help
+ Trusted devices are identity-mapped, giving them unrestricted access
+ to memory with minimal performance overhead. Equivalent to passing
+ "iommu.passthrough=1" (historically "iommu=pt") on the command line.
+
+ If this mode is not supported by the IOMMU driver, the effective
+ runtime default will fall back to IOMMU_DEFAULT_DMA_STRICT.
+
+endchoice
config OF_IOMMU
def_bool y
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d3b562a33ac4..4fad6d427d9d 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -30,7 +30,7 @@ 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_DMA_STRICT);
static u32 iommu_cmd_line __read_mostly;
struct iommu_group {
--
2.25.1
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