Add a bootup option to make the system manager can choose which mode to
be used. The default mode is strict.
Signed-off-by: Zhen Lei <thunder.leiz...@huawei.com>
---
Documentation/admin-guide/kernel-parameters.txt | 13 +++++++++++++
drivers/iommu/arm-smmu-v3.c | 22 +++++++++++++++++++++-
2 files changed, 34 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index 5cde1ff..cb9d043e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1720,6 +1720,19 @@
nobypass [PPC/POWERNV]
Disable IOMMU bypass, using IOMMU for PCI devices.
+ iommu.non_strict= [ARM64]
+ Format: { "0" | "1" }
+ 0 - strict mode, default.
+ Release IOVAs after the related TLBs are invalid
+ completely.
+ 1 - non-strict mode.
+ Put off TLBs invalidation and release memory first.
+ It's good for scatter-gather performance but lacks
+ full isolation, an untrusted device can access the
+ reused memory because the TLBs may still valid.
+ Please take full consideration before choosing this
+ mode. Note that, VFIO will always use strict mode.
+
iommu.passthrough=
[ARM64] Configure DMA to bypass the IOMMU by default.
Format: { "0" | "1" }
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 61eb7ec..0eda90e 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -631,6 +631,26 @@ struct arm_smmu_option_prop {
{ 0, NULL},
};
+static bool smmu_non_strict __read_mostly;
+
+static int __init arm_smmu_setup(char *str)
+{
+ int ret;
+
+ ret = kstrtobool(str, &smmu_non_strict);
+ if (ret)
+ return ret;
+
+ if (smmu_non_strict) {
+ pr_warn("WARNING: iommu non-strict mode is chosen.\n"
+ "It's good for scatter-gather performance but lacks
full isolation\n");
+ add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
+ }
+
+ return 0;
+}
+early_param("iommu.non_strict", arm_smmu_setup);
+
static inline void __iomem *arm_smmu_page1_fixup(unsigned long offset,
struct arm_smmu_device *smmu)
{
@@ -1622,7 +1642,7 @@ static int arm_smmu_domain_finalise(struct iommu_domain
*domain)
if (smmu->features & ARM_SMMU_FEAT_COHERENCY)
pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_NO_DMA;
- if (domain->type == IOMMU_DOMAIN_DMA) {
+ if ((domain->type == IOMMU_DOMAIN_DMA) && smmu_non_strict) {
domain->non_strict = true;
pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
}
--
1.8.3
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