From: Zhen Lei <thunder.leiz...@huawei.com>
Add a generic command line option to enable lazy unmapping via IOVA
flush queues, which will initally be suuported by iommu-dma. This echoes
the semantics of "intel_iommu=strict" (albeit with the opposite default
value), but in the driver-agnostic fashion of "iommu.passthrough".
Signed-off-by: Zhen Lei <thunder.leiz...@huawei.com>
[rm: move handling out of SMMUv3 driver, clean up documentation]
Signed-off-by: Robin Murphy <robin.mur...@arm.com>
---
v8:
- Rename "non-strict" to "strict" to better match existing options
- Rewrite doc text/commit message
- Downgrade boot-time message from warn/taint to info
.../admin-guide/kernel-parameters.txt | 12 ++++++++++
drivers/iommu/iommu.c | 23 +++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index 9871e649ffef..92ae12aeabf4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1749,6 +1749,18 @@
nobypass [PPC/POWERNV]
Disable IOMMU bypass, using IOMMU for PCI devices.
+ iommu.strict= [ARM64] Configure TLB invalidation behaviour
+ Format: { "0" | "1" }
+ 0 - Lazy mode.
+ Request that DMA unmap operations use deferred
+ invalidation of hardware TLBs, for increased
+ throughput at the cost of reduced device isolation.
+ Will fall back to strict mode if not supported by
+ the relevant IOMMU driver.
+ 1 - Strict mode (default).
+ DMA unmap operations invalidate IOMMU hardware TLBs
+ synchronously.
+
iommu.passthrough=
[ARM64] Configure DMA to bypass the IOMMU by default.
Format: { "0" | "1" }
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 8c15c5980299..02b6603f0616 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -41,6 +41,7 @@ static unsigned int iommu_def_domain_type =
IOMMU_DOMAIN_IDENTITY;
#else
static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA;
#endif
+static bool iommu_dma_strict __read_mostly = true;
struct iommu_callback_data {
const struct iommu_ops *ops;
@@ -131,6 +132,21 @@ static int __init iommu_set_def_domain_type(char *str)
}
early_param("iommu.passthrough", iommu_set_def_domain_type);
+static int __init iommu_dma_setup(char *str)
+{
+ int ret;
+
+ ret = kstrtobool(str, &iommu_dma_strict);
+ if (ret)
+ return ret;
+
+ if (!iommu_dma_strict)
+ pr_info("Enabling deferred TLB invalidation for DMA; protection
against malicious/malfunctioning devices may be reduced.\n");
+
+ return 0;
+}
+early_param("iommu.strict", iommu_dma_setup);
+
static ssize_t iommu_group_attr_show(struct kobject *kobj,
struct attribute *__attr, char *buf)
{
@@ -1072,6 +1088,13 @@ struct iommu_group *iommu_group_get_for_dev(struct
device *dev)
group->default_domain = dom;
if (!group->domain)
group->domain = dom;
+
+ if (dom && !iommu_dma_strict) {
+ int attr = 1;
+ iommu_domain_set_attr(dom,
+ DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
+ &attr);
+ }
}
ret = iommu_group_add_device(group, dev);
--
2.19.0.dirty
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