From: Zhen Lei <thunder.leizhen@huawei.com>
Date: Thu, 20 Sep 2018 17:10:23 +0100
Subject: iommu: Add "iommu.strict" command line option
Git-commit: 68a6efe86f6a16e25556a2aff40efad41097b486
Patch-mainline: v4.20-rc1
References: fate#326252
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.leizhen@huawei.com>
[rm: move handling out of SMMUv3 driver, clean up documentation]
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: dropped broken printk when parsing command-line option]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
Documentation/admin-guide/kernel-parameters.txt | 12 ++++++++++++
drivers/iommu/iommu.c | 14 ++++++++++++++
2 files changed, 26 insertions(+)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1664,6 +1664,18 @@
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" }
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -41,6 +41,7 @@ static unsigned int iommu_def_domain_typ
#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;
@@ -129,6 +130,12 @@ static int __init iommu_set_def_domain_t
}
early_param("iommu.passthrough", iommu_set_def_domain_type);
+static int __init iommu_dma_setup(char *str)
+{
+ return kstrtobool(str, &iommu_dma_strict);
+}
+early_param("iommu.strict", iommu_dma_setup);
+
static ssize_t iommu_group_attr_show(struct kobject *kobj,
struct attribute *__attr, char *buf)
{
@@ -1047,6 +1054,13 @@ struct iommu_group *iommu_group_get_for_
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);