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authorRobin Murphy <robin.murphy@arm.com>2021-08-11 13:21:35 +0100
committerJoerg Roedel <jroedel@suse.de>2021-08-18 13:27:49 +0200
commit26225bea1d84b090b378838a1797daec62d4ad0e (patch)
tree5b3a07ac54b9c42482adf6bfca897240ac30037c
parentc208916fe6c7b84e3ec95cd91853039596eeb2cf (diff)
downloadlinux-26225bea1d84b090b378838a1797daec62d4ad0e.tar.bz2
iommu: Expose DMA domain strictness via sysfs
The sysfs interface for default domain types exists primarily so users can choose the performance/security tradeoff relevant to their own workload. As such, the choice between the policies for DMA domains fits perfectly as an additional point on that scale - downgrading a particular device from a strict default to non-strict may be enough to let it reach the desired level of performance, while still retaining more peace of mind than with a wide-open identity domain. Now that we've abstracted non-strict mode as a distinct type of DMA domain, allow it to be chosen through the user interface as well. Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: John Garry <john.garry@huawei.com> Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/0e08da5ed4069fd3473cfbadda758ca983becdbf.1628682049.git.robin.murphy@arm.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
-rw-r--r--Documentation/ABI/testing/sysfs-kernel-iommu_groups6
-rw-r--r--drivers/iommu/iommu.c2
2 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/ABI/testing/sysfs-kernel-iommu_groups b/Documentation/ABI/testing/sysfs-kernel-iommu_groups
index eae2f1c1e11e..b15af6a5bc08 100644
--- a/Documentation/ABI/testing/sysfs-kernel-iommu_groups
+++ b/Documentation/ABI/testing/sysfs-kernel-iommu_groups
@@ -42,8 +42,12 @@ Description: /sys/kernel/iommu_groups/<grp_id>/type shows the type of default
======== ======================================================
DMA All the DMA transactions from the device in this group
are translated by the iommu.
+ DMA-FQ As above, but using batched invalidation to lazily
+ remove translations after use. This may offer reduced
+ overhead at the cost of reduced memory protection.
identity All the DMA transactions from the device in this group
- are not translated by the iommu.
+ are not translated by the iommu. Maximum performance
+ but zero protection.
auto Change to the type the device was booted with.
======== ======================================================
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index e09f0d433683..f653a70389ef 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3268,6 +3268,8 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
req_type = IOMMU_DOMAIN_IDENTITY;
else if (sysfs_streq(buf, "DMA"))
req_type = IOMMU_DOMAIN_DMA;
+ else if (sysfs_streq(buf, "DMA-FQ"))
+ req_type = IOMMU_DOMAIN_DMA_FQ;
else if (sysfs_streq(buf, "auto"))
req_type = 0;
else