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...@linux.intel.com> Reviewed-by: John Garry <john.ga...@huawei.com> Signed-off-by: Robin Murphy <robin.mur...@arm.com> --- v3: Summarise the implications in the documentation for completeness --- Documentation/ABI/testing/sysfs-kernel-iommu_groups | 6 +++++- drivers/iommu/iommu.c | 2 ++ 2 files changed, 7 insertions(+), 1 deletion(-) 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 55ca5bf3cafc..b141161d5bbc 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3267,6 +3267,8 @@ 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 -- 2.25.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu