On Tue, Mar 16, 2021 at 04:38:22PM +0100, Christoph Hellwig wrote:

From: Robin Murphy <robin.murphy@arm.com>

Instead make the global iommu_dma_strict paramete in iommu.c canonical by
exporting helpers to get and set it and use those directly in the drivers.

This make sure that the iommu.strict parameter also works for the AMD and
Intel IOMMU drivers on x86.  As those default to lazy flushing a new
IOMMU_CMD_LINE_STRICT is used to turn the value into a tristate to
represent the default if not overriden by an explicit parameter.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>.
[ported on top of the other iommu_attr changes and added a few small
 missing bits]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/iommu/amd/iommu.c                   | 23 +-------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 50 +---------------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  1 -
 drivers/iommu/arm/arm-smmu/arm-smmu.c       | 27 +--------
 drivers/iommu/dma-iommu.c                   |  9 +--
 drivers/iommu/intel/iommu.c                 | 64 ++++-----------------
 drivers/iommu/iommu.c                       | 27 ++++++---
 include/linux/iommu.h                       |  4 +-
 8 files changed, 40 insertions(+), 165 deletions(-)

I really like this cleanup, but I can't help wonder if it's going in the
wrong direction. With SoCs often having multiple IOMMU instances and a
distinction between "trusted" and "untrusted" devices, then having the
flush-queue enabled on a per-IOMMU or per-domain basis doesn't sound
unreasonable to me, but this change makes it a global property.

For example, see the recent patch from Lu Baolu:

https://lore.kernel.org/r/20210225061454.2864009-1-baolu.lu@linux.intel.com (local)

Will