Re: [PATCH 0/2] Add arm-smmu-v3 support for instcfg data override feature

Will Deacon <[email protected]> Sun, 26 Jul 2026 14:16:42 +0100
Newsgroups dev.linux.lists.iommu,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-devicetree,org.kernel.vger.linux-kernel
Message-ID <amYIuhYenP4-qHyV@willie-the-truck>
On Fri, Jul 24, 2026 at 01:39:41PM +0100, Peter Griffin wrote:
> These two patches add support for a new "arm,instdata-override" DT property
> that enables the override of the instruction/data attribute of incoming
> traffic to Data by setting the INSTCFG override bits.
> 
> It is intended to be specified when the smmu can't guarantee that these
> attributes are provided correctly from the client device.

This is going to need an in-tree user and a much more detailed
description of what is being worked around before we consider this for
inclusion.

In particular, if a particular client is emitting data reads as
instructions, then a better work around would be to avoid mapping its
domains using IOMMU_NOEXEC. But I can't tell what's going on from the
limited description provided here.

Cheers,

Will