[PATCH rc v1 3/4] iommu/arm-smmu-v3: Ignore STE EATS when computing the update sequence

Jason Gunthorpe jgg at nvidia.com
Sat Dec 6 11:46:37 PST 2025


On Fri, Dec 05, 2025 at 04:52:02PM -0800, Nicolin Chen wrote:
> From: Jason Gunthorpe <jgg at nvidia.com>
> 
> If a VM want to toggle EATS off the hypervisor will see EATS change to 0
> and insert a V=0 breaking update into the STE even though the VM did not
> ask for that.

"EATS off at the same time as changing CFG"

In bare metal EATS is ignored by CFG=ABORT/BYPASS which is why this
doesn't cause a problem until we have nested where CFG is always a
variation of S2 trans that does use EATS.

Jason



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