IOMMU regression in linux-6.18.y

Mario Limonciello
2026-01-21T02:08:39Z

Hi,

Recently I found out that amdxdna stopped working in linux-6.18.4. This
is because of this commit in linux-6.18.y:

commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set")

That was originally backported from upstream:

commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set")

---

SVA support is a requirement for amdxdna.

The series that this commit came from was part of a larger 8 patch
series, but this was the only commit that was CC'ed to stable.

As a result this is not broken in 6.19-rc, but it is broken in
linux-6.18.y (and presumably any older stable kernels still around that
picked it up).

So there are two options I see:

1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel that
picked it up but has amdxdna)

2) Bring the entire 8 patch series to linux-6.18.y.

This is the entire series (I didn't look up the hashes from mainline,
but they should have all landed):
https://lore.kernel.org/linux-iommu/20251022082635.2462433-1-baolu.lu@linux.intel.com/

What should we do?