5.10.40-1 - Invalid SGL for payload:131072 nents:13

[Andy Smith]

Hi Keith,

On Tue, Jul 20, 2021 at 05:34:34PM -0700, Keith Busch wrote:
> Are you using swiotlb?

I've just realised that there was another change to my config
besides the kernel version: I increased the amount of memory
allocated to dom0 from 3GiB to 8GiB.

If I understand things correctly swiotlb is not used when memory is
< 4GiB, so I previously would not have been using swiotlb but now
will be.

What's the least invasive way of disabling swiotlb? Would it be

    swiotlb=noforce

Or

    iommu=off

Or maybe

    swiotlb=1

to reduce it to an amount that would never be used?

(Going by kernel parameters available in 5.10.40)

This is an Intel system and I see the various intel_iommu parameters
but don't know if any of them would be more appropriate.

> If so, this recent patch sounds like it should fix offset issues:

As I don't have an easy way to reproduce the problem on demand I
think I would like to first try going back to a situation where
swiotlb is not used, to see if the problem goes away in that case.
Happy to do more experimentation later…

Thanks!
Andy