[PATCH v3 06/25] KVM: arm64: Save/restore POE registers

[Marc Zyngier]

On Fri, 24 Nov 2023 16:34:51 +0000,
Joey Gouly <joey.gouly at arm.com> wrote:
> 
> Define the new system registers that POE introduces and context switch them.

Thinking about it some more, I don't think this is enough.

One fundamental thing that POE changes is that read permissions can
now be removed from S1 by the guest. Which means that if we take a
(for example) a permission fault at S2 and perform (as we do today) a
"AT S1E1R" to obtain the faulting IPA, we can end-up with a failing
translation because POE, under control of the guest, has removed the
read permission.

Which is why FEAT_ATS1A exists, and ignores permission overlays so
that we can get to the IPA.

I think this means we need to teach __translate_far_to_hpfar() about
AT S1E1A

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.