[PATCH v2 0/2] KVM: arm64: Uphold 64bit-only behavior on asymmetric systems

[Marc Zyngier]

On Tue, 16 Aug 2022 20:25:52 +0100,
Oliver Upton <oliver.upton at linux.dev> wrote:
> 
> Small series to fix a couple issues around when 64bit-only behavior is
> applied. As KVM is more restrictive than the kernel in terms of 32bit
> support (no asymmetry), we really needed our own predicate when the
> meaning of system_supports_32bit_el0() changed in commit 2122a833316f
> ("arm64: Allow mismatched 32-bit EL0 support").
> 
> Lightly tested as I do not have any asymmetric systems on hand at the
> moment. Attention on patch 2 would be appreciated as it affects ABI.

I don't think this significantly affect the ABI, as it is pretty
unlikely that you'd have been able to execute the result, at least on
VM creation (set PSTATE.M=USR, start executing, get the page fault on
the first instruction... bang).

You could have tricked it in other ways, but at the end of the day
you're running a broken hypervisor on an even more broken system...

Anyway, I've applied this to fixes.

Thanks,

	M.

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