On Fri, 01 Oct 2021 10:27:18 +0100,
Suzuki K Poulose [off-list ref] wrote:

On 30/09/2021 11:29, Marc Zyngier wrote:

quoted

On Wed, 29 Sep 2021 11:35:46 +0100,
Suzuki K Poulose [off-list ref] wrote:

quoted

quoted

+	if (strcmp(arg, "none") == 0 && !WARN_ON(is_kernel_in_hyp_mode())) {

nit: Does this really need to WARN here ? Unlike the "nvhe" case, if the
user wants to keep the KVM out of the picture for, say debugging
something, it is perfectly Ok to allow the kernel to be running at EL2
without having to change the Firmware to alter the landing EL for the
kernel ?

Well, the doc says "run in nVHE mode" and the option forces
id_aa64mmfr1.vh=0. The WARN_ON() will only fires on broken^Wfruity HW
that is VHE only. Note that this doesn't rely on any firmware change
(we drop from EL2 to EL1 and stay there).

Ah, ok. So the "none" is in fact "nvhe + no-kvm". Thats the bit I
missed. TBH, that name to me sounds like "no KVM" at all, which is what
we want. The question is, do we really need "none" to force vh == 0 ? I
understand this is only a problem on a rare set of HWs. But the generic
option looks deceiving.

That said, I am happy to leave this as is and the doc says so.

I think you have a point here. Conflating the two things is a bit odd,
and we might as well let the user pick the configuration they want
(they can always pass 'id_aa64mmfr1.vh=0' themselves).

I'll respin the patch with this change.

Thanks,

	M.

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

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