Re: [PATCH 1/2] ARM: hyp-stub: improve ABI

Russell King - ARM Linux
2016-12-15T11:34:46Z

On Thu, Dec 15, 2016 at 11:18:48AM +0000, Marc Zyngier wrote:
> On 14/12/16 10:46, Russell King wrote:
> > @@ -231,10 +244,14 @@ ENDPROC(__hyp_stub_do_trap)
> > * initialisation entry point.
> > */
> > ENTRY(__hyp_get_vectors)
> > - mov r0, #-1
> > + mov r0, #HVC_GET_VECTORS
>
> This breaks the KVM implementation of __hyp_get_vectors, easily fixed
> with the following patchlet:

Right, so what Mark said is wrong:

"The hyp-stub is part of the kernel image, and the API is private to
that particular image, so we can change things -- there's no ABI to
worry about."

So no, I'm going with my original patch (which TI has tested) which is
the minimal change, and if we _then_ want to rework the HYP mode
interfaces, that's the time to do the other changes when more people
(such as KVM folk) are paying attention and we can come to a cross-
hypervisor agreement on what the interface should be.

--
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