[RFC PATCH v2 1/3] KVM: arm64: Add hypercall support for retrieving migration targets

[Oliver Upton]

On Tue, Oct 29, 2024 at 04:00:39PM +0000, Shameerali Kolothum Thodi wrote:
> > We can't treat a single register as both a signed quantity *and* a full
> > 64 bits of bitfields. Maybe just scrap the version and have this thing
> > either return a negative error or positive quantity of implementations.
> 
> Ok. I had  a look at PV_TIME_ST/ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID
> and got that idea. Separate registers make sense though.
> 
> Do we really need to skip the version number? The idea was to use that as a
> future proof for data format in case we realize that MIDR/REVIDR is not good
> enough for errata later.

That is definitely an approach we can take. The alternative I had in
mind was that we'd allocate a new function ID if we needed to break ABI
to correct shortcomings of the original interface.

-- 
Thanks,
Oliver