[PATCH v2 01/36] KVM: arm64: Account for RES1 bits in DECLARE_FEAT_MAP() and co

[Sascha Bischoff]

On Tue, 2026-01-06 at 17:23 +0000, Jonathan Cameron wrote:
> On Fri, 19 Dec 2025 15:52:36 +0000
> Sascha Bischoff <Sascha.Bischoff at arm.com> wrote:
> 
> > From: Marc Zyngier <maz at kernel.org>
> > 
> > None of the registers we manage in the feature dependency
> > infrastructure
> > so far has any RES1 bit. This is about to change, as VTCR_EL2 has
> > its bit 31 being RES1.
> 
> Oh goody.
> 
> > 
> > In order to not fail the consistency checks by not describing a
> > bit,
> > add RES1 bits to the set of immutable bits. This requires some
> > extra
> > surgery for the FGT handling, as we now need to track RES1 bits
> > there
> > as well.
> > 
> > There are no RES1 FGT bits *yet*. Watch this space.
> > 
> > Signed-off-by: Marc Zyngier <maz at kernel.org>
> FWIW it seems correct.  The only thing I wondered about is
> the assumption that if there is an error best thing to do is
> to assume it was res0 that was wrong and paper over it.
> I guess we can't do anything better if that does happen.
> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron at huawei.com>
> 
> Process thing though: before anyone can merge this, Sasha
> please take a look at submitting patches documentation.
> 
> When you 'post' a patch that was written by someone else you have
> handled the patch and for the Developer Certificate of origin stuff
> to work you have to add your Signed-off-by after theirs.

Thanks for pointing that out. As Marc has posted this for review
separately I'd wrongly (!) assumed that that I shouldn't have signed it
off here. Have added that now, thanks.

Sascha

> 
> Jonathan