Re: [PATCH 2/2] KVM: arm64: Remove extra argument for __pvkm_host_{share,unshare}_hyp()

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi Marc,

On Thu, Dec 11, 2025 at 08:15:28AM +0000, Marc Zyngier wrote:
> On Wed, 10 Dec 2025 13:21:02 +0000,
> Alexandru Elisei <alexandru.elisei@arm.com> wrote:
> > 
> > __pvkm_host_share_hyp() and __pkvm_host_unshare_hyp() both have one
> > parameter, the pfn, not two. Even though correctness isn't impacted because
> > the SMCCC handlers pass the first argument and ignore the second one, let's
> > call the functions with the proper number of arguments.
> > 
> > Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> > ---
> >  arch/arm64/kvm/mmu.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 7cc964af8d30..6c6abcd8e89e 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -497,7 +497,7 @@ static int share_pfn_hyp(u64 pfn)
> >  	this->count = 1;
> >  	rb_link_node(&this->node, parent, node);
> >  	rb_insert_color(&this->node, &hyp_shared_pfns);
> > -	ret = kvm_call_hyp_nvhe(__pkvm_host_share_hyp, pfn, 1);
> > +	ret = kvm_call_hyp_nvhe(__pkvm_host_share_hyp, pfn);
> >  unlock:
> >  	mutex_unlock(&hyp_shared_pfns_lock);
> >  
> 
> Yeah, we lost all form of type-checking when everything was hastily
> converted to SMCCC to avoid function pointers. Somehow, I feel that
> the cure was worse than the disease.
> 
> I wish we'd reintroduce some form of compile-time checks, maybe by
> having generated stubs?

I also think compile-time checks would be useful, do you have something
particular in mind?

If not, right now I can't think of a way to generate the stubs automagically,
but I can give it a (probably bad) try and take it from there.

Thanks,
Alex