[PATCH v5 09/14] KVM: arm64: Atomically update stage 2 leaf attributes in parallel walks

[Sean Christopherson]

On Wed, Nov 09, 2022, Ben Gardon wrote:
> On Mon, Nov 7, 2022 at 1:58 PM Oliver Upton <oliver.upton at linux.dev> wrote:
> > @@ -1054,7 +1066,7 @@ kvm_pte_t kvm_pgtable_stage2_mkold(struct kvm_pgtable *pgt, u64 addr)
> >  bool kvm_pgtable_stage2_is_young(struct kvm_pgtable *pgt, u64 addr)
> >  {
> >         kvm_pte_t pte = 0;
> > -       stage2_update_leaf_attrs(pgt, addr, 1, 0, 0, &pte, NULL);
> > +       stage2_update_leaf_attrs(pgt, addr, 1, 0, 0, &pte, NULL, 0);
> 
> Would be nice to have an enum for KVM_PGTABLE_WALK_EXCLUSIVE so this
> doesn't just have to pass 0.

That's also dangerous though since the param is a set of flags, not unique,
arbitrary values.  E.g. this won't do the expected thing

	if (flags & KVM_PGTABLE_WALK_EXCLUSIVE)

I assume compilers would complain, but never say never when it comes to compilers :-)