Re: [PATCH 13/17] kvm-arm: Add stage2 page table modifiers

[Suzuki K Poulose]

On 08/04/16 18:03, Christoffer Dall wrote:
> On Fri, Apr 08, 2016 at 04:37:02PM +0100, Suzuki K Poulose wrote:
> > On 08/04/16 14:42, Christoffer Dall wrote:
> > > On Mon, Apr 04, 2016 at 05:26:13PM +0100, Suzuki K Poulose wrote:
> >
> > > > -static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> > > > +static void clear_stage2_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> > > >   {
> > > > -	pmd_t *pmd_table = pmd_offset(pud, 0);
> > > > -	VM_BUG_ON(pud_huge(*pud));
> > > > -	pud_clear(pud);
> > > > +	pmd_t *pmd_table __maybe_unused = stage2_pmd_offset(pud, 0);
> > >
> > > The __maybe_unused are slightly ugly, so it may be nicer to create the
> > > stage2_pmd_free() as static inline's if they're defined to do nothing
> > > instead.
> >
> > Sure, we could do that for stage2. However, we will need to fix the host helpers
> > as well for making such a change in the _hyp version (for 16K + 36bit VA).
>
> I thought the host helpers were already done like that, since we don't
> need the __maybe_unused currently.  If it involves changing core code
> etc. then don't bother.

Unfortunately no, e.g,

include/asm-generic/pgtable-nopud.h defines:

#define pud_free(mm, x)                         do { } while (0)

Cheers
Suzuki