Subject: Re: [PATCH v3 0/5] KVM: arm64: nv: Implement nested stage-2 reverse map

From: Marc Zyngier <[email-masked]>
Date: Thu, 28 May 2026 11:19:34 +0100

On Wed, 20 May 2026 08:31:12 +0100,
Itaru Kitayama <[email-masked]> wrote:
> 
> Hi Wei Lin,
> 
> On Sun, May 10, 2026 at 03:53:33PM +0100, Wei-Lin Chang wrote:
> > Hi,
> > 
> > This is v3 of optimizing the shadow s2 mmu unmapping during MMU
> > notifiers.
> > 
> > Two new preparatory patches are added, one reduces a hole in kvm_s2_mmu
> > and another refactors the code a bit during s2 faults. Other changes are
> > listed below.
> > 
> > * Changes from v2 [1]:
> > 
> >   - Removed "polluted" teminology.
> > 
> >   - Use xa_{mk, to}_value() when storing and retriving values from maple
> >     trees.
> > 
> >   - Avoid using the 63rd bit in maple tree values so that xa_{mk, to}_value()
> >     does not lose us a bit.
> > 
> >   - Added reverse map removal during TLBI handling.
> > 
> >   - Other suggested refactorings.
> > 
> > Thanks!
> 
> With this series applied on the recent kvmarm/fixes (minor local modification), 
> your v3 hello_nested runs fine on all three page granules; without this 16KB 
> kernel can't handle stage 2 unmapping paths. I tested using the latest QEMU only 
> so wonder how you're testing.

Can you clarify this statement?

Are you saying that 16kB S2 unmap do not work with upstream? That
seems odd, as it would mean NV wouldn't work on Apple HW, which
represents two thirds of my development boxes...

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.