On Mon, 19 Jul 2021 07:31:30 +0100,
Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
> On 17/07/21 11:55, Marc Zyngier wrote:
> > We currently rely on the kvm_is_transparent_hugepage() helper to
> > discover whether a given page has the potential to be mapped as
> > a block mapping.
> >
> > However, this API doesn't really give un everything we want:
> > - we don't get the size: this is not crucial today as we only
> > support PMD-sized THPs, but we'd like to have larger sizes
> > in the future
> > - we're the only user left of the API, and there is a will
> > to remove it altogether
> >
> > To address the above, implement a simple walker using the existing
> > page table infrastructure, and plumb it into transparent_hugepage_adjust().
> > No new page sizes are supported in the process.
> >
> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
>
> If it's okay for you to reuse the KVM page walker that's fine of
> course, but the arch/x86/mm functions lookup_address_in_{mm,pgd} are
> mostly machine-independent and it may make sense to move them to mm/.
>
> That would also allow reusing the x86 function host_pfn_mapping_level.
That could work to some extent, but the way the x86 code equates level
to mapping size is a bit at odds with the multiple page sizes that
arm64 deals with.
We're also trying to move away from the whole P*D abstraction, because
this isn't something we want to deal with in the self-contained EL2
object.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
