On Mon, 19 Jul 2021 07:31:30 +0100,
Paolo Bonzini [off-list ref] wrote:

On 17/07/21 11:55, Marc Zyngier wrote:

quoted

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@kernel.org>

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.

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