Re: powerpc/powernv/npu: Remove redundant change_pte() hook

[Michael Ellerman]

On Thu, 2019-01-31 at 10:30:22 UTC, Peter Xu wrote:
> The change_pte() notifier was designed to use as a quick path to
> update secondary MMU PTEs on write permission changes or PFN changes.
> For KVM, it could reduce the vm-exits when vcpu faults on the pages
> that was touched up by KSM.  It's not used to do cache invalidations,
> for example, if we see the notifier will be called before the real PTE
> update after all (please see set_pte_at_notify that set_pte_at was
> called later).
> 
> All the necessary cache invalidation should all be done in
> invalidate_range() already.
> 
> CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> CC: Paul Mackerras <paulus@xxxxxxxxx>
> CC: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> CC: Alistair Popple <alistair@xxxxxxxxxxxx>
> CC: Alexey Kardashevskiy <aik@xxxxxxxxx>
> CC: Mark Hairgrove <mhairgrove@xxxxxxxxxx>
> CC: Balbir Singh <bsingharora@xxxxxxxxx>
> CC: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> CC: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> CC: Jerome Glisse <jglisse@xxxxxxxxxx>
> CC: Jason Wang <jasowang@xxxxxxxxxx>
> CC: linuxppc-dev@xxxxxxxxxxxxxxxx
> CC: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Reviewed-by: Alistair Popple <alistair@xxxxxxxxxxxx>
> Reviewed-by: Balbir Singh <bsingharora@xxxxxxxxx>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/1b58a975be36994a572ae3b3fb3e0232

cheers