[PATCH] powerpc/powernv/npu: Remove redundant change_pte() hook

[Peter Xu]

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 at kernel.crashing.org>
CC: Paul Mackerras <paulus at samba.org>
CC: Michael Ellerman <mpe at ellerman.id.au>
CC: Alistair Popple <alistair at popple.id.au>
CC: Alexey Kardashevskiy <aik at ozlabs.ru>
CC: Mark Hairgrove <mhairgrove at nvidia.com>
CC: Balbir Singh <bsingharora at gmail.com>
CC: David Gibson <david at gibson.dropbear.id.au>
CC: Andrea Arcangeli <aarcange at redhat.com>
CC: Jerome Glisse <jglisse at redhat.com>
CC: Jason Wang <jasowang at redhat.com>
CC: linuxppc-dev at lists.ozlabs.org
CC: linux-kernel at vger.kernel.org
Signed-off-by: Peter Xu <peterx at redhat.com>
---
 arch/powerpc/platforms/powernv/npu-dma.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c
index 3f58c7dbd581..c003b29d870e 100644
--- a/arch/powerpc/platforms/powernv/npu-dma.c
+++ b/arch/powerpc/platforms/powernv/npu-dma.c
@@ -917,15 +917,6 @@ static void pnv_npu2_mn_release(struct mmu_notifier *mn,
 	mmio_invalidate(npu_context, 0, ~0UL);
 }
 
-static void pnv_npu2_mn_change_pte(struct mmu_notifier *mn,
-				struct mm_struct *mm,
-				unsigned long address,
-				pte_t pte)
-{
-	struct npu_context *npu_context = mn_to_npu_context(mn);
-	mmio_invalidate(npu_context, address, PAGE_SIZE);
-}
-
 static void pnv_npu2_mn_invalidate_range(struct mmu_notifier *mn,
 					struct mm_struct *mm,
 					unsigned long start, unsigned long end)
@@ -936,7 +927,6 @@ static void pnv_npu2_mn_invalidate_range(struct mmu_notifier *mn,
 
 static const struct mmu_notifier_ops nv_nmmu_notifier_ops = {
 	.release = pnv_npu2_mn_release,
-	.change_pte = pnv_npu2_mn_change_pte,
 	.invalidate_range = pnv_npu2_mn_invalidate_range,
 };
 
-- 
2.17.1