KVM: arm64: Convert memslot cache-flushing code to generic page-table API

Convert stage2_flush_memslot() to call the kvm_pgtable_stage2_flush()
function of the generic page-table code instead of walking the page-table
directly.
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200911132529.19844-16-will@kernel.org

arch/arm64/kvm/mmu.c

@@ -460,21 +460,10 @@ static void stage2_flush_p4ds(struct kvm_s2_mmu *mmu, pgd_t *pgd,
 static void stage2_flush_memslot(struct kvm *kvm,
 				 struct kvm_memory_slot *memslot)
 {
-	struct kvm_s2_mmu *mmu = &kvm->arch.mmu;
 	phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT;
 	phys_addr_t end = addr + PAGE_SIZE * memslot->npages;
-	phys_addr_t next;
-	pgd_t *pgd;
 
-	pgd = mmu->pgd + stage2_pgd_index(kvm, addr);
-	do {
-		next = stage2_pgd_addr_end(kvm, addr, end);
-		if (!stage2_pgd_none(kvm, *pgd))
-			stage2_flush_p4ds(mmu, pgd, addr, next);
-
-		if (next != end)
-			cond_resched_lock(&kvm->mmu_lock);
-	} while (pgd++, addr = next, addr != end);
+	stage2_apply_range_resched(kvm, addr, end, kvm_pgtable_stage2_flush);
 }
 
 /**