KVM: arm64: Convert write-protect operation to generic page-table API

Convert stage2_wp_range() to call the kvm_pgtable_stage2_wrprotect()
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/20200911132529.19844-14-will@kernel.org

arch/arm64/kvm/mmu.c

@@ -71,6 +71,9 @@ static int stage2_apply_range(struct kvm *kvm, phys_addr_t addr,
 	return ret;
 }
 
+#define stage2_apply_range_resched(kvm, addr, end, fn)			\
+	stage2_apply_range(kvm, addr, end, fn, true)
+
 static bool memslot_is_logging(struct kvm_memory_slot *memslot)
 {
 	return memslot->dirty_bitmap && !(memslot->flags & KVM_MEM_READONLY);
@@ -1302,27 +1305,7 @@ static void  stage2_wp_p4ds(struct kvm_s2_mmu *mmu, pgd_t *pgd,
 static void stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
 {
 	struct kvm *kvm = mmu->kvm;
-	pgd_t *pgd;
-	phys_addr_t next;
-
-	pgd = mmu->pgd + stage2_pgd_index(kvm, addr);
-	do {
-		/*
-		 * Release kvm_mmu_lock periodically if the memory region is
-		 * large. Otherwise, we may see kernel panics with
-		 * CONFIG_DETECT_HUNG_TASK, CONFIG_LOCKUP_DETECTOR,
-		 * CONFIG_LOCKDEP. Additionally, holding the lock too long
-		 * will also starve other vCPUs. We have to also make sure
-		 * that the page tables are not freed while we released
-		 * the lock.
-		 */
-		cond_resched_lock(&kvm->mmu_lock);
-		if (!READ_ONCE(mmu->pgd))
-			break;
-		next = stage2_pgd_addr_end(kvm, addr, end);
-		if (stage2_pgd_present(kvm, *pgd))
-			stage2_wp_p4ds(mmu, pgd, addr, next);
-	} while (pgd++, addr = next, addr != end);
+	stage2_apply_range_resched(kvm, addr, end, kvm_pgtable_stage2_wrprotect);
 }
 
 /**