KVM: arm64: Refactor kvm_arch_commit_memory_region()

Refactor kvm_arch_commit_memory_region() as a preparation for a future
commit to look cleaner and more understandable. Also, it looks more
like its x86 counterpart (in kvm_mmu_slot_apply_flags()).
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20230426172330.1439644-8-ricarkol@google.comSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

arch/arm64/kvm/mmu.c

@@ -1794,20 +1794,32 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 				   const struct kvm_memory_slot *new,
 				   enum kvm_mr_change change)
 {
+	bool log_dirty_pages = new && new->flags & KVM_MEM_LOG_DIRTY_PAGES;
+
 	/*
 	 * At this point memslot has been committed and there is an
 	 * allocated dirty_bitmap[], dirty pages will be tracked while the
 	 * memory slot is write protected.
 	 */
-	if (change != KVM_MR_DELETE && new->flags & KVM_MEM_LOG_DIRTY_PAGES) {
+	if (log_dirty_pages) {
+
+		if (change == KVM_MR_DELETE)
+			return;
+
 		/*
-		 * If we're with initial-all-set, we don't need to write
-		 * protect any pages because they're all reported as dirty.
-		 * Huge pages and normal pages will be write protect gradually.
+		 * Pages are write-protected on either of these two
+		 * cases:
+		 *
+		 * 1. with initial-all-set: gradually with CLEAR ioctls,
 		 */
-		if (!kvm_dirty_log_manual_protect_and_init_set(kvm)) {
-			kvm_mmu_wp_memory_region(kvm, new->id);
-		}
+		if (kvm_dirty_log_manual_protect_and_init_set(kvm))
+			return;
+		/*
+		 * or
+		 * 2. without initial-all-set: all in one shot when
+		 *    enabling dirty logging.
+		 */
+		kvm_mmu_wp_memory_region(kvm, new->id);
 	}
 }