KVM: Separate out dirty_bitmap allocation code as kvm_kvzalloc()

Will be used for lpage_info allocation later.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>

virt/kvm/kvm_main.c

@@ -516,16 +516,32 @@ static struct kvm *kvm_create_vm(unsigned long type)
 	return ERR_PTR(r);
 }
 
+/*
+ * Avoid using vmalloc for a small buffer.
+ * Should not be used when the size is statically known.
+ */
+static void *kvm_kvzalloc(unsigned long size)
+{
+	if (size > PAGE_SIZE)
+		return vzalloc(size);
+	else
+		return kzalloc(size, GFP_KERNEL);
+}
+
+static void kvm_kvfree(const void *addr)
+{
+	if (is_vmalloc_addr(addr))
+		vfree(addr);
+	else
+		kfree(addr);
+}
+
 static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
 {
 	if (!memslot->dirty_bitmap)
 		return;
 
-	if (2 * kvm_dirty_bitmap_bytes(memslot) > PAGE_SIZE)
-		vfree(memslot->dirty_bitmap);
-	else
-		kfree(memslot->dirty_bitmap);
-
+	kvm_kvfree(memslot->dirty_bitmap);
 	memslot->dirty_bitmap = NULL;
 }
 
@@ -617,11 +633,7 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
 #ifndef CONFIG_S390
 	unsigned long dirty_bytes = 2 * kvm_dirty_bitmap_bytes(memslot);
 
-	if (dirty_bytes > PAGE_SIZE)
-		memslot->dirty_bitmap = vzalloc(dirty_bytes);
-	else
-		memslot->dirty_bitmap = kzalloc(dirty_bytes, GFP_KERNEL);
-
+	memslot->dirty_bitmap = kvm_kvzalloc(dirty_bytes);
 	if (!memslot->dirty_bitmap)
 		return -ENOMEM;