+    def create_vfs(self, pf_port: Port) -> None:
+        """Overrides :meth:`~.os_session.OSSession.create_vfs`.
+
+        Raises:
+            InternalError: If the number of VFs is greater than 0 but less than the
+            maximum for `pf_port`.
+        """
+        sys_bus_path = f"/sys/bus/pci/devices/{pf_port.pci}".replace(":", "\\:")
+        curr_num_vfs = int(self.send_command(f"cat {sys_bus_path}/sriov_numvfs").stdout)
+        max_num_vfs = int(
+            self.send_command(f"cat {sys_bus_path}/sriov_totalvfs", privileged=True).stdout
+        )
+        if 0 < curr_num_vfs < max_num_vfs:
+            raise InternalError("There are existing VFs on the port which must be deleted.")