we'll discuss an extension of the work of kudla-millson on the modularity of special cycles on a non-compact shimura variety associated to u(n,1) over a split cm field. the volume of their intersections with a diagonally embedded shimura subvariety is related to fourier coefficients of a hilbert modular form coming from the restriction of an eisenstein series on u(n,n). the main new idea is an application of the regularized siegel-weil formula of gan-qiu-takeda.