That is not what I asked. When I boot XFCE Live on QEMU with virgl I get empty screen. But logging in I see that full graphical session was started and all processes are active - just nothing is displayed. It works without virgl.
As long as the only information you provide is “it does not work” the only possible answer is “something is wrong”. At least, start with full log from booted system (full journalctl output), it may give some hints.