failed to start vm after add vsock device

["longguang.yue" <libvirt@xxxxxxx>]

Hi, all:

    there is no error when launch qemu-kvm from cli directly,  but vm fails to start via libvirtd.
i have tried to chmod 0666 /dev/vhost-vsock.


error: internal error: qemu unexpectedly closed the monitor: 2021-01-26T13:06:06.403097Z qemu-kvm: -device vhost-vsock-pci,id=vhost-vsock-pci0,guest-cid=4: vhost-vsock: failed to open vhost device: Unknown error -13



<qemu:commandline>
    <qemu:arg value='-device'/>
    <qemu:arg value='vhost-vsock-pci,id=vhost-vsock-pci0,guest-cid=4'/>
  </qemu:commandline>



thanks