failed to start vm after add vsock device

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