Vsock device

crosvm supports virtio-vsock device for communication between the host and a guest VM.

Assign a context id to a guest VM by passing it with the --vsock flag.


crosvm run \
  --vsock "${GUEST_CID}" \
  <usual crosvm arguments>

Then, the guest and the host can communicate with each other via vsock. Host always has 2 as its context id.

crosvm assumes that the host has a vsock device at /dev/vhost-vsock. If you want to use a device at a different path or one given as an fd, you can use --vhost-vsock-device flag or --vhost-vsock-fd flag respectively.

Example usage

At host shell:


# Listen at host
ncat -l --vsock ${PORT}

At guest shell:


# Make a connection to the host
ncat --vsock ${HOST_CID} ${PORT}

If a vsock device is configured properly in the guest VM, a connection between the host and the guest can be established and packets can be sent from both side. In the above example, your inputs to a shell on one's side should be shown at the shell on the other side if a connection is successfully established.