Saving vm with shared folder results in Error: State blocked by non-migratable device  '000.../vhost-user-fs'
Description of problem:
Saving a vm with savevm in the QEMU Monitor with a shared folder causes the following error message:
`Error: State blocked by non-migratable device '0000:00:05.0/vhost-user-fs'`
Steps to reproduce:
1. Get an qcow2 image that can boot (not sure if working qcow2 image is actually needed)
2. Start virtiofsd with this /usr/libexec/virtiofsd --socket-path=/tmp/virtiofs_socket -o source=/path/to/share
3. Run qemu-system-x86_64 -m 4G -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on -numa node,memdev=mem  -smp 2 -hda image.qcow2 -vga qxl -virtfs local,path=/path/to/share,mount_tag=share,security_model=passthrough,id=virtiofs -chardev socket,id=char0,path=/tmp/virtiofs_socket -device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=share
4. Let the image boot and/or go into the QEMU monitor.
5. type savevm testvm
6. See error.
Additional information:
This happens with both the legacy virtio-fs and the rust version.

According to the first reply to https://gitlab.com/virtio-fs/virtiofsd/-/issues/81 there needs to be "a lot of changes not only in virtiofsd but also in the rust-vmm crates and qemu (and maybe in the vhost-user protocol)" so I'm reporting this here in the hopes it will speed something up.

I followed the following to get virtiofsd working with command line QEMU:
https://github.com/virtio-win/kvm-guest-drivers-windows/wiki/Virtiofs:-Shared-file-system

This is blocking our migration from VirtualBox because it doesn't have problems like this. The least I need is a work around or alternative shared filesystem. We are trying to avoid networked shares.