I am able to get virtio-fs working on bare metal Ubuntu Server 21.04 (libvirt 7.0.0, qemu 5.2.0), but not Unraid 6.9.2 (libvirt 6.5.0, qemu 5.1.0).

 

For my (Windows 10) VM domain, I used Virt-manager to insert the following in XML:

  <memoryBacking>
    <access mode="shared"/>
  </memoryBacking>
...

  <cpu ...>
...

    <numa>
      <cell id="0" cpus="0-7" memory="8388608" unit="KiB" memAccess="shared"/>
    </numa>
  </cpu>

 

Then added a Filesystem using the following XML:

<filesystem type="mount" accessmode="passthrough">
  <driver type="virtiofs"/>
  <source dir="/mnt/user"/>
  <target dir="unraid"/>
</filesystem>

 

Virt-manager/libvirt assigned the filesystem the following hardware address:

  <address type="pci" domain="0x0000" bus="0x00" slot="0x0b" function="0x0"/>

 

Everything adds fine, but the VM won't start. Log is as follows:

-rtc base=localtime \
-no-hpet \
-no-shutdown \
-boot strict=on \
-device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x3 \
-device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x7.0x7 \
-device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x7 \
-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x7.0x1 \
-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x7.0x2 \
-device ahci,id=sata0,bus=pci.0,addr=0xa \
-device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 \
-blockdev '{"driver":"file","filename":"/mnt/cache/domains/Windows-10/vdisk1.img","node-name":"libvirt-2-storage","cache":{"direct":false,"no-flush":false},"auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-2-format","read-only":false,"cache":{"direct":false,"no-flush":false},"driver":"raw","file":"libvirt-2-storage"}' \
-device virtio-blk-pci,bus=pci.0,addr=0x9,drive=libvirt-2-format,id=virtio-disk2,bootindex=1,write-cache=on \
-blockdev '{"driver":"file","filename":"/mnt/user/isos/virtio-win-0.1.190.iso","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-1-format","read-only":true,"driver":"raw","file":"libvirt-1-storage"}' \
-device ide-cd,bus=sata0.0,drive=libvirt-1-format,id=sata0-0-0 \
-chardev socket,id=chr-vu-fs0,path=/var/lib/libvirt/qemu/domain-4-Windows-10/fs0-fs.sock \
-device vhost-user-fs-pci,chardev=chr-vu-fs0,tag=unraid,bus=pci.0,addr=0xb \
-netdev tap,fd=34,id=hostnet0 \
-device virtio-net,netdev=hostnet0,id=net0,mac=52:54:00:7c:b2:7b,bus=pci.0,addr=0x4 \
-chardev pty,id=charserial0 \
-device isa-serial,chardev=charserial0,id=serial0 \
-chardev socket,id=charchannel0,fd=36,server,nowait \
-device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 \
-device usb-tablet,id=input0,bus=usb.0,port=1 \
-vnc 0.0.0.0:0,websocket=5700 \
-k en-us \
-device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pci.0,addr=0x2 \
-device ich9-intel-hda,id=sound0,bus=pci.0,addr=0x8 \
-device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 \
-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6 \
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
-msg timestamp=on
2021-05-03 12:49:46.800+0000: Domain id=4 is tainted: high-privileges
2021-05-03 12:49:46.800+0000: Domain id=4 is tainted: host-cpu
char device redirected to /dev/pts/0 (label charserial0)
2021-05-03T12:49:46.936396Z qemu-system-x86_64: -device vhost-user-fs-pci,chardev=chr-vu-fs0,tag=unraid,bus=pci.0,addr=0xb: Failed to write msg. Wrote -1 instead of 12.
2021-05-03T12:49:46.936455Z qemu-system-x86_64: -device vhost-user-fs-pci,chardev=chr-vu-fs0,tag=unraid,bus=pci.0,addr=0xb: vhost_dev_init failed: Operation not permitted
2021-05-03 12:49:46.971+0000: shutting down, reason=failed

 

Obviously there is a difference in version of qemu+libvirt between the two systems. Hoping these packages will be updated to at least 5.2.0+7.0.0 respectively in the next release of Unraid. I think they're up to at least release 6.0.0+7.2.0.

 

That aside, anyone else pounding away at this?

 

 

I was able to get virtio-fs working on Unraid 6.9.2. See this thread for details: