Set up VirtFS (9p virtio) for sharing files between Guest and Host on Proxmox VE

9p_virtio.md

How-to

1. On Host(PVE), edit /etc/pve/qemu-server/VMID.conf

args: -fsdev local,security_model=mapped,id=fsdev0,path=/path/to/share -device virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=hostshare

This tells qemu to create a 9pvirtio device exposing the mount_tag hostshare (just a name to identify the mount point). That device is coupled to an fsdev named fsdev0, which specifies which portion of the host filesystem we are sharing, and in which mode.

According to the QEMU wiki, mapped security_model,

Files are created with Qemu user credentials and the client-user's credentials are saved in extended attributes.

I think it is better to use mapped over passthrough

2. On Guest

edit /etc/fstab, add a line

hostshare   /path/to/mount 9p  trans=virtio,version=9p2000.L   0   0

Then, mount -a. Voilà!

Troubleshoot

1. 9p: Could not find request transport: virtio

Add following lines to /etc/initramfs-tools/modules

# 9p
# 9pnet
9pnet_virtio

then,

sudo update-initramfs -u

Reference

• QEMU wiki: 9psetup
• Example Sharing Host files with the Guest
• PVE forum: virtfs / virtio 9p plans to incorporate?

Hi ho to do that using Virt-Manager GUI, I already add virtio-9p Filesystem but how to access it from my OS (arch Linux ) and the gust OS (win 11)

Hi ho to do that using Virt-Manager GUI, I already add virtio-9p Filesystem but how to access it from my OS (arch Linux ) and the gust OS (win 11)

I do not know if you can access 9p config via GUI and if Windows supports it. But if the host and guest OS are both Linux, you can follow the above guide.

However, I do not notice a great performance gain by 9p compared to nfs. Since 9p also uses network to share the data. I switch to nfs for compatibility reasons.