I am running a VM on a Linux host using qemu+kvm and libvirt, the guest system is CentOS 7. I wish to share a folder between the two such that host:/some/dir becomes accessible as guest:/some/other/dir.
I wish to minimise effort and cannot re-compile the kernel on either side. I experimented with plan9 but cannot get it to run (the p9 dkms module won't compile on the CentOS 7 guest).
There must be a better way? Performance is secondary as it does not work at all right now.
Just set up sshfs/samba/nfs/etc, it's easier and it just works
EDIT: The point here is, just use a regular file share between the host and the VM, there is absolutely no need to go into dirty untested hacks like plan9.
qemu's built-in Samba server could be an option? I searched but could not find a way to enable it using libvirt/virsh's XML config file.
For Centos 8 or later or Ubuntu 24.04+, you can use virtiofs to realize that: https://libvirt.org/kbase/virtiofs.html
Edit your domain file with (you may first want to shutdown the domain if it is currently running):
$ virsh edit <domain-name>
And add the following two XML blocks if not there yet:
<domain>
...
<memoryBacking>
<source type='memfd'/>
<access mode='shared'/>
</memoryBacking>
...
<devices>
...
<filesystem type='mount' accessmode='passthrough'>
<driver type='virtiofs' queue='1024'/>
<source dir='/path'/>
<target dir='mount_tag'/>
</filesystem>
...
</devices>
</domain>
The virtiofs driver will be required, you need to install it with something like:
$ sudo apt-get install virtiofsd
Then restart your domain:
$ virsh start <domain-name>
Once logged in your domain, run the following mount command:
$ mkdir mount_point
$ sudo mount -t virtiofs mount_tag mount_point
$ ls mount_point
The folder is mounted in read/write mode.
The mount_tag name is anything you want. Whatever makes sense to you. The mount_point can be anywhere in your guest file system.
For more features, check out the docs (link above).
