As I know, paravirtualization solution is a good way to share data for VM and VMM since it has better performance.
Please use Virtio 9p solution for QEMU/KVM. Note that you need to load 9p related modules for guest kernel.
Add following in your virsh start xml file.
<filesystem type='mount' accessmode='passthrough'>
After start guest OS, run following command
# mount testlabel /mnt/ -t 9p -o trans=virtio