Description of problem:

I installed virtual machine manager from the software store. 
This installed enough for me to use a windows VM.
However, it did not install 

qemu-virtiofsd

It took me a while to work out that this package was missing. I was getting unhelpful error messages when trying to use a filesystem hardware device in the VM, and the VM would not start. 

I think this package should be a dependency on virtual machine manager so it is installed automatically.