Re: [virtio-dev] Backend libraries for VirtIO device emulation

[Matias Ezequiel Vara Larsen <matiasevara@gmail.com>]

Hello Alex,
On Fri, Mar 06, 2020 at 06:33:57PM +0000, Alex Bennée wrote:
> Hi,
> 
> So the context of my question is what sort of common software layer is
> required to implement a virtio backend entirely in userspace?
> 
> Currently most virtio backends are embedded directly in various VMMs
> which emulate a number of devices as well as deal with handling devices
> that are vhost aware and link with the host kernel. However there seems
> to be a growing interest in having backends implemented in separate
> processes, potentially even hosted in other guest VMs.
> 
> As far as I can tell there is a lot of duplicated effort in handling the
> low level navigation of virt queues and buffers. QEMU has code in
> hw/virtio as well as contrib/libvhost-user which is used by the recent
> virtiofsd daemon. kvm-tool has a virtio subdirectory that implements a
> similar set of functionality for it's emulation. The Rust-vmm project
> has libraries for implementing the device traits.
> 
> Another aspect to this is the growing interest in carrying virtio over
> other hypervisors. I'm wondering if there is enough abstraction possible
> to have a common library that is hypervisor agnostic? Can a device
> backend be emulated purely with some shared memory and some sockets for
> passing messages/kicks from/to the VMM which then deals with the hypervisor
> specifics of the virtio-transport?
> 
> Thoughts?

I am currently investigating the use of metamodeling to capture virtio
concepts. The work is still a draft but you can give a look at
https://github.com/MatiasVara/virtioml. One of the ideas is to base on a
metamodel to generate the code for different targets, e.g., rust,
c, etc. For the moment, I just played by generating the c header. This
could be extended to other languages. 

Regards, Matias.
> 
> -- 
> Alex Bennée
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org
> For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org
>