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

["Alex Bennée" <alex.bennee@linaro.org>]

Stefan Hajnoczi <stefanha@redhat.com> writes:

> On Fri, Mar 06, 2020 at 06:33:57PM +0000, Alex Bennée wrote:
>> So the context of my question is what sort of common software layer is
>> required to implement a virtio backend entirely in userspace?
>
> Yes and no.
>
> vhost-user is currently the most widely-used (cross-VMM) interface for
> out-of-process VIRTIO device emulation.
>
> However, it's not a library, just a protocol specification involving
> UNIX domain sockets.  You mentioned the various implementations below:
>
<snip>
>
>> 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?
>
> Yes, that is what vhost-user does.

I thought so - but does any vhost-user implementation assume it has
access to the entire of the guests memory space? I can see why that
might be seen as undesirable from a security point of view.

So aside from virtiofsd and crosvm's various pieces for crostini
emulation what other out-of-VMM device emulation daemons are you aware
of?

-- 
Alex Bennée

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