Re: [Qemu-devel] Sharing virtio-devices between several kvm virtual machines over network

[Stefan Hajnoczi]

On Tue, Nov 15, 2011 at 5:37 PM, Leib, David <address@hidden> wrote:
> I am trying to share devices between vm’s. For example I want to use a
> cdrom-drive who is exposed to a vm from another vm over the network.

The normal way of doing this would be to export the CD-ROM using
NFS/CIFS or iSCSI.  It has nothing to do with virtualization.

> In addition to this I want to use virtio for this idea.

Why?  It's not clear what problem you are trying to solve and why you
want to use virtio.

> What I am trying to do step by step:
>
> If virtqueue_pop is called on the KVM 2 I take the iovec structure
> information
> I send it over to the KVM 1
> KVM 1 put it into the own virtqueue_pop
> KVM 1 wait for virtqueue_push
> KVM 1 take the information from virtqueue_push
> KVM 1 send it over to KVM 2
> KVM 2 put it into the virtqueue push
> I tried it already slightly different by stopping KVM 1 and only waiting for
> request of KVM 2 but there are some problems with the iovec buffer address I
> am not able to use as a address of the buffer.
> Has somebody experience with that or an idea of doing this maybe in a more
> smarter way or is it generally possible to do that?

In theory it would be possible to implement a virtio TCP/IP transport.
 The protocol needs to support virtqueue operations (push, pop),
notify, configuration space, and device lifecycle.  Then it would be
possible to launch a virtio-blk server on machine A and attach to the
device from machine B.

But back to my first two points: what are you really trying to do?

Stefan