[kata-dev] virtio-fs + VM Templating

Peng Tao bergwolf at hyper.sh
Wed Jun 5 07:06:12 UTC 2019

On Tue, Jun 4, 2019 at 5:53 PM Dr. David Alan Gilbert
<dgilbert at redhat.com> wrote:
> * Tao Peng (bergwolf at hyper.sh) wrote:
> > On Tue, Jun 4, 2019 at 7:18 AM Mahalingam, Ganesh
> > <ganesh.mahalingam at intel.com> wrote:
> > >
> > > Peng, Stefan,
> > > While working on enabling virtio-fs on Kata there was a small confusion on whether virtio-fs can work with VM Templating. With the current setup of kata, VM templating and virtio-fs are mutually exclusive (VM templating is enabled in qemu-lite and virtio-fs currently only with NEMU), but they will converge very soon.
> > >
> > > An open question we had was, would they both work with each other given that VM templating turns off memory sharing for all VMs other than the first one and virtio-fs expects guest memory be shared & file-backed for all VMs.
> > Hi Stefan,
> >
> > What happens if we specify share=on and share=off for different memory
> > file backends? Can virtio-fs only pick up the shared one?
> All vhost-user devices (including virtio-fs) need the share=on - because
> that's the only way that the vhost-user process sees the writes done
> by qemu or the guest.  I think we need it for all of RAM.
Hmm, vm templating needs the initial ram to be mapped private so that
it can be shared safely across multiple VM instances. It does conflict
with vhost-user requirement that guest memory can be accessed by a
different process.

Ganesh, how about we just marking vm templating and vhost-user
conflict with each other?

Into something rich and strange.

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