Re: QEMU-KVM offers OPAL firmware interface? OpenBSD guest support?

[Greg Kurz]

On Fri, 27 Aug 2021 15:12:31 +0000
Joseph <joseph.mayer@protonmail.com> wrote:

> On Friday, August 27th, 2021 at 11:01 PM, Greg Kurz <groug@kaod.org> wrote:
> > Linux knows how to drive both powernv and pseries platforms.
> ..
> > OpenBSD might have to implement proper guest-side pseries support to run as
> > a guest under an hypervisor on POWER. I don't know OpenBSD but this likely a
> > huge effort.
> >
> > More details in the "Linux on POWER Architecture Reference":
> > https://openpowerfoundation.org/wp-content/uploads/2020/07/LoPAR-20200611.pdf
> > and under the arch/powerpc/platforms/pseries/ directory in the linux
> > kernel sources.
> 
> Hi Greg,
> 
> Thanks for following up.
> 
> (Meanwhile I posted this Q to KVM-PPC and QEMU-PPC too. On the latter it's 
> https://lists.nongnu.org/archive/html/qemu-ppc/2021-08/msg00416.html and on 
> the further it didn't register yet.)
> 
> First I believe KVM-QEMU and "PowerKVM" are different - the latter was
> a KVM fork maintained by IBM. The further is just the KVM and QEMU
> repo. Did IBM their contributions so PowerKVM was upstreamed, you tell
> me.
> 

Yes you're right that PowerKVM was an IBM internal fork of KVM and
QEMU, but it was discontinued ages ago. All the relevant bits have
been merged upstream and all development since then happens upstream.
So it doesn't make a big difference now to use PowerKVM instead of
QEMU-KVM on POWER.

> Are you saying that KVM-QEMU has all relevant Power9 support
> already, for a Linux host OpenBSD as a guest on bare metal
> ("powernv" mode)?
> 

There's some confusion here. In bare metal, you just have a single
instance of the OS running unvirtualized directly on the host.
KVM-QEMU isn't involved at all in this case. According to the OpenBSD
statement, you can already install and run it in this mode on an
OpenPOWER system.

> In this case why would there be any relevance in OpenBSD implementing
> pseries.
> 

If you want to also run OpenBSD inside a VM, then OpenBSD must
implement proper support to be able to run in the paravirtualized
PAPR environment provided by KVM-QEMU on POWER. The OpenBSD statement
seem to indicate this is missing. Nothing special "should" be needed
on the KVM-QEMU side.

> Best regards

Cheers,

--
Greg