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

[Greg Kurz]

On Fri, 27 Aug 2021 14:21:15 +0000
Joseph <joseph.mayer@protonmail.com> wrote:

> Hi QEMU PPC emailing list!
> 
> (And maintainers https://wiki.qemu.org/Documentation/Platforms/POWER )
> 
> https://www.openbsd.org/powerpc64.html says "OpenBSD/powerpc64 does
> not run under a hypervisor such as PowerVM or PowerKVM".
> 
> QEMU-KVM is not listed here but I have heard no success report
> anywhere, so I presume it doesn't work.
> 

PowerKVM is QEMU-KVM on POWER actually.

> From talking to people, I gather that the limit to running OpenBSD
> as VM guest on POWER, is that it operates based on the OPAL firmware
> interface, and for some reason previous VM:s did not export it. But
> also, I may have gotten this detail wrong.
> (https://www.talospace.com/2020/07/when-will-openpower-openbsd-be-now-now.html)
> 

The OPAL firmware interface is really an OpenPOWER thingy, for baremetal
only (powernv platform). VMs, either PowerVM or PowerKVM run the pseries
platform, which follows the PAPR specification, with a completely different
firmware interface (OpenFirmware).

Linux knows how to drive both powernv and pseries platforms.

> Watching the POWER QEMU Wiki page 
> https://wiki.qemu.org/Documentation/Platforms/POWER
> I don't see any mentioning of any of this .
> 
> Can you who work with QEMU POWER support help clarify, can OpenBSD
> run as a QEMU-KVM guest - if so what are the steps to get it going -
> and or are any updates to QEMU coming that will enable it?
> 
> Any cues much appreciated.
> 

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.

> I brought up this same question on the OpenBSD PPC emailing list,
> https://marc.info/?l=openbsd-ppc&m=163006851125546&w=2 , waiting for
> response.
> 
> Thanks!
> Joseph

Cheers,

--
Greg