On Fri, Jun 05, 2026 at 12:55:50PM +0530, Vaibhav Jain wrote:
> Hi Gautam,
>
> Thanks for testing this patch. Few questions:
> Gautam Menghani <[email protected]> writes:
>
> > On Wed, Jun 03, 2026 at 07:45:39PM +0530, Amit Machhiwal wrote:
> >> On IBM POWER systems, newer processor generations can operate in
> >> compatibility modes corresponding to earlier generations. This becomes
> >> relevant for nested virtualization, where nested KVM guests may need to
> >> run with a specific processor compatibility level.
> >>
> <snip>
> >
> > I booted a KVM guest on LPAR with this patch in the following scenarios:
> <snip>
>
> > 3. P11 guest on P11 host booted in P10 compat mode: No error observed
> This should have resulted in an error since booting a P11 guest on P10
> compat mode host is not allowed with/without this patch. Can you please
> check your test env and share the boot results.
- lscpu output (host P11 LPAR booted in p10 compat mode)
# lscpu
03:35:13 [3/3]
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 960
On-line CPU(s) list: 0-959
Model name: POWER10 (architected), altivec supported
Model: 2.0 (pvr 0082 0200)
Thread(s) per core: 8
Core(s) per socket: 15
Socket(s): 8
Physical sockets: 4
Physical chips: 2
Physical cores/chip: 16
- lscpu output from guest
# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Model name: Power11 (raw), altivec supported
Model: 2.0 (pvr 0082 0200)
Thread(s) per core: 1
Core(s) per socket: 4
Socket(s): 1
- QEMU command line
/usr/bin/qemu-system-ppc64 -device virtio-blk-pci,drive=drive0,id=virtblk0 \
-drive file=/home/gautam/images/fc41.qcow2,format=qcow2,if=none,id=drive0 \
-m 100G -smp 4 -cpu host -nographic -machine pseries,ic-mode=xics -accel kvm
Thanks,
Gautam
