[Qemu-ppc] [PATCH 0/3] spapr: fix backward migration from POWER9 to POWER8 hosts

[Greg Kurz]

Hi,

It is expected to be able to migrate a guest started with

     -machine max-cpu-compat=power8

from a POWER9 host to a POWER8 host. It works with recent QEMU versions,
but it is badly broken if the destination runs QEMU 2.7 or older.

This can cause problems in cloud environments that still have systems with
older QEMU versions, eg, hosts running ubuntu LTS 16.04.4 (QEMU 2.5) which
are likely to stay around until admins could transition to some newer OS.

This series was lightly tested, but the patches are simple enough, so I'm
confident they shouldn't break anything :)

Please review as I'd like these to go to QEMU 2.11.2 as well.

--
Greg

---

Greg Kurz (3):
      target/ppc: always set PPC_MEM_TLBIE in pre 2.8 migration hack
      spapr: don't migrate "spapr_option_vector_ov5_cas" to pre 2.8 machines
      spapr: don't advertise radix GTSE if max-compat-cpu < power9


 hw/ppc/spapr.c       |   19 +++++++++++++------
 target/ppc/machine.c |    5 +++++
 2 files changed, 18 insertions(+), 6 deletions(-)