KVM on POWER9 doesn't use the XIVE VP space optimally. This currently
limits the number of VMs we can start to 127. Starting with the 128th
one, KVM fails to create the XIVE or the XICS-on-XIVE device and we
go through the fallback paths in QEMU.

The XICS error path still has an issue that prevents the guest to do
interrupts, even after QEMU fell back on XICS emulation. This is
fixed with patch 2.

Patch 1 is just a _trivial_ improvement of the warning that gets
emited when falling back to emulated IC. Feel free to apply it to
4.2 or even to drop it if you don't want it in 4.1.

--
Greg

---

Greg Kurz (2):
      spapr/irq: Inform the user when falling back to emulated IC
      xics/kvm: Fix fallback to emulated XICS


 hw/intc/xics_kvm.c |   11 -----------
 hw/ppc/spapr_irq.c |    1 +
 2 files changed, 1 insertion(+), 11 deletions(-)

On Wed, Jul 24, 2019 at 06:57:09PM +0200, Greg Kurz wrote:
> KVM on POWER9 doesn't use the XIVE VP space optimally. This currently
> limits the number of VMs we can start to 127. Starting with the 128th
> one, KVM fails to create the XIVE or the XICS-on-XIVE device and we
> go through the fallback paths in QEMU.
> 
> The XICS error path still has an issue that prevents the guest to do
> interrupts, even after QEMU fell back on XICS emulation. This is
> fixed with patch 2.
> 
> Patch 1 is just a _trivial_ improvement of the warning that gets
> emited when falling back to emulated IC. Feel free to apply it to
> 4.2 or even to drop it if you don't want it in 4.1.

Applied to ppc-for-4.1.  Finding a time to do a PR will be
interesting, but I'll see what I can do

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson