[PATCH 3/3] powerpc/pseries: Add KVM guest doorbell restrictions

[Paul Mackerras]

On Sun, Jun 28, 2020 at 01:04:28AM +1000, Nicholas Piggin wrote:
> KVM guests have certain restrictions and performance quirks when
> using doorbells. This patch tests for KVM environment in doorbell
> setup, and optimises IPI performance:
> 
>  - PowerVM guests may now use doorbells even if they are secure.
> 
>  - KVM guests no longer use doorbells if XIVE is available.

It seems, from the fact that you completely remove
kvm_para_available(), that you perhaps haven't tried building with
CONFIG_KVM_GUEST=y.  Somewhat confusingly, that option is not used or
needed when building for a PAPR guest (i.e. the "pseries" platform)
but is used on non-IBM platforms using the "epapr" hypervisor
interface.

If you did intend to remove support for the epapr hypervisor interface
then that should have been talked about in the commit message (and
would I expect be controversial).

So NAK on the kvm_para_available() removal.

Paul.