Re: [PATCH v4] target/ppc: Add POWER9 DD2.2 model

[Nicholas Piggin]

On Tue May 16, 2023 at 5:56 PM AEST, Frederic Barrat wrote:
>
>
> On 15/05/2023 18:02, Nicholas Piggin wrote:
> > POWER9 DD2.1 and earlier had significant limitations when running KVM,
> > including lack of "mixed mode" MMU support (ability to run HPT and RPT
> > mode on threads of the same core), and a translation prefetch issue
> > which is worked around by disabling "AIL" mode for the guest.
> > 
> > These processors are not widely available, and it's difficult to deal
> > with all these quirks in qemu +/- KVM, so create a POWER9 DD2.2 CPU
> > and make it the default POWER9 CPU.
> > 
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> > ---
>
> Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
>
> Which makes me wonder if the P9 DD1 and P10 DD1 cpu definitions are 
> worth keeping, since we don't really try emulating the differences and 
> we don't support them in firmware/skiboot. The only place where we seem 
> to bother is in target/ppc/kvm.c and that's precisely what this patch is 
> trying to avoid.

+1. We could do a follow up as Cedric suggested.

Thanks,
Nick