On Thu, Jul 09, 2020 at 08:16:12AM -0700, Cameron Kaiser wrote: > > It would probably be better to disallow SAO on all machines than have > > it available on some hosts and not others. (Yes I know there is a > > check on CPU_FTR_ARCH_206 in there, but that has been a no-op since we > > removed the PPC970 KVM support.) > > May I ask a very stupid question here -- is that meant to imply KVM > cannot emulate a 970, or that KVM (at least HV, anyway) won't work on a 970? The PVR is able to be accessed from supervisor mode in the Power ISA, which means that a guest under KVM-HV always sees the real PVR of the CPU; it can't be spoofed by KVM. So for the first half of your question, about emulating a 970, the answer is "no" or at least "not completely". (KVM-PR can of course make the machine look like anything you want, pretty much, at the expense of lower performance.) What I was referring to in my original message is that we used to be able to run KVM-HV on a PPC970 as a host, and we took that out. So the answer to the second half of your question is yes. Paul.
