Comment 16 for bug 1790457

------- Comment From <email address hidden> 2018-09-11 13:18 EDT-------
(In reply to comment #19)
> > c18719638cc1 KVM: s390: generate facility mask from readable list
> > d6450dc35e21 KVM: s390: Populate mask of non-hypervisor managed facility bits
> > bb0258cde7a6 s390/facilities: add helper tool to generate facility lists
> > 35b3fde6203b KVM: s390: wire up bpb feature
> >
> > I'm afraid we would take some time to backport all the requested fixes and their pre-reqs and get it right.
>
> With the kernel version 4.4 this indeed takes some extra patches. In
> addition to
> that we would need a matching qemu version as well which is probably
> overkill.
>
> I have talked to Christian Borntr?ger about the KVM aspect and he would be
> fine
> if we do not backport the KVM related patches. The end result is that the KVM
> guests would use the expoline mitigation by default, even on machines with
> the etoken facility. You can still use the spectre_v2=off kernel parameter to
> disable expolines.
>

To write down the obvious.
That is of course only true for the 4.4 kernel. We can drop the KVM etoken and cpumodel patches from 4.4 because it does not yet provide the cpu model. We certainly want to have the KVM patches in the 4.15 kernel (bionic and future HWE)