On Thu, 16 Jan 2020 15:19:13 -0500 Matthew Rosato <mjros...@linux.ibm.com> wrote:
> On 1/16/20 7:20 AM, Thomas Huth wrote: > > The AIS feature has been disabled late in the v2.10 development > > cycle since there were some issues with migration (see commit > > 3f2d07b3b01ea61126b - "s390x/ais: for 2.10 stable: disable ais > > facility"). We originally wanted to enable it again for newer > > machine types, but apparently we forgot to do this so far. Let's > > do it for the new s390-ccw-virtio-5.0 machine now. > > > > Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1756946 > > Signed-off-by: Thomas Huth <th...@redhat.com> > > --- > > hw/s390x/s390-virtio-ccw.c | 4 ++++ > > include/hw/s390x/s390-virtio-ccw.h | 4 ++++ > > target/s390x/kvm.c | 11 ++++++++--- > > 3 files changed, 16 insertions(+), 3 deletions(-) (...) > > diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c > > index 15260aeb9a..4c1c8c0208 100644 > > --- a/target/s390x/kvm.c > > +++ b/target/s390x/kvm.c > > @@ -329,6 +329,8 @@ static void ccw_machine_class_foreach(ObjectClass *oc, > > void *opaque) > > > > int kvm_arch_init(MachineState *ms, KVMState *s) > > { > > + S390CcwMachineClass *smc = S390_CCW_MACHINE_OBJ_GET_CLASS(ms); > > + > > I still can't run a proper test due to unavailable hw but in the > meantime I tried to virsh define a libvirt guest pointed at qemu (master > + this patch). Regardless of machine type (s390-ccw-virtio-5.0 or > s390-ccw-virtio-4.2) I get: > > virsh define guest.xml > error: Failed to define domain from /path/to/guest.xml > error: invalid argument: could not find capabilities for arch=s390x > domaintype=kvm > > Similarly: > > virsh domcapabilities > error: failed to get emulator capabilities > error: invalid argument: unable to find any emulator to serve 's390x' > architecture > > Rolling back to qemu master, the define and domcapabilities work (with > no ais of course). > > So: there is some incompatibility between the way libvirt invokes qemu > to detect capabilities and this code. The above line seems to be the > root problem - if I take your patch and remove 'smc' then libvirt works > as expected and I can see ais in the domcapabilities. > > Looking at those wrappers David mentioned... I suspect you need this > for the 'none' machine case. I tried a quick hack with the following: > > bool ais_allowed(void) > { > /* for "none" machine this results in true */ > return get_machine_class()->kvm_ais_allowed; > } > > and > > if (ais_allowed() && > kvm_check_extension(s, KVM_CAP_S390_AIS_MIGRATION)) { > kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); > } > > This works and doesn't break libvirt compatibility detection. Oh, "none" machine fun again... I think you're on the right track, and we really need a wrapper.
