On Fri, 20 Oct 2017 16:54:37 +0200 Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote: > Starting a guest with > <os> > <type arch='s390x' machine='s390-ccw-virtio-2.9'>hvm</type> > </os> > <cpu mode='host-model'/> > > on an IBM z14 results in > > "qemu-system-s390x: Some features requested in the CPU model are not > available in the configuration: gs" > > This is because guarded storage is fenced for compat machines that did not have > guarded storage support, but libvirt expands the cpu model according to the > latest available machine. > > While this prevents future migration abort (by not starting the guest at all), > not being able to start a "host-model" guest is very much unexpected. As it > turns out, even if we would modify libvirt to not expand the cpu model to > contain "gs" for compat machines, it cannot guarantee that a migration will > succeed. For example if the kernel changes its features (or the user has > nested=1 on one host but not on the other) the migration will fail > nevertheless. So instead of fencing "gs" for machines <= 2.9 lets allow it for > all machine types that support the CPU model. This will make "host-model" > runnable all the time, while relying on the CPU model to reject invalid > migration attempts. > > Suggested-by: David Hildenbrand <david@xxxxxxxxxx> > Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> > --- > hw/s390x/s390-virtio-ccw.c | 8 -------- > include/hw/s390x/s390-virtio-ccw.h | 3 --- > target/s390x/kvm.c | 2 +- > 3 files changed, 1 insertion(+), 12 deletions(-) Acked-by: Cornelia Huck <cohuck@xxxxxxxxxx> -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
