Merge tag 'kvm-s390-master-20150730' of git://git.kernel.org/pub/scm/linux/kernel...

KVM: s390: bugfix for kvm/master (4.2)

Here is a bugfix for a regression that was introduced after 4.1
with the commit commit 785dbef407d8 ("KVM: s390: optimize round
trip time in request handling"). After lots of cpu hotplugs in the
guest (online/offline) sometimes a guest CPU did loop within host
KVM code. Reason was that PROG_REQUEST was set in the sie control
block, but no request was pending. This made commit 785dbef407d8
the suspect and changing that area to always reset PROG_REQUEST
did indeed fix the problem.

Special thanks to David Hildenbrand, who helped understanding the
exact sequence that led to the problem.