This commit fixes iotest 068 for s390x as s390x uses virtio-scsi-ccw.
It's based on commit c324fd0a39c by Stefan Hajnoczi. 
Thanks!

Change history:
v3:
    Take Christian Borntraeger and Cornelia Huck's comment to check
    if kvm is enabled in s390_assign_subch_ioeventfd instead of
    kvm_s390_assign_subch_ioeventfd to as the former is a general one.

v2:
    Remove Stefan from sign-off list and change the patch's commit message 
    according to Christian Borntraeger's comment.

QingFeng Hao (1):
  virtio-scsi-ccw: use ioeventfd even when KVM is disabled

 hw/s390x/virtio-ccw.c | 2 +-
 target/s390x/cpu.h    | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

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2.11.2