Sync s390x KVM code with upstream kernel v5.15
Bugzilla: http://bugzilla.redhat.com/1870686
Sync s390x KVM code with upstream kernel v5.15 (and some additional fixes that have been merged for v5.16 already). All patches are clean cherry-picks.
Sanity-tested by running a KVM guest on a host with the modified kernel.
Signed-off-by: Thomas Huth thuth@redhat.com