K 10
svn:author
V 5
sephe
K 8
svn:date
V 27
2016-02-29T04:58:40.635946Z
K 7
svn:log
V 420
hyperv: Use proper fence function to keep store-load order for msgs

sfence only makes sure about the store-store order, which is not
sufficient here.  Use atomic_thread_fence_seq_cst() as suggested
jhb and kib (a locked op in the nutshell, which should have the

Reviewed by:	jhb, kib, Jun Su <junsu microsoft com>
MFC after:	1 week
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D5436

END