Just in case folks are still interested in this topic, I applied the patch to the qemu sources from here: http://lists.gnu.org/archive/html/qemu-devel/2014-03/msg01397.html
Since I wasn't able to find a downloadable version of the patch, I copy-pasted it and had to adjust a number of lines so the patch could actually be applied, which was a bit tedious, but what matters is the end result.
Which is: it seems to be working fine for a linux guest - but the ONTAP simulator still doesn't like it, as the next screenshot illustrates.

Might have to do with the comments on the patch code in the follow-up post of the thread: http://lists.gnu.org/archive/html/qemu-devel/2014-03/msg01831.html
I too would prefer to see the simulator running on KVM, but at this point I'm inclined to stick with virtual box, where it's working fine for me.
Of course, should anybody manage to get this to work with KVM, please share.
Thanks,
Gerhard