I noticed a change 12 days ago in the VDSM master branch with what version of qemu that VDSM requires. (Commit: 1ce73032d9238a1bf4c55400392d5ce47dfa2d43)

Change:
 # Update the qemu-kvm requires when block_stream will be included
-Requires: qemu-kvm >= 2:0.12.1.2-2.227
-Requires: qemu-img >= 2:0.12.1.2-2.227
+Requires: qemu-kvm >= 2:0.12.1.2-2.295.el6_3.4
+Requires: qemu-img >= 2:0.12.1.2-2.295.el6_3.4

However the version of qemu required has not yet materialized in any of the released EL sources/updates.

- DHC