Comment 65 for bug 1896617

Sounds like a valid bug.
I think setting 0x711 should not cause any issues and should prevent the problem you are facing on hardened Ubuntu systems. By the way, it seems more logical than 0x701.

Setting to 0x710 should be better, but like you, I'm unsure about distro side effects, and I lack experience with nova, to be sure. Advice from the nova team should help here.