Comment 109 for bug 1759920

I was never able to reproduce this issue on Ubuntu 14.04 but, after reviewing the Spectre V2 mitigations in the 3.13 based 14.04 kernel, I think the 14.04 kernel could be affected by this bug. Additionally, I didn't want the decision on when to make use of IBPB to be different in 14.04 than in all of the newer Ubuntu releases (16.04, 17.10, and soon to be 18.04). That's why I marked this bug as affecting 14.04 and submitted a fix for that kernel.

That being said, I don't think that we have any 14.04 users watching this bug so I did some SRU verification work myself. I installed sssd, the 3.13.0-145.194 kernel from trusty-proposed, and experienced no issues. I verified that the /proc/sys/kernel/ibpb_enabled file reported '1', indicating that IBPB was enabled. I also verified that the IBRS/IBPB/retpoline/spectre messages emitted from the kernel at boot time were as-expected. Retpoline was present, IBRS was disabled (due to retpoline), and IBPB was enabled.