Description: Indirect Branch Prediction Barrier is force-disabled when STIBP is unavailable or enhanced IBRS is available.
References:
 https://lkml.org/lkml/2020/6/9/183
 https://www.openwall.com/lists/oss-security/2020/06/10/1
Notes:
Bugs:
upstream:
4.19-upstream-stable:
4.9-upstream-stable:
3.16-upstream-stable:
sid:
4.19-buster-security:
4.9-stretch-security:
3.16-jessie-security: