Pull x86 fix from Ingo Molnar:
 "Fix the 'IBPB mitigated RETBleed' mode of operation on AMD CPUs (not
  turned on by default), which also need STIBP enabled (if available) to
  be '100% safe' on even the shortest speculation windows"

* tag 'x86-urgent-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/bugs: Enable STIBP for IBPB mitigated RETBleed