Non-transparent sharing of return predictor targets between contexts in some Intel(R) Processors may allow an authorized user to potentially enable information disclosure via local access. https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00982.html
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 2270735]
"Intel is releasing a firmware update to mitigate this potential vulnerability." And again, another microcode, not kernel.