Cross-Hyperthread Spectre V2 Mitigation Ready For Linux With STIBP
Written by Michael Larabel in Security on 23 October 2018 at 11:54 AM EDT. 5 Comments
SECURITY --
On the Spectre front for the recently-started Linux 4.20~5.0 kernel is STIBP support for cross-hyperthread Spectre Variant Two mitigation.

Going back to the end of the summer was the patch work for this cross-hyperthread Spectre V2 mitigation with STIBP while now it's being merged to mainline.

The Single Thread Indirect Branch Predictors (STIBP) allows for preventing cross-hyperthread control of decisions that are made by indirect branch predictors (IBP). Obviously this is only relevant to the Intel CPU models that have Hyper Threading and where it is enabled... If going for "full" mitigation for L1TF/Foreshadow it will already disable SMT/HT support and OpenBSD for example now ships with Hyper Threading disabled over security concerns.

STIBP also requires the functionality be supported by the Intel microcode in use. This cross-hyperthread Spectre V2 STIBP mitigation is landing as part of the x86/pti changes queued for the Linux 4.20~5.0 kernel. Also included in that pull request are changes to make the IBPB (Indirect Branch Predictor Barrier) more strict as well as some other minor optimizations.
About The Author
Author picture

Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

Related Security News
Popular News This Week