Linux 4.19 Will Have Enhanced IBRS For Better Spectre V2 Protection On Future Intel CPUs

Written by Michael Larabel in Linux Security on 3 August 2018 at 07:36 AM EDT. 4 Comments
Besides the Linux 4.19 kernel slated to introduce initial SpectreRSB protection, this next kernel version should also introduce support for Enhanced IBRS as a better means of Spectre Variant Two mitigation to be supported by future Intel CPUs.

Last month I wrote about an Intel engineer preparing a Linux kernel patch to handle enhanced IBRS. IBRS as a reminder is the Indirect Branch Restricted Speculation. The enhanced IBRS mode aims to let up on the performance impact of Spectre V2 mitigation compared to current x86 CPUs.

On the yet-to-be-relased Intel CPUs supporting enhanced IBRS, with the kernel patch it will be used rather than the existing Retpolines (return trampolines) approach.

The enhanced IBRS patch is now queued into Thomas Gleixner's x86/pti Git tree -- along with the SpectreRSB patch -- of the new material that should be merged for the upcoming Linux 4.19 kernel cycle.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 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 automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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