On Fri, Mar 02, 2018 at 01:32:08PM -0800, Tim Chen wrote: > Greg, > > I will like to propose backporting "x86/speculation: Use Indirect Branch > Prediction Barrier on context switch" from commit 18bf3c3e in upstream > to 4.9 and 4.4 stable. The patch has already been ported to 4.14 and > 4.15 stable. The patch needs mm context id that Andy added in commit > f39681ed. I have lifted the mm context id change from Andy's upstream > patch and included it here. What does this patch "fix" in those older kernels? Is this a performance improvement or something else? thanks, greg k-h