Re: [PATCH 0/2] Backport IBPB on context switch to non-dumpable process

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