[PATCH 4.9 66/96] x86/Documentation: Add PTI description

4.9-stable review patch. If anyone has any objections, please let me know. -- From: Dave Hansen commit 01c9b17bf673b05bb401b76ec763e9730ccf1376 upstream. Add some details about how PTI works, what some of the downsides are, and how to debug it

[PATCH 4.9 66/96] x86/Documentation: Add PTI description

4.9-stable review patch. If anyone has any objections, please let me know. -- From: Dave Hansen commit 01c9b17bf673b05bb401b76ec763e9730ccf1376 upstream. Add some details about how PTI works, what some of the downsides are, and how to debug it when things go wrong. Also