On Fri, Nov 1, 2019 at 10:33 AM Moger, Babu <Babu.Moger@xxxxxxx> wrote: > > AMD 2nd generation EPYC processors support UMIP (User-Mode Instruction > Prevention) feature. The UMIP feature prevents the execution of certain > instructions if the Current Privilege Level (CPL) is greater than 0. > If any of these instructions are executed with CPL > 0 and UMIP > is enabled, then kernel reports a #GP exception. > > The idea is taken from articles: > https://lwn.net/Articles/738209/ > https://lwn.net/Articles/694385/ > > Enable the feature if supported on bare metal and emulate instructions > to return dummy values for certain cases. What are these cases?
