On 01/09/2018 05:06 PM, Thomas Gleixner wrote: > --- a/arch/x86/kernel/cpu/bugs.c > +++ b/arch/x86/kernel/cpu/bugs.c > @@ -79,6 +79,7 @@ enum spectre_v2_mitigation_cmd { > SPECTRE_V2_CMD_RETPOLINE, > SPECTRE_V2_CMD_RETPOLINE_GENERIC, > SPECTRE_V2_CMD_RETPOLINE_AMD, > + SPECTRE_V2_CMD_IBRS, > };
A few nits on this: IBRS should not default on anywhere, which goes double when retpolines are available. I think I'd also prefer that we separate the IBRS and retpoline enabling so that you can do both if you want. They do nearly the same thing in practice, but I can't convince myself that you never ever need IBRS once retpolines are in place.