On 01/06/2018 09:41 AM, Van De Ven, Arjan wrote: >>>> .macro DISABLE_IBRS >>>> - ALTERNATIVE "jmp .Lskip_\@", "", X86_FEATURE_SPEC_CTRL >>>> + testl $1, dynamic_ibrs >>> On every system call we end up hammering on this 'dynamic_ibrs' >>> variable. And it looks like it can be flipped via the IPI mechanism. >>> >>> Would it make sense for this to be per-cpu? >> >> It's probably better to either just make it __read_mostly or get the >> static branches that folks were suggesting actually working. > > I still wonder if this isn't just better as a boot command line
It's simpler that way. But, ideally, we want to make it runtime switchable to match the implementation in the distros.
