On Sat, Jan 06, 2018 at 08:47:19PM +0100, Thomas Gleixner wrote: > On Sat, 6 Jan 2018, Dave Hansen wrote: > > > 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. > > Stop this silly argument please. The distros shipped lots of crap which we > dont want to have at all. > > I told you folks yesterday what I want to see and the sysctl thing is the > least on that list and it's not needed for getting the important thing - > the protection - to work.
I agree. But this is what customers are told to inspect to see if they are impacted. And if in the future versions this goes away or such - they will freak out and cause needless escalations. > > Can we pretty please do the basics and worry about that sysctl or whatever > people have on their wishlist once the dust settled. > > Thanks, > > tglx >
