Messages in this thread | | | Date | Sat, 6 Jan 2018 20:47:19 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature |
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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.
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
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