Re: [PATCH 2/2] x86/speculation: Provide application property based STIBP protection

[Jon Masters]

Quick reply: I agree, I'm just supporting this :)

-- 
Computer Architect


> On Oct 2, 2018, at 11:43, Jiri Kosina <jikos@xxxxxxxxxx> wrote:
> 
> On Tue, 2 Oct 2018, Jon Masters wrote:
> 
>>> This patch provides an application property based spectre_v2
>>> protection with STIBP against attack from another app from
>>> a sibling hyper-thread.  For security sensitive non-dumpable
>>> app, STIBP will be turned on before switching to it for Intel
>>> processors vulnerable to spectre_v2.
>> 
>> A general comment. I think in practice this will be similar to the
>> speculative store buffer bypass (aka "variant 4") issue in terms of
>> opt-in mitigation. Many users won't want to take the performance hit of
>> having STIBP by default for peer threads. We should make sure that we
>> don't force users into a mitigation but retain an option. Whether it's
>> default-on or not can be debated, though I think the vendors lean toward
>> having default-off with an opt-in, and customers will probably agree. So
>> anyway, I encourage a pragmatic approach similar to that for SSBD.
> 
> Which is what Tim's patchset is implementing on top.
> 
> Thanks,
> 
> -- 
> Jiri Kosina
> SUSE Labs
>