Re: [PATCH v5 2/2] x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigation
From: Thomas Gleixner
Date: Tue Sep 11 2018 - 17:46:21 EST
On Tue, 11 Sep 2018, Thomas Gleixner wrote:
> On Tue, 11 Sep 2018, Tim Chen wrote:
> > On 09/10/2018 04:46 AM, Jiri Kosina wrote:
> > > Nah, IBPB is actuall there, sorry. So I'll add reporting of STIBP + fixup
> > > the missing reporting of RSB_CTXSW for v6.
> > >
> > I anticipate that STIBP could affect workloads with a lot of indirect
> > branches (see previous discussion with Andrea). We should have a
> > knob for people to opt in or opt out of STIBP.
> Feel free to send a patch to that effect.
Along with a proper explanation why it makes sense to disable this
particular piece separate from the rest of the V2 mitigations. You surely
can come up with a rationale based on facts rather than on anticipations.