Re: [PATCH v5 2/2] x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigation

From: Tom Lendacky
Date: Wed Sep 12 2018 - 13:16:32 EST




On 09/11/2018 04:16 PM, 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.

Tim, are you planning on sending a patch for this? If so, what type of
opt in/out are you thinking about, something similar to SSBD?

Thanks,
Tom

>
> Thanks,
>
> tglx
>