Re: [Patch v5 11/16] x86/speculation: Add Spectre v2 app to app protection modes

[Tim Chen]

On 11/19/2018 12:55 PM, Jiri Kosina wrote:
> On Mon, 19 Nov 2018, Thomas Gleixner wrote:
> 
>>
>> So before that change IBPB was usable without STIBP, now not longer. What's
>> the rationale?
>>
>> This patch changes a gazillion things at once and is completely
>> unreviewable.
> 
> The patchset actually ties together IBPB and STIBP pretty closely, which 
> is IMO a good thing; there is no good reason why anone would want just one 
> of those (or each in a different mode), at least before this magical 
> coscheduling exists.
> 
> But I guess this fact should be documented somewhere.
> 

Yes, it wouldn't make sense for having just one of those if a task
is worried about attack from user space.

I'll document it.

Tim