Re: [RFC PATCH] asm/generic: introduce if_nospec and nospec_barrier

[Jiri Kosina]

On Thu, 4 Jan 2018, Alan Cox wrote:

> You never go from one user process to another except via the kernel. We
> have no hardware scheduling going on. That means that if the kernel
> and/or CPU imposes the correct speculation barriers you can't attack
> anyone but yourself.

So how does this work on HT with the shared BTB? There is no context 
switch (and hence no IBPB) happening between the threads sharing it.

-- 
Jiri Kosina
SUSE Labs