Re: [PATCH v4] x86/power: Fix 'nosmt' vs. hibernation triple fault during resume

[Jiri Kosina]

On Fri, 31 May 2019, Andy Lutomirski wrote:

> 2. Put the CPU all the way to sleep by sending it an INIT IPI.
> 
> Version 2 seems very simple and robust.  Is there a reason we can't do
> it?  We obviously don't want to do it for normal offline because it
> might be a high-power state, but a cpu in the wait-for-SIPI state is
> not going to exit that state all by itself.
> 
> The patch to implement #2 should be short and sweet as long as we are
> careful to only put genuine APs to sleep like this.  The only downside
> I can see is that an new kernel resuming and old kernel that was
> booted with nosmt is going to waste power, but I don't think that's a
> showstopper.

Well, if *that* is not an issue, than the original 3-liner that just 
forces them to 'hlt' [1] would be good enough as well.

[1] https://lore.kernel.org/lkml/nycvar.YFH.7.76.1905291230130.1962@xxxxxxxxxxxxx/

Thanks,

-- 
Jiri Kosina
SUSE Labs