[MODERATED] Is: Sleep states ?Was:Re: SSB status - V18 pushed out

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, May 17, 2018 at 10:53:28PM +0200, speck for Thomas Gleixner wrote:
> Folks,
> 
> we finally reached a stable state with the SSB patches. I've updated all 3
> branches master/linux-4.16.y/linux-4.14.y in the repo and attached the
> resulting git bundles. They merge cleanly on top of the current HEADs of
> the relevant trees.
> 
> The lot survived light testing on my side and it would be great if everyone
> involved could expose it to their test scenarios.
> 
> Thanks to everyone who participated in that effort (patches, review,
> testing ...)!

Yeey! Thank you.

I was reading the updated Intel doc today (instead of skim reading it) and it mentioned:

"Intel recommends that the SSBD MSR bit be cleared when in a sleep state on such processors."

We don't seem to be doing that? 

To do that we would need to:

1) Revert 4b59bdb56945 x86/bugs: Remove x86_spec_ctrl_set()

2) Peppering 

	if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
		x86_spec_ctrl_set(~SPEC_CTRL_SSBD);

	[when enterring sleep state]

	and:
	if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
		x86_spec_ctrl_set(SPEC_CTRL_SSBD);

	[when coming out]

	in mwait_idle_with_hints, mwait_idle, and native_play_dead 

	Or alternatively fiddle with the MSR directly.

3) And then uhuh, I am not sure how you would want to deal when the applications
   are running. That is when the !static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE)
   but still want the MSR toggled.


> 
> Thanks,
> 
> 	tglx