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From: Jiri Kosina <jkosina@suse.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: Date/Time?
Date: Sun, 20 May 2018 20:48:38 +0200 (CEST)	[thread overview]
Message-ID: <nycvar.YFH.7.76.1805202037560.27054@cbobk.fhfr.pm> (raw)
In-Reply-To: <alpine.LFD.2.21.999.1805201135200.15835@i7.lan>

On Sun, 20 May 2018, speck for Linus Torvalds wrote:

> > Why wouldn't I also want the IBRS stuff for the upstream 4.4.y?  Am I
> > missing patches that I should have backported but didn't?
> 
> I think Jiri is talking about the bat-shit-crazy stuff that I refused to 
> take upstream. The stuff that adds thousands of cycles to every kernel 
> entry and doesn't actually fix any real problem except for "but but in 
> theory" PR problems.

Yes, that is exactly the one :)

We are providing the option of toggling the IBRS on kernel entry/exit only 
on CPUs that can fall back to using (potentially) poisoned indirect branch 
predictor in case of RSB underflow (Skylake; fortunately on those CPUs the 
IBRS overhead is considerably lower than on other CPUs) if the user/admin 
wants to.

And that is the same MSR as SSBD, so there will be some minor conflicts to 
resolve.

-- 
Jiri Kosina
SUSE Labs

  reply	other threads:[~2018-05-20 18:48 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-19 17:26 [MODERATED] Date/Time? Greg KH
2018-05-19 17:51 ` [MODERATED] Date/Time? Borislav Petkov
2018-05-19 18:45   ` Linus Torvalds
2018-05-19 19:07     ` [MODERATED] " Borislav Petkov
2018-05-19 19:48       ` Linus Torvalds
2018-05-19 20:22         ` [MODERATED] " Borislav Petkov
2018-05-20 20:58     ` Jon Masters
2018-05-19 18:21 ` David Woodhouse
2018-05-19 19:05   ` Greg KH
2018-05-20 19:23   ` David Woodhouse
2018-05-20 23:01   ` David Woodhouse
2018-05-21  8:35     ` Greg KH
2018-05-20 17:45 ` Jiri Kosina
2018-05-20 18:19   ` Greg KH
2018-05-20 18:35     ` Borislav Petkov
2018-05-20 19:57       ` Greg KH
2018-05-20 18:36     ` Linus Torvalds
2018-05-20 18:48       ` Jiri Kosina [this message]
2018-05-20 20:59 ` Jon Masters
2018-05-20 21:09   ` Jiri Kosina
2018-05-21  6:11     ` Greg KH
2018-05-20 21:48   ` Linus Torvalds
2018-05-20 21:56     ` David Woodhouse
2018-05-21  6:16   ` Greg KH
2018-05-21  7:18     ` David Woodhouse
2018-05-21 15:23       ` Date/Time? Thomas Gleixner
2018-05-21 16:46   ` [MODERATED] Date/Time? Greg KH
2018-05-21 17:12     ` Konrad Rzeszutek Wilk
2018-05-21 19:42       ` Greg KH
2018-05-21 19:48         ` Jiri Kosina
2018-05-21 20:30           ` Jon Masters
2018-05-22  8:00             ` Peter Zijlstra
2018-05-22  9:26               ` Greg KH
2018-05-22 16:32                 ` Andi Kleen
2018-05-23 14:15                 ` Jon Masters
2018-05-21 17:22     ` Jon Masters
2018-05-21 18:56       ` Date/Time? Thomas Gleixner
2018-05-21 19:16         ` [MODERATED] Date/Time? Jon Masters
2018-05-21 20:43           ` Greg KH
2018-05-21 17:31     ` Jon Masters
2018-05-21 18:53     ` Date/Time? Thomas Gleixner

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