linux-kernel - Re: Patch "x86/pm: Introduce quirk framework to save/restore extra MSR registers around suspend/resume" has been added to the 4.4-stable tree

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Date:   Wed, 28 Aug 2019 11:11:55 +0200
From:   Greg KH <greg@...ah.com>
To:     Yu Chen <yu.c.chen@...el.com>
Cc:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable-commits@...r.kernel.org
Subject: Re: Patch "x86/pm: Introduce quirk framework to save/restore extra
 MSR registers around suspend/resume" has been added to the 4.4-stable tree

On Wed, Aug 28, 2019 at 05:00:44PM +0800, Yu Chen wrote:
> On Wed, Aug 28, 2019 at 10:43:51AM +0200, Greg KH wrote:
> > On Wed, Aug 28, 2019 at 12:12:39AM -0400, Sasha Levin wrote:
> > > This is a note to let you know that I've just added the patch titled
> > > 
> > >     x86/pm: Introduce quirk framework to save/restore extra MSR registers around suspend/resume
> > > 
> > > to the 4.4-stable tree which can be found at:
> > >     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> > > 
> > > The filename of the patch is:
> > >      x86-pm-introduce-quirk-framework-to-save-restore-ext.patch
> > > and it can be found in the queue-4.4 subdirectory.
> > > 
> > > If you, or anyone else, feels it should not be added to the stable tree,
> > > please let <stable@...r.kernel.org> know about it.
> > > 
> > > 
> > > 
> > > commit d63273440aa0fdebc30d0c931f15f79beb213134
> > > Author: Chen Yu <yu.c.chen@...el.com>
> > > Date:   Wed Nov 25 01:03:41 2015 +0800
> > > 
> > >     x86/pm: Introduce quirk framework to save/restore extra MSR registers around suspend/resume
> > >     
> > >     A bug was reported that on certain Broadwell platforms, after
> > >     resuming from S3, the CPU is running at an anomalously low
> > >     speed.
> > >     
> > >     It turns out that the BIOS has modified the value of the
> > >     THERM_CONTROL register during S3, and changed it from 0 to 0x10,
> > >     thus enabled clock modulation(bit4), but with undefined CPU Duty
> > >     Cycle(bit1:3) - which causes the problem.
> > >     
> > >     Here is a simple scenario to reproduce the issue:
> > >     
> > >      1. Boot up the system
> > >      2. Get MSR 0x19a, it should be 0
> > >      3. Put the system into sleep, then wake it up
> > >      4. Get MSR 0x19a, it shows 0x10, while it should be 0
> > >     
> > >     Although some BIOSen want to change the CPU Duty Cycle during
> > >     S3, in our case we don't want the BIOS to do any modification.
> > >     
> > >     Fix this issue by introducing a more generic x86 framework to
> > >     save/restore specified MSR registers(THERM_CONTROL in this case)
> > >     for suspend/resume. This allows us to fix similar bugs in a much
> > >     simpler way in the future.
> > >     
> > >     When the kernel wants to protect certain MSRs during suspending,
> > >     we simply add a quirk entry in msr_save_dmi_table, and customize
> > >     the MSR registers inside the quirk callback, for example:
> > >     
> > >       u32 msr_id_need_to_save[] = {MSR_ID0, MSR_ID1, MSR_ID2...};
> > >     
> > >     and the quirk mechanism ensures that, once resumed from suspend,
> > >     the MSRs indicated by these IDs will be restored to their
> > >     original, pre-suspend values.
> > >     
> > >     Since both 64-bit and 32-bit kernels are affected, this patch
> > >     covers the common 64/32-bit suspend/resume code path. And
> > >     because the MSRs specified by the user might not be available or
> > >     readable in any situation, we use rdmsrl_safe() to safely save
> > >     these MSRs.
> > >     
> > >     Reported-and-tested-by: Marcin Kaszewski <marcin.kaszewski@...el.com>
> > >     Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> > >     Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > >     Acked-by: Pavel Machek <pavel@....cz>
> > >     Cc: Andy Lutomirski <luto@...capital.net>
> > >     Cc: Borislav Petkov <bp@...en8.de>
> > >     Cc: Brian Gerst <brgerst@...il.com>
> > >     Cc: Denys Vlasenko <dvlasenk@...hat.com>
> > >     Cc: H. Peter Anvin <hpa@...or.com>
> > >     Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> > >     Cc: Peter Zijlstra <peterz@...radead.org>
> > >     Cc: Thomas Gleixner <tglx@...utronix.de>
> > >     Cc: bp@...e.de
> > >     Cc: len.brown@...el.com
> > >     Cc: linux@...izon.com
> > >     Cc: luto@...nel.org
> > >     Cc: rjw@...ysocki.net
> > >     Link: http://lkml.kernel.org/r/c9abdcbc173dd2f57e8990e304376f19287e92ba.1448382971.git.yu.c.chen@intel.com
> > >     [ More edits to the naming of data structures. ]
> > >     Signed-off-by: Ingo Molnar <mingo@...nel.org>
> > 
> > No git id of the patch in Linus's tree, or your signed-off-by?
> >
> I think the commit id in Linus'tree should be 7a9c2dd08eadd5c6943115dbbec040c38d2e0822

Ah, and Sasha added it because a later patch needed it :(

Sasha, can you fix this patch's headers up to be in the "proper" format?

thanks,

greg k-h