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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Message-ID: <20190828084351.GC29927@kroah.com>
Date:   Wed, 28 Aug 2019 10:43:51 +0200
From:   Greg KH <greg@...ah.com>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, yu.c.chen@...el.com,
        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 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?

Sasha, did your scripts trigger this unintentionally somehow?

thanks,

greg k-h