linux-kernel - Re: x86/mce/therm_throt incorrect THERM_STATUS_CLEAR_CORE

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Date:   Thu, 02 Jun 2022 08:52:49 -0700
From:   srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     Arnd Bergmann <arnd@...nel.org>, Len Brown <len.brown@...el.com>,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: x86/mce/therm_throt incorrect THERM_STATUS_CLEAR_CORE_MASK?

On Thu, 2022-06-02 at 11:19 +0200, Arnd Bergmann wrote:
> I have a Xeon W-2265 (family 6, model 85, stepping 7) that started
> constantly spewing messages from the therm_throt driver after one
> core overheated:
> 
I think this is a Cascade Lake system. Have you tried the latest micro-
code?

Thanks,
Srinivas


> May 31 13:57:54 kernel: [15512.209474] unchecked MSR access error:
> WRMSR to 0x19c (tried to write 0x0000000000002a80) at rIP:
> 0xffffffff9f67f974 (native_write_msr+0x4/0x20)
> May 31 13:57:54 kernel: [15512.209486] Call Trace:
> May 31 13:57:54 kernel: [15512.209488]  <TASK>
> May 31 13:57:54 kernel: [15512.209489]  ?
> throttle_active_work+0xea/0x1f0
> May 31 13:57:54 kernel: [15512.209498]  process_one_work+0x21d/0x3c0
> May 31 13:57:54 kernel: [15512.209502]  worker_thread+0x4d/0x3f0
> May 31 13:57:54 kernel: [15512.209505]  ?
> process_one_work+0x3c0/0x3c0
> May 31 13:57:54 kernel: [15512.209508]  kthread+0x127/0x150
> May 31 13:57:54 kernel: [15512.209510]  ?
> set_kthread_struct+0x40/0x40
> May 31 13:57:54 kernel: [15512.209513]  ret_from_fork+0x1f/0x30
> ...
> May 31 13:57:59 kernel: [15517.333445] CPU11: Core temperature is
> above threshold, cpu clock is throttled (total events = 3)
> 
> I could not find CPU model specific documentation for this register,
> but I see that in [1], the bits 13 through 15 are marked as reserved
> in some cases but not others. Manually writing the value 0xa80
> instead of 0x2a80 from user space makes the warnings stop, so
> my guess is that this CPU does not support the 0x2000 bit:
> 
> $ sudo  wrmsr -p 11 0x19c 0xa80 ; dmesg
> [177764.874555] msr: Write to unrecognized MSR 0x19c by wrmsr (pid:
> 142969).
> [177764.874560] msr: See
> https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/about for
> details.
> [177765.371180] CPU11: Core temperature/speed normal (total events =
> 42)
> [177765.371180] CPU23: Core temperature/speed normal (total events =
> 42)
> 
> I have not tried the patch below, but I think this would address it
> on my
> system, while likely breaking other machines. Any ideas what the
> correct fix is?
> 
>       Arnd
> 
> diff --git a/drivers/thermal/intel/therm_throt.c
> b/drivers/thermal/intel/therm_throt.c
> index 8352083b87c7..620d7f4c013e 100644
> --- a/drivers/thermal/intel/therm_throt.c
> +++ b/drivers/thermal/intel/therm_throt.c
> @@ -196,7 +196,7 @@ static const struct attribute_group
> thermal_attr_group = {
>  #define THERM_THROT_POLL_INTERVAL      HZ
>  #define THERM_STATUS_PROCHOT_LOG       BIT(1)
> 
> -#define THERM_STATUS_CLEAR_CORE_MASK (BIT(1) | BIT(3) | BIT(5) |
> BIT(7) | BIT(9) | BIT(11) | BIT(13) | BIT(15))
> +#define THERM_STATUS_CLEAR_CORE_MASK (BIT(1) | BIT(3) | BIT(5) |
> BIT(7) | BIT(9) | BIT(11))
>  #define THERM_STATUS_CLEAR_PKG_MASK  (BIT(1) | BIT(3) | BIT(5) |
> BIT(7) | BIT(9) | BIT(11))
> 
>  static void clear_therm_status_log(int level)
> 
> [1]
> https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-vol-3b-part-2-manual.pdf