Re: x86/mce/therm_throt incorrect THERM_STATUS_CLEAR_CORE_MASK?

[Arnd Bergmann]

On Thu, Jun 2, 2022 at 6:25 PM srinivas pandruvada
<srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote:
> On Thu, 2022-06-02 at 18:18 +0200, Arnd Bergmann wrote:
> > On Thu, Jun 2, 2022 at 5:52 PM srinivas pandruvada
> > <srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote:
> > >
> > > 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 for your quick reply. I have installed the latest microcode
> > 0x5003302
> > now (manually, because the version provided by the distro was still
> > using
> > version 0x5003102).
> >
> > After that, I tried writing the value 0x2a80 from userspace, and
> > that did not cause a trap, so I assume that fixed it.
> >
> Thanks for reporting.
> I am aware of this issue and should be fixed by microcode update.

I wonder how common this problem it is. Would it help to add a driver workaround
like this?

diff --git a/drivers/thermal/intel/therm_throt.c
b/drivers/thermal/intel/therm_throt.c
index 8352083b87c7..acb402e56796 100644
--- a/drivers/thermal/intel/therm_throt.c
+++ b/drivers/thermal/intel/therm_throt.c
@@ -214,7 +214,13 @@ static void clear_therm_status_log(int level)

        rdmsrl(msr, msr_val);
        msr_val &= mask;
-       wrmsrl(msr, msr_val & ~THERM_STATUS_PROCHOT_LOG);
+       if (wrmsrl_safe(msr, msr_val & ~THERM_STATUS_PROCHOT_LOG)) {
+               /* work around Cascade Lake SKZ57 erratum */
+               printk_once(KERN_WARNING "Failed to update IA32_THERM_STATUS, "
+                                       "please upgrade microcode\n");
+               wrmsrl(msr, msr_val & ~THERM_STATUS_PROCHOT_LOG &
+                       ~BIT(13) & ~BIT(15));
+       }
 }

 static void get_therm_status(int level, bool *proc_hot, u8 *temp)

        Arnd