Re: [BUG?] unchecked MSR access error: WRMSR to 0x19c

[srinivas pandruvada]

Hi Rui,

On Thu, 2023-04-06 at 23:36 +0200, Borislav Petkov wrote:
> CCing more appropiate people and quoting the whole mail...
> 
> On Wed, Apr 05, 2023 at 11:14:45PM +0100, Rui Salvaterra wrote:
> > Hi, everyone,
> > 
> > I have a Haswell (Core i7-4770R) machine running Linux 6.3-rc5 on
> > which, after a while under load (say, compiling the kernel), I get
> > this trace…
> > 
> > [  832.549630] unchecked MSR access error: WRMSR to 0x19c (tried to
> > write 0x000000000000aaa8) at rIP: 0xffffffff816f66a6

Please send output of : cpuid -1

Also please try this:

#wrmsr 0x19c 0xaaa8
This should give "wrmsr: CPU 0 cannot set MSR 0x0000019c to
0x000000000000aaa8

#wrmsr 0x19c 0x0aa8

I think this will not return error.

Thanks,
Srinivas

> > (throttle_active_work+0xa6/0x1d0)
> > [  832.549652] Call Trace:
> > [  832.549654]  <TASK>
> > [  832.549655]  process_one_work+0x1ab/0x300
> > [  832.549661]  worker_thread+0x4b/0x340
> > [  832.549664]  ? process_one_work+0x300/0x300
> > [  832.549676]  kthread+0xac/0xc0
> > [  832.549679]  ? kthread_exit+0x20/0x20
> > [  832.549682]  ret_from_fork+0x1f/0x30
> > [  832.549693]  </TASK>
> > 
> > … after which I get these from time to time in dmesg.
> > 
> > [  836.709562] CPU7: Core temperature is above threshold, cpu clock
> > is
> > throttled (total events = 219)
> > [  836.709569] CPU3: Core temperature is above threshold, cpu clock
> > is
> > throttled (total events = 219)
> > [ 1272.792138] CPU2: Core temperature is above threshold, cpu clock
> > is
> > throttled (total events = 1)
> > [ 1272.792156] CPU6: Core temperature is above threshold, cpu clock
> > is
> > throttled (total events = 1)
> > 
> > This is the microcode revision on the CPU.
> > 
> > [    0.000000] microcode: updated early: 0xe -> 0x1c, date = 2019-
> > 11-12
> > 
> > Note that I have the exact same issue on an Ivy Bridge (Core
> > i7-3720QM) machine, but not on an Ivy Bridge laptop (Celeron
> > 1007U).
> > Maybe this is a legitimate warning, but please note that I've
> > thorughly cleaned the machines before retesting to see if, by
> > coincidence, I had any airway/cooling issues. The fact that it
> > started
> > happening recently (since Linux 6.1, I believe), and the fact that
> > running stress-ng --cpu 16 before the unchecked WRMSR error happens
> > doesn't cause any thermal throttling events, lead me to believe
> > this
> > is possibly some unintended oversight.
> > 
> > Please let me know if you need any additional information (.config,
> > or
> > anything else).
> > 
> > Thanks in advance,
> > Rui
>