Re: [perf] unchecked MSR access error: WRMSR to 0x3f1

[Liang, Kan]

On 2025-06-19 11:17 a.m., Vince Weaver wrote:
> On Wed, 18 Jun 2025, Vince Weaver wrote:
> 
>> On Wed, 18 Jun 2025, Liang, Kan wrote:
>>
>>> No, the error message doesn't say it. Just want to check if you have
>>> extra information. Because the Topdown perf metrics is only supported on
>>> p-core. I want to understand whether the code messes up with e-core.
>>
>> I can't easily tell from the fuzzer as it intentionally switches cores 
>> often.  I guess I could patch the kernel to report CPU when the WRMSR 
>> error triggers.
> 
> I've patched the kernel to get rid of the warn_once() and added a printk
> for smp_processor_id()  (is that what I want to print?)  In any case that 
> reports the warning is happening on CPU1 which is actually a P core, not 
> an atom core.

Thanks for the confirmation.
I've tried fuzzer in some newer machines (later than raptor-lake), but I
haven't reproduce it yet. I will try to find a raptor-lake for more tests.

Thanks,
Kan