Re:

Xin Li
2024-06-12T02:56:01Z

On 6/11/2024 7:04 PM, Sean Christopherson wrote:
> On Tue, Jun 11, 2024, Jacob Pan wrote:
>> To tackle these challenges, Intel introduced NMI source reporting as a part
>> of the FRED specification (detailed in Chapter 9).
>
> Chapter 9 of the linked spec is "VMX Interactions with FRED Transitions". I
> spent a minute or so poking around the spec and didn't find anything that describes
> how "NMI source reporting" works.

I did the same thing when I saw NMI source was added to the spec :)

>
>> 1. Performance monitoring.
>> 2. Inter-Processor Interrupts (IPIs) for functions like CPU backtrace,
>> machine check, Kernel GNU Debugger (KGDB), reboot, panic stop, and
>> self-test.
>>
>> Other NMI sources will continue to be handled as previously when the NMI
>> source is not utilized or remains unidentified.
>>
>> Next steps:
>> 1. KVM support
>
> I can't tell for sure since I can't find the relevant spec info, but doesn't KVM
> support need to land before this gets enabled? Otherwise the source would get
> lost if the NMI arrived while the CPU was in non-root mode, no? E.g. I don't
> see any changes to fred_entry_from_kvm() in this series.

You're absolutely right!

There is a patch in NMI source KVM patches for this, but as you
mentioned it has to be in this NMI source native patches instead.

Thanks!
Xin