Re:

[Xin Li]

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