Re: [Qemu-devel] [PATCH v3 1/4] cpus: Define NMI callback

[Alexander Graf]

On 06/10/2014 06:29 PM, Paolo Bonzini wrote:
> Il 10/06/2014 16:48, Luiz Capitulino ha scritto:
> > > The s390 restart interrupt is a per-vcpu interrupt, which we really
> > > don't want to inject on _all_ vcpus. OTOH, we want to inject that
> > > interrupt on any vcpu - we don't care which one it is. So I'd really
> > > like an "inject nmi on default cpu" option.
> >
> > We could define a default CPU for the command. What isn't going to work
> > is to use the human monitor's "current CPU" concept (set with the cpu
> > command).
>
> It isn't going to work, but to me it seems like a bug.  Why was the 
> NMI command even converted to QAPI if it cannot work?  Let's just use 
> monitor_set_cpu from qmp_cpu and call it a day.
>
> The amount of churn that Alexey is going through for this feature is 
> unreasonable.

I agree. I see two different paths forward:

  1) Use the patches as they are - they seem pretty sound and take the 
existing x86/s390 only feature to spapr
  2) Model an "NMI" button. That button would get instantiated by the 
machine model. That would allow the wiring to be defined by the board. 
Monitor / QMP would only "press" that button (trigger an edge interrupt? 
call a function? something).


I don't mind much either way - option 2 is the architecturally correct 
way of doing this. Option 1 probably won't hurt us either.

Alex