Re: [RFC PATCH] hw/arm/virt: Support NMI injection

[Marc Zyngier]

Gavin,

On 2020-01-29 21:54, Gavin Shan wrote:
> On 1/29/20 6:57 PM, Julien Thierry wrote:
> > On 1/29/20 3:46 AM, Gavin Shan wrote:
> > > On 1/28/20 7:29 PM, Julien Thierry wrote:
>
> .../...
>
> > > Julien, thanks for the explanation. The question we're not sure if 
> > > NMI should
> > > be injected on receiving HMP/QMP "nmi" command. It means it's not 
> > > clear what
> > > behavior we should have for this command on ARM. However, I have one 
> > > more
> > > unrelated question: "pseudo" NMI on ARM64 should be PPI? I mean SPI 
> > > can't
> > > be "pseudo" NMI.
> >
> > I'm not sure I understand why you say "SPI can't be "pseudo" NMI". 
> > Currently both PPI and SPI are supported in the "pseudo" NMI scheme. 
> > Do you think that should not be the case? If so, can you elaborate?
> >
> > Thanks,
>
> Julien, NMI interrupt is connected to the system by request_nmi() where 
> we have
> a check as below. -EINVAL will be returned from request_nmi() on those
> interrupts
> whose descriptors aren't marked with IRQ_NOAUTOEN. SPI falls into this 
> category.

The IRQ_NOAUTOEN is set on PPIs because you can't enable them all at 
once,
for obvious reasons.

This doesn't mean you cannot set it on other interrupt classes, 
including SPIs.
It is actually a fairly common thing to do when you want to decouple 
requesting
the interrupt from the enabling, if you do not want the interrupt to be 
able to
fire right away.

        M.
--
Jazz is not dead. It just smells funny...