Re: [PATCH v2] report IRQ injection status to userspace.

Gleb Natapov
2009-01-28T16:39:42Z

On Tue, Jan 27, 2009 at 01:41:07PM -0200, Marcelo Tosatti wrote:
> On Tue, Jan 27, 2009 at 03:27:39PM +0200, Gleb Natapov wrote:
> > > -1 here ?
> > >
> > I think 1 is better here. For level=0 we always want to report that interrupt
> > was injected and for the case of edge triggered interrupt and level=1
> > ioapic_service() will always be called. BTW it seems that expression
> > old_irr != ioapic->irr in:
> > if ((!entry.fields.trig_mode && old_irr != ioapic->irr)
> > || !entry.fields.remote_irr)
> > ret = ioapic_service(ioapic, irq);
> > Will always be true since for edge triggered interrupt irr is always
> > cleared by ioapic_service(). Am I right?
>
> Right, I was thinking about
>
> if (irq >= 0 && irq < IOAPIC_NUM_PINS) {
>
> Should return MASKED if irq is outside the acceptable range?
>
Is this ever can be false? Should we BUG() if irq is out of range?

> > > + }
> > > + }
> > > #endif
> > >
> > > Is that what you intended ?
> > >
> > Yes! If interrupt was lost due to making it should not be reinjected.
>
> That assumes guests won't mask the interrupt temporarily in the irqchip,
> hope that is OK (as Avi noted earlier guests use CPU to mask irqs
> temporarily, most of the time).
And if a guest masks interrupts it can't complain that some are lost. I
haven't seen Windows masking RTC irq.

--
Gleb.