Re: [Xen-devel] [PATCH 8/9] x86/IRQ: make fixup_irqs() skip unconnected internally used interrupts

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, May 06, 2019 at 08:25:51AM -0600, Jan Beulich wrote:
> >>> On 06.05.19 at 15:52, <roger.pau@xxxxxxxxxx> wrote:
> > On Mon, Apr 29, 2019 at 05:26:41AM -0600, Jan Beulich wrote:
> >> --- a/xen/arch/x86/irq.c
> >> +++ b/xen/arch/x86/irq.c
> >> @@ -2412,8 +2412,20 @@ void fixup_irqs(const cpumask_t *mask, b
> >>          vector = irq_to_vector(irq);
> >>          if ( vector >= FIRST_HIPRIORITY_VECTOR &&
> >>               vector <= LAST_HIPRIORITY_VECTOR )
> >> +        {
> >>              cpumask_and(desc->arch.cpu_mask, desc->arch.cpu_mask, mask);
> >>  
> >> +            /*
> >> +             * This can in particular happen when parking secondary 
> >> threads
> >> +             * during boot and when the serial console wants to use a PCI 
> >> IRQ.
> >> +             */
> >> +            if ( desc->handler == &no_irq_type )
> > 
> > I found it weird that a irq has a vector assigned (in this case a
> > high-priority vector) but no irq type set.
> > 
> > Shouldn't the vector be assigned when the type is set?
> 
> In general I would agree, but the way the serial console IRQ
> gets set up is different - see smp_intr_init(). When it's a PCI
> IRQ (IO-APIC pin 16 or above), we'll know how to program
> the IO-APIC RTE (edge/level, activity high/low) only when
> Dom0 boots, and hence we don't set ->handler early.

Oh, OK. I guess assuming level triggered active low unless dom0
provides a different configuration is not safe.

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks, Roger.

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