Re: [Minios-devel] [UNIKRAFT PATCH] plat/kvm: don't crash on unhandled IRQ

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hey Florian,

On 16.08.2018 11:19, Simon Kuenzer wrote:
> Hey,
>
> I agree with this new behavior. It makes Unikraft a bit more resistant 
> as long as we do not support all default-enabled platform interrupts 
> (e.g., keyboard controller).
> Could you provide a patch that introduces this behavior also to Xen?
> I think, the file should be plat/common/x86/traps.c.
Forget this comment. We have do not have yet interrupts support on Xen 
as we have on KVM.
> Cheers,
>
> Simon
>
> Reviewed-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
>
> On 16.08.2018 09:07, Florian Schmidt wrote:
> > Crashing on unhandled interrupts is not very helpful, because things as
> > simple as hitting a key on the VGA console leads to a crash (because
> > there is no keyboard driver yet).
> >
> > Generally speaking, crashing on an unhandled IRQ is unnecessarily harsh.
> > If we just ignore it, the worst thing that can happen is that the
> > hardware that raised the interrupt feels ignored and floods us with
> > additional interrupts, which could lead to the system stalling; but that
> > is not any worse than an immediate crash, and in most cases, just
> > showing an error message and continuing will be completely fine.
> >
> > Also removed a comment that seems somewhat misleading about what the
> > function actually does.
> >
> > Signed-off-by: Florian Schmidt <florian.schmidt@xxxxxxxxx>
> > ---
> >   plat/kvm/irq.c | 6 +-----
> >   1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/plat/kvm/irq.c b/plat/kvm/irq.c
> > index f482942..bad45e2 100644
> > --- a/plat/kvm/irq.c
> > +++ b/plat/kvm/irq.c
> > @@ -36,7 +36,6 @@
> >   #include <errno.h>
> >   #include <uk/arch/atomic.h>
> > -
> >   static struct uk_alloc *allocator;
> >   struct irq_handler {
> > @@ -105,11 +104,8 @@ void _ukplat_irq_handle(unsigned long irq)
> >       }
> >       if (!handled)
> > -        UK_CRASH("Unhandled irq=%lu\n", irq);
> > +        uk_printd(DLVL_CRIT, "Unhandled irq=%lu\n", irq);
> >       else
> > -        /* Only ACK the IRQ if handled; we only need to know
> > -         * about an unhandled IRQ the first time round.
> > -         */
> >           intctrl_ack_irq(irq);
> >   }
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