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

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

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.

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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