Re: NetBSD dom0 PVH: hardware interrupts stalls

[Jan Beulich <jbeulich@xxxxxxxx>]

On 27.11.2020 11:59, Roger Pau Monné wrote:
> --- a/xen/arch/x86/hvm/irq.c
> +++ b/xen/arch/x86/hvm/irq.c
> @@ -187,6 +187,10 @@ void hvm_gsi_assert(struct domain *d, unsigned int gsi)
>       * to know if the GSI is pending or not.
>       */
>      spin_lock(&d->arch.hvm.irq_lock);
> +    if ( gsi == TRACK_IRQ )
> +        debugtrace_printk("hvm_gsi_assert irq %u trig %u assert count %u\n",
> +                          gsi, trig, hvm_irq->gsi_assert_count[gsi]);

This produces

81961 hvm_gsi_assert irq 34 trig 1 assert count 1

Since the logging occurs ahead of the call to assert_gsi(), it
means we don't signal anything to Dom0, because according to our
records there's still an IRQ in flight. Unfortunately we only
see the tail of the trace, so it's not possible to tell how / when
we got into this state.

Manuel - is this the only patch you have in place? Or did you keep
any prior ones? Iirc there once was one where Roger also suppressed
some de-assert call.

Jan