Re: [PATCH] xen: Allow platform PCI interrupt to be shared

[Juergen Gross <jgross@xxxxxxxx>]

On 18.01.23 13:22, David Woodhouse wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
> When we don't use the per-CPU vector callback, we ask Xen to deliver event
> channel interrupts as INTx on the PCI platform device. As such, it can be
> shared with INTx on other PCI devices.
>
> Set IRQF_SHARED, and make it return IRQ_HANDLED or IRQ_NONE according to
> whether the evtchn_upcall_pending flag was actually set. Now I can share
> the interrupt:
>
>   11:         82          0   IO-APIC  11-fasteoi   xen-platform-pci, ens4
>
> Drop the IRQF_TRIGGER_RISING. It has no effect when the IRQ is shared,
> and besides, the only effect it was having even beforehand was to trigger
> a debug message in both I/OAPIC and legacy PIC cases:
>
> [    0.915441] genirq: No set_type function for IRQ 11 (IO-APIC)
> [    0.951939] genirq: No set_type function for IRQ 11 (XT-PIC)
>
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>

> ---
> What does xen_evtchn_do_upcall() exist for? Can we delete it? I don't
> see it being called anywhere.
It can be deleted.


Juergen

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