Re: [PATCH 4/5] spapr: Handle irq backend changes with VFIO PCI devices

["Cédric Le Goater" <clg@kaod.org>]

On 21/11/2019 01:56, David Gibson wrote:
> pseries machine type can have one of two different interrupt controllers in
> use depending on feature negotiation with the guest.  Usually this is
> invisible to devices, because they route to a common set of qemu_irqs which
> in turn dispatch to the correct back end.
> 
> VFIO passthrough devices, however, wire themselves up directly to the KVM
> irqchip for performance, which means they are affected by this change in
> interrupt controller.  To get them to adjust correctly for the change in
> irqchip, we need to fire the kvm irqchip change notifier.
> 
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>


Reviewed-by: Cédric Le Goater <clg@kaod.org>

> ---
>  hw/ppc/spapr_irq.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
> index 168044be85..1d27034962 100644
> --- a/hw/ppc/spapr_irq.c
> +++ b/hw/ppc/spapr_irq.c
> @@ -508,6 +508,12 @@ static void set_active_intc(SpaprMachineState *spapr,
>      }
>  
>      spapr->active_intc = new_intc;
> +
> +    /*
> +     * We've changed the kernel irqchip, let VFIO devices know they
> +     * need to readjust.
> +     */
> +    kvm_irqchip_change_notify();
>  }
>  
>  void spapr_irq_update_active_intc(SpaprMachineState *spapr)
>