Re: XIVE VFIO kernel resample failure in INTx mode under heavy load

[Cédric Le Goater]

> > After re-reading what I just wrote, I am leaning towards disabling use of 
> > KVM_CAP_IRQFD_RESAMPLE as it seems last worked on POWER8 and never since :)
> >
> > Did I miss something in the picture (hey Cedric)?
>
> How about disabling it like this?
>
> =====
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 5bfd4aa9e5aa..c999f7b1ab1b 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -732,7 +732,7 @@ static PCIINTxRoute spapr_route_intx_pin_to_irq(void 
> *opaque, int pin)
>       SpaprPhbState *sphb = SPAPR_PCI_HOST_BRIDGE(opaque);
>       PCIINTxRoute route;
>
> -    route.mode = PCI_INTX_ENABLED;
> +    route.mode = PCI_INTX_DISABLED;
>
> =====

I like it.


You now know how to test all the combinations :) Prepare your matrix,
variables are :

 * Host OS              POWER8, POWER9+
 * KVM device           XICS (P8), XICS-on-XIVE (P9), XIVE-on-XIVE (P9)
 * kernel_irqchip       off, on
 * ic-mode              xics, xive
 * Guest OS             msi or nomsi

Ideally you should check TCG, but that's like kernel_irqchip=off.

Cheers,

C.
 
> (btw what the heck is PCI_INTX_INVERTED for?)
>
>
> --
> Alexey