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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 27 Aug 2013 20:32:28 +1000
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Subject: Re: [Qemu-devel] [PATCH 1/2] kvm irqfd: support msimessage to irq
 translation in PHB
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Alexey Kardashevskiy <aik@ozlabs.ru>, Alexander Graf <agraf@suse.de>, qemu-devel@nongnu.org, Alex Williamson <alex.williamson@redhat.com>, qemu-ppc@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Paul Mackerras <paulus@samba.org>

On Tue, 2013-08-27 at 13:26 +0300, Michael S. Tsirkin wrote:
> e would end up with something like
> > 
> > diff --git a/kvm-all.c b/kvm-all.c
> > index 716860f..ca3251e 100644
> > --- a/kvm-all.c
> > +++ b/kvm-all.c
> > @@ -1190,6 +1190,10 @@ int kvm_irqchip_add_msi_route(KVMState *s, MSIMessage msg)
> >      struct kvm_irq_routing_entry kroute = {};
> >      int virq;
> > 
> > +    if (kvm_gsi_routing_linear()) {
> > +        return msi.data & 0xffff;
> > +    }
> > +

I haven't followed the whole discussion, Alexey, is this the per-host
bridge source number or the global XIRR (XICS interrupt number) ?

Because in the latter case, it can be up to 24 bits... (And yes, MSI
data is limited to 16).

However maybe we can decide arbitrarily that under qemu/kvm we only
support 16-bit XIRRs (it's fine, from a PAPR perspective at least if it
keep things simpler).

Cheers,
Ben.