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Date: Thu, 12 Oct 2017 16:54:58 +0200
From: Cornelia Huck <cohuck@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v1 4/5] s390x/pci: Refuse to realize
 VFIO-PCI if AIS needed but supported
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To: Pierre Morel <pmorel@linux.vnet.ibm.com>
Cc: pasic@linux.vnet.ibm.com, zyimin@linux.vnet.ibm.com, qemu-devel@nongnu.org, agraf@suse.de, borntraeger@de.ibm.com, Alex Williamson <alex.williamson@redhat.com>

On Thu, 12 Oct 2017 16:48:26 +0200
Pierre Morel <pmorel@linux.vnet.ibm.com> wrote:

> On 11/10/2017 14:20, Cornelia Huck wrote:
> > On Tue, 10 Oct 2017 18:01:53 +0200
> > Pierre Morel <pmorel@linux.vnet.ibm.com> wrote:
> >   
> >> Since in the case we have no AIS in KVM only PCI is impacted, do you
> >> think we can fence IRQFD for MSI with
> >>
> >> kvm_msi_via_irqfd_allowed = false;
> >>
> >> in kvm_arch_init_irq_routing() ?  
> > 
> > Hm, it seems we never set that for s390x... does that imply that we
> > never support irqfd for pci anyway?  
> 
> ... yes, we never supported irqfd for virtio-pci anyway.
> This explains a lot of things to me.
> :)

:D

> 
> >   
> >>
> >> In fact, if we also verify the AIS availability in the same routine we
> >> can avoid the ugly include of vfio/pci.h  
> > 
> > If we can get the serialization right (and setting that value to false
> > does indeed have the desired effect), that's probably the way to go.
> >   
> 
> So now, in v2, we will be able to **enable** irqfd if we detect that we 
> handle AIS in kernel. :)

Let's see how that works out :)