Re: [Qemu-ppc] [Qemu-devel] [PATCH] RFCv3 kvm irqfd: support msimessage to irq translation in PHB

[Anthony Liguori]

On Sun, Jun 30, 2013 at 2:37 AM, Alexey Kardashevskiy <address@hidden> wrote:
> On 06/30/2013 12:28 AM, Anthony Liguori wrote:
>
> Ah. Everybody ignored, I'll try asking again :)
>
> kvm_irqchip_update_msi_route() - where should it go? What is it for?
> virtio-pci and pci device assignment use it but vfio does not - is it a bug
> of vfio? Thanks.

The data part of an MSI message contains information about how to
deliver the interrupt.  But when we add a virq, it has essentially a
fixed data value.

So if the guest sends a data message that contains anything but the
fixed data value, we need to swizzle the routing table to use the new
data value.

Michael can probably describe why this is needed in practice and Alex
why this isn't used in VFIO.

Regards,

Anthony Liguori

>
>
>
> --
> Alexey