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SubjectRe: [PATCH v2 1/6] kvm: Pass kvm_irqfd to functions
On Thu, Jun 28, 2012 at 02:00:41PM +0200, Cornelia Huck wrote:
> On Thu, 28 Jun 2012 12:34:43 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> > On Thu, Jun 28, 2012 at 11:03:16AM +0200, Cornelia Huck wrote:
>
> > > How about something like this as parameter for the new ioctl?
> > >
> > > struct kvm_irqfd2 {
> > > __u32 fd;
> > > __u32 flags; /* for things like deassign */
> > > __u64 type; /* determines the payload */
> > > union {
> > > /* type traditional */
> > > struct {
> > > __u32 gsi;
> > > } trad;
> > > /* type s390 */
> > > struct {
> > > __u32 int_type;
> > > __u32 parm;
> > > __u64 parm64;
> > > } s390;
> > > __u8 pad[20];
> > > };
> > > }
> > >
> > > This could be combined with an arch or a per-kvm callback to keep the
> > > generic code clean of architecture dependencies.
> > >
> > > Cornelia
> >
> > Looks a bit weird - shouldn't all this be part of gsi routing?
> > But no idea really, I don't see the big picture here.
> >
>
> Well, on s390 we don't have anything like "gsi routing" (I'm not even
> really sure what that is).

I really mean kvm_irq_routing. This has options for
irqchip, msi, I guess we can add more.


> My understanding is the following:
>
> - Basically, we want to notify the guest for a virtqueue.
> - For this, we want to inject an interrupt for the associated device.
> - On x86, this means raising an interrupt on an interrupt line, as
> specified by some kind of number.

Not just that: for MSI we pass in data encoding priority
destination etc.

> - On s390, we need some more information to (a) identify the device and
> (b) additional information that needs to be transmitted for an
> interrupt (device specific). (This is what basically goes into struct
> kvm_s390_interrupt, which I reproduced in the s390 part.)
>
> Cornelia

Is this b mostly static or does it change for each interrupt?


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