Re: [Qemu-devel] [PATCH v2 11/13] spapr_irq: Allow synchronization of a single irq state to KVM

[Greg Kurz <groug@kaod.org>]

On Mon, 14 Jan 2019 17:29:48 +0100
Cédric Le Goater <clg@kaod.org> wrote:

> On 1/14/19 4:10 PM, Greg Kurz wrote:
> > On Mon, 14 Jan 2019 09:19:50 +0100
> > Cédric Le Goater <clg@kaod.org> wrote:
> >   
> >> On 1/11/19 10:04 PM, Greg Kurz wrote:  
> >>> When using the in-kernel interrupt controller, the state of all irqs is
> >>> synchronized to KVM at machine reset time. In the case of PHB hotplug, we
> >>> will need to synchronize LSIs manually.    
> >>
> >> Yes. This is because the interrupt sources in the KVM XICS device have 
> >> already been initialized as MSIs. 
> >>
> >> Can not we reset the source when it is claimed ? 
> >>
> >> An alternative solution would be to initialize the SPAPR_IRQ_PCI_LSI range 
> >> as LSIs at a KVM level.
> >>  
> > 
> > I don't really want to add some dependency to sPAPR code in KVM XICS... what
> > about claiming LSIs for all possible PHBs at machine init time ?  
> 
> you can not claim IRQ numbers twice. So if a new PHB is hot-plugged, 
> it will fail the claim its LSIs.
> 

The intent is to claim all these LSIs for the lifetime of the machine, instead
of having each PHB to claim its own ones during realize.

> C.