From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: in-kernel interrupt controller steering
Date: Thu, 7 Mar 2013 02:43:30 -0500 (EST)
Message-ID: <619961226.3656112.1362642210758.JavaMail.root@redhat.com>
References: <20130307003246.GA2385@drongo>
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Cc: Gleb Natapov <gleb@redhat.com>, kvm@vger.kernel.org,
	kvm-ppc@vger.kernel.org, Stuart Yoder <stuart.yoder@freescale.com>,
	Scott Wood <scottwood@freescale.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Alexander Graf <agraf@suse.de>
To: Paul Mackerras <paulus@samba.org>
Return-path: <kvm-ppc-owner@vger.kernel.org>
In-Reply-To: <20130307003246.GA2385@drongo>
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> On Wed, Mar 06, 2013 at 03:48:54PM +0100, Alexander Graf wrote:
> > 
> > Paul, Scott, do you think we can move the "this CPU can receive
> > interrupts from MPIC / XICS" part into an ENABLE_CAP that gets set
> > dynamically? That ENABLE_CAP would allocate the structures in the
> > vcpu and register the vcpu with the interrupt controller pool.
> > 
> > The interrupt controller device would still iterate through all
> > vcpus to find the ones that match so that we support the ENABLE_CAP
> > at any point in time.
> 
> When you say "gets set dynamically", do you mean some time in the
> interval between vcpu creation and when it starts running, or do you
> mean at any time, potentially after the vcpu has accessed and
> modified
> its per-vcpu interrupt controller (~ LAPIC) state?
> 
> If the former, then sure, I don't see a major problem.

Only the former.  But I don't think you need a capability even.
KVM_SET_IRQCHIP_TYPE should force the usage of in-kernel per-VCPU
interrupt controllers.

Paolo