From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [kvmarm] [RFC PATCH 0/3] KVM: ARM: Get rid of hardcoded VGIC
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Date: Fri, 26 Oct 2012 21:37:18 +1100
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Cc: Jan Kiszka <jan.kiszka@siemens.com>,
	Paul Mackerras <paulus@samba.org>,
	Christoffer Dall <c.dall@virtualopensystems.com>,
	Alexander Graf <agraf@suse.de>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	kvm-ppc <kvm-ppc@vger.kernel.org>,
	Peter Maydell <peter.maydell@linaro.org>
To: Paolo Bonzini <pbonzini@redhat.com>
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On Fri, 2012-10-26 at 11:58 +0200, Paolo Bonzini wrote:
> Il 25/10/2012 21:40, Benjamin Herrenschmidt ha scritto:
> >> > Probably you do need a variant of KVM_CREATE_IRQCHIP to create the
> >> > IOAPICs/source controllers (Paul's proposal at
> >> > http://permalink.gmane.org/gmane.comp.emulators.kvm.powerpc.devel/5674
> >> > for example), assign chip ids to them, set the number of input lines,
> >> > etc. but the configuration should work well with the existing ioctls,
> >> > with no limit on the number of sources. 
> > But what do you mean by "configuration" really ? I don't see anything in
> > common there.
> 
> Wiring which MSI-X interrupts go to which source controllers.  If you
> have one source controller per PCI bridge, you need to tell the kernel
> the mapping between MSI messages interrupts and PCI bridges, and update
> it whenever the MSI masking changes.

Not sure I get it. Are you talking in the context of PCI pass-through ?
Each PCI bridge on POWER has its own set of MSIs though for emulated
bridges it's a non-issue, it's all dealt with by qemu, so I'm not sure
what you mean here.

> The other problem is configuring the redirection table.  If you need >64
> sources you need ioctls like KVM_GET/SET_IRQCHIP_ONE_REG.

Well, all of that is totally specific to the IO-APIC design &
limitations as far as I can tell. What is the "redirection table" ?

Cheers,
Ben.