From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [kvmarm] [RFC PATCH 0/3] KVM: ARM: Get rid of hardcoded VGIC
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Date: Fri, 26 Oct 2012 13:57:54 +0200
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Cc: Jan Kiszka <jan.kiszka@siemens.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	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>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Il 26/10/2012 13:09, Benjamin Herrenschmidt ha scritto:
> The only cases I can think of are the association between a virtual
> interrupt (ie, an interrupt in the guest interrupt number space) and an
> in-kernel source for that interrupt, ie, vhost and PCI pass-through
> essentially.

If you exclude old-style PCI pass-through and limit yourself to vhost
and VFIO, you can treat irqfd as "the" in-kernel source of the
interrupt.  Then you need a mapping between MSIs and numbers used in
KVM_IRQFD ("GSIs").

This is what KVM_SET_GSI_ROUTING modifies, and basically the mapping is
modified every time a vector is masked/unmasked in the MSI-X table.

Paolo