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From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	gleb@kernel.org, mtosatti@redhat.com, alex.williamson@redhat.com,
	jan.kiszka@siemens.com
Subject: Re: [PATCH v2 3/4] KVM: ioapic: extract body of kvm_ioapic_set_irq
Date: Mon, 24 Mar 2014 18:55:11 +0100	[thread overview]
Message-ID: <20140324175508.GA6143@potion.brq.redhat.com> (raw)
In-Reply-To: <532E9EEF.2080906@redhat.com>

2014-03-23 09:44+0100, Paolo Bonzini:
> Il 21/03/2014 19:58, Radim Krčmář ha scritto:
> >>> +	/*
> >>> +	 * Return 0 for coalesced interrupts; for edge-triggered interrupts,
> >>> +	 * this only happens if a previous edge has not been delivered due
> >>> +	 * do masking.  For level interrupts, the remote_irr field tells
> >          (^ to)
> >>> +	 * us if the interrupt is waiting for an EOI.
> >
> >How do we know we haven't delivered an edge-triggered interrupt when
> >ioapic_service() always clears this IRR bit?
> 
> We know we have at least delivered it to the local APIC(s).  If it
> is masked in the ioredirtbl, ioapic_service doesn't clear the IRR.

I see, LAPIC can't "refuse" an interrupt, so kvm_irq_delivery_to_apic()
won't (mustn't) fail. (The code looks fragile if it returned -1.)

Thanks.

  reply	other threads:[~2014-03-24 17:55 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-21  9:27 [PATCH v2 0/4] KVM: cleanup ioapic and fix KVM_SET_IRQCHIP with irr != 0 Paolo Bonzini
2014-03-21  9:27 ` [PATCH v2 1/4] KVM: ioapic: merge ioapic_deliver into ioapic_service Paolo Bonzini
2014-03-21 17:39   ` Eduardo Habkost
2014-03-21  9:27 ` [PATCH v2 2/4] KVM: ioapic: clear IRR for edge-triggered interrupts at delivery Paolo Bonzini
2014-03-21 18:34   ` Eduardo Habkost
2014-03-22  7:48     ` Paolo Bonzini
2014-03-21  9:28 ` [PATCH v2 3/4] KVM: ioapic: extract body of kvm_ioapic_set_irq Paolo Bonzini
2014-03-21 18:58   ` Radim Krčmář
2014-03-23  8:44     ` Paolo Bonzini
2014-03-24 17:55       ` Radim Krčmář [this message]
2014-03-21  9:28 ` [PATCH v2 4/4] KVM: ioapic: reinject pending interrupts on KVM_SET_IRQCHIP Paolo Bonzini
2014-03-21 14:00   ` Alex Williamson
2014-03-24 17:58   ` Radim Krčmář
2014-03-24 18:14     ` Paolo Bonzini
2014-03-24 19:28       ` Radim Krčmář
2014-03-24 17:59 ` [PATCH v2 0/4] KVM: cleanup ioapic and fix KVM_SET_IRQCHIP with irr != 0 Radim Krčmář

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