From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH v4 3/9] KVM: Clear assigned guest IRQ on release Date: Tue, 09 Nov 2010 12:20:11 +0100 Message-ID: <4CD92E6B.5010000@siemens.com> References: <4CD92950.1070309@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm , Alex Williamson , "Michael S. Tsirkin" To: Avi Kivity Return-path: Received: from thoth.sbs.de ([192.35.17.2]:22409 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755494Ab0KILU0 (ORCPT ); Tue, 9 Nov 2010 06:20:26 -0500 In-Reply-To: <4CD92950.1070309@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Am 09.11.2010 11:58, Avi Kivity wrote: > On 11/08/2010 01:21 PM, Jan Kiszka wrote: >> When we deassign a guest IRQ, clear the potentially asserted guest line. >> There might be no chance for the guest to do this, specifically if we >> switch from INTx to MSI mode. >> >> Signed-off-by: Jan Kiszka >> --- >> virt/kvm/assigned-dev.c | 3 +++ >> 1 files changed, 3 insertions(+), 0 deletions(-) >> >> diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c >> index 7c98928..ecc4419 100644 >> --- a/virt/kvm/assigned-dev.c >> +++ b/virt/kvm/assigned-dev.c >> @@ -141,6 +141,9 @@ static void deassign_guest_irq(struct kvm *kvm, >> kvm_unregister_irq_ack_notifier(kvm,&assigned_dev->ack_notifier); >> assigned_dev->ack_notifier.gsi = -1; >> >> + kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id, >> + assigned_dev->guest_irq, 0); >> + >> if (assigned_dev->irq_source_id != -1) >> kvm_free_irq_source_id(kvm, assigned_dev->irq_source_id); >> assigned_dev->irq_source_id = -1; > > I guess this can't hurt. Did you see it happen in practice? Yes, with prefer_msi=off and an e1000e-driven NIC: The legacy IRQ stayed asserted when the guest actually enabled MSI. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux