From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v4 3/9] KVM: Clear assigned guest IRQ on release Date: Tue, 09 Nov 2010 12:58:24 +0200 Message-ID: <4CD92950.1070309@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm , Alex Williamson , "Michael S. Tsirkin" To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:29676 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753875Ab0KIK63 (ORCPT ); Tue, 9 Nov 2010 05:58:29 -0500 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: 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? Note: all this kvm_set_irq(..., [01]) is incorrect as it doesn't account for polarity. Currently the qemu-emulated chipset uses level high pci interrupts, but that's not a given from kvm's point of view. I think vfio fixes this by only routing msi interrupts via the kernel, and routing level interrupts through userspace, which can adjust polarity. Alex/Michael? -- error compiling committee.c: too many arguments to function