From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55995) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YVzcg-0000jL-1Z for qemu-devel@nongnu.org; Thu, 12 Mar 2015 05:41:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YVzcd-00063V-B4 for qemu-devel@nongnu.org; Thu, 12 Mar 2015 05:41:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35781) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YVzcd-00063P-3P for qemu-devel@nongnu.org; Thu, 12 Mar 2015 05:41:43 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t2C9ffAa019578 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Thu, 12 Mar 2015 05:41:42 -0400 Date: Thu, 12 Mar 2015 10:41:39 +0100 From: "Michael S. Tsirkin" Message-ID: <20150312103850-mutt-send-email-mst@redhat.com> References: <1426142455-3739-1-git-send-email-famz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1426142455-3739-1-git-send-email-famz@redhat.com> Subject: Re: [Qemu-devel] [PATCH] virtio-pci: Clear IRQ at reset List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: qemu-devel@nongnu.org On Thu, Mar 12, 2015 at 02:40:55PM +0800, Fam Zheng wrote: > Currently we could leave PCI IRQ asserted even after reset, it is safer > to clear it. > > In the case that a buggy driver has disabled MSI-X unintentially, we may > have already injected IRQ in previous virtio_pci_notify, which will not > be cleared by guest because it doesn't expect it (i.e. no irq handler). > However the driver may eventually notice the unresponsiveness and reset > the device, at that point, clearing the irq is meaningful. > > Signed-off-by: Fam Zheng I don't think we care about buggy drivers being able to recover, but the same would apply to e.g. kdump when using virtio blk/scsi after a crash, correct? > --- > hw/virtio/virtio-pci.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index e7baf7b..2600f1e 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -988,6 +988,7 @@ static void virtio_pci_reset(DeviceState *qdev) > virtio_pci_stop_ioeventfd(proxy); > virtio_bus_reset(bus); > msix_unuse_all_vectors(&proxy->pci_dev); > + pci_irq_deassert(&proxy->pci_dev); > } > > static Property virtio_pci_properties[] = { > -- > 1.9.3