On Thu, Mar 12, 2015 at 06:00:28PM +0800, Fam Zheng wrote: > On Thu, 03/12 10:41, Michael S. Tsirkin wrote: > > 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 <f...@redhat.com> > > > > 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? > > OK, yes, get your point. And this also relates to the patch you replied > yesterday: > > http://www.spinics.net/lists/kernel/msg1943182.html
About that one, I still don't know why it's necessary. reboot causes a system reset and that will eventually deassert an irq, no? > /* > > The hanging problem, which is due to irq not being acknowledged, can only be > fixed by your patch if the irq is cleared at reset. > > The uninterruptable process doesn't really matter, the system would still > shutdown, as long as the wrong irq is cleard. > > See also RHBZ https://bugzilla.redhat.com/show_bug.cgi?id=1199155 > > */ > > Fam > > > > > > --- > > > 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 > >
