On Tue, 2010-11-09 at 12:58 +0200, 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<[email protected]> > > --- > > 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?
The latest patches will route legacy interrupts via irqfd if available too. We do have the issue that KVM pulses interrupts injected this way, but it seems to work nonetheless. I was thinking about proposing a level flag for set_irqfd to only set it, allowing the ack notifier to deassert it. Perhaps we also need a flag to toggle the polarity. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
