On Sun, 2014-02-16 at 13:41 +0200, Michael S. Tsirkin wrote:
> On Fri, Feb 14, 2014 at 11:13:04PM +0100, Alexander Graf wrote:
> >
> > On 14.02.2014, at 23:06, Gabriel L. Somlo <gsomlo@xxxxxxxxx> wrote:
> >
> > > On Fri, Feb 14, 2014 at 10:21:09PM +0100, Alexander Graf wrote:
> > >>
> > >> Can't you just turn the polarity around in the pci host adapter?
> > >
> > > I tried this:
> > >
> > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > > index 1221f32..0e86d21 100644
> > > --- a/hw/pci/pci.c
> > > +++ b/hw/pci/pci.c
> > > @@ -118,13 +118,13 @@ static int pci_bar(PCIDevice *d, int reg)
> > >
> > > static inline int pci_irq_state(PCIDevice *d, int irq_num)
> > > {
> > > - return (d->irq_state >> irq_num) & 0x1;
> > > + return !(d->irq_state >> irq_num) & 0x1;
> > > }
> > >
> > > static inline void pci_set_irq_state(PCIDevice *d, int irq_num, int level)
> > > {
> > > d->irq_state &= ~(0x1 << irq_num);
> > > - d->irq_state |= level << irq_num;
> > > + d->irq_state &= ~(level << irq_num);
> > > }
> > >
> > > static void pci_change_irq_level(PCIDevice *pci_dev, int irq_num, int change)
> > > @@ -229,7 +229,7 @@ static void pcibus_reset(BusState *qbus)
> > > }
> > >
> > > for (i = 0; i < bus->nirq; i++) {
> > > - assert(bus->irq_count[i] == 0);
> > > + assert(bus->irq_count[i] != 0);
> > > }
> > > }
> > >
> > > ---
> > >
> > > but now OS X freezes during boot right after
> > >
> > > [ PCI configuration begin ]
> > > [ PCI configuration end, bridges 1, devices 10 ]
> > > RTC: Only single RAM bank (128 bytes)
> > >
> > > which all looks normal, except the process is supposed to continue on
> > > from there and doesn't :)
> > >
> > > On Linux, I get Fedora 20 live all the way up with no obvious/loud
> > > complaints, but mouse and keyboard don't work at all...
> > >
> > > I have to admit I'm a bit out of my depth here, though :)
> >
> > Yeah, another thing we have to take into account is vhost-net which generates IRQs directly through irqfd. I guess for those we'll have to configure the polarity in the irq routing table?
> >
> >
> > Alex
>
> What will be affected is VFIO which uses IRQFD
> for level interrupts with KVM_IRQFD_FLAG_RESAMPLE.
> I suspect this will need a kernel change, maybe
> a new flag for IRQFD: KVM_IRQFD_FLAG_ACTIVE_LOW,
> since at the moment that does:
>
> static void
> irqfd_inject(struct work_struct *work)
> {
> struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
> struct kvm *kvm = irqfd->kvm;
>
> if (!irqfd->resampler) {
> kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
> false);
> kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
> false);
> } else
> kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
> irqfd->gsi, 1, false);
> }
As you said in a previous message, devices just want assert & de-assert,
1 & 0, which is what we have here. I would think that what asserted
means only needs to be interpreted at the IOAPIC, so I'd hope we could
get it right w/o an API change. Thanks,
Alex
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