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);
}
--
MST
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