On Mon, Feb 17, 2014 at 12:57:00PM -0500, Gabriel L. Somlo wrote:
> On Sun, Feb 16, 2014 at 06:23:11PM +0200, Michael S. Tsirkin wrote:
> > Well there is a bigger issue: any interrupt with
> > multiple sources is broken.
> >
> > __kvm_irq_line_state does a logical OR of all sources,
> > before XOR with polarity.
> >
> > This makes no sense if polarity is active low.
>
> So, do you think something like this would make sense, to address
> active-low polarity in __kvm_irq_line_state ?
> (this would be independent of the subsequent xor in
> kvm_ioapic_set_irq()):
Make that rather:
-static inline int __kvm_irq_line_state(unsigned long *irq_state,
+static inline int __kvm_irq_line_state(unsigned long *irq_state, int polarity,
int irq_source_id, int level)
{
- /* Logical OR for level trig interrupt */
if (level)
__set_bit(irq_source_id, irq_state);
else
__clear_bit(irq_source_id, irq_state);
- return !!(*irq_state);
+ if (polarity) {
+ /* Logical AND for level trig interrupt, active-low */
+ return !~(*irq_state);
+ } else {
+ /* Logical OR for level trig interrupt, active-high */
+ return !!(*irq_state);
+ }
}
Thanks, and sorry for the noise :)
--Gabriel
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