Yang, Sheng wrote:
To deal with guest shared interrupt bug in in-kernel irqchip, we should:
1. Identify each level trig interrupt source.
2. Implement logical OR on the same IRQ line for each interrupt source.
Here I chose a simple method: the caller of kvm_set_irq() has responsiblity
to identify interrupt sources, and IOAPIC/PIC ensure logical OR on IRQ line.
The downside is that every caller has to do this edge detection.
How about allocating a vector of u32s (one per irq), and each source
will allocate a bit within this vector. The 'or' operation becomes
(word != 0).
For example:
irq_src = kvm_irq_allocate_source(kvm); /* allocate bit within irq
vector */
...
kvm_set_irq(kvm, irq, 1, irq_src);
kvm_set_irq(...)
{
// locking?
if (level)
set_bit(irq_src, &kvm->irq_state[irq]);
else
clear_bit(irq_src, &kvm->irq_state[irq]);
kvm_pic_set_irq(kvm, irq, !!kvm->irq_state[irq]);
kvm_ioapic_set_irq(kvm, irq, !!kvm->irq_state[irq]);
}
kvm_irq_allocate_source(kvm)
{
irq_src = find_first_clear_bit(kvm->irq_sources);
set_bit(irq_src, &kvm->irq_sources);
return irq_src;
}
This also keeps the pic and ioapic out of the picture, which is good.
It also allows us to implement negative polarity easily in the future.
--
error compiling committee.c: too many arguments to function
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