Re: [RFC][PATCH 0/2] Fix guest shared interrupt with in-kernel irqchip

[Sheng Yang <yasker@gmail.com>]

On Thu, Oct 02, 2008 at 04:27:18PM +0300, Avi Kivity wrote:
> 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).

Oh, that's what I called the "alternative" one... I just think the
request/allocation/free make thing complicate and unnecessary for now, for
we are already ensure that kvm_set_irq() are called in pair.

I once think if we use resource allocating method, the irqs should bind with
the resources, and it's unnecessary. But I think your method is better,
reserve one bit for each source on every irq_state make things simpler.

OK, I will update the patch following this method.

--
regards
Yang, Sheng