Re: [PATCH] Move irq sharing information to irqchip level.

[Avi Kivity <avi@redhat.com>]

On 08/23/2009 02:36 PM, Gleb Natapov wrote:
>>>
>>> The problem is that at this level it is not known if GSI is MSI or not.
>>> Current code dials with this by arbitrary assuming that GSI is MSI if it
>>> is greater then KVM_IOAPIC_NUM_PINS, but this is not enforced when
>>> routing table is installed and userspace is free to use any GSI as MSI.
>>> Of cause this problem would not exist if MSIs were not linked to GSIs
>>> in the first place.
>>>        
>> Does msi actually care about the states?  I don't think it does.
>>
>>      
> That is the point. MSI doesn't care, but we don't know if GSI is MSI or
> not.
>    

So we toggle the bits needlessly.  Just like with edge-triggered interrupts.
>> No, it's more correct at the GSI level, since all interrupt lines
>> connected to one GSI are shared.
>>
>>      
> Why? All interrupts connected to the same irqchip pin (through pci irq
> router or other onboard logic) are shared. GSI is pure logical
> abstraction.
>    

All interrupts connected through one GSI are shared, so why not keep the 
level information shared as well?


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