Re: [PATCH 2/3] KVM: Add irqdevice object

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Gregory Haskins wrote:
>   
>>>  
>>>  	if (vcpu- >rmode.active) {
>>>  		inject_rmode_irq(vcpu, irq);
>>> @@ - 1246,7 +1241,7 @@ static void do_interrupt_requests(struct kvm_vcpu 
>>>       
>> *vcpu,
>>     
>>>  		 (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0);
>>>  
>>>  	if (vcpu- >interrupt_window_open &&
>>> -	    vcpu- >irq_summary &&
>>> +	    kvm_irqdevice_pending(&vcpu- >irq_dev, 0) &&
>>>  	    !(vmcs_read32(VM_ENTRY_INTR_INFO_FIELD) & INTR_INFO_VALID_MASK))
>>>   
>>>       
>> What if an irq is made pending here?
>>     
>
> The only race I see is related to what you pointed out previously:  A level-sensitive interrupt could be asserted when pending() is read, and deasserted when read_vector() is read.  Handling the irq == -1 from read_vector() should fix the race.  Or are you pointing out something else?
>   

That one.

I think there are probably a few more hiding in there.  To reduce the 
number of combinations, I'd suggest putting the irq and the inter-vcpu 
communication things under the same lock, and to make sure ->pending() 
and ->read_vector() are always called in the same critical section (or 
even better, to unify them into one function).

-- 
error compiling committee.c: too many arguments to function


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