On Tue, Mar 19, 2013 at 12:19:55PM -0300, Marcelo Tosatti wrote:
> See the previous argument: should never enter guest mode with PIR ON bit
> set. With logic above:  
> 
> context1                              context2                      context3
>                                       set_bit(PIR-1)                   
>                                       r = pi_test_and_set_on()        
> set_bit(PIR-40)
>                                       set_bit(KVM_REQ_EVENT)
> if (kvm_check_request(KVM_REQ_EVENT)  
>  if (test_and_clear_bit(on))
> 
>    kvm_apic_update_irr()                                              r = 
> pi_test_and_set_on()
> 
> guest entry with PIR ON=1
> 
> 
> Thats the reason for unconditional clearing on guest entry: it is easy
> to verify its correct. I understand and agree the callback (and VMWRITE)
> is not nice.

Re: KVM_REQ_EVENT setting after set_bit(KVM_REQ_EVENT) assures no guest
entry with PIR ON=1.

Might be, would have to verify. Its trickier though. Maybe add a FIXME:
to the callback and remove it later.

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