Re: FW: [kvm-commits] KVM: Move interrupt injection out of interruptdisabled section

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

Dong, Eddie wrote:
> Avi Kivity wrote:
>   
>> Dong, Eddie wrote:
>>     
>>> Avi Kivity wrote:
>>>
>>>       
>>>> [we can try to improve it by using vm86 interrupt redirection which
>>>> may allow event injection using VT instead of writing to the guest
>>>> stack]. 
>>>>
>>>>
>>>>         
>>> Avi:
>>> 	I did an investigation to try to find a way if we can deliver
>>> IRQ to guest real mode using VM_ENTRY_INTR_INFO like what
>>> is did in protect mode with minimal changes. It looks like we can't
>>> do that without a VMXassist similar VM86 monitor in guest.
>>>
>>>
>>>       
>> Can you explain why a monitor is needed?  I thought of using the VME
>> interrupt redirection bitmap, does this approach not work?
>>     
>
> Yes I think so at beginning. But then I realized there are tricky:
> VMX will restore guest state first and then inject HW IRQ if there is.
> (SDM 22.5)
>
> SDM 3 16.3 & 16.3.1.1 says the processor will switch to protect mode
> exception interrupt & exception handler instead of 8086 program IVT
> which we want in this case, where the VM86 monitor resides:-(
>
> Only software interrupt can let processor directly refer IVT per 
> manual 16.3.1.1 & 22.5. So I tried to inject a software interrupt 
> for guest external interrupt, but it violatesSDM 20.8.3 and 
> VM Resume fails. 
>
>   

I didn't see anything in 20.8.3 regarding injection of software 
interrupts to vm86 mode.  And other sections in the manual (22.5.1) 
imply that it is possible.

Maybe it's failing on something else?  VM-entry instruction length?  I 
see that it must be in the range 1-15.

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


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