Re: [patch 1/2] KVM: x86: handle double and triple faults for every exception

[Avi Kivity <avi@redhat.com>]

On 11/15/2009 04:29 PM, Jan Kiszka wrote:
> Avi Kivity wrote:
>    
>> On 11/15/2009 02:51 PM, Gleb Natapov wrote:
>>      
>>>        
>>>> "replacing" exceptions is dangerous in the case of debug exceptions
>>>> and machine checks, since restarting execution won't recover them.
>>>>
>>>>
>>>>          
>>> But not replacing them is not better. No point in re-injecting
>>> exception that causes another exception.
>>>
>>>        
>> Right, just pointing out there's still a small hole left.  Replacing is
>> much better ignoring.
>>      
> Is the hardware doing some queuing in this case?

Gleb has verified by testing, and Intel has confirmed, that the hardware 
does not queue, and will in fact lose traps and NMIs in such a case.  So 
the small hole is actually present in the processor and we're better off 
not queueing!  I've forgotten about this but Gleb reminded me.

> Would it be overly
> complicated to adopt the real behavior here?
>    

Not only would it be difficult, it would also be incorrect.

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