Re: [Regression] kvm-userspace: VM freezes after booting FreeDOS

[Avi Kivity <avi@qumranet.com>]

Mohammed Gamal wrote:
>
>>>> +        vmx_inject_irq(vcpu, vec);
>>>>
>>>>         
>>> kvm_queue_exception()
>>>       
>> OK.
>>     
>
> Not so fast, the GP# pops up again with kvm_queue_exception(). Why
> should we use kvm_queue_exception() here? 

kvm_queue_exception() will also block interrupt injection.  Without 
this, there's the risk that the breakpoint injection will be overridden 
by a following interrupt injection.

> Shouldn't this be the part
> where we handle/service that exception, rather than adding it, may be
> I am misunderstanding so CIIW.
>   

It is indeed where we handle the guest exception, and we handle it by 
queuing it right back.


Of course, we need to find out why kvm_queue_exception() is broken.  It 
probably needs the same hacky treatment as vmx_inject_irq() for real 
mode.  Eventually I'd like to inject real mode interrupts by writing the 
stack frame, but currently this is diffcult as everything happens in 
interrupts disabled context on the host.

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