Re: [PATCH] kvm-vmx: add module parameter to avoid trapping HLT instructions (v2)

[Anthony Liguori <anthony@codemonkey.ws>]

On 12/06/2010 08:33 AM, Avi Kivity wrote:
> On 12/06/2010 04:03 PM, Anthony Liguori wrote:
>>> It does.  Good, it simplifies the patch.
>>
>>
>> Any ideas if the unit test framework can be used to validate this?  
>> The behavior makes perfect sense but I wanted an excuse to play 
>> around with it :-)
>>
>
> Not the user space one.  The exit we're interested in is external 
> interrupt, and that one isn't delivered to userspace.
>
> I guess you could have a loop
>
>  1:  hlt
>       jmp 1b
>
> and enter it programming a timer to something close, and examine the 
> vcpu state afterwards.  However you don't propagate the VMCS halted 
> state to the corresponding kvm state, so there's no way to test it. (a 
> minor bug in your patch)

The activity state doesn't get propagated at all to the kvm state.  Can 
we get into a non-zero activity state today (either SHUTDOWN or WAIT_SIPI)?

Regards,

Anthony Liguori

>> Not sure if there's a way to validate VMCS state after a hand crafted 
>> exit.
>>
>
> KVM_GET_REGS and friends.
>
>
>