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

[Anthony Liguori <anthony@codemonkey.ws>]

On 12/06/2010 09:16 AM, Avi Kivity wrote:
> On 12/06/2010 05:07 PM, Anthony Liguori wrote:
>>> 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)?
>
> No, right now we intercept SHUTDOWN (and turn it back, in qemu, into a 
> RESET), and we emulate all the SIPI stuff.  We also intercepted HLT so 
> we couldn't get that activity state either.

Ok, looks like I need to make this per-VM and use a CAP along with an 
interface to enable it to ensure that userspace to ensure it gets 
saved/restored appropriately.  I'll rework it.

Regards,

Anthony Liguori