Re: [Xen-devel] [RFC Patch v2 45/45] x86/hvm: Always set pending event injection when loading VMC[BS] state.

[Wen Congyang <wency@xxxxxxxxxxxxxx>]

At 08/28/2014 04:54 PM, Andrew Cooper Write:
> On 28/08/14 02:04, Wen Congyang wrote:
>> At 08/27/2014 10:58 PM, Aravind Gopalakrishnan Write:
>>> On 8/26/2014 7:46 PM, Wen Congyang wrote:
>>>> At 08/27/2014 12:02 AM, Jan Beulich Write:
>>>>>>>> On 08.08.14 at 09:01, <wency@xxxxxxxxxxxxxx> wrote:
>>>>>> In colo mode, secondary vm is running, so VM_ENTRY_INTR_INFO may
>>>>>> valid before restoring vmcs. If there is no pending event after
>>>>>> restoring vm, we should clear it.
>>>>>>
>>>>>> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
>>>>>>
>>>>>> Also clear pending software exceptions.
>>>>>> Copy the fix to SVM as well.
>>>>>>
>>>>>> Signed-off-by: Tim Deegan <tim@xxxxxxx>
>>>>> I only now realized that it's no surprise we're not getting acks from
>>>>> the VMX maintainers on this - the majority of them wasn't Cc-ed.
>>>>> Now done, but please take care to do so yourself in the future.
>>>>>
>>>>> As to the SVM maintainers - Ping (I Cc-ed you on an earlier reply)?
>>>> Thanks for doing this.
>>>> I have repost it in the bugfix patchset, and cc vmx and svm maintainers
>>>>
>>> Hi,
>>> Apologies for the delay.
>>>
>>> As for the svm changes, the patch seems fairly straightforward and harmless.
>>> However, I am not familiar with 'colo mode', so I'm not sure I understand 
>>> the problem..
>> In colo mode, secondary vm runs like this:
>> 1. suspend
>> 2. update the vm's state(All state is transfered from primary)
>> 3. resume
> 
> Is this accurate?  From previous review, I seem to remember that you are
> pausing the vm, not suspending it, which is where all of these event
> issues derive from.

Not pause. We suspend the guest(not save the state). Pausing vm meant that
the vm is not running, but the state cannot be updated. For example, if the
vm uses pvdriver(not supported now), the backend and frontend share some
information, and we only update frontend(backend state is not transfered
from primary dom0)...

Thanks
Wen Congyang

> 
> ~Andrew
> .
> 


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