Re: [RFC Patch v3 18/18] x86/hvm: Always set pending event injection when loading VMC[BS] state.

[Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>]

On 9/17/14 2:56 AM, Wen Congyang wrote:
> On 09/11/2014 06:35 PM, Tim Deegan wrote:
>> At 10:06 -0500 on 10 Sep (1410340016), Aravind Gopalakrishnan wrote:
>>> Hi,
>>> You mention that this 'fix' is just copied for svm. But you have not
>>> seen the problem of "VM_ENTRY_INTR_INFO may be valid" (whose svm
>>> equivalent is "vmcb->eventinj.bytes is valid").
>>> My concern is that we should test colo mode for svm first, since, if the
>>> problem is never really seen on svm, then fix may not be _necessary_
>> I think it's obvious by inspection of the code (and indeed the patch)
>> that SVM has the equivalent bug.
>>
>>> At this point, my problems are with test setups. I can help testing
>>> scenarios, but as Wen had mentioned, 'colo testing' might be the way to
>>> test.
>>> So, if I can get some pointers to how I can reproduce the issue at hand,
>>> then it would be very helpful.
>>>
>>> (Tim had mentioned we could try to simulate it by running a guest that
>>> takes lot of faults and save-restore another guest over it. However,
>>> I am not having much luck following this route. I got a hvm guest to
>>> continuously take SW exceptions on all vcpus and tried to save-restore.
>>> I can't see vmcb->eventinj.bytes containing any valid info.)
>> Although I think that getting COLO running on SVM is a gret idea, it
>> shouldn't block acceptance of this fix.  I've attached a program
>> that tests for the bug.  Run it against any HVM guest (and then
>> destroy the guest because the test will have corrupted its state).
> Hi, Aravind Gopalakrishnan
>
> Do you have time to test this patch with the test program?
>
Thanks for the test program Tim.
I tested it on a HVM guest and test prints 'good' w/ the patch applied 
and 'bad' w/o the patch.

Thanks,
-Aravind.