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

[Aravind Gopalakrishnan <aravind.gopalakrishnan@xxxxxxx>]

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.

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