Re: [Xen-devel] Crash of guest with nested vmx with Unknown nested vmexit reason 80000021.

[Jeroen Groenewegen van der Weyden <groen692@xxxxxxxxx>]

Hi,

Is there any test I can do on changed code?

mvg,
Jeroen.

Jan Beulich schreef op 16-10-2014 om 08:41:
> > > > On 16.10.14 at 08:18, <yang.z.zhang@xxxxxxxxx> wrote:
> > Sorry for the later reply. Yes, this is a known issue to me but I didn't
> > have time to cook a patch fix it. As Jan pointed out, the NMI handling logic
> > is wrong in current nested logic. But it is not a trivial task to fix them. I
> > will do it once I have the time or if you are interesting in it, a patch from
> > you is welcome.
> If you were to at least comment on the two possible routes I
> outlined (quoted below), I could see to get to this (considering
> that the issue - as you point out subsequently - got brought up
> more than half a year ago the first time, and is still unaddressed)
> at least if the vmx_idtv_reinject() related route would be a
> possible one.
>
> Jan
>
> > > > > From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> > > > > So the problem here is that
> > > > >
> > > > > > (XEN) Interruptibility=0008 ActivityState=0000
> > > > > VMX_INTR_SHADOW_NMI is set while
> > > > >
> > > > > > (XEN) PinBased=0000003f CPUBased=b6b9e5fa SecondaryExec=000004eb
> > > > > PIN_BASED_VIRTUAL_NMIS is active and
> > > > >
> > > > > > (XEN) VMEntry: intr_info=80000202 errcode=5d021101 ilen=00000003
> > > > > > (XEN) VMExit: intr_info=00000000 errcode=00000000 ilen=00000003
> > > > > > (XEN)         reason=80000021 qualification=00000000
> > > > > > (XEN) IDTVectoring: info=80000202 errcode=00000000
> > > > > an NMI is being injected. This case is explicitly mentioned in Vol
> > > > > 3 section 31.7.1.2 (Resuming Guest Software after Handling an
> > > > > Exception). Either there needs to be extra code in vvmx.c to clear
> > > > > VMX_INTR_SHADOW_NMI (as the second sub-bullet point of the last
> > > > > bullet point says), or the second half of vmx_idtv_reinject() needs
> > > > > to be done without regard to nestedhvm_vcpu_in_guestmode(v) (and
> > > > > maybe also without regard to EXIT_REASON_TASK_SWITCH).
> > > > >
> > > > > Speaking of SDM sections: There are quite a few references in the
> > > > > code that name just section numbers (in the case here, several
> > > > > references to sections 25.7.1.* exist). These numbers become stale
> > > > > quite quickly (here they're now 31.7.1.*), so in order to help
> > > > > digging through issues like the one here, can I please ask one of
> > > > > you to go through and replace (or at least amend) these numbers
> > > > > with the sections' titles (which I hope won't get altered that quickly)?

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