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

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

Add Yang as the nested vmx owner.

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Tuesday, October 07, 2014 12:59 AM
> 
> >>> On 30.09.14 at 17:55, <groen692@xxxxxxxxx> wrote:
> > Recently I updated my openSuse box from 12.3 to 13.1. On this box I run
> > xen with several guests. One of these guests is an appliance that has 4
> > kvm guests running.
> > When I start this appliance with the nested vmx feature the appliance
> > crashes either immediately or after a few minutes.
> >
> > This same guest was running without a problem on opensuse releases 11.4
> > until 12.3
> >[...]
> > ==== outup xl demsg
> > (XEN) vvmx.c:2459:d5 Unknown nested vmexit reason 80000021.
> > (XEN) Failed vm entry (exit reason 0x80000021) caused by invalid guest
> > state (0).
> > (XEN) ************* VMCS Area **************
> >[...]
> 
> 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)?
> 
> Jan


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