Re: Crash of guest with nested vmx with Unknown nested vmexit reason 80000021.

[Jeroen Groenewegen van der Weyden <groen692@grosc.com>]

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@intel.com> 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@suse.com]
>>>>> 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)?
>
>