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

Hi all,

Any input from my side necessary to keep this rolling?


Tian, Kevin schreef op 7-10-2014 om 21:56:
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

(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 (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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