From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v3] xen: fix reboot/shutdown with running
 HVM guests
Date: Thu, 5 Jun 2014 16:46:37 +0100
Message-ID: <539090DD.2040700@citrix.com>
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To: Roger Pau Monne <roger.pau@citrix.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Keir Fraser <keir@xen.org>, Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>, Eddie Dong <eddie.dong@intel.com>, Jan Beulich <jbeulich@suse.com>, Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>, Jun Nakajima <jun.nakajima@intel.com>, xen-devel@lists.xenproject.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>
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On 05/06/14 16:01, Roger Pau Monne wrote:
> If there's a guest using VMX/SVM when the hypervisor shuts down, it
> can lead to the following crash due to VMX/SVM functions being called
> after hvm_cpu_down has been called. In order to prevent that, check in
> {svm/vmx}_ctxt_switch_from that the cpu virtualization extensions are
> still enabled.
>
>

I feel that this is still trying to fix the problem from the wrong end. 
It is incorrect to be in a context switch at the point identified in the
stack trace.

How about having the hvm_cpu_down functions look at current, and
optionally run sync_exec_state() ?

~Andrew