Re: [Xen-devel] [PATCH v3] xen: fix reboot/shutdown with running HVM guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.06.14 at 17:46, <andrew.cooper3@xxxxxxxxxx> wrote:
> 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() ?

I considered this too before suggesting the other alternative,
but why would getting into the context switch path this way
be any better than through map_domain_page()?

Jan


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