From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Handling CPU unplug failure
Date: Thu, 4 Feb 2016 11:59:54 -0500
Message-ID: <56B3838A.5060203@oracle.com>
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While playing with CPU hotplug I noticed that if a guest fails to unplug 
a VCPU the toolstack will mark VCPU's availability in xenstore as 
"offline" even though that VCPU is still running in the guest.

It's easy to see this by doing 'xl vcpu-set <domid> 0', which is 
presumably not a realistic scenario but we can get into the same 
situation if, for example, the guest is configured without hotplug 
support or some operations during unplug fail.

Should we at least document this behavior (that 'availability' entry in 
xenstore is unreliable) somewhere?

-boris