From mboxrd@z Thu Jan  1 00:00:00 1970
From: Juergen Gross <jgross@suse.com>
Subject: Re: [PATCH v3 01/15] xen: add xenstore domain flag to
	hypervisor
Date: Fri, 8 Jan 2016 15:22:07 +0100
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To: Jan Beulich <JBeulich@suse.com>
Cc: Tim Deegan <tim@xen.org>, wei.liu2@citrix.com, Ian.Campbell@citrix.com, stefano.stabellini@eu.citrix.com, Andrew Cooper <andrew.cooper3@citrix.com>, ian.jackson@eu.citrix.com, xen-devel@lists.xen.org, David Vrabel <david.vrabel@citrix.com>, Keir Fraser <keir@xen.org>, dgdegra@tycho.nsa.gov
List-Id: xen-devel@lists.xenproject.org

On 08/01/16 15:07, Jan Beulich wrote:
>>>> On 08.01.16 at 14:08, <JGross@suse.com> wrote:
>> --- a/xen/common/domain.c
>> +++ b/xen/common/domain.c
>> @@ -318,6 +318,12 @@ struct domain *domain_create(domid_t domid, unsigned int domcr_flags,
>>          hardware_domain = d;
>>      }
>>  
>> +    if ( domcr_flags & DOMCRF_xs_domain )
>> +    {
>> +        d->is_xenstore = 1;
>> +        d->disable_migrate = 1;
>> +    }
> 
> It only occurred to me now: Wouldn't it be worth denying the domain
> creation request if there already is a xenstore domain?

Hmm, the only cases where this would make sense would be:

- some bug in dom0 resulting in parallel calls of init-xenstore-domain
- an out-of-tree tool in dom0 (or another domain capable of creating
  domains) creating a domain with the xenstore flag set

I'm really not sure what would be best here. Should the hypervisor
really be responsible for this decision?

In case it is desired, I can modify the patch accordingly (the
modification would be trivial).


Juergen