WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] Re: scrubbing pages on vm pause

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: [Xen-devel] Re: scrubbing pages on vm pause
From: Joanna Rutkowska <joanna@xxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 25 May 2010 16:19:48 +0200
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Rafal Wojtczuk <rafal@xxxxxxxxxxxxxxxxxxxxxx>
Delivery-date: Tue, 25 May 2010 07:17:29 -0700
Dkim-signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=messagingengine.com; h=message-id:date:from:mime-version:to:cc:subject:references:in-reply-to:content-type; s=smtpout; bh=kgLJO3whd9V6gF6EYC/vi3X3PZU=; b=BPX90teUWD5lSb0ZkFeYPsck3OBBAunbyiXNXqMPIo8iQFjCq0mZzrzMAB6qzqsizdk5CTOFaO2COEh5wpaPWF2tSTUbf+sTFXtIO3fmqG9A1VV2bAUM+yCF06rOahaIYramMDe2fB90DqQX4omc0tcQzXuJZroPEGJ0leVIX0s=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C821999F.15423%keir.fraser@xxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <C821999F.15423%keir.fraser@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Lightning/1.0b2pre Thunderbird/3.0.4
On 05/25/2010 04:13 PM, Keir Fraser wrote:
> On 25/05/2010 15:12, "Joanna Rutkowska" <joanna@xxxxxxxxxxxxxxxxxxxxxx>
> wrote:
> 
>>> New domains are not guaranteed to receive zeroed memory. The only guarantee
>>> Xen provides is that when it frees memory for a *dead* domain, it will scrub
>>> the contents before reallocation (it may not write zeroes however, in a
>>> debug build of Xen for example!). Other memory pages the domain freeing the
>>> pages must scrub them itself before freeing them back to Xen.
>>>
>>
>> And what happens when we pause and save a domain? Are the pages zero-out
>> by xen in that case?
> 
> If the original domain is subsequently destroyed then yes, Xen zeroes the
> pages.
> 

Let's consider this scenario:

xm save domain1

xm create domain2

Can the domain2 get *unscrubbed* pages that were previously used by
domain1, but were not scrubbed properly by domain1?

j.

Attachment: signature.asc
Description: OpenPGP digital signature

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel