Re: [Xen-devel] Xen memory management

To:	Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Subject:	Re: [Xen-devel] Xen memory management
From:	David Xu <davidxu06@xxxxxxxxx>
Date:	Thu, 23 Jun 2011 18:08:13 -0400
Cc:	xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thanks. My concern is that if several VMs are mapped to same memory, one VM may get something from the memory which has ever been used by another VM. This may cause some secure problems.

Regards,

Cong

2011/6/23 Tim Deegan <Tim.Deegan@xxxxxxxxxx>

Hi David,

At 18:59 -0400 on 22 Jun (1308769177), David Xu wrote:
> Is there anybody who has some experience at memory management of Xen? I just
> want to know whether Xen hypervisor will map memory from different VMs to
> the same physical memory address

Yes; see page-sharing, grant tables, privileged foreign mappings &c.

>, which is insecure.

Not if you do it right. :) What exactly is your concern?

Tim.

--
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)

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Re: [Xen-devel] Xen memory management