Re: [Xen-users] Xen Memory Management

[David Alston <dalston@xxxxxxxxxxxx>]

Greetings!

     I've been looking all over and haven't found a way to get at DomU memory 
from Dom0 without hacking some of the drivers..

WARNING: These links are dated 2008, so the ideas may not be valid anymore.

Slideshow
http://invisiblethingslab.com/resources/bh08/part1.pdf

Addendum
http://theinvisiblethings.blogspot.com/2008/08/attacking-xen-domu-vs-dom0.html


     The best methods for communicating Dom0<->DomU seem to revolve around 
using the xen-store.

     So to answer your questions (as well as I can)..

> Does the Dom0 have direct access to these memory spaces or does it just issue 
> hypercalls to do the memory management?
Probably the latter.


> Does the Dom0 know about the memory mapping or just the Xen hypervisor?
Probably just the hypervisor


     Now someone who understands Xen better than I do can jump in and correct 
anything I might have said incorrectly :^)


David Alston
Nearband Networks
Senior Systems Administrator

dalston@xxxxxxxxxxxx
O: 972.881.1090
M: 469.939.4403



On Fri, 2 Dec 2011, Jason Thomas wrote:

> I understand that for HVM guests the Xen hypervisor creates shadow pages to
> monitor each guest's memory usage. Does the Dom0 have direct access to
> these memory spaces or does it just issue hypercalls to do the memory
> management? Does the Dom0 know about the memory mapping or just the Xen
> hypervisor? For example, Dom0 must have the ability to copy these pages for
> guest relocation, but does it do this copying of memory space through the
> Xen VMM (hypercalls) or is there any direct access by the Dom0?
>
> Jason
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