RE: Academic Project

[Mats Petersson <mats@planetcatfish.com>]

I'm absolutely not sure I follow what you are trying to do, but if 
what you want to do is "hide" a device in a particular domain, and 
give the memory "behind" that device to the domain, then that is not 
likely to work. You can only "get to" memory hidden behind a PCI 
device if you can turn the PCI device off. Turning the device off is 
of course a valid option if the device is not needed at all by the 
system. If it is needed, then you have no option but to leave it 
enabled, and the physical memory behind the device will be hidden by 
the PCI device.

There are certain memory controller chipsets (e.g. the memory 
controller integrated into the Athlon64/Opteron/etc models after Rev 
E or so) that have "hidden memory hoisting", which essentially means 
that you can tell the memory controller that "take the memory behind 
the PCI device in this range, and move it up a bit", which means that 
if you have (say) 4GB of RAM, and a PCI bus hole of 768MB, the system 
will appear to have memory from 0-3.25GB, then PCI devices for 
0.75GB, and then another 0.75GB of RAM.

--
Mats

At 19:54 03/03/2009, dinesh chandrasekaran wrote:
>Can some one tell me how to go about achieving this.
>
>How to allocate real memory (which is behind a PCI device) to guests?
>I need to modify Xen source to achieve the above.
>where exactly in the source I should do so?
>
>Thanks,
>Dinesh C
>
>----------
>From: dinesh_chan8@hotmail.com
>To: xen-devel@lists.xensource.com
>Subject: [Xen-devel] Academic Project
>Date: Mon, 23 Feb 2009 22:11:53 +0530
>
>
>Absolutly. This could be achieved through xen hooks which informs 
>the device about the currently scheduled domain.
>This would prevent the guest memory from compromised dom0.
>
>Dinesh C
>
>----------
>Date: Mon, 23 Feb 2009 11:16:22 -0500
>Subject: Re: [Xen-devel] Academic Project
>From: zephyr.zhao@gmail.com
>To: dinesh_chan8@hotmail.com
>
>One more thing is that the device should be able to tell if the 
>access is from the owner of protected domain or from others (like 
>dom0). If the dom0 is compromised, it may mimic the request from that domU.
>
>Weiming
>
>On Mon, Feb 23, 2009 at 11:07 AM, dinesh chandrasekaran 
><<mailto:dinesh_chan8@hotmail.com>dinesh_chan8@hotmail.com> wrote:
>Yes. It will appear to be another PCI device sitting between the CPU 
>and guest memory.
>
>To achieve this I need to make sure that xen allocates guest memory 
>from memory behind the crypto coprocessor.
>This is the implementation issue I need to solve to get the project going.
>
>
>I did try modifying common/memory.c : populate_physmap(), but I am 
>afraid this is not the right place.
>Since I have allocate real memory to domU, I am clueless.
>
>Thanks,
>Dinesh C
>
>----------
>Date: Mon, 23 Feb 2009 10:44:34 -0500
>
>Subject: Re: [Xen-devel] Academic Project
>From: <mailto:zephyr.zhao@gmail.com>zephyr.zhao@gmail.com
>
>To: <mailto:dinesh_chan8@hotmail.com>dinesh_chan8@hotmail.com
>CC: <mailto:xen-devel@lists.xensource.com>xen-devel@lists.xensource.com
>
>
>I'm curious about the crypto coprocessor. Does it work like a memory 
>controller? So every memory read/write will be encrypted/decrypted by it?
>
>Thanks,
>Weiming
>
>On Mon, Feb 23, 2009 at 10:31 AM, dinesh chandrasekaran 
><<mailto:dinesh_chan8@hotmail.com>dinesh_chan8@hotmail.com> wrote:
>
>
>
>----------
>From: <mailto:dinesh_chan8@hotmail.com>dinesh_chan8@hotmail.com
>To: <mailto:michal@rsbac.org>michal@rsbac.org
>Subject: RE: [Xen-devel] Academic Project
>Date: Mon, 23 Feb 2009 00:46:01 +0530
>
>Essentially, first step towards minimizing the trusted computing base.
>
>Assuming the VMM is not compromised (after a secure boot), domU 
>doesnt have to trust dom0.
>
>For example, the following command issued from dom0 would dump the 
>guest memory in dom0 hard disk,
>                      xm save Guest guest_mem.dump
>
>Using the crypto coprocessor, this can be encrypted, so that only 
>domU can read/write and not dom0.
>The result of the above command will store an encrypted dump file on 
>the dom0 disk.
>
>Thanks,
>Dinesh C
>
>----------
>From: <mailto:michal@rsbac.org>michal@rsbac.org
>To: <mailto:dinesh_chan8@hotmail.com>dinesh_chan8@hotmail.com
>Subject: Re: [Xen-devel] Academic Project
>Date: Sun, 22 Feb 2009 19:31:32 +0100
>
>And what is the purpose of this?
>Seems to be trivial to get over it.
>
>Sent from my iPhone
>
>On Feb 22, 2009, at 6:19 PM, dinesh chandrasekaran 
><<mailto:dinesh_chan8@hotmail.com>dinesh_chan8@hotmail.com> wrote:
>
>Hi Folks,
>                I'm developing a secure memory manager module for 
> xen as a part of my academic project.
>  Thereby protecting DomU memory by moving the trust for memory 
> protection from Dom0 to hardware by encrypting/
>  decrypting the guest memory on per-domain-secret key basis and 
> realizing the same using a crypto coprocessor (FPGA)
>  with necessary software (XEN) hooks and interfaces.
>
>  Now one of the implementation issues is that how to move the domU 
> memory allocation (both boot pages and application pages)
>  to fall behind the coprocessor by modifying xen source. If so 
> where in the source tree the changes have to be made.
>
>  I did try modifying common/memory.c : populate_physmap(), but I am 
> afraid this is not the right place.
>  Since I have allocate real memory to domU, I am clueless.
>
>  I would appreciate you If you could send me your valuable suggestions.
>
>Thanks,
>Dinesh C
>
>
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