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RE: [Xen-devel] Academic Project

To: dinesh chandrasekaran <dinesh_chan8@xxxxxxxxxxx>, xen developers community <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Academic Project
From: Mats Petersson <mats@xxxxxxxxxxxxxxxxx>
Date: Tue, 03 Mar 2009 20:17:36 +0000
Cc:
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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@xxxxxxxxxxx
To: xen-devel@xxxxxxxxxxxxxxxxxxx
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@xxxxxxxxx
To: dinesh_chan8@xxxxxxxxxxx

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@xxxxxxxxxxx>dinesh_chan8@xxxxxxxxxxx> 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@xxxxxxxxx>zephyr.zhao@xxxxxxxxx

To: <mailto:dinesh_chan8@xxxxxxxxxxx>dinesh_chan8@xxxxxxxxxxx
CC: <mailto:xen-devel@xxxxxxxxxxxxxxxxxxx>xen-devel@xxxxxxxxxxxxxxxxxxx


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@xxxxxxxxxxx>dinesh_chan8@xxxxxxxxxxx> wrote:



----------
From: <mailto:dinesh_chan8@xxxxxxxxxxx>dinesh_chan8@xxxxxxxxxxx
To: <mailto:michal@xxxxxxxxx>michal@xxxxxxxxx
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@xxxxxxxxx>michal@xxxxxxxxx
To: <mailto:dinesh_chan8@xxxxxxxxxxx>dinesh_chan8@xxxxxxxxxxx
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@xxxxxxxxxxx>dinesh_chan8@xxxxxxxxxxx> 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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