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/
Home Products Support Community News


Re: [Xen-devel] [PATCH] [HVM] Patches to make HVM capable of running OS/

To: Trolle Selander <trolle.selander@xxxxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] [HVM] Patches to make HVM capable of running OS/2.
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Fri, 16 Mar 2007 19:07:58 +0000
Cc: Mats.Petersson@xxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, thomas.woller@xxxxxxx
Delivery-date: Fri, 16 Mar 2007 12:07:15 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <515922b50703161122v4fd3df38v3b92dfd426f5db29@xxxxxxxxxxxxxx>
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/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acdn/mi+p4EwGNPxEduhtwAX8io7RQ==
Thread-topic: [Xen-devel] [PATCH] [HVM] Patches to make HVM capable of running OS/2.
User-agent: Microsoft-Entourage/
Possibly, but I think that allocating, registering and tracking the pages if they were owned by dom0 would be harder. I don;t have a clear idea how we’d do it without changes to the dom0 kernel.

Meanwhile, domUs have plenty of other shared-memory protocols with dom0 kernel and root processes. It just needs some care to make sure the interface is sufficiently narrow and arguments are well checked. Burning 100% CPU is not considered a successful attack (although it would of course be annoying!). You can detect it and fix it up without rebooting the system, for example.

Anyway, I didn’t take your e801 patch, but checked in my own fix as changeset 14415. It should hit the main public tree in a few hours, or you can see it in the staging tree sooner (http://xenbits.xensource.com/staging/xen-unstable.hg).

All your other patches are in except the smsw one. I’m looking at that now.

 -- Keir

On 16/3/07 18:22, "Trolle Selander" <trolle.selander@xxxxxxxxx> wrote:

Keeping them out of the guest's way is good enough for my current practical concerns, and this was the path my patch took, after all.
For the record, though, I do think that the most correct thing would be to have the iopage & buffered_iopages owned by dom0, since they don't "belong" to the domU anymore than any other data structure used by the qemu-dm process.
In fact, one could argue that domU access to these pages could be a theoretical way for a compromised domU to attack a process running as root in dom0. From what I've seen, the worst that can practically be done at the moment is making qemu-dm lock up while eating 100% cpu (by setting the buffered_iopage->read_pointer > buffered_iopage->read_pointer) but more evil minds than mine might be able to figure out a way to exploit this in a worse way.

Xen-devel mailing list