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] Is exposing shared_info to user-land secure?

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Is exposing shared_info to user-land secure?
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Fri, 01 Aug 2008 13:35:23 -0700
Cc: "dan.magenheimer@xxxxxxxxxx" <dan.magenheimer@xxxxxxxxxx>, "Xen-Devel \(E-mail\)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Fri, 01 Aug 2008 13:35:49 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C4B90575.1BBE5%keir.fraser@xxxxxxxxxxxxx>
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <C4B90575.1BBE5%keir.fraser@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird (X11/20080501)
Keir Fraser wrote:
I think it might be okay. One issue is that how to let the user-space
process know what vcpu it is running on, so it can use the correct timestamp
info in a way that is safe against preemption. Bear in mind that the user
address space may be shared by multiple concurrent threads on different
VCPUs! If you assume consistent-tsc across all CPUs then the task is easier,
but I don't think we'll want to bake that assumption into guest kernels and
their interface to user processes.

x86-64 already exports the current cpu and nodeid in the limit of a gdt entry, so you can fetch it from userspace with lsl.


Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>