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] Re: how to handle paged hypercall args?

To: Olaf Hering <olaf@xxxxxxxxx>
Subject: Re: [Xen-devel] Re: how to handle paged hypercall args?
From: Keir Fraser <keir@xxxxxxx>
Date: Wed, 17 Nov 2010 16:52:07 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Jan Beulich <JBeulich@xxxxxxxxxx>
Delivery-date: Wed, 17 Nov 2010 08:52:50 -0800
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:user-agent:date :subject:from:to:cc:message-id:thread-topic:thread-index:in-reply-to :mime-version:content-type:content-transfer-encoding; bh=0lAtTK8qZK5M+8d/Fy20qPiYfY01W46sOABSk+CDRWQ=; b=l/9JuhX1+W7FD7dD44+hBf9ACzF1yXngreoRy/fDhsvgUvLcT5g/5FAxn7tPCf+Bzf hhtCRs1OeFN9STDnVAUeypKW9jdblfvLtkc65C/7nR+mHWwmTtQ65438yrYiakTsNpiB O77X1UHxJdW2wszgKkaKmTJF6z1rIWZJ9648I=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:user-agent:date:subject:from:to:cc:message-id:thread-topic :thread-index:in-reply-to:mime-version:content-type :content-transfer-encoding; b=XLdsVHDSB6oyIBg9Z6FZwWZ/9JtSy2e+9X3XpD1sFk1z696+zpW8bZPPneioLk7f1z 5gXTsF0EC/Rogypw1XDrpVJD4Ac1gUnLjmr+wuTVn8DNGyzeJgsGYNRZFxM6IPDt83Nj fV5NmoKtmljZSoraNU5i5df+CMObg4ujgCQ/Y=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <20101115131219.GA10719@xxxxxxxxx>
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>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcuGd8S6wj5FFyIaQk24t8qYIZ3cEg==
Thread-topic: [Xen-devel] Re: how to handle paged hypercall args?
User-agent: Microsoft-Entourage/
On 15/11/2010 13:12, "Olaf Hering" <olaf@xxxxxxxxx> wrote:

> On Fri, Nov 12, Keir Fraser wrote:
>> On 12/11/2010 10:47, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
>>> Sounds good, and you helping with this will be much appreciated
>>> (Olaf - unless you had plans doing this yourself). Whether it's going
>>> to be widely used I can't tell immediately - for the moment,
>>> overcoming the paging problems seems like the only application.
>> Yeah, I'll get on this.
> Sorry for being late here.
> I'm glad you volunteer for this task.

The basis of what you need is checked in as xen-unstable:22396. You can
include <xen/wait.h> and you get an interface like a very simplified version
of Linux waitqueues. There are still some details to be worked out but it
basically works as-is and you can start using it now.

The one big cleanup/audit we will need is that all callers of __hvm_copy()
(which ends up being all HVM guest callers of the copy_to/from_guest*
macros) must not hold any locks. This is because you are going to modify
__hvm_copy() such that it may sleep. Probably you should
ASSERT(!in_atomic()) at the top of __hvm_copy(), and go from there. :-)

 -- Keir

> Olaf

Xen-devel mailing list