From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: question on iommu _map_page Date: Thu, 27 May 2010 21:46:04 +0100 Message-ID: References: <285BD4A3-D6E2-422C-94B7-436822845BBC@rice.edu> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <285BD4A3-D6E2-422C-94B7-436822845BBC@rice.edu> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Kaushik Kumar Ram , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org It looks like the person who implemented that never needed the read-only case. We need a function to map pages into the iommu read-only and to call that from the grant code. A patch to just call iommu_map_page() for any kind of grant mapping would be acceptable for now, if you want to submit a patch. -- Keir On 27/05/2010 21:37, "Kaushik Kumar Ram" wrote: > Hi all, > > I am trying to use the VT-d support with a PV driver domain which performs > network I/O on behalf of guest domains. > When I initiate any network I/O it results in I/O page faults. On taking a > closer look I find that iommu_map_page() is called only for writable pages > from __gnttab_map_grant_ref(). This results in page faults during packet > transmission since pages are mapped read-only in this case. > When I remove this restriction, I can get it working without any page faults. > > Is this a bug? or am I missing something here? I am using the latest unstable > version of Xen. This part of the source code hasn't changed in a long time. > > Thanks! > -Kaushik > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel