From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Yu, Zhang" Subject: Re: One question about the hypercall to translate gfn to mfn. Date: Tue, 09 Dec 2014 18:37:17 +0800 Message-ID: <5486D0DD.1000902@linux.intel.com> References: <5486CAAF.9070807@linux.intel.com> <9AAE0902D5BC7E449B7C8E4E778ABCD02578573A@AMSPEX01CL01.citrite.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <9AAE0902D5BC7E449B7C8E4E778ABCD02578573A@AMSPEX01CL01.citrite.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Paul Durrant , "Keir (Xen.org)" , "Tim (Xen.org)" , "JBeulich@suse.com" , Kevin Tian , "Xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 12/9/2014 6:19 PM, Paul Durrant wrote: > I think use of an raw mfn value currently works only because dom0 is using a 1:1 IOMMU mapping scheme. Is my understanding correct, or do you really need raw mfn values? Thanks for your quick response, Paul. Well, not exactly for this case. :) In XenGT, our need to translate gfn to mfn is for GPU's page table, which contains the translation between graphic address and the memory address. This page table is maintained by GPU drivers, and our service domain need to have a method to translate the guest physical addresses written by the vGPU into host physical ones. We do not use IOMMU in XenGT and therefore this translation may not necessarily be a 1:1 mapping. B.R. Yu