From mboxrd@z Thu Jan 1 00:00:00 1970 From: annie li Subject: Re: Rebooting domu fails in nfs share exported from another domu on the same dom0 Date: Tue, 22 Jul 2014 21:58:17 -0400 Message-ID: <53CF16B9.1070204@oracle.com> References: <20140718185312.GE15947@laptop.dumpdata.com> <53C9761F.3040803@oracle.com> <20140718194334.GK15947@laptop.dumpdata.com> <53C980BE.5040208@oracle.com> <20140718202215.GC14318@konrad-lan.dumpdata.com> <53C98411.6020404@oracle.com> <20140718210730.GB32582@laptop.dumpdata.com> <53C994FB.80705@oracle.com> <20140721100227.GA1040@zion.uk.xensource.com> <53CD2B9E.60706@oracle.com> <20140721230558.GA13229@zion.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140721230558.GA13229@zion.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Wei Liu Cc: "xen-devel@lists.xen.org" , =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= List-Id: xen-devel@lists.xenproject.org On 2014/7/21 19:05, Wei Liu wrote: > On Mon, Jul 21, 2014 at 11:02:54AM -0400, annie li wrote: > [...] >>>>> being the source it is the C guest (vm2)? Thought I don't know if >>>>> the hypercall allows us to make a grant_copy on behalf of two >>>>> other guests. >>>> Oh... I remember netback did have some grant_copy code on behalf of two >>>> guests on same server, and it was removed later on. So I think grantcopy >>>> A->C works for this case with the precondition that we can recognize this >>>> page is mapped from another guest. >>>> >>> I have not followed this thread closely. >>> >>> The tracking facility was removed because it was dead at that time. See >>> 43e9d19 ("xen-netback: remove page tracking facility"). >>> >>> However I think the latest netback with mapping scheme does have >>> something similar. I can see there's a "foreign_queue" check in >>> xenvif_gop_frag_copy. Is that not enough? >> Correct, this mapping scheme does similar thing, but it is for communication >> between two vifs on the same server, the original page is mapped by netback >> tx path. Here, this issue is caused when the page mapped by blkback. >> > I see. > >> What I am thinking is: checking whether the page is mapped, if yes, then >> does grant copy from source to dest directly instead of Dom0->dest since a >> condition check fails in mm.c if the original page is from another vm for >> situation Dom0->dist . >> > The foreign frame is marked with FOREIGN_FRAME_BIT in p2m code so you > can probably make use of that? However gref is not embedded in struct > page. Yes, no gref. Let me look at xen grant table code to see whether there is a way to get gref for specific page. Thanks Annie