From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755327Ab2C0R7H (ORCPT ); Tue, 27 Mar 2012 13:59:07 -0400 Received: from andromeda.dapyr.net ([206.212.254.10]:43885 "EHLO andromeda.dapyr.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754774Ab2C0R7B (ORCPT ); Tue, 27 Mar 2012 13:59:01 -0400 Date: Tue, 27 Mar 2012 13:58:43 -0400 From: Konrad Rzeszutek Wilk To: Stefano Stabellini Cc: konrad.wilk@oracle.com, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org Subject: Re: [Xen-devel] [PATCH] xen-blkfront: set pages are FOREIGN_FRAME when sharing them Message-ID: <20120327175843.GA4299@andromeda.dapyr.net> References: <1332856198-29770-1-git-send-email-stefano.stabellini@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1332856198-29770-1-git-send-email-stefano.stabellini@eu.citrix.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 27, 2012 at 02:49:58PM +0100, Stefano Stabellini wrote: > Set pages as FOREIGN_FRAME whenever blkfront shares them with another > domain. Then when blkfront un-share them, also removes the > FOREIGN_FRAME_BIT from the p2m. > > We do it so that when the source and the destination domain are the same > (blkfront connected to blkback in the same domain) we can more easily > recognize which ones are the source pfns and which ones are the > destination pfns (both are going to be pointing to the same mfns). > > Without this patch enstablishing a connection between blkfront and QEMU > qdisk in the same domain causes QEMU to hang and never return. > Considering that it fixes a serious bug, it should be backported to > previous releases. ERROR: "set_phys_to_machine" [drivers/block/xen-blkfront.ko] undefined! > Signed-off-by: Stefano Stabellini > --- > drivers/block/xen-blkfront.c | 30 +++++++++++++++++++++++++----- > 1 files changed, 25 insertions(+), 5 deletions(-) > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index 2f22874..e027aa7 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -262,7 +262,7 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode, > static int blkif_queue_request(struct request *req) > { > struct blkfront_info *info = req->rq_disk->private_data; > - unsigned long buffer_mfn; > + unsigned long buffer_mfn, buffer_pfn; > struct blkif_request *ring_req; > unsigned long id; > unsigned int fsect, lsect; > @@ -321,7 +321,8 @@ static int blkif_queue_request(struct request *req) > BLKIF_MAX_SEGMENTS_PER_REQUEST); > > for_each_sg(info->sg, sg, ring_req->u.rw.nr_segments, i) { > - buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg))); > + buffer_pfn = page_to_pfn(sg_page(sg)); > + buffer_mfn = pfn_to_mfn(buffer_pfn); > fsect = sg->offset >> 9; > lsect = fsect + (sg->length >> 9) - 1; > /* install a grant reference. */ > @@ -340,6 +341,16 @@ static int blkif_queue_request(struct request *req) > .gref = ref, > .first_sect = fsect, > .last_sect = lsect }; > + /* > + * Set the page as foreign, considering that we are giving > + * it to a foreign domain. > + * This is important in case the destination domain is > + * ourselves, so that we can more easily recognize the > + * source pfn from destination pfn, both mapping to the same > + * mfn. > + */ > + set_phys_to_machine(buffer_pfn, > + FOREIGN_FRAME(buffer_mfn)); > } > } > > @@ -715,8 +726,11 @@ static void blkif_completion(struct blk_shadow *s) > int i; > /* Do not let BLKIF_OP_DISCARD as nr_segment is in the same place > * flag. */ > - for (i = 0; i < s->req.u.rw.nr_segments; i++) > + for (i = 0; i < s->req.u.rw.nr_segments; i++) { > gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL); > + set_phys_to_machine(s->frame[i], > + get_phys_to_machine(s->frame[i]) & ~FOREIGN_FRAME_BIT); > + } > } > > static irqreturn_t blkif_interrupt(int irq, void *dev_id) > @@ -1051,13 +1065,19 @@ static int blkif_recover(struct blkfront_info *info) > memcpy(&info->shadow[req->u.rw.id], ©[i], sizeof(copy[i])); > > if (req->operation != BLKIF_OP_DISCARD) { > + unsigned long buffer_pfn; > + unsigned long buffer_mfn; > /* Rewrite any grant references invalidated by susp/resume. */ > - for (j = 0; j < req->u.rw.nr_segments; j++) > + for (j = 0; j < req->u.rw.nr_segments; j++) { > + buffer_pfn = info->shadow[req->u.rw.id].frame[j]; > + buffer_mfn = pfn_to_mfn(buffer_pfn); > gnttab_grant_foreign_access_ref( > req->u.rw.seg[j].gref, > info->xbdev->otherend_id, > - pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]), > + buffer_mfn, > rq_data_dir(info->shadow[req->u.rw.id].request)); > + set_phys_to_machine(buffer_pfn, FOREIGN_FRAME(buffer_mfn)); > + } > } > info->shadow[req->u.rw.id].req = *req; > > -- > 1.7.2.5 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel