lkml.org 
[lkml]   [2012]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [Xen-devel] [PATCH] xen-blkfront: set pages are FOREIGN_FRAME when sharing them
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 <stefano.stabellini@eu.citrix.com>
> ---
> 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], &copy[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


\
 
 \ /
  Last update: 2012-03-27 20:01    [W:0.065 / U:0.860 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site