[PATCH 0 of 2] Paging support updates for XCP dom0

[Andres Lagar-Cavilla <andres@lagarcavilla.org>]

This is a cherry pick of two patches that add support for guest paged out
frames in the XCP 2.6.32 dom0 patch queue.

First patch propagates the ENOENT returned by the hypervisor in the case
of a paged out page, all the way up the call chain to the MMAPBATCH_V2
ioctl. The ioctl is mainly used to harvest those return values and retry.

The second patch adds retry loops to all backend grant operations (map and
netback copy), in the case of a paged out frame.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Patrick Colp <pjcolp@cs.ubc.ca>
Acked-by: Andres Lagar-Cavilla <andres@lagarcavilla>
Ported and submitted by Andres Lagar-Cavilla

 arch/x86/mm/ioremap-xen.c                  |  12 ++----
 drivers/xen/blkback/blkback.c              |   6 ++-
 drivers/xen/blkback/interface.c            |   9 +++-
 drivers/xen/core/gnttab.c                  |   4 +-
 drivers/xen/gntdev/gntdev.c                |  49 +++++++++++++++++------------
 drivers/xen/netback/interface.c            |   5 +-
 drivers/xen/netback/netback.c              |  16 ++++++---
 drivers/xen/scsiback/interface.c           |  10 +++---
 drivers/xen/scsiback/scsiback.c            |   4 +-
 drivers/xen/tpmback/interface.c            |   7 +--
 drivers/xen/tpmback/tpmback.c              |  20 ++++-------
 drivers/xen/usbback/interface.c            |  16 ++++----
 drivers/xen/usbback/usbback.c              |   4 +-
 drivers/xen/xenbus/xenbus_backend_client.c |  10 +++---
 include/xen/gnttab.h                       |  37 ++++++++++++++++++++++
 15 files changed, 130 insertions(+), 79 deletions(-)