[Qemu-devel] [PATCH 0/2][RFC] postcopy migration: Linux char device for postcopy

[Isaku Yamahata <yamahata@valinux.co.jp>]

This is Linux kernel driver for qemu/kvm postcopy live migration.
This is used by qemu/kvm postcopy live migration patch.

TODO:
- Consider FUSE/CUSE option
  So far several mmap patches for FUSE/CUSE are floating around. (their
  purpose isn't different from our purpose, though). They haven't merged
  into the upstream yet.
  The driver specific part in qemu patches is modularized. So I expect it
  wouldn't be difficult to switch kernel driver to CUSE based driver.

ioctl commands:

UMEM_DEV_CRATE_UMEM: create umem device for qemu
UMEM_DEV_LIST: list created umem devices
UMEM_DEV_REATTACH: re-attach the created umem device
		  UMEM_DEV_LIST and UMEM_DEV_REATTACH are used when
		  the process that services page fault disappears or get stack.
		  Then, administrator can list the umem devices and unblock
		  the process which is waiting for page.

UMEM_GET_PAGE_REQUEST: retrieve page fault of qemu process
UMEM_MARK_PAGE_CACHED: mark the specified pages pulled from the source
                       for daemon

UMEM_MAKE_VMA_ANONYMOUS: make the specified vma in the qemu process
			 This is _NOT_ implemented yet.
                         anonymous I'm not sure whether this can be implemented
                         or not.


---
Changes version 1 -> 2:
- make ioctl structures padded to align
- un-KVM
  KVM_VMEM -> UMEM
- dropped some ioctl commands as Avi requested

Isaku Yamahata (2):
  export necessary symbols
  umem: chardevice for kvm postcopy

 drivers/char/Kconfig  |    9 +
 drivers/char/Makefile |    1 +
 drivers/char/umem.c   |  898 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/umem.h  |   83 +++++
 mm/memcontrol.c       |    1 +
 mm/shmem.c            |    1 +
 6 files changed, 993 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/umem.c
 create mode 100644 include/linux/umem.h