[Qemu-devel] [PATCH 0/4] Add ignore-external migration capability

[Yury Kotov]

Hi,

The series adds migration capability which allows to skip 'external' RAM blocks
during migration. External block is a RAMBlock which available from the outside
of current QEMU process (e.g. file in /dev/shm). It's useful for fast local
migration to update QEMU for the running guests.

Patches:
1. Add offset validation to make sure that external RAM block has the same
   physical offset on target side,
2. Add RAM_EXTERNAL flag to determine external RAM blocks,
3. Add ignore-external migration capability,
4. Add a test.

Usage example:
1. Start source VM:
   qemu-system-x86 \
     -m 4G \
     -object 
memory-backend-file,id=mem0,size=4G,share=on,mem-path=/dev/shm/mem0 \
     -numa node,memdev=mem0 \
     -qmp unix:/tmp/qemu-qmp-1.sock,server,nowait \

2. Start target VM:
   qemu-system-x86 \
     -m 4G \
     -object 
memory-backend-file,id=mem0,size=4G,share=on,mem-path=/dev/shm/mem0 \
     -numa node,memdev=mem0 \
     -qmp unix:/tmp/qemu-qmp-2.sock,server,nowait \
     -incoming defer

3. Enable ignore-external capability on both VMs:
   { "execute": "migrate-set-capabilities" , "arguments":
     { "capabilities": [ { "capability": "x-ignore-external", "state": true } ] 
} }

4. Start migration.

Regards,
Yury

Yury Kotov (4):
  migration: add RAMBlock's offset validation
  exec: add RAM_EXTERNAL flag to mark non-QEMU allocated blocks
  migration: introduce ignore-external capability
  tests/migration-test: Add a test for ignore-external capability

 backends/hostmem-file.c   |   3 +-
 exec.c                    |   7 ++-
 include/exec/cpu-common.h |   1 +
 include/exec/memory.h     |   3 ++
 migration/migration.c     |   9 ++++
 migration/migration.h     |   1 +
 migration/ram.c           |  52 ++++++++++++++++--
 numa.c                    |   4 +-
 qapi/migration.json       |   6 ++-
 tests/migration-test.c    | 109 +++++++++++++++++++++++++++++++-------
 10 files changed, 165 insertions(+), 30 deletions(-)

-- 
2.20.1