The workflow to make a snapshot is the following:
1. Pause the vm
2. Make a snapshot of block devices using the scheme of your choice
3. Turn on background-snapshot migration capability
4. Start the migration using the destination (migration stream) of your choice.
The migration will resume the vm execution by itself
when it has the devices' states saved and is ready to start ram writing
to the migration stream.
5. Listen to the migration finish event
The bakground snapshot works with support of KVM patch:
"x86: mmu: report failed memory access to the userspace"
(not applied to the mainstream, it's in the kvm mailing list)
--
Change log:
v0 => v1:
============
the patch series has been split in smaller chunks
Denis Plotnikov (17):
migration: add background snapshot capability
bitops: add some atomic versions of bitmap operations
threads: add infrastructure to process sigsegv
background snapshot: make a dedicated type for ram block list
ram: extend the data structures for background snapshotting
background snapshot: add helpers to manage a copy of ram block list
background snapshot: introduce page buffer
migration: add helpers to change VM memory protection rights
background snapshot: extend RAM request for holding a page copy
pointer
background snapshots: adapt the page queueing code for using page
copies
background snapshot: add a memory page copying function
ram: add background snapshot support in ram page saving part of
migration
background snapshot: add write-protected page access handler function
kvm: add failed memeory access exit reason
kvm: add vCPU failed memeory access processing
migration: move the device state saving logic to a separate function
background snapshot: enable background snapshot
include/exec/ram_addr.h | 7 +
include/exec/ramlist.h | 4 +-
include/qemu/bitops.h | 25 +++
include/qemu/thread.h | 5 +
linux-headers/linux/kvm.h | 5 +
migration/migration.c | 140 +++++++++++++-
migration/migration.h | 1 +
migration/ram.c | 374 ++++++++++++++++++++++++++++++++++++--
migration/ram.h | 17 +-
migration/savevm.c | 91 +++++-----
migration/savevm.h | 2 +
qapi/migration.json | 6 +-
target/i386/kvm.c | 17 ++
util/qemu-thread-posix.c | 52 ++++++
14 files changed, 684 insertions(+), 62 deletions(-)
--
2.17.0
