What? This patch series adds the live migration cpr-transfer mode, which allows the user to transfer a guest to a new QEMU instance on the same host. It is identical to cpr-exec in most respects, except as described below.
The new user-visible interfaces are: * cpr-transfer (MigMode migration parameter) * cpr-uri (migration parameter) * cpr-uri (command-line argument) In this mode, the user starts new QEMU on the same host as old QEMU, with the same arguments as old QEMU, plus the -incoming and the -cpr-uri options. The user issues the migrate command to old QEMU, which stops the VM, saves state to the migration channels, and enters the postmigrate state. Execution resumes in new QEMU. This mode requires a second migration channel, specified by the cpr-uri migration property on the outgoing side, and by the cpr-uri QEMU command-line option on the incoming side. The channel must be a type, such as unix socket, that supports SCM_RIGHTS. This series depends on the series "Live update: cpr-exec mode". Why? cpr-transfer offers the same benefits as cpr-exec mode, but with a model for launching new QEMU that may be more natural for some management packages. How? The file descriptors are kept open by sending them to new QEMU via the cpr-uri, which must support SCM_RIGHTS. Example: In this example, we simply restart the same version of QEMU, but in a real scenario one would use a new QEMU binary path in terminal 2. Terminal 1: start old QEMU # qemu-kvm -monitor stdio -object memory-backend-file,id=ram0,size=4G,mem-path=/dev/shm/ram0,share=on -m 4G -machine anon-alloc=memfd ... Terminal 2: start new QEMU # qemu-kvm ... -incoming unix:vm.sock -cpr-uri unix:cpr.sock Terminal 1: QEMU 9.1.50 monitor - type 'help' for more information (qemu) info status VM status: running (qemu) migrate_set_parameter mode cpr-transfer (qemu) migrate_set_parameter cpr-uri unix:cpr.sock (qemu) migrate -d unix:vm.sock (qemu) info status VM status: paused (postmigrate) Terminal 2: QEMU 9.1.50 monitor - type 'help' for more information (qemu) info status VM status: running Steve Sistare (6): migration: SCM_RIGHTS for QEMUFile migration: VMSTATE_FD migration: cpr-transfer save and load migration: cpr-uri parameter migration: cpr-uri option migration: cpr-transfer mode include/migration/cpr.h | 4 ++ include/migration/vmstate.h | 9 +++++ migration/cpr-transfer.c | 81 +++++++++++++++++++++++++++++++++++++++++ migration/cpr.c | 16 +++++++- migration/meson.build | 1 + migration/migration-hmp-cmds.c | 10 +++++ migration/migration.c | 37 +++++++++++++++++++ migration/options.c | 29 +++++++++++++++ migration/options.h | 1 + migration/qemu-file.c | 83 ++++++++++++++++++++++++++++++++++++++++-- migration/qemu-file.h | 2 + migration/ram.c | 1 + migration/trace-events | 2 + migration/vmstate-types.c | 33 +++++++++++++++++ qapi/migration.json | 38 ++++++++++++++++++- qemu-options.hx | 8 ++++ stubs/vmstate.c | 7 ++++ system/vl.c | 3 ++ 18 files changed, 359 insertions(+), 6 deletions(-) create mode 100644 migration/cpr-transfer.c -- 1.8.3.1
