SORRY for the noise, I type the wrong send-mail command, please ignore this resend of V2 - steve
On 10/26/2023 4:08 PM, Steve Sistare wrote:
> Add a mode migration parameter that can be used to select alternate
> migration algorithms. The default mode is normal, representing the
> current migration algorithm, and does not need to be explicitly set.
>
> Provide the cpr-reboot (CheckPoint and Restart) migration mode for live
> update, which saves state to a file. This allows one to quit qemu, reboot
> to an updated kernel, install an updated version of qemu, and resume via
> the migrate-incoming command. The caller must specify a migration URI
> that writes to and reads from a file, and must set the mode parameter
> before invoking the migrate or migrate-incoming commands.
>
> Unlike normal mode, the use of certain local storage options does not block
> cpr-reboot mode, but the caller must not modify guest block devices between
> the quit and restart. To avoid saving guest RAM to the state file, the memory
> backend must be shared, and the @x-ignore-shared migration capability must
> be set.
>
> Guest RAM must be non-volatile across reboot, which can be achieved by
> backing it with a dax device, or /dev/shm PKRAM as proposed in
> https://lore.kernel.org/lkml/1617140178-8773-1-git-send-email-anthony.yznaga@oracle.com
> but this is not enforced. The restarted qemu arguments must match those used
> to initially start qemu, plus the -incoming option.
>
> This patch series contains minimal functionality. Future patches will enhance
> reboot mode by preserving vfio devices for suspended guests. They will also
> add a new mode for updating qemu using the exec system call, which will keep
> vfio devices and certain character devices alive.
>
> Here is an example of updating the host kernel using reboot mode.
>
> window 1 | window 2
> |
> # qemu-system-$arch -monitor stdio |
> mem-path=/dev/dax0.0 ... |
> QEMU 8.1.50 monitor - type 'help' for more info |
> (qemu) info status |
> VM status: running |
> | # yum update kernel-uek
> (qemu) migrate_set_capability x-ignore-shared on|
> (qemu) migrate_set_parameter mode cpr-reboot |
> (qemu) migrate -d file:vm.state |
> (qemu) info status |
> VM status: paused (postmigrate) |
> (qemu) quit |
> |
> # systemctl kexec |
> kexec_core: Starting new kernel |
> ... |
> |
> # qemu-system-$arch -monitor stdio |
> mem-path=/dev/dax0.0 -incoming defer ... |
> QEMU 8.1.50 monitor - type 'help' for more info |
> (qemu) info status |
> VM status: paused (inmigrate) |
> (qemu) migrate_set_capability x-ignore-shared on|
> (qemu) migrate_set_parameter mode cpr-reboot |
> (qemu) migrate_incoming file:vm.state |
> (qemu) info status |
> VM status: running |
>
> Changes in V2:
> - moved "migration mode" code and comments to more appropriate places
> - clarified the behavior of non-shared-memory backends
> - split blocker patches and reverted some blockers
> - added a test
>
> Steve Sistare (6):
> migration: mode parameter
> migration: per-mode blockers
> cpr: relax blockdev migration blockers
> cpr: relax vhost migration blockers
> cpr: reboot mode
> tests/qtest: migration: add reboot mode test
>
> block/parallels.c | 2 +-
> block/qcow.c | 2 +-
> block/vdi.c | 2 +-
> block/vhdx.c | 2 +-
> block/vmdk.c | 2 +-
> block/vpc.c | 2 +-
> block/vvfat.c | 2 +-
> hw/core/qdev-properties-system.c | 14 ++++++
> hw/scsi/vhost-scsi.c | 2 +-
> hw/virtio/vhost.c | 2 +-
> include/hw/qdev-properties-system.h | 4 ++
> include/migration/blocker.h | 44 +++++++++++++++--
> include/migration/misc.h | 1 +
> migration/migration-hmp-cmds.c | 9 ++++
> migration/migration.c | 95 ++++++++++++++++++++++++++++++++-----
> migration/options.c | 21 ++++++++
> migration/options.h | 1 +
> qapi/migration.json | 40 ++++++++++++++--
> stubs/migr-blocker.c | 10 ++++
> tests/qtest/migration-test.c | 27 +++++++++++
> 20 files changed, 255 insertions(+), 29 deletions(-)
>