BTW, this series depends on the patch "migration: simplify blockers".
- Steve On 10/19/2023 4:47 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 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. The guest RAM memory-backend must be shared, and the > @x-ignore-shared migration capability must be set, to avoid saving RAM to the > file. 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.yzn...@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 | > > Steve Sistare (4): > migration: mode parameter > migration: per-mode blockers > cpr: relax some blockers > cpr: reboot mode > > backends/tpm/tpm_emulator.c | 2 +- > 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/9pfs/9p.c | 2 +- > hw/core/qdev-properties-system.c | 12 +++++ > 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 | 8 ++++ > migration/migration.c | 95 > ++++++++++++++++++++++++++++++++----- > migration/options.c | 21 ++++++++ > migration/options.h | 1 + > qapi/migration.json | 41 ++++++++++++++-- > stubs/migr-blocker.c | 10 ++++ > target/i386/nvmm/nvmm-all.c | 3 +- > 22 files changed, 230 insertions(+), 32 deletions(-) >
