| Message ID | 1625589956-81651-1-git-send-email-steven.sistare@oracle.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Live Update | expand |
Hi Steve On Tue, Jul 6, 2021 at 8:58 PM Steve Sistare <steven.sistare@oracle.com> wrote: > Provide the cprsave, cprexec, and cprload commands for live update. These > save and restore VM state, with minimal guest pause time, so that qemu may > be updated to a new version in between. > > cprsave stops the VM and saves vmstate to an ordinary file. It supports > any > type of guest image and block device, but the caller must not modify guest > block devices between cprsave and cprload. It supports two modes: reboot > and restart. > > In reboot mode, the caller invokes cprsave and then terminates qemu. > The caller may then update the host kernel and system software and reboot. > The caller resumes the guest by running qemu with the same arguments as the > original process and invoking cprload. To use this mode, guest ram must be > mapped to a persistent shared memory file such as /dev/dax0.0, or /dev/shm > PKRAM as proposed in > https://lore.kernel.org/lkml/1617140178-8773-1-git-send-email-anthony.yznaga@oracle.com > . > > The reboot mode supports vfio devices if the caller first suspends the > guest, such as by issuing guest-suspend-ram to the qemu guest agent. The > guest drivers' suspend methods flush outstanding requests and re-initialize > the devices, and thus there is no device state to save and restore. > > Restart mode preserves the guest VM across a restart of the qemu process. > After cprsave, the caller passes qemu command-line arguments to cprexec, > which directly exec's the new qemu binary. The arguments must include -S > so new qemu starts in a paused state and waits for the cprload command. > The restart mode supports vfio devices by preserving the vfio container, > group, device, and event descriptors across the qemu re-exec, and by > updating DMA mapping virtual addresses using VFIO_DMA_UNMAP_FLAG_VADDR and > VFIO_DMA_MAP_FLAG_VADDR as defined in > https://lore.kernel.org/kvm/1611939252-7240-1-git-send-email-steven.sistare@oracle.com/ > and integrated in Linux kernel 5.12. > > To use the restart mode, qemu must be started with the memfd-alloc option, > which allocates guest ram using memfd_create. The memfd's are saved to > the environment and kept open across exec, after which they are found from > the environment and re-mmap'd. Hence guest ram is preserved in place, > albeit with new virtual addresses in the qemu process. > > The caller resumes the guest by invoking cprload, which loads state from > the file. If the VM was running at cprsave time, then VM execution > resumes. > If the VM was suspended at cprsave time (reboot mode), then the caller must > issue a system_wakeup command to resume. > > The first patches add reboot mode: > - qemu_ram_volatile > - cpr: reboot mode > - cpr: QMP interfaces for reboot > - cpr: HMP interfaces for reboot > > The next patches add restart mode: > - as_flat_walk > - oslib: qemu_clr_cloexec > - machine: memfd-alloc option > - vl: add helper to request re-exec > - string to strList > - util: env var helpers > - cpr: restart mode > - cpr: QMP interfaces for restart > - cpr: HMP interfaces for restart > > The next patches add vfio support for restart mode: > - pci: export functions for cpr > - vfio-pci: refactor for cpr > - vfio-pci: cpr part 1 > - vfio-pci: cpr part 2 > > The next patches preserve various descriptor-based backend devices across > cprexec: > - vhost: reset vhost devices upon cprsave > - hostmem-memfd: cpr support > - chardev: cpr framework > - chardev: cpr for simple devices > - chardev: cpr for pty > - chardev: cpr for sockets > - cpr: only-cpr-capable option > - simplify savevm > > Here is an example of updating qemu from v4.2.0 to v4.2.1 using > restart mode. The software update is performed while the guest is > running to minimize downtime. > > window 1 | window 2 > | > # qemu-system-x86_64 ... | > QEMU 4.2.0 monitor - type 'help' ... | > (qemu) info status | > VM status: running | > | # yum update qemu > (qemu) cprsave /tmp/qemu.sav restart | > (qemu) cprexec qemu-system-x86_64 -S ... | > QEMU 4.2.1 monitor - type 'help' ... | > (qemu) info status | > VM status: paused (prelaunch) | > (qemu) cprload /tmp/qemu.sav | > (qemu) info status | > VM status: running | > > > Here is an example of updating the host kernel using reboot mode. > > window 1 | window 2 > | > # qemu-system-x86_64 ...mem-path=/dev/dax0.0 ...| > QEMU 4.2.1 monitor - type 'help' ... | > (qemu) info status | > VM status: running | > | # yum update kernel-uek > (qemu) cprsave /tmp/qemu.sav restart | > (qemu) quit | > | > # systemctl kexec | > kexec_core: Starting new kernel | > ... | > | > # qemu-system-x86_64 -S mem-path=/dev/dax0.0 ...| > QEMU 4.2.1 monitor - type 'help' ... | > (qemu) info status | > VM status: paused (prelaunch) | > (qemu) cprload /tmp/qemu.sav | > (qemu) info status | > VM status: running | > > Changes from V1 to V2: > - revert vmstate infrastructure changes > - refactor cpr functions into new files > - delete MADV_DOEXEC and use memfd + VFIO_DMA_UNMAP_FLAG_SUSPEND to > preserve memory. > - add framework to filter chardev's that support cpr > - save and restore vfio eventfd's > - modify cprinfo QMP interface > - incorporate misc review feedback > - remove unrelated and unneeded patches > - refactor all patches into a shorter and easier to review series > > Changes from V2 to V3: > - rebase to qemu 6.0.0 > - use final definition of vfio ioctls (VFIO_DMA_UNMAP_FLAG_VADDR etc) > - change memfd-alloc to a machine option > - Use qio_channel_socket_new_fd instead of adding > qio_channel_socket_new_fd > - close monitor socket during cpr > - fix a few unreported bugs > - support memory-backend-memfd > > Changes from V3 to V4: > - split reboot mode into separate patches > - add cprexec command > - delete QEMU_START_FREEZE, argv_main, and /usr/bin/qemu-exec > - add more checks for vfio and cpr compatibility, and recover after > errors > - save vfio pci config in vmstate > - rename {setenv,getenv}_event_fd to {save,load}_event_fd > - use qemu_strtol > - change 6.0 references to 6.1 > - use strerror(), use EXIT_FAILURE, remove period from error messages > - distribute MAINTAINERS additions to each patch > > Steve Sistare (21): > qemu_ram_volatile > cpr: reboot mode > as_flat_walk > oslib: qemu_clr_cloexec > machine: memfd-alloc option > vl: add helper to request re-exec > string to strList > util: env var helpers > cpr: restart mode > cpr: QMP interfaces for restart > cpr: HMP interfaces for restart > pci: export functions for cpr > vfio-pci: refactor for cpr > vfio-pci: cpr part 1 > vfio-pci: cpr part 2 > hostmem-memfd: cpr support > chardev: cpr framework > chardev: cpr for simple devices > chardev: cpr for pty > cpr: only-cpr-capable option > simplify savevm > > Mark Kanda, Steve Sistare (4): > cpr: QMP interfaces for reboot > cpr: HMP interfaces for reboot > vhost: reset vhost devices upon cprsave > chardev: cpr for sockets > > MAINTAINERS | 12 +++ > backends/hostmem-memfd.c | 21 ++-- > chardev/char-mux.c | 1 + > chardev/char-null.c | 1 + > chardev/char-pty.c | 15 ++- > chardev/char-serial.c | 1 + > chardev/char-socket.c | 35 +++++++ > chardev/char-stdio.c | 8 ++ > chardev/char.c | 41 +++++++- > gdbstub.c | 1 + > hmp-commands.hx | 62 ++++++++++++ > hw/core/machine.c | 19 ++++ > hw/pci/msix.c | 20 ++-- > hw/pci/pci.c | 7 +- > hw/vfio/common.c | 78 ++++++++++++-- > hw/vfio/cpr.c | 154 ++++++++++++++++++++++++++++ > hw/vfio/meson.build | 1 + > hw/vfio/pci.c | 230 > +++++++++++++++++++++++++++++++++++++++--- > hw/vfio/trace-events | 1 + > hw/virtio/vhost.c | 11 ++ > include/chardev/char.h | 6 ++ > include/exec/memory.h | 25 +++++ > include/hw/boards.h | 1 + > include/hw/pci/msix.h | 5 + > include/hw/pci/pci.h | 2 + > include/hw/vfio/vfio-common.h | 8 ++ > include/hw/virtio/vhost.h | 1 + > include/migration/cpr.h | 20 ++++ > include/monitor/hmp.h | 4 + > include/qemu/env.h | 23 +++++ > include/qemu/osdep.h | 1 + > include/sysemu/runstate.h | 2 + > include/sysemu/sysemu.h | 1 + > linux-headers/linux/vfio.h | 27 +++++ > migration/cpr.c | 195 +++++++++++++++++++++++++++++++++++ > migration/meson.build | 1 + > migration/migration.c | 5 + > migration/savevm.c | 21 ++-- > migration/savevm.h | 2 + > monitor/hmp-cmds.c | 75 ++++++++++++-- > monitor/hmp.c | 3 + > monitor/qmp-cmds.c | 36 +++++++ > monitor/qmp.c | 3 + > qapi/char.json | 5 +- > qapi/cpr.json | 88 ++++++++++++++++ > qapi/meson.build | 1 + > qapi/qapi-schema.json | 1 + > qemu-options.hx | 39 ++++++- > softmmu/globals.c | 1 + > softmmu/memory.c | 48 +++++++++ > softmmu/physmem.c | 49 +++++++-- > softmmu/runstate.c | 58 ++++++++++- > softmmu/vl.c | 14 ++- > stubs/cpr.c | 3 + > stubs/meson.build | 1 + > trace-events | 1 + > util/env.c | 95 +++++++++++++++++ > util/meson.build | 1 + > util/oslib-posix.c | 9 ++ > util/oslib-win32.c | 4 + > util/qemu-config.c | 4 + > 61 files changed, 1525 insertions(+), 83 deletions(-) > create mode 100644 hw/vfio/cpr.c > create mode 100644 include/migration/cpr.h > create mode 100644 include/qemu/env.h > create mode 100644 migration/cpr.c > create mode 100644 qapi/cpr.json > create mode 100644 stubs/cpr.c > create mode 100644 util/env.c > > -- > 1.8.3.1 > > > It doesn't apply on master, could you rebase and resend? thanks
On 7/7/2021 8:31 AM, Marc-André Lureau wrote: > Hi Steve > > On Tue, Jul 6, 2021 at 8:58 PM Steve Sistare <steven.sistare@oracle.com <mailto:steven.sistare@oracle.com>> wrote: > >[...] > It doesn't apply on master, could you rebase and resend? > thanks > -- > Marc-André Lureau Will do, sorry about that - steve
Provide the cprsave, cprexec, and cprload commands for live update. These save and restore VM state, with minimal guest pause time, so that qemu may be updated to a new version in between. cprsave stops the VM and saves vmstate to an ordinary file. It supports any type of guest image and block device, but the caller must not modify guest block devices between cprsave and cprload. It supports two modes: reboot and restart. In reboot mode, the caller invokes cprsave and then terminates qemu. The caller may then update the host kernel and system software and reboot. The caller resumes the guest by running qemu with the same arguments as the original process and invoking cprload. To use this mode, guest ram must be mapped to a persistent shared memory file such as /dev/dax0.0, or /dev/shm PKRAM as proposed in https://lore.kernel.org/lkml/1617140178-8773-1-git-send-email-anthony.yznaga@oracle.com. The reboot mode supports vfio devices if the caller first suspends the guest, such as by issuing guest-suspend-ram to the qemu guest agent. The guest drivers' suspend methods flush outstanding requests and re-initialize the devices, and thus there is no device state to save and restore. Restart mode preserves the guest VM across a restart of the qemu process. After cprsave, the caller passes qemu command-line arguments to cprexec, which directly exec's the new qemu binary. The arguments must include -S so new qemu starts in a paused state and waits for the cprload command. The restart mode supports vfio devices by preserving the vfio container, group, device, and event descriptors across the qemu re-exec, and by updating DMA mapping virtual addresses using VFIO_DMA_UNMAP_FLAG_VADDR and VFIO_DMA_MAP_FLAG_VADDR as defined in https://lore.kernel.org/kvm/1611939252-7240-1-git-send-email-steven.sistare@oracle.com/ and integrated in Linux kernel 5.12. To use the restart mode, qemu must be started with the memfd-alloc option, which allocates guest ram using memfd_create. The memfd's are saved to the environment and kept open across exec, after which they are found from the environment and re-mmap'd. Hence guest ram is preserved in place, albeit with new virtual addresses in the qemu process. The caller resumes the guest by invoking cprload, which loads state from the file. If the VM was running at cprsave time, then VM execution resumes. If the VM was suspended at cprsave time (reboot mode), then the caller must issue a system_wakeup command to resume. The first patches add reboot mode: - qemu_ram_volatile - cpr: reboot mode - cpr: QMP interfaces for reboot - cpr: HMP interfaces for reboot The next patches add restart mode: - as_flat_walk - oslib: qemu_clr_cloexec - machine: memfd-alloc option - vl: add helper to request re-exec - string to strList - util: env var helpers - cpr: restart mode - cpr: QMP interfaces for restart - cpr: HMP interfaces for restart The next patches add vfio support for restart mode: - pci: export functions for cpr - vfio-pci: refactor for cpr - vfio-pci: cpr part 1 - vfio-pci: cpr part 2 The next patches preserve various descriptor-based backend devices across cprexec: - vhost: reset vhost devices upon cprsave - hostmem-memfd: cpr support - chardev: cpr framework - chardev: cpr for simple devices - chardev: cpr for pty - chardev: cpr for sockets - cpr: only-cpr-capable option - simplify savevm Here is an example of updating qemu from v4.2.0 to v4.2.1 using restart mode. The software update is performed while the guest is running to minimize downtime. window 1 | window 2 | # qemu-system-x86_64 ... | QEMU 4.2.0 monitor - type 'help' ... | (qemu) info status | VM status: running | | # yum update qemu (qemu) cprsave /tmp/qemu.sav restart | (qemu) cprexec qemu-system-x86_64 -S ... | QEMU 4.2.1 monitor - type 'help' ... | (qemu) info status | VM status: paused (prelaunch) | (qemu) cprload /tmp/qemu.sav | (qemu) info status | VM status: running | Here is an example of updating the host kernel using reboot mode. window 1 | window 2 | # qemu-system-x86_64 ...mem-path=/dev/dax0.0 ...| QEMU 4.2.1 monitor - type 'help' ... | (qemu) info status | VM status: running | | # yum update kernel-uek (qemu) cprsave /tmp/qemu.sav restart | (qemu) quit | | # systemctl kexec | kexec_core: Starting new kernel | ... | | # qemu-system-x86_64 -S mem-path=/dev/dax0.0 ...| QEMU 4.2.1 monitor - type 'help' ... | (qemu) info status | VM status: paused (prelaunch) | (qemu) cprload /tmp/qemu.sav | (qemu) info status | VM status: running | Changes from V1 to V2: - revert vmstate infrastructure changes - refactor cpr functions into new files - delete MADV_DOEXEC and use memfd + VFIO_DMA_UNMAP_FLAG_SUSPEND to preserve memory. - add framework to filter chardev's that support cpr - save and restore vfio eventfd's - modify cprinfo QMP interface - incorporate misc review feedback - remove unrelated and unneeded patches - refactor all patches into a shorter and easier to review series Changes from V2 to V3: - rebase to qemu 6.0.0 - use final definition of vfio ioctls (VFIO_DMA_UNMAP_FLAG_VADDR etc) - change memfd-alloc to a machine option - Use qio_channel_socket_new_fd instead of adding qio_channel_socket_new_fd - close monitor socket during cpr - fix a few unreported bugs - support memory-backend-memfd Changes from V3 to V4: - split reboot mode into separate patches - add cprexec command - delete QEMU_START_FREEZE, argv_main, and /usr/bin/qemu-exec - add more checks for vfio and cpr compatibility, and recover after errors - save vfio pci config in vmstate - rename {setenv,getenv}_event_fd to {save,load}_event_fd - use qemu_strtol - change 6.0 references to 6.1 - use strerror(), use EXIT_FAILURE, remove period from error messages - distribute MAINTAINERS additions to each patch Steve Sistare (21): qemu_ram_volatile cpr: reboot mode as_flat_walk oslib: qemu_clr_cloexec machine: memfd-alloc option vl: add helper to request re-exec string to strList util: env var helpers cpr: restart mode cpr: QMP interfaces for restart cpr: HMP interfaces for restart pci: export functions for cpr vfio-pci: refactor for cpr vfio-pci: cpr part 1 vfio-pci: cpr part 2 hostmem-memfd: cpr support chardev: cpr framework chardev: cpr for simple devices chardev: cpr for pty cpr: only-cpr-capable option simplify savevm Mark Kanda, Steve Sistare (4): cpr: QMP interfaces for reboot cpr: HMP interfaces for reboot vhost: reset vhost devices upon cprsave chardev: cpr for sockets MAINTAINERS | 12 +++ backends/hostmem-memfd.c | 21 ++-- chardev/char-mux.c | 1 + chardev/char-null.c | 1 + chardev/char-pty.c | 15 ++- chardev/char-serial.c | 1 + chardev/char-socket.c | 35 +++++++ chardev/char-stdio.c | 8 ++ chardev/char.c | 41 +++++++- gdbstub.c | 1 + hmp-commands.hx | 62 ++++++++++++ hw/core/machine.c | 19 ++++ hw/pci/msix.c | 20 ++-- hw/pci/pci.c | 7 +- hw/vfio/common.c | 78 ++++++++++++-- hw/vfio/cpr.c | 154 ++++++++++++++++++++++++++++ hw/vfio/meson.build | 1 + hw/vfio/pci.c | 230 +++++++++++++++++++++++++++++++++++++++--- hw/vfio/trace-events | 1 + hw/virtio/vhost.c | 11 ++ include/chardev/char.h | 6 ++ include/exec/memory.h | 25 +++++ include/hw/boards.h | 1 + include/hw/pci/msix.h | 5 + include/hw/pci/pci.h | 2 + include/hw/vfio/vfio-common.h | 8 ++ include/hw/virtio/vhost.h | 1 + include/migration/cpr.h | 20 ++++ include/monitor/hmp.h | 4 + include/qemu/env.h | 23 +++++ include/qemu/osdep.h | 1 + include/sysemu/runstate.h | 2 + include/sysemu/sysemu.h | 1 + linux-headers/linux/vfio.h | 27 +++++ migration/cpr.c | 195 +++++++++++++++++++++++++++++++++++ migration/meson.build | 1 + migration/migration.c | 5 + migration/savevm.c | 21 ++-- migration/savevm.h | 2 + monitor/hmp-cmds.c | 75 ++++++++++++-- monitor/hmp.c | 3 + monitor/qmp-cmds.c | 36 +++++++ monitor/qmp.c | 3 + qapi/char.json | 5 +- qapi/cpr.json | 88 ++++++++++++++++ qapi/meson.build | 1 + qapi/qapi-schema.json | 1 + qemu-options.hx | 39 ++++++- softmmu/globals.c | 1 + softmmu/memory.c | 48 +++++++++ softmmu/physmem.c | 49 +++++++-- softmmu/runstate.c | 58 ++++++++++- softmmu/vl.c | 14 ++- stubs/cpr.c | 3 + stubs/meson.build | 1 + trace-events | 1 + util/env.c | 95 +++++++++++++++++ util/meson.build | 1 + util/oslib-posix.c | 9 ++ util/oslib-win32.c | 4 + util/qemu-config.c | 4 + 61 files changed, 1525 insertions(+), 83 deletions(-) create mode 100644 hw/vfio/cpr.c create mode 100644 include/migration/cpr.h create mode 100644 include/qemu/env.h create mode 100644 migration/cpr.c create mode 100644 qapi/cpr.json create mode 100644 stubs/cpr.c create mode 100644 util/env.c