qemu/hw/core
Peter Maydell c4d1069c25 Add dbus-vmstate
Hi,
 
 With external processes or helpers participating to the VM support, it
 becomes necessary to handle their migration. Various options exist to
 transfer their state:
 1) as the VM memory, RAM or devices (we could say that's how
    vhost-user devices can be handled today, they are expected to
    restore from ring state)
 2) other "vmstate" (as with TPM emulator state blobs)
 3) left to be handled by management layer
 
 1) is not practical, since an external processes may legitimatelly
 need arbitrary state date to back a device or a service, or may not
 even have an associated device.
 
 2) needs ad-hoc code for each helper, but is simple and working
 
 3) is complicated for management layer, QEMU has the migration timing
 
 The proposed "dbus-vmstate" object will connect to a given D-Bus
 address, and save/load from org.qemu.VMState1 owners on migration.
 
 Thus helpers can easily have their state migrated with QEMU, without
 implementing ad-hoc support (such as done for TPM emulation)
 
 D-Bus is ubiquitous on Linux (it is systemd IPC), and can be made to
 work on various other OSes. There are several implementations and good
 bindings for various languages.  (the tests/dbus-vmstate-test.c is a
 good example of how simple the implementation of services can be, even
 in C)
 
 dbus-vmstate is put into use by the libvirt series "[PATCH 00/23] Use
 a slirp helper process".
 
 v2:
  - fix build with broken mingw-glib
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Merge remote-tracking branch 'remotes/elmarco/tags/dbus-vmstate7-pull-request' into staging

Add dbus-vmstate

Hi,

With external processes or helpers participating to the VM support, it
becomes necessary to handle their migration. Various options exist to
transfer their state:
1) as the VM memory, RAM or devices (we could say that's how
   vhost-user devices can be handled today, they are expected to
   restore from ring state)
2) other "vmstate" (as with TPM emulator state blobs)
3) left to be handled by management layer

1) is not practical, since an external processes may legitimatelly
need arbitrary state date to back a device or a service, or may not
even have an associated device.

2) needs ad-hoc code for each helper, but is simple and working

3) is complicated for management layer, QEMU has the migration timing

The proposed "dbus-vmstate" object will connect to a given D-Bus
address, and save/load from org.qemu.VMState1 owners on migration.

Thus helpers can easily have their state migrated with QEMU, without
implementing ad-hoc support (such as done for TPM emulation)

D-Bus is ubiquitous on Linux (it is systemd IPC), and can be made to
work on various other OSes. There are several implementations and good
bindings for various languages.  (the tests/dbus-vmstate-test.c is a
good example of how simple the implementation of services can be, even
in C)

dbus-vmstate is put into use by the libvirt series "[PATCH 00/23] Use
a slirp helper process".

v2:
 - fix build with broken mingw-glib

# gpg: Signature made Mon 06 Jan 2020 14:43:35 GMT
# gpg:                using RSA key 87A9BD933F87C606D276F62DDAE8E10975969CE5
# gpg:                issuer "marcandre.lureau@redhat.com"
# gpg: Good signature from "Marc-André Lureau <marcandre.lureau@redhat.com>" [full]
# gpg:                 aka "Marc-André Lureau <marcandre.lureau@gmail.com>" [full]
# Primary key fingerprint: 87A9 BD93 3F87 C606 D276  F62D DAE8 E109 7596 9CE5

* remotes/elmarco/tags/dbus-vmstate7-pull-request:
  tests: add dbus-vmstate-test
  tests: add migration-helpers unit
  dockerfiles: add dbus-daemon to some of latest distributions
  configure: add GDBUS_CODEGEN
  Add dbus-vmstate object
  util: add dbus helper unit
  docs: start a document to describe D-Bus usage
  vmstate: replace DeviceState with VMStateIf
  vmstate: add qom interface to get id

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2020-01-06 18:22:42 +00:00
..
bus.c Include hw/qdev-properties.h less 2019-08-16 13:31:53 +02:00
cpu.c cpu: hook plugin vcpu events 2019-10-28 15:12:38 +00:00
empty_slot.c Include hw/hw.h exactly where needed 2019-08-16 13:31:52 +02:00
fw-path-provider.c Include qemu/module.h where needed, drop it from qemu-common.h 2019-06-12 13:18:33 +02:00
generic-loader.c hw/core: Move cpu.c, cpu.h from qom/ to hw/core/ 2019-08-21 13:24:01 +02:00
hotplug.c call HotplugHandler->plug() as the last step in device realization 2018-10-19 13:44:12 +02:00
irq.c Revert "irq: introduce qemu_irq_proxy()" 2019-11-05 23:33:12 +01:00
Kconfig hw/core: Add a config switch for the generic loader device 2019-08-20 09:11:17 +02:00
loader-fit.c hw/core: Fix fit_load_fdt() error API violations 2019-12-18 08:36:15 +01:00
loader.c hw/core/loader: Fix possible crash in rom_copy() 2019-10-01 11:42:27 +02:00
machine-hmp-cmds.c hmp: drop Error pointer indirection in hmp_handle_error 2019-12-18 08:36:16 +01:00
machine-qmp-cmds.c qapi: report the default CPU type for each machine 2019-09-03 14:39:46 -03:00
machine.c x86 and machine queue, 2019-12-20 2020-01-06 14:08:04 +00:00
Makefile.objs vmstate: add qom interface to get id 2020-01-06 18:41:32 +04:00
nmi.c Include qemu/module.h where needed, drop it from qemu-common.h 2019-06-12 13:18:33 +02:00
null-machine.c hw/core: Move cpu.c, cpu.h from qom/ to hw/core/ 2019-08-21 13:24:01 +02:00
numa.c numa: remove not needed check 2019-12-19 14:54:11 -03:00
or-irq.c Include hw/qdev-properties.h less 2019-08-16 13:31:53 +02:00
platform-bus.c Clean up inclusion of sysemu/sysemu.h 2019-08-16 13:31:53 +02:00
ptimer.c ptimer: Remove old ptimer_init_with_bh() API 2019-11-11 13:44:16 +00:00
qdev-fw.c Include hw/qdev-properties.h less 2019-08-16 13:31:53 +02:00
qdev-properties-system.c audio: add audiodev properties to frontends 2019-08-21 09:13:37 +02:00
qdev-properties.c Include hw/qdev-properties.h less 2019-08-16 13:31:53 +02:00
qdev.c vmstate: replace DeviceState with VMStateIf 2020-01-06 18:41:32 +04:00
register.c Include hw/qdev-properties.h less 2019-08-16 13:31:53 +02:00
reset.c qemu/queue.h: leave head structs anonymous unless necessary 2019-01-11 15:46:55 +01:00
split-irq.c Include hw/qdev-properties.h less 2019-08-16 13:31:53 +02:00
stream.c Include qemu/module.h where needed, drop it from qemu-common.h 2019-06-12 13:18:33 +02:00
sysbus.c Include qemu/module.h where needed, drop it from qemu-common.h 2019-06-12 13:18:33 +02:00
trace-events loader: Trace loaded images 2019-09-18 10:18:51 +01:00
uboot_image.h Support u-boot noload images for arm as used by, NetBSD/evbarm GENERIC kernel. 2019-01-07 15:46:20 +00:00
vm-change-state-handler.c sysemu: Split sysemu/runstate.h off sysemu/sysemu.h 2019-08-16 13:37:36 +02:00
vmstate-if.c vmstate: add qom interface to get id 2020-01-06 18:41:32 +04:00