Re: [Qemu-devel] [PATCH 00/35] pc: ACPI memory hotplug

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Hello Igor,

while testing your patchset i came to a very stupid problem.

I wanted to test migration and it cames out that the migration works
fine after plugging in memory only if i run the target VM without the
-daemonize option.

If i enable the -daemonize option the target vm tries to read from non
readable memory.

proc maps shows:
7f9334021000-7f9338000000 ---p 00000000 00:00 0

where it tries to read from.

Also the memory layout is different in daemonize mode than in non
daemonize mode.

Stefan

Am 04.04.2014 15:36, schrieb Igor Mammedov:
> What's new since v7:
> 
> * Per Andreas' suggestion dropped DIMMBus concept.
> 
> * Added hotplug binding for bus-less devices
> 
> * DIMM device is split to backend and frontend. Therefore following
>   command/options were added for supporting it:
> 
>   For memory-ram backend:
>       CLI: -object-add memory-ram,
>           with options: 'id' and 'size'
>   For dimm frontend:
>       option "size" became readonly, pulling it's size from attached backend
>       added option "memdev" for specifying backend by 'id'
> 
> * dropped support for 32 bit guests
> 
> * failed hotplug action doesn't consume 1 slot anymore
> 
> * vaious fixes adressing reviewer's comments most of them in ACPI part
> ---
> 
> This series allows to hotplug 'arbitrary' DIMM devices specifying size,
> NUMA node mapping (guest side), slot and address where to map it, at runtime.
> 
> Due to ACPI limitation there is need to specify a number of possible
> DIMM devices. For this task -m option was extended to support
> following format:
> 
>   -m [mem=]RamSize[,slots=N,maxmem=M]
> 
> To allow memory hotplug user must specify a pair of additional parameters:
>     'slots' - number of possible increments
>     'maxmem' - max possible total memory size QEMU is allowed to use,
>                including RamSize.
> 
> minimal monitor command syntax to hotplug DIMM device:
> 
>   object_add memory-ram,id=memX,size=1G
>   device_add dimm,id=dimmX,memdev=memX
> 
> DIMM device provides following properties that could be used with
> device_add / -device to alter default behavior:
> 
>   id    - unique string identifying device [mandatory]
>   slot  - number in range [0-slots) [optional], if not specified
>           the first free slot is used
>   node  - NUMA node id [optional] (default: 0)
>   size  - amount of memory to add, readonly derived from backing memdev
>   start - guest's physical address where to plug DIMM [optional],
>           if not specified the first gap in hotplug memory region
>           that fits DIMM is used
> 
>  -device option could be used for adding potentially hotunplugable DIMMs
> and also for specifying hotplugged DIMMs in migration case.
> 
> Tested guests:
>  - RHEL 6x64
>  - Windows 2012DCx64
>  - Windows 2008DCx64
> 
> Known limitations/bugs/TODOs:
>  - hot-remove is not supported, yet
>  - max number of supported DIMM devices 255 (due to ACPI object name
>    limit), could be increased creating several containers and putting
>    DIMMs there. (exercise for future) 
>  - e820 table doesn't include DIMM devices added with -device /
>    (or after reboot devices added with device_add)
>  - Windows 2008 remembers DIMM configuration, so if DIMM with other
>    start/size is added into the same slot, it refuses to use it insisting
>    on old mapping.
> 
> QEMU git tree for testing is available at:
>   https://github.com/imammedo/qemu/commits/memory-hotplug-v8
> 
> Example QEMU cmd line:
>   qemu-system-x86_64 -enable-kvm -monitor unix:/tmp/mon,server,nowait \ 
>      -m 4096,slots=4,maxmem=8G guest.img
> 
> PS:
>   Windows guest requires SRAT table for hotplug to work so add an extra option:
>    -numa node
>   to QEMU command line.
> 
> 
> Igor Mammedov (34):
>   vl: convert -m to QemuOpts
>   object_add: allow completion handler to get canonical path
>   add memdev backend infrastructure
>   vl.c: extend -m option to support options for memory hotplug
>   add pc-{i440fx,q35}-2.1 machine types
>   pc: create custom generic PC machine type
>   qdev: hotplug for buss-less devices
>   qdev: expose DeviceState.hotplugged field as a property
>   dimm: implement dimm device abstraction
>   memory: add memory_region_is_mapped() API
>   dimm: do not allow to set already busy memdev
>   pc: initialize memory hotplug address space
>   pc: exit QEMU if slots > 256
>   pc: add 'etc/reserved-memory-end' fw_cfg interface for SeaBIOS
>   pc: add memory hotplug handler to PC_MACHINE
>   dimm: add busy address check and address auto-allocation
>   dimm: add busy slot check and slot auto-allocation
>   acpi: rename cpu_hotplug_defs.h to acpi_defs.h
>   acpi: memory hotplug ACPI hardware implementation
>   trace: add acpi memory hotplug IO region events
>   trace: add DIMM slot & address allocation for target-i386
>   acpi:piix4: make plug/unlug callbacks generic
>   acpi:piix4: add memory hotplug handling
>   pc: ich9 lpc: make it work with global/compat properties
>   acpi:ich9: add memory hotplug handling
>   pc: migrate piix4 & ich9 MemHotplugState
>   pc: propagate memory hotplug event to ACPI device
>   pc: ACPI BIOS: punch holes in PCI0._CRS for memory hotplug IO region
>   pc: ACPI BIOS: name CPU hotplug ACPI0004 device
>   pc: ACPI BIOS: implement memory hotplug interface
>   pc: ACPI BIOS: use enum for defining memory affinity flags
>   pc: ACPI BIOS: reserve SRAT entry for hotplug mem hole
>   pc: ACPI BIOS: make GPE.3 handle memory hotplug event on PIIX and Q35
>     machines
>   pc: ACPI BIOS: update pregenerated ACPI table blobs
> 
> Paolo Bonzini (1):
>   qemu-option: introduce qemu_find_opts_singleton
> 
>  backends/Makefile.objs              |   2 +
>  backends/hostmem-ram.c              |  54 +++
>  backends/hostmem.c                  | 110 +++++
>  default-configs/i386-softmmu.mak    |   1 +
>  default-configs/x86_64-softmmu.mak  |   1 +
>  docs/specs/acpi_mem_hotplug.txt     |  44 ++
>  hw/Makefile.objs                    |   1 +
>  hw/acpi/Makefile.objs               |   1 +
>  hw/acpi/ich9.c                      |  46 ++
>  hw/acpi/memory_hotplug.c            | 184 ++++++++
>  hw/acpi/piix4.c                     |  52 ++-
>  hw/core/qdev.c                      |  30 ++
>  hw/i386/Makefile.objs               |   3 +-
>  hw/i386/acpi-build.c                |  74 +++-
>  hw/i386/acpi-dsdt-cpu-hotplug.dsl   |   1 +
>  hw/i386/acpi-dsdt.dsl               |  17 +-
>  hw/i386/acpi-dsdt.hex.generated     | 102 ++++-
>  hw/i386/pc.c                        | 165 +++++++-
>  hw/i386/pc_piix.c                   |  64 ++-
>  hw/i386/pc_q35.c                    |  38 +-
>  hw/i386/q35-acpi-dsdt.dsl           |  17 +-
>  hw/i386/q35-acpi-dsdt.hex.generated | 104 ++++-
>  hw/i386/ssdt-mem.dsl                |  75 ++++
>  hw/i386/ssdt-mem.hex.generated      | 197 +++++++++
>  hw/i386/ssdt-misc.dsl               | 163 ++++++++
>  hw/i386/ssdt-misc.hex.generated     | 809 +++++++++++++++++++++++++++++++++++-
>  hw/isa/lpc_ich9.c                   |  33 +-
>  hw/mem/Makefile.objs                |   1 +
>  hw/mem/dimm.c                       | 234 +++++++++++
>  include/exec/memory.h               |   8 +
>  include/hw/acpi/acpi_defs.h         |  35 ++
>  include/hw/acpi/cpu_hotplug.h       |   2 +-
>  include/hw/acpi/cpu_hotplug_defs.h  |  32 --
>  include/hw/acpi/ich9.h              |   4 +
>  include/hw/acpi/memory_hotplug.h    |  37 ++
>  include/hw/boards.h                 |  10 +
>  include/hw/i386/pc.h                |  59 +++
>  include/hw/mem/dimm.h               |  72 ++++
>  include/qemu/config-file.h          |   2 +
>  include/sysemu/hostmem.h            |  60 +++
>  memory.c                            |  15 +-
>  qemu-options.hx                     |  14 +-
>  qmp.c                               |  11 +-
>  trace-events                        |  17 +
>  util/qemu-config.c                  |  14 +
>  vl.c                                | 145 +++++--
>  46 files changed, 2987 insertions(+), 173 deletions(-)
>  create mode 100644 backends/hostmem-ram.c
>  create mode 100644 backends/hostmem.c
>  create mode 100644 docs/specs/acpi_mem_hotplug.txt
>  create mode 100644 hw/acpi/memory_hotplug.c
>  create mode 100644 hw/i386/ssdt-mem.dsl
>  create mode 100644 hw/i386/ssdt-mem.hex.generated
>  create mode 100644 hw/mem/Makefile.objs
>  create mode 100644 hw/mem/dimm.c
>  create mode 100644 include/hw/acpi/acpi_defs.h
>  delete mode 100644 include/hw/acpi/cpu_hotplug_defs.h
>  create mode 100644 include/hw/acpi/memory_hotplug.h
>  create mode 100644 include/hw/mem/dimm.h
>  create mode 100644 include/sysemu/hostmem.h
>