Re: [Qemu-devel] [RFC PATCH v2 00/21] ACPI memory hotplug

[Blue Swirl <blauwirbel@gmail.com>]

On Wed, Jul 11, 2012 at 10:31 AM, Vasilis Liaskovitis
<vasilis.liaskovitis@profitbricks.com> wrote:
> This is v2 of the ACPI memory hotplug prototype for x86_64 target.

I think the concept of DIMMs (what about SIMMs? SODIMMs? I liked
memslot) would be useful for most targets, but hotplugging may be
limited to x86 only. It would be nice to keep these two separate or as
loosely coupled as possible.

>
> Changes v1->v2
>
> - memory map is automatically calculated for hotplug dimms. Dimms are added from
> top-of-memory skipping the pci hole at [PCI_HOLE_START, 4G).
> - Renamed from "-memslot" to "-dimm". Commands changed to "dimm_add", "dimm_del".
> - Seabios ejection array reduced to a byte. Use extraction macros for dimm ssdt.
> - additional SRAT paravirt info does not break previous SRAT fw_cfg layout.
> - Documentation of new acpi_piix4 registers and paravirt data.
> - add ACPI _OST support for _OST enabled guests. This allows qemu to receive
> notification for success / failure of memory hot-add and hot-remove operations.
> Guest needs to support _OST (https://lkml.org/lkml/2012/6/25/321)
> - add monitor info command to report total guest memory (initial + hot-added)
> - add command line options and monitor commands for batch dimm creation/population
>
> Overview:
>
> Dimm devices are modeled with a new qemu command line
>
> "-dimm id=name,size=sz,node=pxm,populated=on|off"
>
> As already mentioned, the starting physical address for all dimms is calculated
> automatically from top of memory, skipping the pci hole at [PCI_HOLE_START, 4G).
> Node is defining numa proximity for this dimm. When not defined it defaults
> to zero.
> "-dimm id=dimm0,size=512M,node=0,populated=off"
> will define a 512M memory slot belonging to numa node 0.
>
> Dimms are added or removed with a new hmp command "dimm_add/dimm_del":
> Hot-add syntax: "dimm_add id"
> Hot-remove syntax: "dimm_del id"
>
> Issues:
>
> - Live migration works as long as populated field is changed to "on" for
> hotplugged dimms at the destination qemu command line (patch 12/21 lifts
> this requirement). The DimmState structure does not yet define a
> VMStateDescription, but i assume this is the preferred way to pass state
> for migration.
>
> - Dimms are abstracted as qdevices attached to the main system bus. However,
> memory hotplugging has its own side channel ignoring main_system_bus's hotplug
> incapability. A cleaner integration is still needed, probably attaching memory
> devices as children-links of an acpi-capable device (in the pc case acpi_piix4)
> instead of the system bus (TBD). Then device_add/device_del instead of new
> commands can hopefully be used.
>
> Comments/review welcome.
>
> series is based on uq/master for qemu-kvm, and master for seabios. Can be found
> also at:
> http://github.com/vliaskov/qemu-kvm/commits/memhp-v2
> http://github.com/vliaskov/seabios/commits/memhp-v2
>
> Vasilis Liaskovitis (14):
>   dimm: Implement memory device abstraction
>   acpi_piix4: Implement memory device hotplug registers
>   pc: calculate dimm physical addresses and adjust memory map
>   pc: Add dimm paravirt SRAT info
>   Implement "-dimm" command line option
>   Implement dimm_add and dimm_del commands for hmp and qmp
>   fix live-migration when "populated=on" is missing
>   Implement memory hotplug notification lists
>   acpi_piix4: _OST dimm support
>   acpi_piix4: Update dimm state on VM reboot
>   acpi_piix4: Update dimm bitmap state on hot-remove fail
>   Implement "info memtotal" and "query-memtotal"
>   Implement -dimms, -dimmspop command line options
>   Implement mem_increase, mem_decrease hmp/qmp commands
>
>  arch_init.c                 |   23 ++-
>  docs/specs/acpi_hotplug.txt |   46 +++++
>  docs/specs/fwcfg.txt        |   28 +++
>  hmp-commands.hx             |   67 +++++++
>  hmp.c                       |   24 +++
>  hmp.h                       |    2 +
>  hw/Makefile.objs            |    2 +-
>  hw/acpi_piix4.c             |  131 ++++++++++++-
>  hw/dimm.c                   |  449 +++++++++++++++++++++++++++++++++++++++++++
>  hw/dimm.h                   |   72 +++++++
>  hw/pc.c                     |   94 +++++++++-
>  hw/pc.h                     |    6 +
>  hw/pc_piix.c                |   18 ++-
>  monitor.c                   |   35 ++++
>  monitor.h                   |    5 +
>  qapi-schema.json            |   38 ++++
>  qemu-config.c               |   70 +++++++
>  qemu-options.hx             |   15 ++
>  qmp-commands.hx             |  137 +++++++++++++
>  sysemu.h                    |    1 +
>  vl.c                        |  122 ++++++++++++-
>  21 files changed, 1368 insertions(+), 17 deletions(-)
>  create mode 100644 docs/specs/acpi_hotplug.txt
>  create mode 100644 docs/specs/fwcfg.txt
>  create mode 100644 hw/dimm.c
>  create mode 100644 hw/dimm.h
>
> Vasilis Liaskovitis (7):
>   Add ACPI_EXTRACT_DEVICE* macros
>   Add SSDT memory device support
>   acpi-dsdt: Implement functions for memory hotplug.
>   acpi: generate hotplug memory devices.
>   pciinit: Fix pcimem_start value
>   acpi_dsdt: Support _OST dimm method
>   acpi_dsdt: Revert internal dimm state on _OST failure
>
>  Makefile              |    2 +-
>  src/acpi-dsdt.dsl     |  120 ++++++++++++++++++++++++++++++++++++-
>  src/acpi.c            |  158 +++++++++++++++++++++++++++++++++++++++++++++++--
>  src/pciinit.c         |    2 +-
>  src/ssdt-mem.dsl      |   69 +++++++++++++++++++++
>  tools/acpi_extract.py |   28 +++++++++
>  6 files changed, 369 insertions(+), 10 deletions(-)
>  create mode 100644 src/ssdt-mem.dsl
>