Re: [Qemu-devel] [RFC PATCH v4 00/30] ACPI memory hotplug

[Zhi Yong Wu]

HI,

One stupid question, 'dimm' presents one guest memory, then why it is
called as "dimm"? what is its full name?

On Tue, Dec 18, 2012 at 8:41 PM, Vasilis Liaskovitis
<address@hidden> wrote:
> This is v4 of the ACPI memory hotplug functionality. Only x86_64 target is
> supported (both i440fx and q35). There are still several issues, but it's
> been a while since v3 and I wanted to get some more feedback on the current
> state of the patchseries.
>
> Overview:
>
> Dimm device layout is modeled with a normal qemu device:
>
> "-device dimm,id=name,size=sz,node=pxm,populated=on|off,bus=membus.0"
>
> The starting physical address for all dimms is calculated from top of memory,
> during memory controller init, skipping the pci hole at [PCI_HOLE_START, 4G).
> e.g.
> "-device dimm,id=dimm0,size=512M,node=0,populated=off,bus=membus.0"
> will define a 512M memory dimm belonging to numa node 0, on bus membus.0.
>
> Because dimm layout needs to be configured on machine-boot, all dimm devices
> need to be specified on startup command line (either with populated=on or with
> populated=off). The dimm information is stored in dimm configuration 
> structures.
>
> After machine startup, dimms are hot-added or removed with normal device_add
> and device_del operations e.g.:
> Hot-add syntax: "device_add dimm,id=mydimm0,bus=membus.0"
> Hot-remove syntax: "device_del dimm,id=mydimm0"
>
> Changes v3->v4
>
> - Dimms added with normal -device argument (extra -dimm arg dropped).
> - multiple memory buses can be registered. Memory buses of the real hw/chipset
>   or a paravirtual memory bus can be added.
> - acpi implementation uses memory API instead of old ioports.
> - Support for q35/ich9 added (still buggy, see patch 12/31).
> - piix4/i440fx initialization code has been refactored to resemble q35. This
> will allow memory map initialization at chipset qdev init time for both
> machines, as well as more similar code.
> - Hot-remove functionality has been moved to separate patches. Hot-remove no
> longer frees memory but unmaps the dimm/qdev device from the guest's view.
> Freeing the memory should happen when the last user unrefs/unmaps the memory,
> see also (work in progress):
> https://lists.gnu.org/archive/html/qemu-devel/2012-11/msg00728.html
> https://lists.gnu.org/archive/html/qemu-devel/2012-11/msg02697.html
> - new qmp/hmp command for the state of each dimm (on/off)
>
> Changes v2->v3
>
> - qdev integration. Dimms are attached to a dimmbus. The dimmbus is a child
>   of i440fx device in the pc machine. Hot-add and remove are done with normal
>   device_add / device_del operations on the dimmbus. New commands "dimm_add" 
> and
>   "dimm_del" are obsolete.
> - Add _PS3 method to allow OSPM-induced hot operations.
> - pci-window calculation in Seabios takes dimms into account(for both 32-bit 
> and
>   64-bit windows)
> - rename new qmp commands: query-memory-total and query-memory-hotplug
> - balloon driver can see the hotplugged memory
>
> 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)
>
> Issues:
>
> - hot-remove needs to only unmap the dimm device from guest's view. Freeing 
> the
> memory should happen when the last user of the device (e.g. virtio-blk) unrefs
> the device. A testcase is needed for this.
>
> - Live Migration: Ramblocks are migrated before qdev VMStates are migrated. So
> the DimmDevice is handled diferrently than other devices. Should this be
> reworked ?( DimmDevice structure currently does not define a 
> VMStateDescription)
> Live migration works as long as the dimm layout (command line args) are
> identical at the source and destination qemu command line, and destination 
> takes
> into account hot-operations that have occured on source. (v3 patch 10/19
> created the DimmDevice that corresponds to an unknown incoming ramblock, e.g.
> for a dimm that was hot-added on source. but has been dropped for the moment).
>
> - A main blocker issue is windows guest functionality. The patchset does not
> work for windows currently.  Testing on win2012 server RC or windows2008
> consumer prerelease, when adding a DIMM, there is a BSOD with ACPI_BIOS_ERROR
> message. After this, the VM keeps rebooting with ACPI_BIOS_ERROR. The windows
> pnpmem driver obviosuly has a problem with the seabios dimm implementation
> (or the seabios dimm implementation is not fully ACPI-compliant). If someone
> can review the seabios patches or has any ideas to debug this, let me know.
>
> - hot-operation notification lists need to be added to migration state.
>
> series is based on:
> - qemu master (commit a8a826a3) + patch:
> https://lists.gnu.org/archive/html/qemu-devel/2012-11/msg02699.html
> - seabios master (commit a810e4e7)
>
> Can also be found at:
>
> http://github.com/vliaskov/qemu-kvm/commits/memhp-v4
> http://github.com/vliaskov/seabios/commits/memhp-v4
>
> Vasilis Liaskovitis (21):
>   qapi: make visit_type_size fallback to type_int
>   Add SIZE type to qdev properties
>   qemu-option: export parse_option_number
>   Implement dimm device abstraction
>   vl: handle "-device dimm"
>   acpi_piix4 : Implement memory device hotplug registers
>   acpi_ich9 : Implement memory device hotplug registers
>   piix_pci and pc_piix: refactor
>   piix_pci: Add i440fx dram controller initialization
>   q35: Add i440fx dram controller initialization
>   pc: Add dimm paravirt SRAT info
>   Introduce paravirt interface QEMU_CFG_PCI_WINDOW
>   Implement "info memory-total" and "query-memory-total"
>   balloon: update with hotplugged memory
>   Implement dimm-info
>   dimm: add hot-remove capability
>   acpi_piix4: add hot-remove capability
>   acpi_ich9: add hot-remove capability
>   Implement qmp and hmp commands for notification lists
>   Add _OST dimm support
>   Implement _PS3 for dimm
>
>  docs/specs/acpi_hotplug.txt |   54 ++++++
>  docs/specs/fwcfg.txt        |   28 +++
>  hmp-commands.hx             |    6 +
>  hmp.c                       |   41 ++++
>  hmp.h                       |    3 +
>  hw/Makefile.objs            |    2 +-
>  hw/acpi.h                   |    5 +
>  hw/acpi_ich9.c              |  115 +++++++++++-
>  hw/acpi_ich9.h              |   12 +-
>  hw/acpi_piix4.c             |  126 ++++++++++++-
>  hw/dimm.c                   |  444 
> +++++++++++++++++++++++++++++++++++++++++++
>  hw/dimm.h                   |  102 ++++++++++
>  hw/fw_cfg.h                 |    1 +
>  hw/lpc_ich9.c               |    2 +-
>  hw/pc.c                     |   28 +++-
>  hw/pc.h                     |    1 +
>  hw/pc_piix.c                |   74 ++++++--
>  hw/pc_q35.c                 |   18 ++-
>  hw/piix_pci.c               |  249 ++++++++-----------------
>  hw/q35.c                    |   27 +++
>  hw/q35.h                    |    5 +
>  hw/qdev-properties.c        |   60 ++++++
>  hw/qdev-properties.h        |    3 +
>  hw/virtio-balloon.c         |   13 +-
>  monitor.c                   |   21 ++
>  qapi-schema.json            |   63 ++++++
>  qapi/qapi-visit-core.c      |   11 +-
>  qemu-option.c               |    4 +-
>  qemu-option.h               |    4 +
>  qmp-commands.hx             |   57 ++++++
>  sysemu.h                    |    1 +
>  vl.c                        |   60 ++++++
>  32 files changed, 1432 insertions(+), 208 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 (9):
>   Add ACPI_EXTRACT_DEVICE* macros
>   Add SSDT memory device support
>   acpi-dsdt: Implement functions for memory hotplug
>   acpi: generate hotplug memory devices
>   q35: Add memory hotplug handler
>   pci: Use paravirt interface for pcimem_start and pcimem64_start
>   acpi: add _EJ0 operation and eject port for memory devices
>   Add _OST dimm method
>   Implement _PS3 method for memory device
>
>  Makefile                      |    2 +-
>  src/acpi-dsdt-mem-hotplug.dsl |  136 +++++++++++++++++++++++++++++++++++
>  src/acpi-dsdt.dsl             |    5 +-
>  src/acpi.c                    |  158 
> +++++++++++++++++++++++++++++++++++++++--
>  src/paravirt.c                |    6 ++
>  src/paravirt.h                |    2 +
>  src/pciinit.c                 |    9 +++
>  src/q35-acpi-dsdt.dsl         |    6 +-
>  src/ssdt-mem.dsl              |   73 +++++++++++++++++++
>  tools/acpi_extract.py         |   28 +++++++
>  10 files changed, 415 insertions(+), 10 deletions(-)
>  create mode 100644 src/acpi-dsdt-mem-hotplug.dsl
>  create mode 100644 src/ssdt-mem.dsl
>
> --
> 1.7.9
>
>



-- 
Regards,

Zhi Yong Wu