Re: [Qemu-devel] [PATCH 00/16 v4] target-i386: CPU hot-add with cpu-add QMP command

[Jan Kiszka]

On 2013-04-16 00:12, Igor Mammedov wrote:
> Implements alternative way for hot-adding CPU using cpu-add QMP command,
> wich could be useful until it would be possible to add CPUs via device_add.

Didn't track the full story: What prevents currently a device_add
approach? And that so effectively that we have to create a
to-be-deprecated-again QMP API first?

Thanks,
Jan

> 
> All patches except the last are also applicable to device_add aprroach.
> 
> To hot-add CPU use following command from qmp-shell:
>  cpu-add id=[0..max-cpus - 1)
> 
> git tree for testing: https://github.com/imammedo/qemu/tree/cpu_add.v4
> 
> based on qom-cpu tree
> 
> v4->v3:
>   * 'id' in cpu-add command will be a thread number instead of APIC ID
>   * split off resume_vcpu() into separate patch
>   * move notifier from rtc code into pc.c
> 
> v2->v3:
>   * use local error & propagate_error() instead of operating on
>     passed in errp in several places
>   * replace CPUClass.get_firmware_id() with CPUClass.get_arch_id()
>   * leave IOAPIC creation to board and just set bus to icc-bus
>   * include kvm-stub.o in cpu libary if no KVM is configured
>   * create resume_vcpu() stub and include it in libqemustub,
>     and use it directly instead of CPU method
>   * acpi_piix4: s/cpu_add_notifier/cpu_added_notifier/
> 
> v1->v2:
>   * generalize cpu sync to KVM, resume and hot-plug notification and
>     invoke them form CPUClass, to make available to all targets.
>   * introduce cpu_exists() and CPUClass.get_firmware_id() and use
>     the last one in acpi_piix to make code target independent.
>   * move IOAPIC to ICC bus, it was suggested and easy to convert.
>   * leave kvmvapic as SysBusDevice, it doesn't affect hot-plug and
>     created only once for all APIC instances. I haven't found yet
>     good/clean enough way to convert it to ICCDevice. May be follow-up
>     though.
>   * split one big ICC patch into several, one per converted device
>   * add cpu_hot_add hook to machine and implement it for target-i386,
>     instead of adding stabs. Could be used by other targets to
>     implement cpu-add.
>   * pre-allocate links<CPU> for all possible CPUs and make them available
>     at /machine/icc-bridge/cpu[0..N] QOM path, so users could find out
>     possible/free CPU IDs to use in cpu-add command.
> 
> CC: address@hidden
> CC: address@hidden
> CC: address@hidden
> 
> Igor Mammedov (16):
>   cpu: make kvm-stub.o a part of CPU library
>   cpu: call cpu_synchronize_post_init() from CPUClass.realize() if
>     hotplugged
>   introduce resume_vcpu(), for single CPU
>   cpu: resume CPU from CPUClass.cpu_common_realizefn() when it is
>     hot-plugged
>   introduce CPU hot-plug notifier
>   target-i386: pc: update rtc_cmos on CPU hot-plug
>   cpu: introduce get_arch_id() method and override it for target-i386
>   cpu: add helper cpu_exists(), to check if CPU with specified id exists
>   acpi_piix4: add infrastructure to send CPU hot-plug GPE to guest
>   target-i386: introduce apic-id property
>   introduce ICC bus/device/bridge
>   target-i386: cpu: attach ICC bus to CPU on its creation
>   target-i386: replace MSI_SPACE_SIZE with APIC_SPACE_SIZE
>   target-i386: move APIC to ICC bus
>   target-i386: move IOAPIC to ICC bus
>   add cpu-add qmp command and implement CPU hot-add for target-i386
> 
>  Makefile.target                    |  14 ++---
>  cpus.c                             |  11 +++-
>  default-configs/i386-softmmu.mak   |   1 +
>  default-configs/x86_64-softmmu.mak |   1 +
>  hw/acpi/piix4.c                    | 114 
> ++++++++++++++++++++++++++++++++++++-
>  hw/cpu/Makefile.objs               |   1 +
>  hw/cpu/icc_bus.c                   | 104 +++++++++++++++++++++++++++++++++
>  hw/i386/kvm/apic.c                 |   2 +-
>  hw/i386/kvm/ioapic.c               |   2 +-
>  hw/i386/kvmvapic.c                 |   1 +
>  hw/i386/pc.c                       |  91 +++++++++++++++++++++++++++--
>  hw/i386/pc_piix.c                  |   7 +++
>  hw/i386/pc_q35.c                   |   7 +++
>  hw/intc/apic.c                     |   2 +-
>  hw/intc/apic_common.c              |  17 ++++--
>  hw/intc/ioapic_common.c            |  15 +++--
>  hw/timer/mc146818rtc.c             |   7 +++
>  hw/xen/xen_apic.c                  |   2 +-
>  include/exec/memory.h              |  10 ++++
>  include/hw/boards.h                |   3 +
>  include/hw/i386/apic_internal.h    |   8 +--
>  include/hw/i386/icc_bus.h          |  53 +++++++++++++++++
>  include/hw/i386/ioapic_internal.h  |   6 +-
>  include/hw/pci/msi.h               |   2 +
>  include/hw/timer/mc146818rtc.h     |   1 +
>  include/qom/cpu.h                  |  21 +++++++
>  include/sysemu/kvm.h               |  22 +++----
>  include/sysemu/sysemu.h            |   3 +
>  kvm-all.c                          |   1 +
>  kvm-stub.c                         |   3 +
>  memory.c                           |  11 ++++
>  qapi-schema.json                   |  11 ++++
>  qmp-commands.hx                    |  23 ++++++++
>  qmp.c                              |  10 ++++
>  qom/cpu.c                          |  44 ++++++++++++++
>  stubs/Makefile.objs                |   1 +
>  stubs/cpus.c                       |   5 ++
>  target-i386/cpu.c                  |  75 +++++++++++++++++++-----
>  target-i386/cpu.h                  |   1 +
>  vl.c                               |   7 ++-
>  40 files changed, 656 insertions(+), 64 deletions(-)
>  create mode 100644 hw/cpu/icc_bus.c
>  create mode 100644 include/hw/i386/icc_bus.h
>  create mode 100644 stubs/cpus.c
> 

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