Re: [Qemu-devel] [PATCH v2 00/10] ACPI CPU hotplug refactoring to support unplug and more than 255 CPUs

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jun 21, 2016 at 09:12:38AM +0200, Igor Mammedov wrote:
> On Thu, 16 Jun 2016 18:55:33 +0200
> Igor Mammedov <imammedo@redhat.com> wrote:
> 
> Michael,
> Do you think that this series will make into 2.7?

Yes, I think it will. I'll try to prioritize review.

> > Changelog:                                                                       
> >  v1->v2:                                                                         
> >   - dropped consolidate legacy ACPI CPU hotplug as they are in master
> > by now     
> >   - pc: start with legacy hotplug and let 2.7 machine type and
> > older to switch inot new hotplug mode. That way legacy BIOS
> > will still work fine as it uses built in ACPI tables and will
> > continue to use legacy CPU hotplug
> > interface.                                         
> >   - poll for CPU objects with events (insert/remove) instead
> > of looping over all CPUs to find CPUs with
> > events.                              
> >   - drop dynamic PXM support as it could be implemented in static
> > way at acpi tabels build time. It will be an additional series on top
> > of this.   
> >   - resplit patches on basic present CPU support, hot-add and
> > hot-remove parts
> > Patches: 1-7: add new CPU hotplug
> > impl. 8: makes 2.7 machine type to use new AML code
> > that will switch piix4/ich9 into new mode
> > + switching logic with migration glue for piix4/ich9                  
> >           9: drops the last dependency in ACPI parts on
> > apic_id_limit sized
> > map.
> > RFC->v1:                                                                        
> >   - drop machine.cpu-hotplug property and leave CPU
> > hotplug always enabled as it used to
> > be. (it also simplifies, series a
> > bit)                                           
> >   - reshuffle/squash some patches to make series
> > bisectable wrt 'make check'
> > failures                                                    
> >   - add doc comment in qapi
> > schema                                               
> >   - fix 'make check' error for mips target, disableCPU
> > hotplug code path in piix4_pm for
> > mips                                               
> >   - drop some intermediate expected ACPI tables
> > updates                          
> >   - replace _MAT method with named buffer
> > object 
> > Current ACPI interface for CPU hotplug supports
> > hoti-adding only upto 255 CPUs and lacks means to convey
> > additional information needed _OST methods
> > support. Also being bitmap based with bit position specifying APIC
> > ID it doesn't scale up well for 32-bit APIC IDs that will
> > come with x2APIC
> > support. 
> > So add another QEMU-guest interface using as model
> > memory-hotplug. New interface will be used since 2.7 machine types
> > and will
> > support:                                                                         
> >     - more than 255 CPUs with 32-bit APIC ID
> > value                               
> >     - a registers set to communicate OST
> > information (extendable without breaking IO
> > layout)                                    
> >     - possible to reuse for ARM's 'virt' machine
> > type with minimal tweaks (add init for MMIO,
> > add ACPI hooks on CPU hotplug path, MADT
> > generation) 
> >                                                                                  
> > Tested with following guests: RHEL7, WS2003EEx64,
> > WS2012R2x64                    
> >  * unplug is tested only with RHEL7 as Windows doesn't support
> > it.               
> >  * tested that migration works as
> > well. 
> > git tree for
> > testing: git@github.com:imammedo/qemu.git
> > modern_cpu_hotplug_v2
> > viewing:
> > https://github.com/imammedo/qemu/commits/modern_cpu_hotplug_v2               
> > 
> > Igor Mammedov (10):
> >   docs: update ACPI CPU hotplug spec with new protocol
> >   pc: piix4/ich9: add 'cpu-hotplug-legacy' property
> >   acpi: cpuhp: add CPU devices AML with _STA method
> >   pc: acpi: introduce AcpiDeviceIfClass.madt_cpu hook
> >   acpi: cpuhp: implement hot-add parts of CPU hotplug interface
> >   acpi: cpuhp: implement hot-remove parts of CPU hotplug interface
> >   acpi: cpuhp: add cpu._OST handling
> >   pc: use new CPU hotplug interface since 2.7 machine type
> >   tests: acpi: add CPU hotplug testcase
> >   pc: acpi: drop intermediate PCMachineState.node_cpu
> > 
> >  docs/specs/acpi_cpu_hotplug.txt      |  94 +++++-
> >  hw/acpi/Makefile.objs                |   1 +
> >  hw/acpi/cpu.c                        | 561
> > +++++++++++++++++++++++++++++++++++
> > hw/acpi/cpu_hotplug.c                |  21 +-
> > hw/acpi/ich9.c                       |  69 ++++-
> > hw/acpi/piix4.c                      |  71 ++++-
> > hw/i386/acpi-build.c                 |  68 +++--
> > hw/i386/pc.c                         |  63 +++-
> > hw/i386/pc_piix.c                    |   2 +
> > hw/i386/pc_q35.c                     |   2 +
> > hw/isa/lpc_ich9.c                    |   1 +
> > include/hw/acpi/acpi_dev_interface.h |   7 +
> > include/hw/acpi/cpu.h                |  67 +++++
> > include/hw/acpi/cpu_hotplug.h        |   6 +
> > include/hw/acpi/ich9.h               |   3 +
> > include/hw/i386/pc.h                 |   8 +-
> > qapi-schema.json                     |   3 +-
> > stubs/Makefile.objs                  |   1 +
> > stubs/pc_madt_cpu_entry.c            |   7 +
> > tests/bios-tables-test.c             |  28 ++
> > trace-events                         |  14 + 21 files changed, 1043
> > insertions(+), 54 deletions(-) create mode 100644 hw/acpi/cpu.c
> >  create mode 100644 include/hw/acpi/cpu.h
> >  create mode 100644 stubs/pc_madt_cpu_entry.c
> > 
>