Re: [PATCH V15 0/7] Add architecture agnostic code to support vCPU Hotplug

[Igor Mammedov]

On Sat, 13 Jul 2024 19:25:09 +0100
Salil Mehta <salil.mehta@huawei.com> wrote:

> [Note: References are present at the last after the revision history]
> 
> Virtual CPU hotplug support is being added across various architectures 
> [1][3].
> This series adds various code bits common across all architectures:
> 
> 1. vCPU creation and Parking code refactor [Patch 1]
> 2. Update ACPI GED framework to support vCPU Hotplug [Patch 2,3]
> 3. ACPI CPUs AML code change [Patch 4,5]
> 4. Helper functions to support unrealization of CPU objects [Patch 6,7]

with patch 1 and 3 fixed should be good to go.

Salil,
Can you remind me what happened to migration part of this?
Ideally it should be a part of of this series as it should be common
for everything that uses GED and should be a conditional part
of GED's VMSTATE.

If this series is just a common base and no actual hotplug
on top of it is merged in this release (provided patch 13 is fixed),
I'm fine with migration bits being a separate series on top.

However if some machine would be introducing cpu hotplug in
the same release, then the migration part should be merged before
it or be a part that cpu hotplug series. 
 
> Repository:
> 
> [*] Architecture *Agnostic* Patch-set (This series)
>    V14: https://github.com/salil-mehta/qemu.git 
> virt-cpuhp-armv8/rfc-v3.arch.agnostic.v15
> 
>    NOTE: This series is meant to work in conjunction with the 
> architecture-specific
>    patch-set. For ARM, a combined patch-set (architecture agnostic + 
> specific) was
>    earlier pushed as RFC V2 [1]. Later, RFC V2 was split into the ARM 
> Architecture
>    specific patch-set RFC V3 [4] (a subset of RFC V2) and the architecture 
> agnostic
>    patch-set. Patch-set V14 is the latest version in that series. This series
>    works in conjunction with RFC V4-rc2, present at the following link.
> 
> [*] ARM Architecture *Specific* Patch-set
>    RFC V3 [4]: https://github.com/salil-mehta/qemu.git virt-cpuhp-armv8/rfc-v3
>    RFC V4-rc2: https://github.com/salil-mehta/qemu.git 
> virt-cpuhp-armv8/rfc-v4-rc2 (combined)
> 
> 
> Revision History:
> 
> Patch-set V14 -> V15
> 1. Addressed commnet from Igor Mammedov's on [PATCH V14 4/7]
>    - Removed ACPI_CPU_SCAN_METHOD
>    - Introduced AML_GED_EVT_CPU_SCAN_METHOD ("\\_SB.GED.CPSCN") macro
> 2. Fix the stray change of "assert (" in "PATCH V14 3/7"
> Link: 
> 20240712134201.214699-4-salil.mehta@huawei.com/">https://lore.kernel.org/qemu-devel/20240712134201.214699-4-salil.mehta@huawei.com/
> 
> Patch-set V13 -> V14
> 1. Addressed Igor Mammedov's following review comments
>    - Mentioned abput new external APIs in the header note of [PATCH 1/7]
>    - Merged Doc [PATCH V13 8/8] with [PATCH V14 3/7]
>    - Introduced GED realize function for various CPU Hotplug regions 
> initializations
>    - Added back event handler method to indirectly expose \\_SB.CPUS.CSCN to 
> GED
>      _EVT. Like for ARM, it would be through \\_SB.GED.CSCN event handler 
> method
>    - Collected the Ack given for [Patch V13 6/8]
>    - Added back the gfree'ing of GDB regs in common finalize and made it 
> conditional
>    - Updated the header notes of [PATCH V13 3/8,4/8,5/8] to reflect the 
> changes
> 
> Patch-set  V12 -> V13
> 1. Added Reviewed-by Tag of Harsh Prateek Bora's (IBM) [PATCH V12 1/8]
> 2. Moved the kvm_{create,park,unpark}_vcpu prototypes from 
> accel/kvm/kvm-cpus.h
>    to include/sysemu/kvm.h. These can later be exported through AccelOps.
> Link: 
> https://lore.kernel.org/qemu-devel/62f55169-1796-4d8e-a35d-7f003a172750@linux.ibm.com/
> 
> Patch-set  V11 -> V12
> 1. Addressed Harsh Prateek Bora's (IBM) comment
>    - Changed @cpu to @vcpu_id in the kvm_unpark_vcpu protoype header/
> 2. Added Zhao Liu's (Intel) Tested-by for whole series
>    - Qtest does not breaks on Intel platforms now.
> 3. Added Zhao Liu's (Intel) Reviewed-by for [PATCH V11 {1/8 - 3/8}]
> Link: https://lore.kernel.org/qemu-devel/ZlRSPuJGBgyEUW6w@intel.com/
> Link: 
> https://lore.kernel.org/qemu-devel/a5f3d78e-cfed-441f-9c56-e3e78fa5edee@linux.ibm.com/
> 
> Patch-set  V10 -> V11
> 1. Addressed Nicholas Piggin's (IBM) comment
>    - moved the traces in kvm_unpark_vcpu and kvm_create_vcpu at the end
>    - Added the Reviewed-by Tag for [PATCH V10 1/8]
> 2.  Addressed Alex Bennée's (Linaro) comments
>    - Added a note explaining dependency of the [PATCH V10 7/8] on Arch 
> specific patch-set
> Link: 
> https://lore.kernel.org/qemu-devel/D1FS5GOOFWWK.2PNRIVL0V6DBL@gmail.com/ 
> Link: https://lore.kernel.org/qemu-devel/87frubi402.fsf@draig.linaro.org/
> 
> Patch-set  V9 -> V10
> 1. Addressed Nicholas Piggin's (IBM) & Philippe Mathieu-Daudé (Linaro) 
> comments
>    - carved out kvm_unpark_vcpu and added its trace
>    - Widened the scope of the kvm_unpark_vcpu so that it can be used by 
> generic framework
>      being thought out
> Link: 
> https://lore.kernel.org/qemu-devel/20240519210620.228342-1-salil.mehta@huawei.com/
> Link: 
> https://lore.kernel.org/qemu-devel/e94b0e14-efee-4050-9c9f-08382a36b63a@linaro.org/
> 
> Patch-set  V8 -> V9
> 1. Addressed Vishnu Pajjuri's (Ampere) comments
>    - Added kvm_fd to trace in kvm_create_vcpu
>    - Some clean ups: arch vcpu-id and sbd variable
>    - Added the missed initialization of cpu->gdb_num_regs
> 2. Addressed the commnet from Zhao Liu (Intel)
>    - Make initialization of CPU Hotplug state conditional 
> (possible_cpu_arch_ids!=NULL)
> Link: 
> https://lore.kernel.org/qemu-devel/20240312020000.12992-1-salil.mehta@huawei.com/
> 
> Patch-set V7 -> V8
> 1. Rebased and Fixed the conflicts
> 
> Patch-set  V6 -> V7
> 1. Addressed Alex Bennée's comments
>    - Updated the docs
> 2. Addressed Igor Mammedov's comments
>    - Merged patches [Patch V6 3/9] & [Patch V6 7/9] with [Patch V6 4/9]
>    - Updated commit-log of [Patch V6 1/9] and [Patch V6 5/9]     
> 3. Added Shaoqin Huang's Reviewed-by tags for whole series.
> Link: 
> https://lore.kernel.org/qemu-devel/20231013105129.25648-1-salil.mehta@huawei.com/
> 
> Patch-set  V5 -> V6
> 1. Addressed Gavin Shan's comments
>    - Fixed the assert() ranges of address spaces
>    - Rebased the patch-set to latest changes in the qemu.git
>    - Added Reviewed-by tags for patches {8,9}
> 2. Addressed Jonathan Cameron's comments
>    - Updated commit-log for [Patch V5 1/9] with mention of trace events
>    - Added Reviewed-by tags for patches {1,5}
> 3. Added Tested-by tags from Xianglai Li
> 4. Fixed checkpatch.pl error "Qemu -> QEMU" in [Patch V5 1/9] 
> Link: 
> https://lore.kernel.org/qemu-devel/20231011194355.15628-1-salil.mehta@huawei.com/
> 
> Patch-set  V4 -> V5
> 1. Addressed Gavin Shan's comments
>    - Fixed the trace events print string for 
> kvm_{create,get,park,destroy}_vcpu
>    - Added Reviewed-by tag for patch {1}
> 2. Added Shaoqin Huang's Reviewed-by tags for Patches {2,3}
> 3. Added Tested-by Tag from Vishnu Pajjuri to the patch-set
> 4. Dropped the ARM specific [Patch V4 10/10]
> Link: 
> https://lore.kernel.org/qemu-devel/20231009203601.17584-1-salil.mehta@huawei.com/
> 
> Patch-set  V3 -> V4
> 1. Addressed David Hilderbrand's comments
>    - Fixed the wrong doc comment of kvm_park_vcpu API prototype
>    - Added Reviewed-by tags for patches {2,4}
> Link: 
> https://lore.kernel.org/qemu-devel/20231009112812.10612-1-salil.mehta@huawei.com/
> 
> Patch-set  V2 -> V3
> 1. Addressed Jonathan Cameron's comments
>    - Fixed 'vcpu-id' type wrongly changed from 'unsigned long' to 'integer'
>    - Removed unnecessary use of variable 'vcpu_id' in kvm_park_vcpu
>    - Updated [Patch V2 3/10] commit-log with details of ACPI_CPU_SCAN_METHOD 
> macro
>    - Updated [Patch V2 5/10] commit-log with details of conditional event 
> handler method
>    - Added Reviewed-by tags for patches {2,3,4,6,7}
> 2. Addressed Gavin Shan's comments
>    - Remove unnecessary use of variable 'vcpu_id' in kvm_par_vcpu
>    - Fixed return value in kvm_get_vcpu from -1 to -ENOENT
>    - Reset the value of 'gdb_num_g_regs' in gdb_unregister_coprocessor_all
>    - Fixed the kvm_{create,park}_vcpu prototypes docs
>    - Added Reviewed-by tags for patches {2,3,4,5,6,7,9,10}
> 3. Addressed one earlier missed comment by Alex Bennée in RFC V1
>    - Added traces instead of DPRINTF in the newly added and some existing 
> functions
> Link: 
> https://lore.kernel.org/qemu-devel/20230930001933.2660-1-salil.mehta@huawei.com/
> 
> Patch-set V1 -> V2
> 1. Addressed Alex Bennée's comments
>    - Refactored the kvm_create_vcpu logic to get rid of goto
>    - Added the docs for kvm_{create,park}_vcpu prototypes
>    - Splitted the gdbstub and AddressSpace destruction change into separate 
> patches
>    - Added Reviewed-by tags for patches {2,10}
> Link: 
> https://lore.kernel.org/qemu-devel/20230929124304.13672-1-salil.mehta@huawei.com/
> 
> References:
> 
> [1] 
> https://lore.kernel.org/qemu-devel/20230926100436.28284-1-salil.mehta@huawei.com/
> [2] https://lore.kernel.org/all/20230913163823.7880-1-james.morse@arm.com/
> [3] 
> https://lore.kernel.org/qemu-devel/cover.1695697701.git.lixianglai@loongson.cn/
> [4] 
> https://lore.kernel.org/qemu-devel/20240613233639.202896-2-salil.mehta@huawei.com/
> 
> Salil Mehta (7):
>   accel/kvm: Extract common KVM vCPU {creation,parking} code
>   hw/acpi: Move CPU ctrl-dev MMIO region len macro to common header file
>   hw/acpi: Update ACPI GED framework to support vCPU Hotplug
>   hw/acpi: Update GED _EVT method AML with CPU scan
>   hw/acpi: Update CPUs AML with cpu-(ctrl)dev change
>   physmem: Add helper function to destroy CPU AddressSpace
>   gdbstub: Add helper function to unregister GDB register space
> 
>  accel/kvm/kvm-all.c                    | 95 +++++++++++++++++---------
>  accel/kvm/kvm-cpus.h                   |  1 -
>  accel/kvm/trace-events                 |  5 +-
>  docs/specs/acpi_hw_reduced_hotplug.rst |  3 +-
>  gdbstub/gdbstub.c                      | 13 ++++
>  hw/acpi/acpi-cpu-hotplug-stub.c        |  6 ++
>  hw/acpi/cpu.c                          | 18 +++--
>  hw/acpi/generic_event_device.c         | 27 ++++++++
>  hw/core/cpu-common.c                   |  4 +-
>  hw/i386/acpi-build.c                   |  3 +-
>  include/exec/cpu-common.h              |  8 +++
>  include/exec/gdbstub.h                 |  6 ++
>  include/hw/acpi/cpu.h                  |  7 +-
>  include/hw/acpi/generic_event_device.h |  5 ++
>  include/hw/core/cpu.h                  |  1 +
>  include/sysemu/kvm.h                   | 25 +++++++
>  system/physmem.c                       | 29 ++++++++
>  17 files changed, 212 insertions(+), 44 deletions(-)
>