Re: [PATCH V13 0/8] Add architecture agnostic code to support vCPU Hotplug

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

On Fri, Jun 07, 2024 at 12:56:41PM +0100, Salil Mehta wrote:
> 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]
> 5. Docs [Patch 8]

Igor - it's been a while. Looks ok to me superficially. Do you plan to review?

> 
> Repository:
> 
> [*] https://github.com/salil-mehta/qemu.git virt-cpuhp-armv8/rfc-v3.arch.agnostic.v13
> 
> NOTE: This series is meant to work in conjunction with Architecture specific patch-set.
> For ARM, a combined patch-set (arch agnostic + specific) was earlier pushed as RFC V2[1].
> A ARM architecture specific patch-set (subset of RFC V2) is being finalized and shall
> be floated soon as RFC-V3. Please find a version of it compatible with this patch-set at
> the below location. (TCG support is broken in below and is being fixed)
> 
> [*] https://github.com/salil-mehta/qemu/tree/virt-cpuhp-armv8/rfc-v3-rc2
> 
> 
> Revision History:
> 
> 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/
> 
> 
> 
> Salil Mehta (8):
>   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
>   docs/specs/acpi_hw_reduced_hotplug: Add the CPU Hotplug Event Bit
> 
>  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                          | 33 ++++++---
>  hw/acpi/generic_event_device.c         | 21 ++++++
>  hw/core/cpu-common.c                   |  1 -
>  hw/i386/acpi-build.c                   |  3 +-
>  include/exec/cpu-common.h              |  8 +++
>  include/exec/gdbstub.h                 |  6 ++
>  include/hw/acpi/cpu.h                  |  5 +-
>  include/hw/acpi/cpu_hotplug.h          |  4 ++
>  include/hw/acpi/generic_event_device.h |  4 ++
>  include/hw/core/cpu.h                  |  1 +
>  include/sysemu/kvm.h                   | 25 +++++++
>  system/physmem.c                       | 29 ++++++++
>  18 files changed, 214 insertions(+), 49 deletions(-)
> 
> -- 
> 2.34.1