[PATCH V16 0/7] Add architecture agnostic code to support vCPU Hotplug

[Salil Mehta via <qemu-devel@nongnu.org>]

[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]

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 V16 is the latest version in that series. This series
   works in conjunction with RFC V4-rc3, 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-rc3: https://github.com/salil-mehta/qemu.git virt-cpuhp-armv8/rfc-v4-rc3 (combined)


Revision History:

Patch-set V15 -> V16
1. Addressed feedbacks from Igor Mammedov on [PATCH V15 1/7,3/7,7/7]
   - Fixed the checkpatch.pl errors and warnings
   - Made initialization of CPU hotplug regions within GED realize conditional
   - Collected {Reviewed,Acked}-Bys for [PATCH V15 1/7,2/7,4/7,5/7,7/7]
Link: https://lore.kernel.org/qemu-devel/20240713182516.1457-1-salil.mehta@huawei.com/

Patch-set V14 -> V15
1. Addressed comment by Igor Mammedov 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: 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         | 50 ++++++++++++++
 hw/core/cpu-common.c                   |  5 +-
 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, 236 insertions(+), 44 deletions(-)

-- 
2.34.1