[RFC PATCH v2 00/35] ACPI/arm64: add support for virtual cpuhotplug

[Salil Mehta]

> From: James Morse <james.morse at arm.com>
> Sent: Wednesday, September 13, 2023 5:38 PM

[...]

> 
> Hello!
> 
> Changes since RFC-v1:
>  * riscv is new, ia64 is gone
>  * The KVM support is different, and upstream - no need to patch the host.
> 
> ---
> 
> This series adds what looks like cpuhotplug support to arm64 for use in
> virtual machines. It does this by moving the cpu_register() calls for
> architectures that support ACPI out of the arch code by using
> GENERIC_CPU_DEVICES, then into the ACPI processor driver.
> 
> The kubernetes folk really want to be able to add CPUs to an existing VM,
> in exactly the same way they do on x86. The use-case is pre-booting guests
> with one CPU, then adding the number that were actually needed when the
> workload is provisioned.
> 

[...]

> 
> I had a go at switching the remaining architectures over to
> GENERIC_CPU_DEVICES,
> so that the Kconfig symbol can be removed, but I got stuck with powerpc
> and s390.
> 
> I've only build tested Loongarch and riscv. I've removed the ia64 specific
> patches, but left the changes in other patches to make git-grep review of
> renames easier.
> 
> If folk want to play along at home, you'll need a copy of Qemu that
> supports this.
> https://github.com/salil-mehta/qemu.git salil/virt-cpuhp-armv8/rfc-v2-rc6


Please use the latest pushed RFC V2 instead:
https://lore.kernel.org/qemu-devel/20230926100436.28284-1-salil.mehta@huawei.com/T/#m523b37819c4811c7827333982004e07a1ef03879

Repository:
https://github.com/salil-mehta/qemu.git  virt-cpuhp-armv8/rfc-v2


Thanks
Salil.


[...]

> Why is this still an RFC? I'm still looking for confirmation from the
> kubernetes/kata folk that this works for them. Because of this I've culled
> the CC list...
> 
> 
> This series is based on v6.6-rc1, and can be retrieved from:
> https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/virtual_cpu_hotplug/rfc/v2