Re: [Qemu-devel] [PATCH 0] A series patches for kvm&qemu to enable vcpu destruction in kvm

[Jan Kiszka]

On 2011-11-25 00:35, Liu Ping Fan wrote:
> A series of patches from kvm, qemu to guest. These patches will finally 
> enable vcpu destruction in kvm instance and let vcpu thread exit in qemu.
>  
> Currently, the vcpu online feature enables the dynamical creation of vcpu and 
> vcpu thread, while the offline feature can not destruct the vcpu and let vcpu 
> thread exit, it just halt in kvm. Because currently, the vcpu will only be 
> destructed when kvm instance is destroyed. We can 
> change vcpu as an refer of kvm instance, and then vcpu's destruction MUST and 
> CAN come before kvm's destruction.
> 
> These patches use guest driver to notify the CPU_DEAD event to qemu, and 
> later qemu asks kvm to release the dead vcpu and finally exit the 
> thread. 
> The usage is: 
>       qemu$cpu_set n online
>       qemu$cpu_set n zap   ------------ This will destroy the vcpu-n in kvm 
> and let vcpu thread exit
>      OR       
>       qemu$cpu_set n offline  --------- This will just block vcpu-n in kvm
> 
> Any comment and suggestion are welcome.

The cpu_set command will probably not make it to QEMU upstream
(device_add/delete is the way to go - IMHO). So I would refrain from
adding anything to qemu-kvm at this point anyway. Also, what would be
the advantage of 'zap' from user perspective?

> 
> 
> Patches include:
> |-- guest
> |   `-- 0001-virtio-add-a-pci-driver-to-notify-host-the-CPU_DEAD-.patch
> |-- kvm
> |   |-- 0001-kvm-make-vcpu-life-cycle-separated-from-kvm-instance.patch
> |   `-- 0002-kvm-exit-to-userspace-with-reason-KVM_EXIT_VCPU_DEAD.patch
> `-- qemu
>     |-- 0001-Add-cpu_phyid_to_cpu-to-map-cpu-phyid-to-CPUState.patch
>     |-- 0002-Add-cpu_free-to-support-arch-related-CPUState-releas.patch
>     |-- 0003-Introduce-a-pci-device-cpustate-to-get-CPU_DEAD-even.patch
>     |-- 0004-Release-vcpu-and-finally-exit-vcpu-thread-safely.patch
>     `-- 0005-tmp-patches-for-linux-header-files.patch
> 

I only found kvm patch 0001 so far. Something probably went wrong with
your postings.

Jan

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