linux-kernel - Re: [PATCH v2: kvm 4/4] Fix hotplug of CPUs for KVM.

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Message-ID: <4AC1C59F.6010703@redhat.com>
Date:	Tue, 29 Sep 2009 10:30:23 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Zachary Amsden <zamsden@...hat.com>
CC:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Marcelo Tosatti <mtosatti@...hat.com>
Subject: Re: [PATCH v2: kvm 4/4] Fix hotplug of CPUs for KVM.

On 09/29/2009 06:04 AM, Zachary Amsden wrote:
> Both VMX and SVM require per-cpu memory allocation, which is done at module
> init time, for only online cpus.
>
> Backend was not allocating enough structure for all possible CPUs, so
> new CPUs coming online could not be hardware enabled.
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e27b7a9..2cd8bc2 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1716,9 +1716,6 @@ static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
>   {
>   	int cpu = (long)v;
>
> -	if (!kvm_usage_count)
> -		return NOTIFY_OK;
> -
>   	val&= ~CPU_TASKS_FROZEN;
>   	switch (val) {
>   	case CPU_DYING:
>    

I still don't see how this bit can work.  Maybe if we move the 
notification registration to the point where kvm_usage_count is bumped.

-- 
error compiling committee.c: too many arguments to function

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