From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zachary Amsden <zamsden@redhat.com>
Subject: Re: [PATCH v2: kvm 4/4] Fix hotplug of CPUs for KVM.
Date: Tue, 29 Sep 2009 05:51:28 -1000
Message-ID: <4AC22D00.5010406@redhat.com>
References: <1254197072-889-1-git-send-email-zamsden@redhat.com> <1254197072-889-2-git-send-email-zamsden@redhat.com> <1254197072-889-3-git-send-email-zamsden@redhat.com> <1254197072-889-4-git-send-email-zamsden@redhat.com> <1254197072-889-5-git-send-email-zamsden@redhat.com> <4AC1C59F.6010703@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Marcelo Tosatti <mtosatti@redhat.com>
To: Avi Kivity <avi@redhat.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:47933 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752830AbZI2Pxi (ORCPT <rfc822;kvm@vger.kernel.org>);
	Tue, 29 Sep 2009 11:53:38 -0400
In-Reply-To: <4AC1C59F.6010703@redhat.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On 09/28/2009 10:30 PM, Avi Kivity wrote:
> 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.

That was stray junk in the patch.  Let me rediff...