From mboxrd@z Thu Jan  1 00:00:00 1970
From: Scott Wood <scottwood@freescale.com>
Subject: Re: [PATCH v2 3/4] kvm/ppc: Call trace_hardirqs_on before entry
Date: Fri, 10 May 2013 17:47:00 -0500
Message-ID: <1368226020.19683.14@snotra>
References: <1368155384-11035-1-git-send-email-scottwood@freescale.com>
 <1368155384-11035-4-git-send-email-scottwood@freescale.com>
 <6A3DF150A5B70D4F9B66A25E3F7C888D0700F4FF@039-SN2MPN1-011.039d.mgd.msft.net>
 <518C7A28.4000903@windriver.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; Format="Flowed"; DelSp="Yes"
Content-Transfer-Encoding: 7bit
Cc: Wood Scott-B07421 <B07421@freescale.com>,
 "kvm@vger.kernel.org" <kvm@vger.kernel.org>, Alexander Graf <agraf@suse.de>,
 "kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
 Bhushan Bharat-R65777 <R65777@freescale.com>,
 "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
To: tiejun.chen <tiejun.chen@windriver.com>
Return-path: <linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org>
In-Reply-To: <518C7A28.4000903@windriver.com> (from
 tiejun.chen@windriver.com on Thu May  9 23:40:08 2013)
Content-Disposition: inline
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>
Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org>
List-Id: kvm.vger.kernel.org

On 05/09/2013 11:40:08 PM, tiejun.chen wrote:
> On 05/10/2013 11:34 AM, Bhushan Bharat-R65777 wrote:
>>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
>>> index 705fc5c..eb89b83 100644
>>> --- a/arch/powerpc/kvm/booke.c
>>> +++ b/arch/powerpc/kvm/booke.c
>>> @@ -673,7 +673,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run,  
>>> struct kvm_vcpu
>>> *vcpu)
>>>   		ret = s;
>>>   		goto out;
>>>   	}
>>> -	kvmppc_lazy_ee_enable();
>>> +	kvmppc_fix_ee_before_entry();
>> 
>> local_irq_disable() is called before kvmppc_prepare_to_enter().
> 
> In patch 4, we call hard_irq_disable() once enter  
> kvmppc_prepare_to_enter().

And before patch 4, we have the code near the end of  
kvmppc_prepare_to_enter() that checks lazy_irq_pending() and aborts  
guest entry if there was a race.  If I'd known about that bit of code  
beforehand, I probably wouldn't have bothered with most of patch 4/4,  
but now that it's been done it seems cleaner.

-Scott