From mboxrd@z Thu Jan  1 00:00:00 1970
From: Scott Wood <scottwood@freescale.com>
Subject: Re: [PATCH v2 2/4] kvm/ppc/booke64: Fix lazy ee handling in
 kvmppc_handle_exit()
Date: Fri, 10 May 2013 17:43:57 -0500
Message-ID: <1368225837.19683.13@snotra>
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Cc: Wood Scott-B07421 <B07421@freescale.com>,
	Alexander Graf <agraf@suse.de>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	Wood Scott-B07421 <B07421@freescale.com>
To: Bhushan Bharat-R65777 <R65777@freescale.com>
Return-path: <kvm-ppc-owner@vger.kernel.org>
In-Reply-To: <6A3DF150A5B70D4F9B66A25E3F7C888D0700F847@039-SN2MPN1-011.039d.mgd.msft.net>
	(from R65777@freescale.com on Fri May 10 00:01:19 2013)
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On 05/10/2013 12:01:19 AM, Bhushan Bharat-R65777 wrote:
> 
> 
> > -----Original Message-----
> > From: kvm-ppc-owner@vger.kernel.org  
> [mailto:kvm-ppc-owner@vger.kernel.org] On
> > Behalf Of Scott Wood
> > Sent: Friday, May 10, 2013 8:40 AM
> > To: Alexander Graf; Benjamin Herrenschmidt
> > Cc: kvm-ppc@vger.kernel.org; kvm@vger.kernel.org;  
> linuxppc-dev@lists.ozlabs.org;
> > Wood Scott-B07421
> > Subject: [PATCH v2 2/4] kvm/ppc/booke64: Fix lazy ee handling in
> > kvmppc_handle_exit()
> >
> > EE is hard-disabled on entry to kvmppc_handle_exit(), so call
> > hard_irq_disable() so that PACA_IRQ_HARD_DIS is set, and  
> soft_enabled
> > is unset.
> >
> > Without this, we get warnings such as  
> arch/powerpc/kernel/time.c:300,
> > and sometimes host kernel hangs.
> >
> > Signed-off-by: Scott Wood <scottwood@freescale.com>
> > ---
> >  arch/powerpc/kvm/booke.c |    5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> > index 1020119..705fc5c 100644
> > --- a/arch/powerpc/kvm/booke.c
> > +++ b/arch/powerpc/kvm/booke.c
> > @@ -833,6 +833,11 @@ int kvmppc_handle_exit(struct kvm_run *run,  
> struct kvm_vcpu
> > *vcpu,
> >  	int r = RESUME_HOST;
> >  	int s;
> >
> > +#ifdef CONFIG_PPC64
> > +	WARN_ON(local_paca->irq_happened != 0);
> > +#endif
> > +	hard_irq_disable();
> 
> It is not actually to hard disable as EE is already clear but to make  
> it looks like hard_disable to host. Right?
> If so, should we write a comment here on why we are doing this?

Yes, I can add a comment.

-Scott