From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [v1][PATCH 1/1] KVM: PPC: disable preemption when using
 hard_irq_disable()
Date: Fri, 12 Jul 2013 13:57:40 +1000
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Cc: Alexander Graf <agraf@suse.de>,
	"<kvm-ppc@vger.kernel.org>" <kvm-ppc@vger.kernel.org>,
	"<kvm@vger.kernel.org> list" <kvm@vger.kernel.org>
To: "tiejun.chen" <tiejun.chen@windriver.com>
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On Fri, 2013-07-12 at 10:13 +0800, tiejun.chen wrote:
> > #define hard_irq_disable()    do {                    \
> >       u8 _was_enabled = get_paca()->soft_enabled;     \
> 
> Current problem I met is issued from the above line.
> 
> >       __hard_irq_disable();                           \
> > -     get_paca()->soft_enabled = 0;                   \
> 
> Not here.
> 
> If I'm misunderstanding what you guys means, please correct me since this is a 
> long discussion thread. I have to reread that carefully.

Then make it
	u8 _was_enabled;
	__hard_irq_disable();
	was_enabled = local_paca->....

Once you have hard disabled, using local_paca directly *should* be safe
(minus that gcc problem I mentioned).

Cheers,
Ben.