From mboxrd@z Thu Jan  1 00:00:00 1970
From: Scott Wood <scottwood@freescale.com>
Subject: Re: [v1][PATCH 1/1] KVM: PPC: disable preemption when using
 hard_irq_disable()
Date: Wed, 10 Jul 2013 14:15:40 -0500
Message-ID: <1373483740.8183.223@snotra>
References: <1373436139-27998-1-git-send-email-tiejun.chen@windriver.com>
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Cc: <agraf@suse.de>, <kvm-ppc@vger.kernel.org>, <kvm@vger.kernel.org>,
	<linuxppc-dev@lists.ozlabs.org>
To: Tiejun Chen <tiejun.chen@windriver.com>
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In-Reply-To: <1373436139-27998-1-git-send-email-tiejun.chen@windriver.com>
	(from tiejun.chen@windriver.com on Wed Jul 10 01:02:19 2013)
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On 07/10/2013 01:02:19 AM, Tiejun Chen wrote:
> We should ensure the preemption cannot occur while calling get_paca()
> insdide hard_irq_disable(), otherwise the paca_struct may be the
> wrong one just after. And btw, we may update timing stats in this  
> case.

The soft-ee mechanism depends on accessing the PACA directly via r13 to  
avoid this.  We probably should be using inline asm to read was_enabled  
rather than hoping the compiler doesn't do anything silly.

Plus what Alex said, regarding this patch specifically.

-Scott