linux-kernel - Re: [PATCH] intel_irq_remapping: Clean up x2apic optout security warning mess

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Date:	Mon, 4 Feb 2013 13:20:15 -0500
From:	Don Zickus <dzickus@...hat.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Gleb Natapov <gleb@...hat.com>,
	Alex Williamson <alex.williamson@...hat.com>, x86@...nel.org,
	LKML <linux-kernel@...r.kernel.org>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Prarit Bhargava <prarit@...hat.com>
Subject: Re: [PATCH] intel_irq_remapping: Clean up x2apic optout security
 warning mess

On Fri, Feb 01, 2013 at 02:57:43PM -0800, Andy Lutomirski wrote:
> Current kernels print this on my Dell server:
> 
>    ------------[ cut here ]------------
>    WARNING: at drivers/iommu/intel_irq_remapping.c:542
>    intel_enable_irq_remapping+0x7b/0x27e()
>    Hardware name: PowerEdge R620
>    Your BIOS is broken and requested that x2apic be disabled
>    This will leave your machine vulnerable to irq-injection attacks
>    Use 'intremap=no_x2apic_optout' to override BIOS request
>    [...]
>    Enabled IRQ remapping in xapic mode
>    x2apic not enabled, IRQ remapping is in xapic mode
> 
> This is inconsistent with itself -- interrupt remapping is *on*.
> 
> Fix the mess by making the warnings say what they mean and my making
> sure that compatibility format interrupts (the dangerous ones) are
> disabled if x2apic is present regardless of BIOS settings.

Yeah, this fixes the problem on our end too.  Thank Andy!

Cheers,
Don
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