linux-kernel - Re: [PATCH 0/5] i387: stable kernel backport

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Date:	Thu, 23 Feb 2012 14:55:11 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Willy Tarreau <w@....eu>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Raphael Prevost <raphael@...o.asia>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/5] i387: stable kernel backport

On 02/23/2012 02:52 PM, Willy Tarreau wrote:
> On Thu, Feb 23, 2012 at 02:48:51PM -0800, H. Peter Anvin wrote:
>> On 02/23/2012 02:38 PM, Linus Torvalds wrote:
>>>
>>> You'd still need an x86-32 machine to test on, because x86-64 was
>>> immune to this issue.
>>>
>>> But yeah, the impact of this seems to be small enough that for older
>>> kernels (which are likely used on older systems for maintenance
>>> anyway) disabling AES-NI on x86-32 really might be the way to go.
>>>
>>
>> That would really suck for users of encrypted hard disks.
> 
> Peter, do you really think there are that many ? I think I only saw
> AES-NI on recent 64-bit capable chips, and it's been a while that
> users have been installing 64-bit distros on such machines. Note that
> I'm not advocating for breaking existing setups, just that I'm surprized
> by this combination (aes-ni + 32-bit).
> 

There are still people running 32-bit systems because they have some odd
compatibility constraints but now have to deal with corporate or other
security constraints; they may also have been using disk encryption
since before AES-NI was in but doing it on the integer side is way slower.

This is not AES-NI in the interrupt path, but I don't think there is a
knob for that.

	-hpa


-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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