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

H. Peter Anvin
2012-02-23T22:55:46Z

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.