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

Willy Tarreau
2012-02-23T23:04:45Z

On Thu, Feb 23, 2012 at 02:55:11PM -0800, H. Peter Anvin wrote:
> 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.

Indeed the combination looks plausible :-)

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

OK. So let's hope this works then !

Willy