linux-kernel - Re: [BUG] x86 : i486 reporting to be vulnerable to Meltdown/Spectre_V1/Spectre

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Message-ID: <1517944227.3677.15.camel@infradead.org>
Date:   Tue, 06 Feb 2018 19:10:27 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>, whiteheadm@....org
Cc:     Hugh Dickins <hughd@...gle.com>, dave.hansen@...ux.intel.com,
        jikos@...nel.org, Borislav Petkov <bp@...en8.de>,
        Guenter Roeck <linux@...ck-us.net>,
        Kees Cook <keescook@...omium.org>,
        Jamie Iles <jamie@...ieiles.com>, eduval@...zon.com,
        labbott@...hat.com, Rik van Riel <riel@...riel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [BUG] x86 : i486 reporting to be vulnerable to
 Meltdown/Spectre_V1/Spectre_V2

On Tue, 2018-02-06 at 11:02 -0800, Greg Kroah-Hartman wrote:
> .
> > 
> > David
> >   I believe I got the patch(es) you mention in in the stable 4.15.1 kernel:
> > 
> > Pull x86/pti updates from Thomas Gleixner: "Another set of melted
> > spectrum related changes"
> > (commit 6304672b7f0a5c010002e63a075160856dc4f88d).
> > 
> > Unfortunately, the symptoms I reported remain on at least the i486 and i686.
> 
> Can you try 4.15.2-rc1?  Or how about Linus's kernel tree now?  There
> was a lot of spectrum patches merged just this week that were not in
> 4.15.1.

No, for the 486 it *should* have worked. The interesting commit
is fec9434a12 ("x86/pti: Do not enable PTI on CPUs which are not
vulnerable to Meltdown") which is indeed pulled in with the merge
commit that Matthew mentions.

Matthew, can you show the content of /proc/cpuinfo please? And perhaps
add a printk or two in early_identify_cpu() to work out what's going
on?

Your CPU *should* hit the x86_match_cpu(cpu_no_speculation) case and
not set any of the three bugs, AFAICT.
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