linux-kernel - Re: [PATCH] x86/speculation/l1tf: fix off-by-one error when warning that system has too much RAM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180824033540.GI12066@tassilo.jf.intel.com>
Date:   Thu, 23 Aug 2018 20:35:40 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Andre Tomt <andre@...t.net>
Cc:     Vlastimil Babka <vbabka@...e.cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Michal Hocko <mhocko@...nel.org>, stable@...r.kernel.org,
        Christopher Snowhill <kode54@...il.com>,
        George Anchev <studio@...hev.net>
Subject: Re: [PATCH] x86/speculation/l1tf: fix off-by-one error when warning
 that system has too much RAM

On Fri, Aug 24, 2018 at 04:22:57AM +0200, Andre Tomt wrote:
> On 23. aug. 2018 17:44, Andi Kleen wrote:
> > On Thu, Aug 23, 2018 at 03:44:18PM +0200, Vlastimil Babka wrote:
> > > Two users have reported [1] that they have an "extremely unlikely" system
> > > with more than MAX_PA/2 memory and L1TF mitigation is not effective. In fact
> > > it's a CPU with 36bits phys limit (64GB) and 32GB memory, but due to holes
> > > in the e820 map, the main region is almost 500MB over the 32GB limit:
> > 
> > Ah I see it's a client part with very large DIMMs and someone being
> > very brave and using that much memory without ECC.
> 
> FYI; It is also happening on Xeon E3v2 (Ivy Bridge generation) w/ 32GB of
> ECC RAM here, a low-end server part that officially supports up to 32GB.

Good point.

-andi