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Date:   Thu, 23 Aug 2018 20:35:40 -0700
From:   Andi Kleen <ak@linux.intel.com>
To:     Andre Tomt <andre@tomt.net>
Cc:     Vlastimil Babka <vbabka@suse.cz>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H . Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Michal Hocko <mhocko@kernel.org>, stable@vger.kernel.org,
        Christopher Snowhill <kode54@gmail.com>,
        George Anchev <studio@anchev.net>
Subject: Re: [PATCH] x86/speculation/l1tf: fix off-by-one error when warning
 that system has too much RAM
Message-ID: <20180824033540.GI12066@tassilo.jf.intel.com>
References: <20180823134418.17008-1-vbabka@suse.cz>
 <20180823154437.GC12066@tassilo.jf.intel.com>
 <0fa72221-2272-4489-d9d3-0f68cb874087@tomt.net>
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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