Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] x86/speculation/l1tf: fix off-by-one error when warning
 that system has too much RAM
To:     Andre Tomt <andre@tomt.net>, Andi Kleen <ak@linux.intel.com>,
        Vlastimil Babka <vbabka@suse.cz>
Cc:     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,
        George Anchev <studio@anchev.net>
References: <20180823134418.17008-1-vbabka@suse.cz>
 <20180823154437.GC12066@tassilo.jf.intel.com>
 <0fa72221-2272-4489-d9d3-0f68cb874087@tomt.net>
From:   Christopher Snowhill <kode54@gmail.com>
Message-ID: <73314d45-85bc-2a7d-a839-9c9ab4260592@gmail.com>
Date:   Tue, 28 Aug 2018 19:04:03 -0700
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On 08/23/2018 07:22 PM, 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.
>

Indeed, I must be "very brave" to not have chucked this CPU and
motherboard and RAM in the bin, and bought a new board, Xeon CPU, and
ECC RAM. Maybe I'll consider that in the future, when I again have
$1000+ to buy new kit. Which will probably be never, at this rate.

>> [=C2=A0=C2=A0=C2=A0 0.000000] microcode: microcode updated early to re=
vision 0x20,
>> date =3D 2018-04-10
>> [=C2=A0=C2=A0=C2=A0 0.029728] L1TF: System has more than MAX_PA/2 memo=
ry. L1TF
>> mitigation not effective.
>> [=C2=A0=C2=A0=C2=A0 1.063155] microcode: sig=3D0x306a9, pf=3D0x2, revi=
sion=3D0x20
>
>
>> processor=C2=A0=C2=A0=C2=A0 : 7
>> vendor_id=C2=A0=C2=A0=C2=A0 : GenuineIntel
>> cpu family=C2=A0=C2=A0=C2=A0 : 6
>> model=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : 58
>> model name=C2=A0=C2=A0=C2=A0 : Intel(R) Xeon(R) CPU E3-1230 V2 @ 3.30G=
Hz
>> stepping=C2=A0=C2=A0=C2=A0 : 9
>> microcode=C2=A0=C2=A0=C2=A0 : 0x20
>> cpu MHz=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : 3500.044
>> cache size=C2=A0=C2=A0=C2=A0 : 8192 KB
>> physical id=C2=A0=C2=A0=C2=A0 : 0
>> siblings=C2=A0=C2=A0=C2=A0 : 8
>> core id=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : 3
>> cpu cores=C2=A0=C2=A0=C2=A0 : 4
>> apicid=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : 7
>> initial apicid=C2=A0=C2=A0=C2=A0 : 7
>> fpu=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : yes
>> fpu_exception=C2=A0=C2=A0=C2=A0 : yes
>> cpuid level=C2=A0=C2=A0=C2=A0 : 13
>> wp=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : yes
>> flags=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : fpu vme de pse tsc m=
sr pae mce cx8 apic sep mtrr pge
>> mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
>> syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl
>> xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor
>> ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic
>> popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm
>> cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority
>> ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts flush_l1d=

>> bugs=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 : cpu_meltdown spectre_=
v1 spectre_v2 spec_store_bypass l1tf
>> bogomips=C2=A0=C2=A0=C2=A0 : 6602.15
>> clflush size=C2=A0=C2=A0=C2=A0 : 64
>> cache_alignment=C2=A0=C2=A0=C2=A0 : 64
>> address sizes=C2=A0=C2=A0=C2=A0 : 36 bits physical, 48 bits virtual
>> power management:
>
>


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