linux-kernel - Re: [PATCH 11/11] EDAC/ghes: Create one memory controller per physical memory array

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Date:   Tue, 24 Mar 2020 19:32:16 +0800
From:   Xiaofei Tan <tanxiaofei@...wei.com>
To:     John Garry <john.garry@...wei.com>, Borislav Petkov <bp@...en8.de>,
        "Robert Richter" <rrichter@...vell.com>
CC:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        James Morse <james.morse@....com>,
        Aristeu Rozanski <aris@...hat.com>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Toshi Kani <toshi.kani@....com>,
        Shiju Jose <shiju.jose@...wei.com>
Subject: Re: [PATCH 11/11] EDAC/ghes: Create one memory controller per
 physical memory array


On 2020/3/18 0:34, John Garry wrote:
> On 16/03/2020 09:51, Borislav Petkov wrote:
>> On Fri, Mar 06, 2020 at 04:13:18PM +0100, Robert Richter wrote:
>>> The ghes driver only creates one memory controller for the whole
>>> system. This does not reflect memory topology especially in multi-node
>>> systems. E.g. a Marvell ThunderX2 system shows:
>>>
>>>   /sys/devices/system/edac/mc/mc0/dimm0
>>>   /sys/devices/system/edac/mc/mc0/dimm1
>>>   /sys/devices/system/edac/mc/mc0/dimm2
>>>   /sys/devices/system/edac/mc/mc0/dimm3
>>>   /sys/devices/system/edac/mc/mc0/dimm4
>>>   /sys/devices/system/edac/mc/mc0/dimm5
>>>   /sys/devices/system/edac/mc/mc0/dimm6
>>>   /sys/devices/system/edac/mc/mc0/dimm7
>>>   /sys/devices/system/edac/mc/mc0/dimm8
>>>   /sys/devices/system/edac/mc/mc0/dimm9
>>>   /sys/devices/system/edac/mc/mc0/dimm10
>>>   /sys/devices/system/edac/mc/mc0/dimm11
>>>   /sys/devices/system/edac/mc/mc0/dimm12
>>>   /sys/devices/system/edac/mc/mc0/dimm13
>>>   /sys/devices/system/edac/mc/mc0/dimm14
>>>   /sys/devices/system/edac/mc/mc0/dimm15
>>>
>>> The DIMMs 9-15 are located on the 2nd node of the system. On
>>> comparable x86 systems there is one memory controller per node. The
>>> ghes driver should also group DIMMs depending on the topology and
>>> create one MC per node.
>>>
>>> There are several options to detect the topology. ARM64 systems
>>> retrieve the (NUMA) node information from the ACPI SRAT table (see
>>> acpi_table_parse_srat()). The node id is later stored in the physical
>>> address page. The pfn_to_nid() macro could be used for a DIMM after
>>> determining its physical address. The drawback of this approach is
>>> that there are too many subsystems involved it depends on. It could
>>> easily break and makes the implementation complex. E.g. pfn_to_nid()
>>> can only be reliable used on mapped address ranges which is not always
>>> granted, there are various firmware instances involved which could be
>>> broken, or results may vary depending on NUMA settings.
>>>
>>> Another approach that was suggested by James' is to use the DIMM's
>>> physical memory array handle to group DIMMs [1]. The advantage is to
>>> only use the information on memory devices from the SMBIOS table that
>>> contains a reference to the physical memory array it belongs too. This
>>> information is mandatory same as the use of DIMM handle references by
>>> GHES to provide the DIMM location of an error. There is only a single
>>> table to parse which eases implementation. This patch uses this
>>> approach for DIMM grouping.
>>>
>>> Modify the DMI decoder to also detect the physical memory array a DIMM
>>> is linked to and create one memory controller per array to group
>>> DIMMs. With the change DIMMs are grouped, e.g. a ThunderX2 system
>>> shows one MC per node now:
>>>
>>>   # grep . /sys/devices/system/edac/mc/mc*/dimm*/dimm_label
>>>   /sys/devices/system/edac/mc/mc0/dimm0/dimm_label:N0 DIMM_A0
>>>   /sys/devices/system/edac/mc/mc0/dimm1/dimm_label:N0 DIMM_B0
>>>   /sys/devices/system/edac/mc/mc0/dimm2/dimm_label:N0 DIMM_C0
>>>   /sys/devices/system/edac/mc/mc0/dimm3/dimm_label:N0 DIMM_D0
>>>   /sys/devices/system/edac/mc/mc0/dimm4/dimm_label:N0 DIMM_E0
>>>   /sys/devices/system/edac/mc/mc0/dimm5/dimm_label:N0 DIMM_F0
>>>   /sys/devices/system/edac/mc/mc0/dimm6/dimm_label:N0 DIMM_G0
>>>   /sys/devices/system/edac/mc/mc0/dimm7/dimm_label:N0 DIMM_H0
>>>   /sys/devices/system/edac/mc/mc1/dimm0/dimm_label:N1 DIMM_I0
>>>   /sys/devices/system/edac/mc/mc1/dimm1/dimm_label:N1 DIMM_J0
>>>   /sys/devices/system/edac/mc/mc1/dimm2/dimm_label:N1 DIMM_K0
>>>   /sys/devices/system/edac/mc/mc1/dimm3/dimm_label:N1 DIMM_L0
>>>   /sys/devices/system/edac/mc/mc1/dimm4/dimm_label:N1 DIMM_M0
>>>   /sys/devices/system/edac/mc/mc1/dimm5/dimm_label:N1 DIMM_N0
>>>   /sys/devices/system/edac/mc/mc1/dimm6/dimm_label:N1 DIMM_O0
>>>   /sys/devices/system/edac/mc/mc1/dimm7/dimm_label:N1 DIMM_P0
>>>
>>> [1] https://lkml.kernel.org/r/f878201f-f8fd-0f2a-5072-ba60c64eefaf@arm.com
>>>
>>> Suggested-by: James Morse <james.morse@....com>
>>> Signed-off-by: Robert Richter <rrichter@...vell.com>
>>> ---
>>>   drivers/edac/ghes_edac.c | 137 ++++++++++++++++++++++++++++++---------
>>>   1 file changed, 107 insertions(+), 30 deletions(-)
>>
>> This is all fine and good but that change affects the one x86 platform
>> we support so the whole patchset should be tested there too. Adding
>> Toshi.
>>
>> As a matter of fact, the final version of this set should be tested on
>> all platforms which are using this thing. Adding John Garry too who
>> reported issues with this driver recently on his platform.
> 
> Adding other RAS-centric guys for H.

Hi John & Borislav & Robert
I have tested this patch set on our platform. Only one memory controller found when there is one DIMM on
each socket or node. Just like this:
estuary:/$ grep . /sys/devices/system/edac/mc/mc*/dimm*/dimm_label
/sys/devices/system/edac/mc/mc0/dimm0/dimm_label:SOCKET 0 CHANNEL 0 DIMM 0 DIMM0
/sys/devices/system/edac/mc/mc0/dimm20/dimm_label:SOCKET 1 CHANNEL 2 DIMM 0 DIMM1

It is not the problem of the patch set. Because our BIOS only defined one "Physical Memory Array Handle" in DMI table.
Just like this:
estuary:/$ dmidecode -t memory | grep "Array Handle"
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000
        Array Handle: 0x0000

BTW, i also test other function of edac driver our platform used. They're all good. :)
> 
> Cheers,
> John
> 
>>
>> Thx.
>>
> 
> 
> .
> 

-- 
 thanks
tanxiaofei