linux-kernel - Re: [PATCH v2] irqchip/gic-v3-its: Allow GIC ITS number more than MAX_NUMNODES

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Message-ID: <5e8aacb2-9c20-0f4a-2c5e-721fe82bfc60@arm.com>
Date:   Wed, 26 Jul 2017 12:05:49 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Hanjun Guo <hanjun.guo@...aro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Hanjun Guo <guohanjun@...wei.com>
Cc:     Marc Zyngier <marc.zyngier@....com>, linux-kernel@...r.kernel.org,
        linuxarm@...wei.com, linux-acpi@...r.kernel.org,
        Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] irqchip/gic-v3-its: Allow GIC ITS number more than
 MAX_NUMNODES

On 26/07/17 09:11, Hanjun Guo wrote:
> On 2017/7/25 18:47, Lorenzo Pieralisi wrote:
>> On Sat, Jul 22, 2017 at 11:54:12AM +0800, Hanjun Guo wrote:
>>> From: Hanjun Guo <hanjun.guo@...aro.org>
>>>
>>> When running 4.13-rc1 on top of D05, I got the boot log:
>>
>> Nit: You should stick to what the problem is and why you need to solve
>> it, "Fixes:" tag gives the commit history you need, the rest (eg "When
>> running 4.13-rc1") does not belong in the commit log.
> 
> Updated as "After enabling the ITS NUMA support on D05, I got
> the boot log:"
> 
>>
>>> [    0.000000] SRAT: PXM 0 -> ITS 0 -> Node 0
>>> [    0.000000] SRAT: PXM 0 -> ITS 1 -> Node 0
>>> [    0.000000] SRAT: PXM 0 -> ITS 2 -> Node 0
>>> [    0.000000] SRAT: PXM 1 -> ITS 3 -> Node 1
>>> [    0.000000] SRAT: ITS affinity exceeding max count[4]
>>>
>>> This is wrong on D05 as we have 8 ITSes with 4 NUMA nodes.
>>>
>>> So dynamically alloc the memory needed instead of using
>>> its_srat_maps[MAX_NUMNODES], which count the number of
>>> ITS entry(ies) in SRAT and alloc its_srat_maps as needed,
>>> then build the mapping of numa node to ITS ID. Of course,
>>> its_srat_maps will be freed after ITS probing because
>>> we don't need that after boot.
>>>
>>> After doing this, I got what I wanted:
>>>
>>> [    0.000000] SRAT: PXM 0 -> ITS 0 -> Node 0
>>> [    0.000000] SRAT: PXM 0 -> ITS 1 -> Node 0
>>> [    0.000000] SRAT: PXM 0 -> ITS 2 -> Node 0
>>> [    0.000000] SRAT: PXM 1 -> ITS 3 -> Node 1
>>> [    0.000000] SRAT: PXM 2 -> ITS 4 -> Node 2
>>> [    0.000000] SRAT: PXM 2 -> ITS 5 -> Node 2
>>> [    0.000000] SRAT: PXM 2 -> ITS 6 -> Node 2
>>> [    0.000000] SRAT: PXM 3 -> ITS 7 -> Node 3
>>
>> Question (unrelated): how are PCI devices (or better PCI host bridges)
>> mapped to ITSs ? I ask because in IORT we currently ignore the notion
>> of ITS groups - so it is just out of curiosity (I suspect you have
>> a static 1:1 mapping PCI-host-bridge->ITS).
> 
> Yes, on D05 we enabled 8 ITSs, and also have 8 PCI hostbridges, here is
> the IORT for D05:
> 
> https://github.com/hisilicon/OpenPlatformPkg/blob/bb17676e6c529732af8adf438fc2c8ceeb9b3271/Chips/Hisilicon/Hi1616/D05AcpiTables/D05Iort.asl

On a further side note, do the SMMUs really have no interrupts, or is
that just a hack to avoid MBIgen-related problems? Now that we have
working probe-deferral for IOMMU masters, it ought to be possible to
address any dependency by deferring the SMMU itself until the IRQs are
available. At a glance I guess ACPI doesn't make it as easy as
of_irq_get() does, but it might be worth looking into.

Robin.

>>> Fixes: dbd2b8267233 ("irqchip/gic-v3-its: Add ACPI NUMA node mapping")
>>> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
>>> Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
>>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>>> Cc: Marc Zyngier <marc.zyngier@....com>
>>> ---
>>>
>>> v1->v2:
>>>    - Add NULL check in acpi_get_its_numa_node() for no ITS affinity
>>> case;
>>>    - Free the its_srat_maps after ITS probing.
>>>
>>>   drivers/irqchip/irq-gic-v3-its.c | 39
>>> ++++++++++++++++++++++++++++++++-------
>>
>> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> 
> Thanks!
> 
> Hanjun
> 
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