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From: Jerry Snitselaar <jsnitsel@redhat.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: iommu@lists.linux-foundation.org, Will Deacon <will@kernel.org>
Subject: Re: arm-smmu.1.auto: Unhandled context fault starting with 5.4-rc1
Date: Sun, 16 Feb 2020 15:11:10 -0700
Message-ID: <20200216221110.zie3o5opbvarir3h@cantor> (raw)
In-Reply-To: <7c9a234e-78b1-2385-84b8-50744b9c4066@arm.com>

On Fri Feb 14 20, Robin Murphy wrote:
>Hi Jerry,
>
>On 2020-02-14 8:13 pm, Jerry Snitselaar wrote:
>>Hi Will,
>>
>>On a gigabyte system with Cavium CN8xx, when doing a fio test against
>>an nvme drive we are seeing the following:
>>
>>[  637.161194] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x8010003f6000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.174329] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x801000036000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.186887] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x8010002ee000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.199275] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x8010003c7000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.211885] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x801000392000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.224580] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x801000018000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.237241] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x801000360000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.249657] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x8010000ba000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.262120] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x80100003e000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>>[  637.274468] arm-smmu arm-smmu.1.auto: Unhandled context fault: 
>>fsr=0x80000402, iova=0x801000304000, fsynr=0x70091, 
>>cbfrsynra=0x9000, cb=7
>
>Those "IOVAs" don't look much like IOVAs from the DMA allocator - if 
>they were physical addresses, would they correspond to an expected 
>region of the physical memory map?
>
>I would suspect that this is most likely misbehaviour in the NVMe 
>driver (issuing a write to a non-DMA-mapped address), and the SMMU is 
>just doing its job in blocking and reporting it.
>
>>I also reproduced with 5.5-rc7, and will check 5.6-rc1 later today. 
>>I couldn't narrow it down further into 5.4-rc1.
>>I don't know smmu or the code well, any thoughts on where to start 
>>digging into this?
>>
>>fio test that is being run is:
>>
>>#fio -filename=/dev/nvme0n1 -iodepth=64 -thread -rw=randwrite 
>>-ioengine=libaio -bs=4k -runtime=43200 -size=-group_reporting 
>>-name=mytest -numjobs=32
>
>Just to clarify, do other tests work OK on the same device?
>
>Thanks,
>Robin.
>

I was able to get back on the system today. I think I know what the problem is:

[    0.036189] iommu: Gigabyte R120-T34-00 detected, force iommu passthrough mode
[    6.324282] iommu: Default domain type: Translated

So the new default domain code in 5.4 overrides the iommu quirk code setting default
passthrough. Testing a quick patch that tracks whether the default domain was set
in the quirk code, and leaves it alone if it was. So far it seems to be working.

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Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-14 20:13 Jerry Snitselaar
2020-02-14 20:58 ` Robin Murphy
2020-02-16 22:11   ` Jerry Snitselaar [this message]
2020-02-17 13:08     ` Robin Murphy
2020-02-17 14:58       ` Jerry Snitselaar

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