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From: Robin Murphy <robin.murphy@arm.com>
To: Jerry Snitselaar <jsnitsel@redhat.com>,
	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: Fri, 14 Feb 2020 20:58:40 +0000
Message-ID: <7c9a234e-78b1-2385-84b8-50744b9c4066@arm.com> (raw)
In-Reply-To: <20200214201353.qlbqcvpztcx55qud@cantor>

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.
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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 [this message]
2020-02-16 22:11   ` Jerry Snitselaar
2020-02-17 13:08     ` Robin Murphy
2020-02-17 14:58       ` Jerry Snitselaar

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