linux-kernel - Re: [ 102/127] iommu/amd: Workaround for ERBT1312

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Message-ID: <51CDD8FD.808@01019freenet.de>
Date:	Fri, 28 Jun 2013 20:42:05 +0200
From:	Andreas Hartmann <andihartmann@...19freenet.de>
To:	Joerg Roedel <joro@...tes.org>
CC:	Alex Williamson <alex.williamson@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [ 102/127] iommu/amd: Workaround for ERBT1312

Hello Joerg,

Joerg Roedel wrote:
> Hi Andreas,
> 
> On Fri, Jun 28, 2013 at 06:11:36PM +0200, Andreas Hartmann wrote:
>> Hello Joerg, hello Alex,
>>
>> the subsequent patch and the patch "iommu/amd: Re-enable IOMMU event log
>> interrupt after handling." 925fe08bce38d1ff052fe2209b9e2b8d5fbb7f98
>> spread /var/log/messages with the following line (> 700 lines/second)
>> right after loading vfio:
>>
>> AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.0 domain=0x0000 address=0x000000fdf9103300 flags=0x0600]
>>
>> lspci -vvvs 0:14.0
>> 00:14.0 SMBus: Advanced Micro Devices [AMD] nee ATI SBx00 SMBus Controller (rev 42)
>>         Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
>>         Status: Cap- 66MHz+ UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
> 
> Most likely a BIOS issue that is uncovered by re-enabling the event-log
> interrupt patch. The device itself is only used by the BIOS and not by
> the Linux kernel

Thanks for this info! Good to know.

[...]

>> I removed the two mentioned patches and all is working
>> fine again as before.
> 
> Without these two patches, can you check dmesg after boot if there are
> other lines which report IO_PAGE_FAULTs?

You're right, there is exactly one entry directly after loading of vfio.
I can see this message, too, with linux 3.4.43.


Regards,
Andreas
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