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

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Date:	Fri, 28 Jun 2013 12:43:26 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Joerg Roedel <joro@...tes.org>
Cc:	Andreas Hartmann <andihartmann@...19freenet.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [ 102/127] iommu/amd: Workaround for ERBT1312

On Fri, 2013-06-28 at 20:29 +0200, Joerg Roedel wrote:
> Hi Alex,
> 
> On Fri, Jun 28, 2013 at 11:49:04AM -0600, Alex Williamson wrote:
> > That's interesting, I PXE boot my system from one NIC then use a
> > different NIC for the iSCSI root.  The PXE boot NIC now screams like
> > this, _until_ I attach it to vfio, then it quiets down.
> 
> Can you please send an example line of the reported fault? The addresses
> it faults on would be interesting.

[   99.613489] AMD-Vi: Event logged [IO_PAGE_FAULT device=02:00.0
domain=0x0000 address=0x000000000008f880 flags=0x0050]

> > > Any idea?
> > 
> > Not really without some digging.  I wonder if it's a new event each time
> > or if something is just not clearing a previous event.  ISTR that a boot
> > used to often, but not always, generate a couple faults between the
> > IOMMU being enabled and the NIC driver being loaded.  All the faults I
> > see are to the same address, so my guess is that it's getting replayed.
> 
> Well, I think it is a problem uncovered by the patch that re-enables the
> event-log interrupt after it happened once. We need to find a strategy
> to cope with those problems.
> 
> To my mind as a quick-fix comes rate-limiting for the printks. Or we use
> the suppress-pf bit in the DTE to suppress all page-faults after the
> first one.
> 
> 
> 	Joerg
> 
> 



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