linux-kernel - DMAR faults from unrelated device when vfio is used

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Message-ID: <1359972630.2498.21.camel@riven-lux.site>
Date:	Mon, 04 Feb 2013 11:10:30 +0100
From:	David Gstir <david@...ma-star.at>
To:	kvm@...r.kernel.org
Cc:	dwmw2@...radead.org, alex.williamson@...hat.com,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	airlied@...ux.ie, dri-devel@...ts.freedesktop.org,
	daniel.vetter@...ll.ch, richard@...ma-star.at
Subject: DMAR faults from unrelated device when vfio is used

Hi!

I get the following error messages over and over again when using vfio in qemu-kvm:

[ 1692.021403] dmar: DMAR:[DMA Read] Request device [00:02.0] fault addr 1a45aa9000 
[ 1692.021403] DMAR:[fault reason 12] non-zero reserved fields in PTE
[ 1692.021416] dmar: DRHD: handling fault status reg 2

This pci device is the graphics card, which I did not assign to qemu! I did assign the following devices:
00:1a.0, 00:1b.0, 00:1c.0, 00:1c.6, 00:1d.0, 03:00.0.

The error occurs at random and is not reproducible every time. It happens about every third reboot. 
I'm running qemu-kvm 1.3.0 (kvm-1.3.0-187.3), kernel 3.8.0-rc5 and windows 7 as guest OS. The hardware uses an Intel IOMMU. See attachments for output of lspci, and details on iommu groups

I'm not sure if this problem originates from qemu, kvm, vfio or the GPU driver.
Do you have any hints how to debug this further?

Thanks,
David

PS: please cc me, I'm not subscribed.

View attachment "lspci.txt" of type "text/plain" (22840 bytes)

View attachment "iommu_groups.txt" of type "text/plain" (3205 bytes)