linux-kernel - Re: DMAR and DRHD errors[DMAR:[fault reason 06] PTE Read access is not set] Vt-d & intel

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Date:	Mon, 17 Dec 2012 11:27:59 -0500
From:	Don Dutile <ddutile@...hat.com>
To:	Robert Hancock <hancockrwd@...il.com>
CC:	Jason Gao <pkill.2012@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org, kvm <kvm@...r.kernel.org>
Subject: Re: DMAR and DRHD errors[DMAR:[fault reason 06] PTE Read access is
 not set] Vt-d & intel_iommu

On 12/15/2012 05:16 PM, Robert Hancock wrote:
> On 12/14/2012 03:32 PM, Don Dutile wrote:
>> On 12/13/2012 04:50 AM, Jason Gao wrote:
>>> Dear List:
>>>
>>> Description of problem:
>>> After installed Centos 6.3(RHEL6.3) on my Dell R710(lastest
>>> bios:Version: 6.3.0,Release Date: 07/24/2012) server,and updated
>>> lastest kernel "2.6.32-279.14.1.el6.x86_64",I want to use the Intel
>>> 82576 ET Dual Port nic's SR-IOV feature,assigning VFs to kvm guest
>>>
>>> appended kernel boot parameter: intel_iommu=on,after boot with the
>>> following messages:
>>>
>>> Dec 13 16:58:15 2 kernel: DRHD: handling fault status reg 2
>>> Dec 13 16:58:15 2 kernel: DMAR:[DMA Read] Request device [03:00.0]
>>> fault addr ffe65000
>>> Dec 13 16:58:15 2 kernel: DMAR:[fault reason 06] PTE Read access is
>>> not set
>>> Dec 13 16:58:15 2 kernel: DRHD: handling fault status reg 102
>>> Dec 13 16:58:15 2 kernel: DMAR:[DMA Read] Request device [03:00.0]
>>> fault addr ffe8a000
>>> Dec 13 16:58:15 2 kernel: DMAR:[fault reason 06] PTE Read access is
>>> not set
>>> Dec 13 16:58:15 2 kernel: scsi 0:0:32:0: Enclosure DP
>>> BACKPLANE 1.07 PQ: 0 ANSI: 5
>>> Dec 13 16:58:15 2 kernel: DRHD: handling fault status reg 202
>>> Dec 13 16:58:15 2 kernel: DMAR:[DMA Read] Request device [03:00.0]
>>> fault addr ffe89000
>>> Dec 13 16:58:15 2 kernel: DMAR:[fault reason 06] PTE Read access is
>>> not set
>>>
>>> full dmesg detail:
>>> http://pastebin.com/BzFQV0jU
>>> lspci -vvv full detail:
>>> http://pastebin.com/9rP2d1br
>>>
>>>
>>> it's a production server,and I'm not sure if this is a critical
>>> problem,how to fix it,any help would be greatly appreciated.
>>
>> DMAR table does not have an entry for this device to this region.
>> Once the driver reconfigs/resets the device to stop polling bios-boot
>> cmd rings and use (new) OS (dma-mapped) rings, there's a period of time
>> during this transition that the hw is babbling away to an area that is no
>> longer mapped.
>
> Maybe some kind of boot PCI quirk is needed to stop the device DMA activity before enabling the IOMMU?
>
No, lack of a *proper* RMRR for this device is the source of the problem;
that's why the RMRR's exist -- so this transition state does not cause these
types of problems.

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