linux-kernel - Re: hpsa driver bug crack kernel down!

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Date:	Mon, 14 Apr 2014 15:01:07 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Davidlohr Bueso <davidlohr@...com>,
	"Woodhouse, David" <david.woodhouse@...el.com>
CC:	"joro@...tes.org" <joro@...tes.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"bhe@...hat.com" <bhe@...hat.com>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"James.Bottomley@...senpartnership.com" 
	<James.Bottomley@...senpartnership.com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"scameron@...rdog.cce.hp.com" <scameron@...rdog.cce.hp.com>
Subject: Re: hpsa driver bug crack kernel down!

Hi Davidlohr,
	Thanks for the information!
	According to lspci output, device 0000:02:00.2 is HP ILO
controller, device 0000:03:00.0 is RAID controller. Both ILO and
RAID controllers need to access reserved memory range
[0x7f61e000 - 0x7f61ffff] in physical mode.

	According to dmesg output, BIOS has reserved memory and
IOMMU has setup 1:1 mapping for ILO and RAID controller to access
this range. Related log messages as below:
BIOS-e820: [mem 0x000000007f61d000-0x000000008fffffff] reserved
IOMMU: Setting RMRR:
IOMMU: Setting identity map for device 0000:03:00.0 [0x7f61e000 -
0x7f61ffff]
IOMMU: Setting identity map for device 0000:02:00.0 [0x7f61e000 -
0x7f61ffff]
IOMMU: Setting identity map for device 0000:02:00.2 [0x7f61e000 -
0x7f61ffff]
	
	From the screenshot, device 0000:02:00.2 fails to access
memory address 0x7f61e000. That indicates IOMMU driver fails to
setup 1:1 mapping for Reserved Memory Range for ILO controller.
So could you please help to check whether you could observe boot
messages like "IOMMU: Setting identity map for device 0000:02:00.2
[0x7f61e000 - 0x7f61ffff]" with the failure kernel image?

	It would be great if boot messages could be saved when
failing to boot, so we could get more information from log.

	BTW, I have double checked related code, and still can't
find a reliable explanation for the regression:(

Thanks!
Gerry

On 2014/4/11 0:19, Davidlohr Bueso wrote:
> On Thu, 2014-04-10 at 08:46 +0000, Woodhouse, David wrote:
>> On Thu, 2014-04-10 at 09:15 +0200, Joerg Roedel wrote:
>>> [+ David, VT-d maintainer ]
>>>
>>> Jiang, David, can you please have a look into this issue?
>>>
>>
>>>>>>>>>>> DMAR:[fault reason 02] Present bit in context entry is clear
>>>>>>>>>>> dmar: DRHD: handling fault status reg 602
>>>>>>>>>>> dmar: DMAR:[DMA Read] Request device [02:00.0] fault addr 7f61e000
>>
>> That "Present bit in context entry is clear" fault means that we have
>> not set up *any* mappings for this PCI device… on this IOMMU.
>>
>>>> Yes, specifically (finally done bisecting):
>>>>
>>>> commit 2e45528930388658603ea24d49cf52867b928d3e
>>>> Author: Jiang Liu <jiang.liu@...ux.intel.com>
>>>> Date:   Wed Feb 19 14:07:36 2014 +0800
>>>>
>>>>     iommu/vt-d: Unify the way to process DMAR device scope array
>>
>> This commit is about how we decide which IOMMU a given PCI device is
>> attached to.
>>
>> Thus, my first guess would be that we are quite happily setting up the
>> requested DMA maps on the *wrong* IOMMU, and then taking faults when the
>> device actually tries to do DMA.
>>
>> However, I'm not 100% convinced of that. The fault address looks
>> suspiciously like a true physical address, not a virtual bus address of
>> the type that we'd normally allocate for a dma_map_* operation. Those
>> would start at 0xfffff000 and work downwards, typically.
>>
>> Do you have 'iommu=pt' on the kernel command line? 
> 
> No.
> 
>> Can I see the full
>> dmesg as this system boots, and also a copy of the DMAR table?
> 
> Attaching a dmesg from one of the kernels that boots. It doesn't appear
> to have much of the related information... is there any debug config
> option I can enable that might give you more data?
> 
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