linux-kernel - Re: [PATCH 1/1] iommu: add a dma remap fault reason.

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Message-ID: <51390850.4080400@redhat.com>
Date:	Thu, 07 Mar 2013 16:36:16 -0500
From:	Don Dutile <ddutile@...hat.com>
To:	"Li, Zhen-Hua" <zhen-hual@...com>, iommu@...ts.linux-foundation.org
CC:	Hannes Reinecke <hare@...e.de>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 1/1] iommu: add a dma remap fault reason.

On 03/07/2013 01:31 PM, Don Dutile wrote:
> cc-ing the upstream iommu-list
>
> On 03/05/2013 09:43 PM, Li, Zhen-Hua wrote:
>> The number of dma fault reasons in intel's document are from 1 to 0xD, but in dmar.c I cannot find fault reason 0xD.
>>
>> In this document:
>> Intel Virtualization Technology for Directed I/O Architecture Specification
>> http://download.intel.com/technology/computing/vptech/Intel(r)_VT_for_Direct_IO.pdf
>>
>> Chapter 4. Support For Device-IOTLBs
>>
>> Table 6. Unsuccessful Translated Requests
>>
>> There is fault reason for 0xD not listed in kernel:
>> Present context-entry used to process translation request
>> specifies blocking of Translation Requests (Translation Type (T)
>> field value not equal to 01b).
>>
>> So I think 0xD should be added.
>>
>> Signed-off-by: Li, Zhen-Hua<zhen-hual@...com>
>> ---
>> drivers/iommu/dmar.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
>> index dc7e478..e5cdaf8 100644
>> --- a/drivers/iommu/dmar.c
>> +++ b/drivers/iommu/dmar.c
>> @@ -1083,6 +1083,7 @@ static const char *dma_remap_fault_reasons[] =
>> "non-zero reserved fields in RTP",
>> "non-zero reserved fields in CTP",
>> "non-zero reserved fields in PTE",
>> + "PCE for translation request specifies blocking",
>> };
>>
>> static const char *irq_remap_fault_reasons[] =
>

Yes, the multiple tables, some short, some long, duplicating error codes,
and in this case, putting it out of order, helped this case!

btw -- Suresh not at intel any longer (email bounces)

So, patch looks good to me. Although, I don't know of any code that
actually sets a translation to 'block translation'.... but
for completeness, rest of code does range checking & sizing such
that it's doing the right thing.
The only other thing I can surmize from the dmar.c file is if one
of these faults occurred, an 'unknown error' would have been outputted.

cheers.. Don
> _______________________________________________
> iommu mailing list
> iommu@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

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