Re: [PATCH v2] vfio: noiommu check error handling

["Jonas Pfefferle" <pepperjo@japf.ch>]

  On Mon, 15 Jan 2018 17:11:58 +0100
  Thomas Monjalon <thomas@monjalon.net> wrote:
> 15/01/2018 13:22, Jonas Pfefferle:
>> 
>>   On Sat, 13 Jan 2018 23:49:30 +0100
>>   Thomas Monjalon <thomas@monjalon.net> wrote:
>> > 13/01/2018 13:15, Burakov, Anatoly:
>> >> On 11-Jan-18 11:45 PM, Thomas Monjalon wrote:
>> >> > 07/11/2017 10:50, Jonas Pfefferle1:
>> >> >>> Is there something urgent for 17.11?
>> >> >>> Or can it be refined in 18.02?
>> >> >>
>> >> >> Nothing urgent. We can refine this for 18.02.
>> >> >>
>> >> >>> Anatoly, any thought?
>> >> > 
>> >> > Anatoly, Jonas, how do you want to proceed with this patch?
>> >> > 
>> >> 
>> >> I don't see anything to be refined here, it's a simple bug fix - 
>> >>code 
>> >> assumes noiommu mode support is always available, when it might 
>>not 
>> >>be 
>> >> the case on older kernels.
>> > 
>> > As a bug fix, the title must start with "fix" and a tag "Fixes:"
>> > must be added to help with backport.
>> > At the same time, the explanation of the bug must be added in
>> > the commit log please.
>> > 
>> > Thanks
>> 
>> It's not really a bug fix since it does not change the semantic of 
>>the 
>> function but just adds nicer error handling.
>> Regarding redefining the code: What I don't like is the special 
>>cases 
>> we have to check for when using the sPAPR iommu because it does not 
>> support VA mappings yet. I think we should decide which iova mode to 
>> use based on the iommu types available, i.e. each iommu type should 
>> report which iova type it supports. Thoughts?
> 
> Have you looked at what Maxime did?
> 	https://dpdk.org/dev/patchwork/patch/33650/
> 
> How does it affect this patch?
> 
> 

IMO it has the same problem. We shouldn't add more exception cases in 
drivers/bus/pci/linux/pci.c but instead keep all the information about 
what an IOMMU can do in lib/librte_eal/linuxapp/eal/eal_vfio.c