Re: [RFC + Queries] Flow of PCI passthrough in ARM

[Julien Grall <julien.grall@linaro.org>]

Hi Manish,

On 06/11/2014 16:20, manish jaggi wrote:
> On 6 November 2014 21:37, Stefano Stabellini
> <stefano.stabellini@eu.citrix.com> wrote:
>> On Thu, 6 Nov 2014, Julien Grall wrote:
>>> Hi Manish,
>>>
>>> On 06/11/2014 15:55, manish jaggi wrote:
>>>> On 6 November 2014 21:18, Stefano Stabellini
>>>> <stefano.stabellini@eu.citrix.com> wrote:
>>>>> On Thu, 6 Nov 2014, manish jaggi wrote:
>>>>>> On 20 October 2014 20:24, Stefano Stabellini
>>>>>> <stefano.stabellini@eu.citrix.com> wrote:
>>>>>>> On Mon, 20 Oct 2014, manish jaggi wrote:
>>>>>>>> On 8 October 2014 20:21, Konrad Rzeszutek Wilk
>>>>>>>> <konrad.wilk@oracle.com> wrote:
>>>>>>>>> On Wed, Oct 08, 2014 at 07:17:48PM +0530, manish jaggi wrote:
>>>>>>>>>> On 8 October 2014 19:15, Ian Campbell <Ian.Campbell@citrix.com>
>>>>>>>>>> wrote:
>>>>>>>>>>> On Wed, 2014-10-08 at 19:07 +0530, manish jaggi wrote:
>>>>>>>>>>>> Thanks for replying. As detailed in this thread, I need to
>>>>>>>>>>>> create a
>>>>>>>>>>>> hypercall that would send the following information to Xen
>>>>>>>>>>>> at the time
>>>>>>>>>>>> of PCI attach
>>>>>>>>>>>> { sbdf , domU sbdf, domainId }.
>>>>>>>>>>>> I am not able to find a way to get the domU sbdf from dom0
>>>>>>>>>>>> at the time
>>>>>>>>>>>> of pci-attach.
>>>>>>>>>>>
>>>>>>>>>>> I think it would need to be done by the pciback driver in the
>>>>>>>>>>> dom0
>>>>>>>>>>> kernel, which AFAIK is the thing which consistently knows both
>>>>>>>>>>> physical
>>>>>>>>>>> and virtual sbdf for a given assigned device.
>>>>>>>>>>>
>>>>>>>>>>> Ian.
>>>>>>>>>>>
>>>>>>>>>> Correct, can you point out which data structure holds the domU
>>>>>>>>>> sbdf
>>>>>>>>>> corresponding to the actual sbdf in pciback.
>>>>>>>>>
>>>>>>>>> See 'xen_pcibk_export_device' or 'xen_pcibk_publish_pci_root'
>>>>>>>>> is that what you are referring to?
>>>>>>>>
>>>>>>>> Xen docs also mention about xen-pciback.passthrough=1. If I set this
>>>>>>>> in dom0 i see that the device is enumerated as the same sbdf in
>>>>>>>> domU,
>>>>>>>> but
>>>>>>>> a) it is not shown in lspci
>>>>>>>> b) no front-back communication is done for reading devices
>>>>>>>> configuration space
>>>>>>>> .
>>>>>>>> Is option useful / fully implemented for ARM ?
>>>>>>>
>>>>>>> I don't think this option is very useful. I wouldn't worry about it
>>>>>>> for
>>>>>>> now.
>>>>>>
>>>>>> Stefano / Ian / Konard / Julien,
>>>>>>
>>>>>> Attached is a first raw code FYI RFC Patches of PCI passthrough support
>>>>>> on ARM.
>>>>>> - Linux Patch (3.18)
>>>>>> - Xen Patch  (4.5 staging)
>>>>>> ---(Smmu changes not included, thats a separate patch altogether)
>>>>>> This patches show the logic, at places need of improvements in code
>>>>>> organization/quality. I wanted to share to get initial comments.
>>>>>> This is working with SRIOV as well.
>>>>>>
>>>>>> Please have a look and let me know your positive comments
>>>>>
>>>>> Please send as individual inline patches. not attachments.
>>>>> Please also add a proper description to each patch and an entry 0/N email
>>>>> with the high level explanation of your work.
>>>>>
>>>>> See http://wiki.xenproject.org/wiki/Submitting_Xen_Project_Patches
>>>> Stefano I just wanted to share the patches as reference to our
>>>> discussion on the approach. Please recall I had shared in this mail a
>>>> design flow. These are just an extension to it. I wanted to move this
>>>> discussion to a conclusion
>>>> There are not patches which I am submitting to xen git.
>>>> If you are ok with the approach I will formally send the patches post
>>>> 4.5 release.
>>>
>>> In this case you can send the patch series tagged "[RFC]" in the subject.
>>
>> That's right. It is difficult to give even just an early feedback
>> without the patch descriptions.
>>
> I assumed that the context is preserved in this mail thread. I shared
> the flow in the first few mails and am sharing the code after a lot of
> discussion in this thread.

There is about 30 mails in this discussion. It's better if you give a 
summary, it will avoid us to read again all the mails to find the 
conclusion.

> Anyhow I will share the code as RFC in some time.

Thanks,

Regards,

-- 
Julien Grall