Re: [Xen-devel] [ARM] SMMU and PCI passthrough Was: Re: Xen 4.5-rc1 update (RC1 is out 2014-Oct-24th)

[manish jaggi <manishjaggi.oss@xxxxxxxxx>]

On 2 November 2014 15:47, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> (Renaming the subject of the thread).
>
> On 02/11/2014 06:03, manish jaggi wrote:
>>
>> On 1 November 2014 23:13, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
>>>
>>> Hi Konrad,
>>>
>>>
>>> On 31/10/2014 21:01, Konrad Rzeszutek Wilk wrote:
>>>>
>>>>
>>>> On Fri, Oct 31, 2014 at 02:31:41PM +0000, Julien Grall wrote:
>>>>>
>>>>>
>>>>> On 10/31/2014 02:24 PM, Konrad Rzeszutek Wilk wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> *  PVH - PCI passthrough for DomU.
>>>>>>>
>>>>>>>
>>>>>>> I am working on Cavium Thunder (ARM64) on this feature.
>>>>>>> [Xen SMMU driver changes + PCI passthrough changes in Xen and Linux]
>>>>>
>>>>>
>>>>>
>>>>> FYI, I'm currently reworking the SMMU drivers to resync with Linux.
>>>>> With
>>>>> thoses changes, you should not need to modify the SMMU code.
>>>>
>>>>
>>>>
>>>> Thank you for the update. Put your name behind that for 4.6.
>>>>>
>>>>>
>>>>>
>>>>>> Ok, replaced Julien's name with yours. Please make sure
>>>>>> that for the Linux patches you CC xen-devel and the
>>>>>> maintainers (David, Stefano, Boris and me).
>>>>>
>>>>>
>>>>>
>>>>> There is 2 distinct passthrough: platform (i.e non-PCI) and PCI one.
>>>>>
>>>>> While Manish is working on PCI passthrough, I'm still working the
>>>>> non-PCI one. Please don't drop my name.
>>>>
>>>>
>>>>
>>>> I thought that Arianna's patches had taken care of that (the MMIO
>>>> part?). Or does each platform need a different implementation of
>>>> that?
>>>
>>>
>>>
>>> To passthrough a platform device you need to be able to assign the device
>>> to
>>> the guest via the IOMMU and map MMIOs (done by Arianna's series) and
>>> interrupts.
>>>
>> For a PCI passthrough SMMU ops are to be added. The way the smmu for a
>> pci device is found needs to be updated in the smmu.c, so there are
>> some substantial changes to smmu.c for pci passthrough.
>
>
> The SMMU drivers in Linux already supports PCI. As I'm currently resync our
> driver with this version PCI assignment in the SMMU should come freely.
>
> I expect the only plumbing for the Xen callback and few bugs fixes will be
> necessary.
>
we can discuss more on design level. There are changes
>> Also MMIO mapping code the same pci device to be added.
>
>
> Hmmm? What do you mean? MMIO mapping code is definitely not part of the SMMU
> drivers.
>
> IIRC, this should be done by either the toolstack or PCI back in Linux.
>
>> So in short there changes, and as they are in the same files and
>> features are also similar,  is it possible that we work together may
>> be julien can provide a design document (simple txt file would do).
>
>
> There is no need of design document for the SMMU drivers. Everything for DT
> passthrough is already there.
>
It would be helpful if you can provide a basic flow.
>> I
>>
>> have already shared mine in another mail thread with stefano.
>
>
> Could you send a link to this mail?
[RFC + Queries] Flow of PCI passthrough in ARM
>
> Regards,
>
> --
> Julien Grall
>
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