Re: RFC: [PATCH 1/3] Enhance platform support for PCI

[Manish Jaggi <mjaggi@caviumnetworks.com>]

On 23/02/15 8:45 pm, Julien Grall wrote:
> On 23/02/15 11:50, Manish Jaggi wrote:
>> On 23/02/15 4:44 pm, Julien Grall wrote:
>>>
>>> On 23/02/2015 10:59, Manish Jaggi wrote:
>>>> On 20/02/15 8:09 pm, Ian Campbell wrote:
>>>>> On Fri, 2015-02-20 at 19:44 +0530, Manish Jaggi wrote:
>>>>>>> Another option might be a new hypercall (assuming one doesn't already
>>>>>>> exist) to register a PCI bus which would take e.g. the PCI CFG base
>>>>>>> address and return a new u16 segment id to be used for all subsequent
>>>>>>> PCI related calls. This would require the dom0 OS to hook its
>>>>>>> pci_bus_add function, which might be doable (more doable than
>>>>>>> handling
>>>>>>> xen_segment_id DT properties I think).
>>>>>> This seems ok, i will try it out.
>>>>> I recommend you let this subthread (e.g. the conversation with Jan)
>>>>> settle upon a preferred course of action before implementing any one
>>>>> suggestion.
>>>> Ian we have also to consider for NUMA / multi node where there are two
>>>> or more its nodes.
>>>> pci0{
>>>>
>>>> msi-parent = <&its0>;
>>>> }
>>>>
>>>> pci1{
>>>>
>>>> msi-parent = <&its1>;
>>>> }
>>>>
>>>> This requires parsing pci nodes in xen and create a mapping between pci
>>>> nodes and its. Xe would need to be aware of PCI nodes in device tree
>>>> prior to dom0 sending a hypercall. Adding a property to pci node in
>>>> device tree should be a good approach.
>>> Why do you need it early? Wouldn't be sufficient to retrieve those
>>> information when the hypercall pci_device_add is called?
>>>
>> The dom0/U device tree should have one 1 its node, xen should map to
>> specific its when trapped.
> The DOM0 device tree should expose the same layout as the hardware. By
> exposing only one ITS you make your life more complicate.
in what way?
>
> PHYSDEVOP_pci_device_add should be called before any initialization is
> done. Therefore ITS should be configured for this PCI after Xen is aware
> of the PCI.
That is for a device, I believe all devices on a host bridge are 
serviced by a single ITS
>
> IHMO, any ITS trap before this is wrong.
AFAIK guest always sees a virtual ITS, could you please explain what is 
wrong in trapping.
> Regards,
>