Re: [Xen-devel] Few Comments on the Xen SMMU ARM code

[manish jaggi <manishjaggi.oss@xxxxxxxxx>]

On 11 December 2014 at 02:30, Stefano Stabellini
<stefano.stabellini@xxxxxxxxxxxxx> wrote:
> On Wed, 10 Dec 2014, manish jaggi wrote:
>> Based on my experience with PCI passthrough code merging, below are
>> some comments:
>> Both require a change in code
>>
>> a) The current code which is non-pci passthrough requires a devices'
>> device tree node to be associated with smmu node, if that device has
>> to be assigned to domU.
>>
>> In our system there is no platform device which can be passthough. All
>> devices (including uart) are enumerated using PCI enumeration.
>> So the device tree looks like
>>
>> pcie0 {
>> }
>>
>> smmu {
>> mmu-masters = <&pcie0 0x100>;
>> }
>>
>> When dom0 boots pcie is assigned to dom0 and a stream ID 0x100 is
>> created which later conflicts with a valid device enumerated later
>>
>> b) Current xen code and linux code used rb_tree with key as dt_node to
>> locate a device and its smmu. With an enumerated device there is no
>> such thing. So this would not work.
>>
>>
>> I need your views how PCI passthrough / Non PCI passthrough code can
>> coexist with the two points mentioned above ?
>
> Hello Manish,
> it is increasingly difficult to reply to your questions without reading
> any patches or well written design documents.

Hi Stefano,
I am sorry about this. I though this mail was discussing on the
approach already being taken in the current code and I was just
pointing out issues. I request you to please read the mail one more
time.

I suggest you send out
> your series, then we can move forward from there.
>

This is the complete smmu.c file which you can refer for PCI
passthrough (http://pastebin.com/QDX8fpDu)
Just FYI this is not a patch, we are still testing on our board and
can post a patch only after our testing is complete.

> Cheers,
>
> Stefano

Best Regards
Manish

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