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

[manish jaggi <manishjaggi.oss@xxxxxxxxx>]

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 ?


-Regards
Manish

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