Re: [PATCH] xen/virtio: Handle PCI devices which Host controller is described in DT

From: Juergen Gross
Date: Fri Oct 07 2022 - 01:57:20 EST

On 06.10.22 19:48, Oleksandr Tyshchenko wrote:
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

Use the same "xen-grant-dma" device concept (based on generic IOMMU
device-tree bindings) for the PCI devices behind device-tree based
PCI Host controller.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Slightly RFC. This is needed to support Xen grant mappings for virtio-pci devices
on Arm at some point in the future. The Xen toolstack side is not published yet.
Here, for PCI devices we use the same way to pass backend domid to the guest as for
platform devices.

I should mention we decided at the Xen Summit, that I will start a try to
modify the virtio spec to include the backend id (domid in the Xen case)
in the device independent config part.

As this will take some time to be accepted (if ever), other means to
specify the backend domid are needed until then. DT is one possibility
(at least on Arm), while Xenstore is the way to go for setups with a
Xen toolstack.


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