Re: [PATCH v9 7/8] xen/arm: enable dom0 to use PCI devices with pci-passthrough=no

[Julien Grall <julien@xxxxxxx>]

Hi Mykyta,

On 14/03/2025 13:34, Mykyta Poturai wrote:
> From: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
>
> Enable the use of IOMMU + PCI in dom0 without having to specify
> "pci-passthrough=yes". We rely on dom0 to initialize the PCI controller
> and perform a PHYSDEVOP_pci_device_add call to add each device to SMMU.
It would be good to explain why Xen cannot initialize the PCI 
controller. Asking, because the reason is the PCI controller is too 
complex, then you will likely need the same approach for PCI passthrough...
> Enable pci_init() for initializing Xen's internal PCI subsystem, and
> allow PHYSDEVOP_pci_device_add when pci-passthrough is disabled.
Effectively, wouldn't this mean dom0 always *have* to call 
PHYSDEVOP_pci_device_add? Otherwise, how would dom0 know whether it 
needs to call PHSYDEVOP_pci_device_add?
Cheers,

--
Julien Grall