On 04.08.25 11:35, Jan Beulich wrote:
> On 01.08.2025 11:22, Mykyta Poturai wrote:
>> Create add_discovered_pci_devices function that calls pci_device_add
>> on every PCI device discovered.
>> The devices will be added to dom_io so that they can be assigned
>> later to other domains.
>
> And why's the intermediate step necessary? IOW can't they be assigned to their
> target domains right away, and only whatever's left would go to DOM_IO?
For Dom0less case, guest domains are not yet created at this point.
>> --- a/xen/drivers/passthrough/pci.c
>> +++ b/xen/drivers/passthrough/pci.c
>> @@ -1180,6 +1180,34 @@ int __init scan_pci_devices(void)
>> return ret;
>> }
>>
>> +static int __init _add_discovered_pci_devices(struct pci_seg *pseg, void
>> *arg)
>> +{
>> + struct pci_dev *pdev;
>> + int ret = 0;
>> +
>> + list_for_each_entry ( pdev, &pseg->alldevs_list, alldevs_list )
>> + {
>> + ret = pci_add_device(dom_io, pdev->seg, pdev->bus, pdev->devfn,
>> NULL,
>> + NUMA_NO_NODE);
>> + if ( ret < 0 )
>> + {
>> + printk(XENLOG_ERR
>> + "%pp: Failure adding the discovered pci device (Error
>> %d)\n",
>> + &pdev->sbdf, ret);
>> + break;
>> + }
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +void __init add_discovered_pci_devices(void)
>> +{
>> + pcidevs_lock();
>> + pci_segments_iterate(_add_discovered_pci_devices, NULL);
>> + pcidevs_unlock();
>> +}
>
> This looks to merely be a specialized form of what ...
>
>> struct setup_hwdom {
>> struct domain *d;
>> int (*handler)(uint8_t devfn, struct pci_dev *pdev);
>
> ... follows below here. By generalizing what we have (perhaps from the top,
> i.e.
> iommu_hwdom_init()), you'd also avoid violating Misra rule 2.1 on x86, as you
> add
> unreachable code there.
>
> Jan
Can you please elaborate a little further on how you see this
generalization? With routines you mentioned being specifically for
hwdom, which may not exist, and the different approaches to PCI
initialization on Arm/x86 (as far as I understand on x86 all of the PCI
related stuff is initialized from iommu helpers, while Arm has a
dedicated init step) I am afraid I can't find a nice point of contact to
generalize this, but I can be missing somthing due to unfamiliarity with
x86 code.
Another way of addressing possible MISRA violation I can see is moving
the add_discovered_pci_devices to xen/arch/arm/pci/pci.c so it will only
be compiled when used.
--
Mykyta
