On 08.05.2023 16:16, Stewart Hildebrand wrote:
> On 5/2/23 03:50, Jan Beulich wrote:
>> On 01.05.2023 22:03, Stewart Hildebrand wrote:
>>> --- a/xen/drivers/passthrough/pci.c
>>> +++ b/xen/drivers/passthrough/pci.c
>>> @@ -1305,7 +1305,7 @@ __initcall(setup_dump_pcidevs);
>>>
>>> static int iommu_add_device(struct pci_dev *pdev)
>>> {
>>> - const struct domain_iommu *hd;
>>> + const struct domain_iommu *hd __maybe_unused;
>>> int rc;
>>> unsigned int devfn = pdev->devfn;
>>>
>>> @@ -1318,17 +1318,30 @@ static int iommu_add_device(struct pci_dev *pdev)
>>> if ( !is_iommu_enabled(pdev->domain) )
>>> return 0;
>>>
>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>> + rc = iommu_add_dt_pci_device(devfn, pdev);
>>> +#else
>>> rc = iommu_call(hd->platform_ops, add_device, devfn, pci_to_dev(pdev));
>>> - if ( rc || !pdev->phantom_stride )
>>> +#endif
>>> + if ( rc < 0 || !pdev->phantom_stride )
>>> + {
>>> + if ( rc < 0 )
>>> + printk(XENLOG_WARNING "IOMMU: add %pp failed (%d)\n",
>>> + &pdev->sbdf, rc);
>>> return rc;
>>> + }
>>>
>>> for ( ; ; )
>>> {
>>> devfn += pdev->phantom_stride;
>>> if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>>> return 0;
>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>> + rc = iommu_add_dt_pci_device(devfn, pdev);
>>> +#else
>>> rc = iommu_call(hd->platform_ops, add_device, devfn,
>>> pci_to_dev(pdev));
>>> - if ( rc )
>>> +#endif
>>> + if ( rc < 0 )
>>> printk(XENLOG_WARNING "IOMMU: add %pp failed (%d)\n",
>>> &PCI_SBDF(pdev->seg, pdev->bus, devfn), rc);
>>> }
>>
>> Such #ifdef-ary may be okay at the call site(s), but replacing a per-
>> IOMMU hook with a system-wide DT function here looks wrong to me.
>
> Perhaps a better approach would be to rely on the existing iommu add_device
> call.
>
> This might look something like:
>
> #ifdef CONFIG_HAS_DEVICE_TREE
> rc = iommu_add_dt_pci_device(pdev);
> if ( !rc ) /* or rc >= 0, or something... */
> #endif
> rc = iommu_call(hd->platform_ops, add_device, devfn,
> pci_to_dev(pdev));
>
> There would be no need to call iommu_add_dt_pci_device() in the loop
> iterating over phantom functions, as I will handle those inside
> iommu_add_dt_pci_device() in v2.
But that still leaves #ifdef-ary inside the function. If for whatever reason
the hd->platform_ops hook isn't suitable (which I still don't understand),
then - as said - I'd view such #ifdef as possibly okay at the call site of
iommu_add_device(), but not inside.
Jan
