On 5/8/23 10:51, Jan Beulich wrote:
> 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),
There's nothing wrong with the existing hd->platform_ops hook. We just need to
ensure we've translated RID to AXI stream ID sometime before it.
> then - as said - I'd view such #ifdef as possibly okay at the call site of
> iommu_add_device(), but not inside.
I'll move the #ifdef-ary.
