Re: [PATCH v2 05/19] hw/pci: Export pci_device_get_iommu_bus_devfn() and return bool

[Eric Auger <eric.auger@redhat.com>]

On 6/23/25 4:47 AM, Duan, Zhenzhong wrote:
>
>> -----Original Message-----
>> From: Eric Auger <eric.auger@redhat.com>
>> Subject: Re: [PATCH v2 05/19] hw/pci: Export pci_device_get_iommu_bus_devfn()
>> and return bool
>>
>> Hi Zhenzhong,
>>
>> On 6/20/25 9:17 AM, Zhenzhong Duan wrote:
>>> Returns true if PCI device is aliased or false otherwise. This will be
>>> used in following patch to determine if a PCI device is under a PCI
>>> bridge.
>>>
>>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> ---
>>>  include/hw/pci/pci.h |  2 ++
>>>  hw/pci/pci.c         | 12 ++++++++----
>>>  2 files changed, 10 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
>>> index 829757b2c2..3029cdf26f 100644
>>> --- a/include/hw/pci/pci.h
>>> +++ b/include/hw/pci/pci.h
>>> @@ -640,6 +640,8 @@ typedef struct PCIIOMMUOps {
>>>                              bool is_write);
>>>  } PCIIOMMUOps;
>>>
>>> +bool pci_device_get_iommu_bus_devfn(PCIDevice *dev, PCIBus
>> **piommu_bus,
>>> +                                    PCIBus **aliased_bus, int *aliased_devfn);
>> if I am correct you have a single caller of the helper using the
>> returned value, in intel_iommu.c, whereas all the existing callers are
>> not using the returned value. You may simply pass a non NULL aliased_bus
>> and aliased_devfn and check whether they differ from the original
>> bus/devfn. Besides the patch looks ok to me.
> I do this way initially, but it doesn't work if PCI device is the first device under
> PCIE-to-PCI bridge, e.g., 01:00.0, in this case aliased BDF==real BDF.
I see.

Thank you for the explanation

Eric
>
> Thanks
> Zhenzhong