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

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

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.

Thanks

Eric
>  AddressSpace *pci_device_iommu_address_space(PCIDevice *dev);
>  bool pci_device_set_iommu_device(PCIDevice *dev, HostIOMMUDevice *hiod,
>                                   Error **errp);
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index df1fb615a8..87f7c942b3 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -2857,20 +2857,21 @@ static void pci_device_class_base_init(ObjectClass *klass, const void *data)
>   * For call sites which don't need aliased BDF, passing NULL to
>   * aliased_[bus|devfn] is allowed.
>   *
> + * Returns true if PCI device is aliased or false otherwise.
> + *
>   * @piommu_bus: return root #PCIBus backed by an IOMMU for the PCI device.
>   *
>   * @aliased_bus: return aliased #PCIBus of the PCI device, optional.
>   *
>   * @aliased_devfn: return aliased devfn of the PCI device, optional.
>   */
> -static void pci_device_get_iommu_bus_devfn(PCIDevice *dev,
> -                                           PCIBus **piommu_bus,
> -                                           PCIBus **aliased_bus,
> -                                           int *aliased_devfn)
> +bool pci_device_get_iommu_bus_devfn(PCIDevice *dev, PCIBus **piommu_bus,
> +                                    PCIBus **aliased_bus, int *aliased_devfn)
>  {
>      PCIBus *bus = pci_get_bus(dev);
>      PCIBus *iommu_bus = bus;
>      int devfn = dev->devfn;
> +    bool aliased = false;
>  
>      while (iommu_bus && !iommu_bus->iommu_ops && iommu_bus->parent_dev) {
>          PCIBus *parent_bus = pci_get_bus(iommu_bus->parent_dev);
> @@ -2907,6 +2908,7 @@ static void pci_device_get_iommu_bus_devfn(PCIDevice *dev,
>                  devfn = parent->devfn;
>                  bus = parent_bus;
>              }
> +            aliased = true;
>          }
>  
>          iommu_bus = parent_bus;
> @@ -2928,6 +2930,8 @@ static void pci_device_get_iommu_bus_devfn(PCIDevice *dev,
>      if (aliased_devfn) {
>          *aliased_devfn = devfn;
>      }
> +
> +    return aliased;
>  }
>  
>  AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)