Re: [PATCH v6 14/19] hw/pci: Introduce helper function pci_device_get_iommu_bus_devfn()

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

On 6/3/24 08:10, Zhenzhong Duan wrote:
> Extract out pci_device_get_iommu_bus_devfn() from
> pci_device_iommu_address_space() to facilitate
> implementation of pci_device_[set|unset]_iommu_device()
> in following patch.
>
> No functional change intended.
>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> ---
>  hw/pci/pci.c | 48 +++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 45 insertions(+), 3 deletions(-)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 324c1302d2..02a4bb2af6 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -2648,11 +2648,27 @@ static void pci_device_class_base_init(ObjectClass *klass, void *data)
>      }
>  }
>  
> -AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
> +/*
> + * Get IOMMU root bus, aliased bus and devfn of a PCI device
> + *
> + * IOMMU root bus is needed by all call sites to call into iommu_ops.
> + * For call sites which don't need aliased BDF, passing NULL to
> + * aliased_[bus|devfn] is allowed.
> + *
> + * @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)
>  {
>      PCIBus *bus = pci_get_bus(dev);
>      PCIBus *iommu_bus = bus;
> -    uint8_t devfn = dev->devfn;
> +    int devfn = dev->devfn;
>  
>      while (iommu_bus && !iommu_bus->iommu_ops && iommu_bus->parent_dev) {
>          PCIBus *parent_bus = pci_get_bus(iommu_bus->parent_dev);
> @@ -2693,7 +2709,33 @@ AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
>  
>          iommu_bus = parent_bus;
>      }
> -    if (!pci_bus_bypass_iommu(bus) && iommu_bus->iommu_ops) {
> +
> +    assert(0 <= devfn && devfn < PCI_DEVFN_MAX);
> +    assert(iommu_bus);
> +
> +    if (pci_bus_bypass_iommu(bus) || !iommu_bus->iommu_ops) {
> +        iommu_bus = NULL;
> +    }
> +
> +    *piommu_bus = iommu_bus;
> +
> +    if (aliased_bus) {
> +        *aliased_bus = bus;
> +    }
> +
> +    if (aliased_devfn) {
> +        *aliased_devfn = devfn;
> +    }
> +}
> +
> +AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
> +{
> +    PCIBus *bus;
> +    PCIBus *iommu_bus;
> +    int devfn;
> +
> +    pci_device_get_iommu_bus_devfn(dev, &iommu_bus, &bus, &devfn);
> +    if (iommu_bus) {
>          return iommu_bus->iommu_ops->get_address_space(bus,
>                                   iommu_bus->iommu_opaque, devfn);
>      }