On Fri, 14 Mar 2025, Mykyta Poturai wrote:
> From: Stewart Hildebrand <stewart.hildebrand@amd.com>
>
> Handle phantom functions in iommu_add_dt_pci_sideband_ids(). Each phantom
> function will have a unique requestor ID (RID)/BDF. On ARM, we need to
> map/translate the RID/BDF to an AXI stream ID for each phantom function
> according to the pci-iommu device tree mapping [1]. The RID/BDF -> AXI stream ID
> mapping in DT could allow phantom devices (i.e. devices with phantom functions)
> to use different AXI stream IDs based on the (phantom) function.
>
> [1] https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/pci-iommu.txt
>
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> ---
> v8->v9:
> * replace DT_NO_IOMMU with 1
>
> v7->v8:
> * no change
>
> v6->v7:
> * no change
>
> v5->v6:
> * no change
>
> v4->v5:
> * no change
>
> v3->v4:
> * s/iommu_dt_pci_map_id/dt_map_id/
>
> v2->v3:
> * new patch title (was: iommu/arm: iommu_add_dt_pci_device phantom handling)
> * rework loop to reduce duplication
> * s/iommu_fwspec_free(pci_to_dev(pdev))/iommu_fwspec_free(dev)/
>
> v1->v2:
> * new patch
>
> ---
> TODO: investigate Jan's comment [2]
> [2] https://lore.kernel.org/xen-devel/806a2978-19fb-4d31-ab6a-35ea7317c8de@suse.com/
> ---
> xen/drivers/passthrough/device_tree.c | 33 ++++++++++++++++-----------
> 1 file changed, 20 insertions(+), 13 deletions(-)
>
> diff --git a/xen/drivers/passthrough/device_tree.c b/xen/drivers/passthrough/device_tree.c
> index 37e1437b65..f5850a2607 100644
> --- a/xen/drivers/passthrough/device_tree.c
> +++ b/xen/drivers/passthrough/device_tree.c
> @@ -169,6 +169,7 @@ int iommu_add_dt_pci_sideband_ids(struct pci_dev *pdev)
> struct device *dev = pci_to_dev(pdev);
> const struct dt_device_node *np;
> int rc;
> + unsigned int devfn = pdev->devfn;
>
> if ( !iommu_enabled )
> return 1;
> @@ -183,21 +184,27 @@ int iommu_add_dt_pci_sideband_ids(struct pci_dev *pdev)
> if ( !np )
> return -ENODEV;
>
> - /*
> - * According to the Documentation/devicetree/bindings/pci/pci-iommu.txt
> - * from Linux.
> - */
> - rc = dt_map_id(np, PCI_BDF(pdev->bus, pdev->devfn), "iommu-map",
> - "iommu-map-mask", &iommu_spec.np, iommu_spec.args);
> - if ( rc )
> - return (rc == -ENODEV) ? 1 : rc;
> + do {
> + /*
> + * According to the Documentation/devicetree/bindings/pci/pci-iommu.txt
> + * from Linux.
> + */
> + rc = dt_map_id(np, PCI_BDF(pdev->bus, devfn), "iommu-map",
> + "iommu-map-mask", &iommu_spec.np, iommu_spec.args);
> + if ( rc )
> + return (rc == -ENODEV) ? 1 : rc;
>
> - rc = iommu_dt_xlate(dev, &iommu_spec, ops);
> - if ( rc < 0 )
> - {
> - iommu_fwspec_free(dev);
> - return -EINVAL;
> + rc = iommu_dt_xlate(dev, &iommu_spec, ops);
> + if ( rc < 0 )
> + {
> + iommu_fwspec_free(dev);
> + return -EINVAL;
> + }
> +
> + devfn += pdev->phantom_stride;
> }
> + while ( (devfn != pdev->devfn) &&
> + (PCI_SLOT(devfn) == PCI_SLOT(pdev->devfn)) );
>
> return rc;
> }
> --
> 2.34.1
>