On Mon, 30 Jun 2025 19:28:33 -0300
Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index d265de874b14b6..f4584ffacbc03d 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -65,8 +65,16 @@ struct iommu_group {
> struct list_head entry;
> unsigned int owner_cnt;
> void *owner;
> +
> + /* Used by the device_group() callbacks */
> + u32 bus_data;
> };
>
> +/*
> + * Everything downstream of this group should share it.
> + */
> +#define BUS_DATA_PCI_UNISOLATED BIT(0)
NON_ISOLATED for consistency w/ enum from the previous patch?
...
> +struct iommu_group *pci_device_group(struct device *dev)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> + struct iommu_group *group;
> + struct pci_dev *real_pdev;
> +
> + if (WARN_ON(!dev_is_pci(dev)))
> + return ERR_PTR(-EINVAL);
> +
> + /*
> + * Arches can supply a completely different PCI device that actually
> + * does DMA.
> + */
> + real_pdev = pci_real_dma_dev(pdev);
> + if (real_pdev != pdev) {
> + group = iommu_group_get(&real_pdev->dev);
> + if (!group) {
> + /*
> + * The real_pdev has not had an iommu probed to it. We
> + * can't create a new group here because there is no way
> + * for pci_device_group(real_pdev) to pick it up.
> + */
> + dev_err(dev,
> + "PCI device is probing out of order, real device of %s is not probed yet\n",
> + pci_name(real_pdev));
> + return ERR_PTR(-EPROBE_DEFER);
> + }
> + return group;
> + }
> +
> + if (pdev->dev_flags & PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT)
> + return iommu_group_alloc();
> +
> + /* Anything upstream of this enforcing non-isolated? */
> + group = pci_hierarchy_group(pdev);
> if (group)
> return group;
>
> - /* No shared group found, allocate new */
> - return iommu_group_alloc();
> + switch (pci_bus_isolated(pdev->bus)) {
> + case PCIE_ISOLATED:
> + /* Check multi-function groups and same-bus devfn aliases */
> + group = pci_get_alias_group(pdev);
> + if (group)
> + return group;
> +
> + /* No shared group found, allocate new */
> + return iommu_group_alloc();
I'm not following how we'd handle a multi-function root port w/o
consistent ACS isolation here. How/where does the resulting group get
the UNISOLATED flag set?
I think that's necessary for the look-back in pci_hierarchy_group(),
right? Thanks,
Alex
