> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Friday, April 12, 2024 4:21 PM
>
> +static int vfio_pci_core_feature_pasid(struct vfio_device *device, u32 flags,
> + struct vfio_device_feature_pasid __user
> *arg,
> + size_t argsz)
> +{
> + struct vfio_pci_core_device *vdev =
> + container_of(device, struct vfio_pci_core_device, vdev);
> + struct vfio_device_feature_pasid pasid = { 0 };
> + struct pci_dev *pdev = vdev->pdev;
> + u32 capabilities = 0;
> + u16 ctrl = 0;
> + int ret;
> +
> + /*
> + * Due to no PASID capability per VF, to be consistent, we do not
> + * support SET of the PASID capability for both PF and VF.
> + */
/* Disallow SET of the PASID capability given it is shared by all VF's
* and configured implicitly by the IOMMU driver.
*/
> + ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_GET,
> + sizeof(pasid));
> + if (ret != 1)
> + return ret;
> +
> + /* VF shares the PASID capability of its PF */
> + if (pdev->is_virtfn)
> + pdev = pci_physfn(pdev);
> +
> + if (!pdev->pasid_enabled)
> + goto out;
> +
> +#ifdef CONFIG_PCI_PASID
> + pci_read_config_dword(pdev, pdev->pasid_cap + PCI_PASID_CAP,
> + &capabilities);
> + pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL,
> + &ctrl);
> +#endif
> +
> + pasid.width = (capabilities >> 8) & 0x1f;
it's cleaner to have helpers instead of directly checking CONFIG_PCI_XXX here.
there is an existing helper for the width: pci_max_pasids()
pci_pasid_features() can report supported features but not the actual
enabled set.
for enabled features it's already stored in pdev->pasid_features. so what's
required here is probably a new pci_pasid_enabled_features() to return
that field.
