Re: [PATCH 26/26] vfio/xe: Add vendor-specific vfio_pci driver for Intel graphics

Jason Gunthorpe
2025-10-21T23:03:31Z

On Sat, Oct 11, 2025 at 09:38:47PM +0200, Michał Winiarski wrote:
> + /*
> + * "STOP" handling is reused for "RUNNING_P2P", as the device doesn't have the capability to
> + * selectively block p2p DMA transfers.
> + * The device is not processing new workload requests when the VF is stopped, and both
> + * memory and MMIO communication channels are transferred to destination (where processing
> + * will be resumed).
> + */
> + if ((cur == VFIO_DEVICE_STATE_RUNNING && new == VFIO_DEVICE_STATE_STOP) ||
> + (cur == VFIO_DEVICE_STATE_RUNNING && new == VFIO_DEVICE_STATE_RUNNING_P2P)) {
> + ret = xe_sriov_vfio_stop(xe_vdev->pf, xe_vdev->vfid);

This comment is not right, RUNNING_P2P means the device can still
receive P2P activity on it's BAR. Eg a GPU will still allow read/write
to its framebuffer.

But it is not initiating any new transactions.

> +static void xe_vfio_pci_migration_init(struct vfio_device *core_vdev)
> +{
> + struct xe_vfio_pci_core_device *xe_vdev =
> + container_of(core_vdev, struct xe_vfio_pci_core_device, core_device.vdev);
> + struct pci_dev *pdev = to_pci_dev(core_vdev->dev);
> +
> + if (!xe_sriov_vfio_migration_supported(pdev->physfn))
> + return;
> +
> + /* vfid starts from 1 for xe */
> + xe_vdev->vfid = pci_iov_vf_id(pdev) + 1;
> + xe_vdev->pf = pdev->physfn;

No, this has to use pci_iov_get_pf_drvdata, and this driver should
never have a naked pf pointer flowing around.

The entire exported interface is wrongly formed:

+bool xe_sriov_vfio_migration_supported(struct pci_dev *pdev);
+int xe_sriov_vfio_wait_flr_done(struct pci_dev *pdev, unsigned int vfid);
+int xe_sriov_vfio_stop(struct pci_dev *pdev, unsigned int vfid);
+int xe_sriov_vfio_run(struct pci_dev *pdev, unsigned int vfid);
+int xe_sriov_vfio_stop_copy_enter(struct pci_dev *pdev, unsigned int vfid);

None of these should be taking in a naked pci_dev, it should all work
on whatever type the drvdata is.

And this gross thing needs to go away too:

> + if (pdev->is_virtfn && strcmp(pdev->physfn->dev.driver->name, "xe") == 0)
> + xe_vfio_pci_migration_init(core_vdev);

Jason