Re: [PATCH v7 4/4] vfio/xe: Add device specific vfio_pci driver variant for Intel graphics

[Angela <angelagbtt1@gmail.com>]

On 11/27/25 01:39, Michał Winiarski wrote:
[snip]
> +static void xe_vfio_pci_reset_done(struct pci_dev *pdev)
> +{
> +	struct xe_vfio_pci_core_device *xe_vdev = pci_get_drvdata(pdev);
> +	int ret;
> +
> +	if (!pdev->is_virtfn)
> +		return;
> +
> +	/*
> +	 * VF FLR requires additional processing done by PF driver.
> +	 * The processing is done after FLR is already finished from PCIe
> +	 * perspective.
> +	 * In order to avoid a scenario where VF is used while PF processing
> +	 * is still in progress, additional synchronization point is needed.
> +	 */
> +	ret = xe_sriov_vfio_wait_flr_done(xe_vdev->xe, xe_vdev->vfid);
> +	if (ret)
> +		dev_err(&pdev->dev, "Failed to wait for FLR: %d\n", ret);
> +
> +	if (!xe_vdev->vfid)
> +		return;
> +
> +	/*
> +	 * As the higher VFIO layers are holding locks across reset and using
> +	 * those same locks with the mm_lock we need to prevent ABBA deadlock
> +	 * with the state_mutex and mm_lock.
> +	 * In case the state_mutex was taken already we defer the cleanup work
> +	 * to the unlock flow of the other running context.
> +	 */
> +	spin_lock(&xe_vdev->reset_lock);
> +	xe_vdev->deferred_reset = true;
> +	if (!mutex_trylock(&xe_vdev->state_mutex)) {
> +		spin_unlock(&xe_vdev->reset_lock);
> +		return;
> +	}
> +	spin_unlock(&xe_vdev->reset_lock);
> +	xe_vfio_pci_state_mutex_unlock(xe_vdev);
> +
> +	xe_vfio_pci_reset(xe_vdev);
> +}
[snip]

My first KVM review :)

I think xe_vfio_pci_reset(xe_vdev) need be protected by state_mutex. So,
we should move xe_vfio_pci_state_mutex_unlock(xe_vdev) after
xe_vfio_pci_reset(xe_vdev). Thoughts?

Thanks,
Angela