Re: [PATCH v5 13/27] vfio/pci: Bracket PCI resets with the CXL reset hooks

[Alex Williamson <alex@shazbot.org>]

On Thu, 17 Sep 2026 00:05:26 +0530
<mhonap@nvidia.com> wrote:

> From: Manish Honap <mhonap@nvidia.com>
> 
> A CXL Type-2 device must quiesce its coherent link before any reset and
> restore its HDM decoder state afterward, or a reset can leave the device
> mastering the bus over decoders that are no longer valid. This has to
> happen around every reset the PCI core drives for the device, not only
> the ones VFIO issues directly.
> 
> Add reset_prepare and reset_done to the CXL ops and register the matching
> pci_error_handlers callbacks.
> 
> Assisted-by: LLM
> Signed-off-by: Manish Honap <mhonap@nvidia.com>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 18 ++++++++++++++++++
>  include/linux/vfio_pci_core.h    |  2 ++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index 2f593b2721a1..a91e07181847 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -2794,8 +2794,26 @@ int vfio_pci_core_sriov_configure(struct vfio_pci_core_device *vdev,
>  }
>  EXPORT_SYMBOL_GPL(vfio_pci_core_sriov_configure);
>  
> +static void vfio_pci_core_reset_prepare(struct pci_dev *pdev)
> +{
> +	struct vfio_pci_core_device *vdev = dev_get_drvdata(&pdev->dev);
> +
> +	if (vdev->cxl_ops)
> +		vdev->cxl_ops->reset_prepare(vdev);
> +}
> +
> +static void vfio_pci_core_reset_done(struct pci_dev *pdev)
> +{
> +	struct vfio_pci_core_device *vdev = dev_get_drvdata(&pdev->dev);
> +
> +	if (vdev->cxl_ops)
> +		vdev->cxl_ops->reset_done(vdev);
> +}

Flagging this because it's introducing one more vfio-pci-core use of
the convention of storing the vfio_pci_core_device in drvdata that's a
barrier for a Rust-based variant driver.  Likely this needs to be added
to the per-variant boilerplate or macro so variants provide the
vfio_pci_core_device pointer rather than expecting it in drvdata.
Thanks,

Alex

> +
>  const struct pci_error_handlers vfio_pci_core_err_handlers = {
>  	.error_detected = vfio_pci_core_aer_err_detected,
> +	.reset_prepare = vfio_pci_core_reset_prepare,
> +	.reset_done = vfio_pci_core_reset_done,
>  };
>  EXPORT_SYMBOL_GPL(vfio_pci_core_err_handlers);
>  
> diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
> index 643f32c2141f..6ebf9a26275e 100644
> --- a/include/linux/vfio_pci_core.h
> +++ b/include/linux/vfio_pci_core.h
> @@ -72,6 +72,8 @@ struct vfio_cxl_ops {
>  	void	(*release)(struct vfio_pci_core_device *vdev);
>  	int	(*open_device)(struct vfio_pci_core_device *vdev);
>  	void	(*close_device)(struct vfio_pci_core_device *vdev);
> +	void	(*reset_prepare)(struct vfio_pci_core_device *vdev);
> +	void	(*reset_done)(struct vfio_pci_core_device *vdev);
>  	/* Pinned per bound CXL device so vfio-cxl cannot unload under usage */
>  	struct module *owner;
>  };