Re: [PATCH v5 12/27] vfio/pci: Call the CXL open and close hooks around device use

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 17 Sep 2026 00:05:25 +0530
<mhonap@nvidia.com> wrote:

> From: Manish Honap <mhonap@nvidia.com>
> 
> Volatile CXL register state must be sampled from live hardware when the
> guest opens the device, not at bind, because a low-power transition
> between bind and open can leave the bind-time values stale.
> 
> Add open and close to the CXL ops and call them from the common enable
> and close paths. A failed open unwinds the enable in reverse order:
> unmap the BARs, drop the excluded ranges, then free the virtual config.
> 
> Factor the BAR unmap out of vfio_pci_core_disable() into a helper so the
> enable failure path and the disable path share it.
> 
> Assisted-by: LLM
> Signed-off-by: Manish Honap <mhonap@nvidia.com>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 40 +++++++++++++++++++++++++-------
>  include/linux/vfio_pci_core.h    |  2 ++
>  2 files changed, 33 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index c5b7a59a4548..2f593b2721a1 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -591,6 +591,21 @@ static const struct dev_pm_ops vfio_pci_core_pm_ops = {
>  
>  static void vfio_pci_free_excluded_ranges(struct vfio_pci_core_device *vdev);
>  
> +static void vfio_pci_core_unmap_bars(struct vfio_pci_core_device *vdev)
> +{
> +	struct pci_dev *pdev = vdev->pdev;
> +	int i, bar;
> +
> +	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
	for (int i = 0; i < PCI_STD_NUM_BARS; i++)
		int bar = i + PCI_STD_RESOURCES;

Nice to keep things tightly scoped where we can.

> +		bar = i + PCI_STD_RESOURCES;
> +		if (IS_ERR_OR_NULL(vdev->barmap[bar]))
> +			continue;
> +		pci_iounmap(pdev, vdev->barmap[bar]);
> +		pci_release_selected_regions(pdev, 1 << bar);
> +		vdev->barmap[bar] = NULL;
> +	}
> +}