Re: [PATCH v14 13/16] PCI/CXL: Reject reset with unsafe function scope

[Bjorn Helgaas]

On Thu, Oct 01, 2026 at 09:22:24AM +0000, Srirangan Madhavan wrote:
> The per-device PCI reset interface must not reset sibling functions.
> Reject cxl_reset and cxl_bus for multifunction devices and PFs with
> enabled VFs.
> 
> Suggested-by: Alex Williamson <alwilliamson@xxxxxxxxxx>
> Link: https://lore.kernel.org/linux-cxl/20260626160846.426e71b6@xxxxxxxxxx/
> Link: https://lore.kernel.org/linux-cxl/6a50441e2bb5e_3cabcb1003e@djbw-dev.notmuch/
> Signed-off-by: Srirangan Madhavan <smadhavan@xxxxxxxxxx>

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

> ---
>  drivers/cxl/core/resource.c | 3 +++
>  drivers/pci/pci.c           | 3 +++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/cxl/core/resource.c b/drivers/cxl/core/resource.c
> index 584b51cd9e28..679a605da24c 100644
> --- a/drivers/cxl/core/resource.c
> +++ b/drivers/cxl/core/resource.c
> @@ -903,6 +903,9 @@ int cxl_reset_function(struct pci_dev *pdev, bool probe)
>  	    !(ctrl & PCI_DVSEC_CXL_MEM_ENABLE))
>  		return -ENOTTY;
>  
> +	if (pdev->multifunction || pci_num_vf(pdev))
> +		return -ENOTTY;
> +
>  	if (probe)
>  		return 0;
>  
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b2879a6be5f8..fe611340f5ab 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5026,6 +5026,9 @@ static int cxl_reset_bus_function(struct pci_dev *dev, bool probe)
>  	if (!dvsec)
>  		return -ENOTTY;
>  
> +	if (dev->multifunction || pci_num_vf(dev))
> +		return -ENOTTY;
> +
>  	if (probe)
>  		return 0;
>  
> -- 
> 2.43.0
>