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Date: Thu, 8 Oct 2026 18:33:15 -0500
From: Bjorn Helgaas <helgaas@kernel.org>
To: Srirangan Madhavan <smadhavan@nvidia.com>
Cc: Alison Schofield <alison.schofield@intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Ira Weiny <ira.weiny@intel.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Vishal Verma <vishal.l.verma@intel.com>, linux-cxl@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	Alex Williamson <alex.williamson@redhat.com>, vsethi@nvidia.com,
	alwilliamson@nvidia.com,
	Sai Yashwanth Reddy Kancherla <skancherla@nvidia.com>,
	Vishal Aslot <vaslot@nvidia.com>, Manish Honap <mhonap@nvidia.com>,
	Jiandi An <jan@nvidia.com>, Richard Cheng <icheng@nvidia.com>,
	linux-tegra@vger.kernel.org
Subject: Re: [PATCH v14 13/16] PCI/CXL: Reject reset with unsafe function
 scope
Message-ID: <20261008233315.GA941474@bhelgaas>
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In-Reply-To: <20261001092227.3004747-14-smadhavan@nvidia.com>

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@nvidia.com>
> Link: https://lore.kernel.org/linux-cxl/20260626160846.426e71b6@nvidia.com/
> Link: https://lore.kernel.org/linux-cxl/6a50441e2bb5e_3cabcb1003e@djbw-dev.notmuch/
> Signed-off-by: Srirangan Madhavan <smadhavan@nvidia.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  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
>