Re: [PATCH 4/4] cxl/pci: Guard decoder accesses after reset

[Dave Jiang]

On 9/28/26 7:04 PM, Richard Cheng wrote:
> cxl_reset_done() runs even when PCI state restoration is skipped.
> Reading HDM decoder registers while the device is inaccessible can
> trigger another error.
> 
> Skip decoder checks if the PCI Command read fails, returns all ones, or
> Memory Space Enable is clear.
> 
> Signed-off-by: Richard Cheng <icheng@xxxxxxxxxx>

Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>

> ---
>  drivers/cxl/pci.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index c7c91e8dc51d..2294f7761e50 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -976,6 +976,12 @@ static void cxl_reset_done(struct pci_dev *pdev)
>  	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
>  	struct cxl_memdev *cxlmd = cxlds->cxlmd;
>  	struct device *dev = &pdev->dev;
> +	u32 command;
> +
> +	/* PCI state restoration may have been skipped after a failed reset. */
> +	if (pci_read_config_dword(pdev, PCI_COMMAND, &command) ||
> +	    PCI_POSSIBLE_ERROR(command) || !(command & PCI_COMMAND_MEMORY))
> +		return;
>  
>  	/*
>  	 * FLR does not expect to touch the HDM decoders and related