Re: [PATCH v7 4/9] PCI: Add additional checks for flr reset

[Niklas Schnelle <schnelle@linux.ibm.com>]

On Wed, 2026-01-07 at 10:32 -0800, Farhan Ali wrote:
> If a device is in an error state, then any reads of device registers can
> return error value. Add addtional checks to validate if a device is in an
> error state before doing an flr reset.
> 
> Cc: stable@vger.kernel.org
> Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
> Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
> ---
>  drivers/pci/pci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 74d21c97654d..b687f51ecc81 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4358,12 +4358,19 @@ EXPORT_SYMBOL_GPL(pcie_flr);
>   */
>  int pcie_reset_flr(struct pci_dev *dev, bool probe)
>  {
> +	u32 reg;
> +
>  	if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
>  		return -ENOTTY;
>  
>  	if (!(dev->devcap & PCI_EXP_DEVCAP_FLR))
>  		return -ENOTTY;
>  
> +	if (pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &reg)) {
> +		pci_warn(dev, "Device unable to do an FLR\n");
> +		return -ENOTTY;
> +	}
> +
>  	if (probe)
>  		return 0;
>  

Looks good to me. I'm not 100% convinced the additional pci_warn() is
needed since at least aer_root_reset() already prints that the FLR
isn't supported but there are other callers which don't and this may
help pinpoint the new behavior in case it does affect something
unexpectedly. So I think I'd also rather keep it.

Feel free to add my:
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>