linux-kernel - Re: [PATCH v3 06/15] PCI/AER: Change AER driver to read UCE fatal status for all CXL PCIe port devices

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Message-ID: <ZzcVzpCXk2IpR7U3@wunner.de>
Date: Fri, 15 Nov 2024 10:35:10 +0100
From: Lukas Wunner <lukas@...ner.de>
To: Terry Bowman <terry.bowman@....com>
Cc: linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, nifan.cxl@...il.com, ming4.li@...el.com,
	dave@...olabs.net, jonathan.cameron@...wei.com,
	dave.jiang@...el.com, alison.schofield@...el.com,
	vishal.l.verma@...el.com, dan.j.williams@...el.com,
	bhelgaas@...gle.com, mahesh@...ux.ibm.com, ira.weiny@...el.com,
	oohall@...il.com, Benjamin.Cheatham@....com, rrichter@....com,
	nathan.fontenot@....com, Smita.KoralahalliChannabasappa@....com,
	Shuai Xue <xueshuai@...ux.alibaba.com>,
	Keith Busch <kbusch@...nel.org>
Subject: Re: [PATCH v3 06/15] PCI/AER: Change AER driver to read UCE fatal
 status for all CXL PCIe port devices

On Wed, Nov 13, 2024 at 03:54:20PM -0600, Terry Bowman wrote:
> The AER service driver's aer_get_device_error_info() function doesn't read
> uncorrectable (UCE) fatal error status from PCIe upstream port devices,
> including CXL upstream switch ports. As a result, fatal errors are not
> logged or handled as needed for CXL PCIe upstream switch port devices.
> 
> Update the aer_get_device_error_info() function to read the UCE fatal
> status for all CXL PCIe port devices. Make the change to not affect
> non-CXL PCIe devices.
> 
> The fatal error status will be used in future patches implementing
> CXL PCIe port uncorrectable error handling and logging.
[...]
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -1250,7 +1250,8 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
>  	} else if (type == PCI_EXP_TYPE_ROOT_PORT ||
>  		   type == PCI_EXP_TYPE_RC_EC ||
>  		   type == PCI_EXP_TYPE_DOWNSTREAM ||
> -		   info->severity == AER_NONFATAL) {
> +		   info->severity == AER_NONFATAL ||
> +		   (pcie_is_cxl(dev) && type == PCI_EXP_TYPE_UPSTREAM)) {
>  
>  		/* Link is still healthy for IO reads */
>  		pci_read_config_dword(dev, aer + PCI_ERR_UNCOR_STATUS,

Just a heads-up, there's another patch pending by Shuai Xue (+cc)
which touches the same code lines.  It re-enables error reporting
for PCIe Upstream Ports (as well as Endpoints) under certain
conditions:

https://lore.kernel.org/all/20241112135419.59491-3-xueshuai@linux.alibaba.com/

That was originally disabled by Keith Busch (+cc) with commit
9d938ea53b26 ("PCI/AER: Don't read upstream ports below fatal errors").

There's some merge conflict potential here if your series goes into
the cxl tree and Shuai's patch into the pci tree in the next cycle.

Thanks,

Lukas