linux-kernel - Re: [RFC PATCH 4/6] PCI/AER: Extend RCH RAS error handling to support VH topology case

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Date: Mon, 25 Mar 2024 14:14:46 -0500
From: Terry Bowman <Terry.Bowman@....com>
To: Li Ming <ming4.li@...el.com>, dan.j.williams@...el.com, rrichter@....com
Cc: linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 4/6] PCI/AER: Extend RCH RAS error handling to support
 VH topology case

Hi Li,

I added comments below

On 3/13/24 03:36, Li Ming wrote:
> When RCEC captures CXL.cachemem protocol errors detected by CXL root
> port, the recommendation from CXL r3.1 9.18.1.5 is :
> 
> 	"Probe all CXL Downstream Ports and determine whether they have logged an
> 	error in the CXL.io or CXL.cachemem status registers."
> 
> The flow is similar with RCH RAS error handling, so reuse it to support
> above case.
> 
> Signed-off-by: Li Ming <ming4.li@...el.com>
> ---
>  drivers/pci/pcie/aer.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 364c74e47273..79bfa5fb78f4 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -996,11 +996,15 @@ static bool is_internal_error(struct aer_err_info *info)
>  	return info->status & PCI_ERR_UNC_INTN;
>  }
>  
> -static int cxl_rch_handle_error_iter(struct pci_dev *dev, void *data)
> +static int cxl_handle_error_iter(struct pci_dev *dev, void *data)
>  {
>  	struct aer_err_info *info = (struct aer_err_info *)data;
>  	const struct pci_error_handlers *err_handler;
>  
> +	/* Skip the RCiEP devices not associating with RCEC */
> +	if ((pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) &&
> +	    !dev->rcec)
> +		return 0>  	if (!is_cxl_mem_dev(dev) || !cxl_error_is_native(dev))
>  		return 0;
>  
> @@ -1025,16 +1029,16 @@ static int cxl_rch_handle_error_iter(struct pci_dev *dev, void *data)
>  	return 0;
>  }
>  
> -static void cxl_rch_handle_error(struct pci_dev *dev, struct aer_err_info *info)
> +static void cxl_handle_error(struct pci_dev *dev, struct aer_err_info *info)
>  {
>  	/*
>  	 * Internal errors of an RCEC indicate an AER error in an
> -	 * RCH's downstream port. Check and handle them in the CXL.mem
> -	 * device driver.
> +	 * RCH's downstream port or a CXL root port. Check and handle
> +	 * them in the CXL.mem device driver.
>  	 */

"Internal errors of an RCEC indicate an AER error in an RCH's downstream port or a CXL root port."

Might be more correct to restate as:

"AER internal errors are used by root ports and RCECs to indicate AER in downstream CXL ports (RCH, USP, DSP) or devices"

Regards,
Terry