linux-kernel - Re: [PATCH v3 05/15] PCI/AER: Add CXL PCIe port correctable error support in AER service driver

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Message-ID:
 <VI1PR10MB201607EB59D6C0884A57995CCE242@VI1PR10MB2016.EURPRD10.PROD.OUTLOOK.COM>
Date: Fri, 15 Nov 2024 22:49:59 +0800
From: Li Ming <ming4.li@...look.com>
To: "Bowman, Terry" <terry.bowman@....com>, Lukas Wunner <lukas@...ner.de>
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
Subject: Re: [PATCH v3 05/15] PCI/AER: Add CXL PCIe port correctable error
 support in AER service driver



On 2024/11/15 2:41, Bowman, Terry wrote:
> Hi Lukas,
> 
> I added comments below.
> 
> On 11/14/2024 10:44 AM, Lukas Wunner wrote:
>> On Wed, Nov 13, 2024 at 03:54:19PM -0600, Terry Bowman wrote:
>>> @@ -1115,8 +1131,11 @@ static void pci_aer_handle_error(struct pci_dev *dev, struct aer_err_info *info)
>>>   
>>>   static void handle_error_source(struct pci_dev *dev, struct aer_err_info *info)
>>>   {
>>> -	cxl_handle_error(dev, info);
>>> -	pci_aer_handle_error(dev, info);
>>> +	if (is_internal_error(info) && handles_cxl_errors(dev))
>>> +		cxl_handle_error(dev, info);
>>> +	else
>>> +		pci_aer_handle_error(dev, info);
>>> +
>>>   	pci_dev_put(dev);
>>>   }
>> If you just do this at the top of cxl_handle_error()...
>>
>> 	if (!is_internal_error(info))
>> 		return;
>>
>> ...you avoid the need to move is_internal_error() around and the
>> patch becomes simpler and easier to review.
> 
> If is_internal_error()==0, then pci_aer_handle_error() should be called to process the PCIe error. Your suggestion would require returning a value from cxl_handle_error(). And then more "if" logic would be required for the cxl_handle_error() return value. Should both is_internal_error() and handles_cxl_errors()be moved into cxl_handle_error()? Would give this:
> 
>   static void handle_error_source(struct pci_dev *dev, struct aer_err_info *info)
>   {
> -	cxl_handle_error(dev, info);
> -	pci_aer_handle_error(dev, info);
> +	if (!cxl_handle_error(dev, info))
> +		pci_aer_handle_error(dev, info);
> +
>   	pci_dev_put(dev);
>   }
> 

I think is_internal_error() can be moved into handles_cxl_errors(). 
handles_cxl_errors() helps to check if the error is a CXL error, avoid 
this detail which CXL error is an internal error in 
handle_error_source(). Like this:

    static void handle_error_source(struct pci_dev *dev, struct 
aer_err_info *info)
    {
  -	cxl_handle_error(dev, info);
  -	pci_aer_handle_error(dev, info);
  +	if (handles_cxl_errors(dev, info))
  +		cxl_handle_error(dev, info);
  +	else
  +		pci_aer_handle_error(dev, info);
  +
    	pci_dev_put(dev);
    }


Ming

>>
>>> The AER service driver supports handling downstream port protocol errors in
>>> restricted CXL host (RCH) mode also known as CXL1.1. It needs the same
>>> functionality for CXL PCIe ports operating in virtual hierarchy (VH)
>>> mode.[1]
>> This is somewhat minor but by convention, patches in the PCI subsystem
>> adhere to spec language and capitalization, e.g. "Downstream Port"
>> instead of "downstream port".  Makes it easier to connect the commit
>> message or code comments to the spec.  So maybe you want to consider
>> that if/when respinning.
>>
>> Thanks,
>>
>> Lukas
> Thanks for pointing that out. I'll update as you suggest.
> 
> Regards,
> Terry
>