linux-kernel - Re: [PATCH v8 10/16] cxl/pci: Add log message if RAS registers are not mapped

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Message-ID: <139b2f1e-2ddd-4e4f-a63c-4516263250cf@amd.com>
Date: Thu, 24 Apr 2025 09:30:48 -0500
From: "Bowman, Terry" <terry.bowman@....com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-pci@...r.kernel.org, nifan.cxl@...il.com, dave@...olabs.net,
 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, lukas@...ner.de,
 ming.li@...omail.com, PradeepVineshReddy.Kodamati@....com
Subject: Re: [PATCH v8 10/16] cxl/pci: Add log message if RAS registers are
 not mapped



On 4/23/2025 11:41 AM, Jonathan Cameron wrote:
> On Wed, 26 Mar 2025 20:47:11 -0500
> Terry Bowman <terry.bowman@....com> wrote:
>
>> The CXL RAS handlers do not currently log if the RAS registers are
>> unmapped. This is needed in order to help debug CXL error handling. Update
>> the CXL driver to log a warning message if the RAS register block is
>> unmapped during RAS error handling.
>>
>> Also, refactor the __cxl_handle_cor_ras() functions check for status.
>> Change it to be consistent with the same status check in
>> __cxl_handle_cor_ras().
> Not keen on an 'also' bit in here.  Seems entirely separable
> into its own patch.
>
> Two trivial one thing patches seems better than one slightly larger one.
> Actual changes seem fine to me so feel free to add
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> to resulting pair of patches.

Hi Jonathan,

I will split the patch as you recommend.

-Terry

>> Signed-off-by: Terry Bowman <terry.bowman@....com>
>> ---
>>  drivers/cxl/core/pci.c | 17 +++++++++++------
>>  1 file changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
>> index 1cf1ab4d9160..4770810b2138 100644
>> --- a/drivers/cxl/core/pci.c
>> +++ b/drivers/cxl/core/pci.c
>> @@ -656,15 +656,18 @@ static void __cxl_handle_cor_ras(struct device *dev,
>>  	void __iomem *addr;
>>  	u32 status;
>>  
>> -	if (!ras_base)
>> +	if (!ras_base) {
>> +		dev_warn_once(dev, "CXL RAS register block is not mapped");
>>  		return;
>> +	}
>>  
>>  	addr = ras_base + CXL_RAS_CORRECTABLE_STATUS_OFFSET;
>>  	status = readl(addr);
>> -	if (status & CXL_RAS_CORRECTABLE_STATUS_MASK) {
>> -		writel(status & CXL_RAS_CORRECTABLE_STATUS_MASK, addr);
>> -		trace_cxl_aer_correctable_error(to_cxl_memdev(dev), status);
>> -	}
>> +	if (!(status & CXL_RAS_CORRECTABLE_STATUS_MASK))
>> +		return;
>> +	writel(status & CXL_RAS_CORRECTABLE_STATUS_MASK, addr);
>> +
>> +	trace_cxl_aer_correctable_error(to_cxl_memdev(dev), status);
>>  }
>>  
>>  static void cxl_handle_endpoint_cor_ras(struct cxl_dev_state *cxlds)
>> @@ -700,8 +703,10 @@ static bool __cxl_handle_ras(struct device *dev, void __iomem *ras_base)
>>  	u32 status;
>>  	u32 fe;
>>  
>> -	if (!ras_base)
>> +	if (!ras_base) {
>> +		dev_warn_once(dev, "CXL RAS register block is not mapped");
>>  		return false;
>> +	}
>>  
>>  	addr = ras_base + CXL_RAS_UNCORRECTABLE_STATUS_OFFSET;
>>  	status = readl(addr);