linux-kernel - Re: [PATCH v5 06/16] PCI/AER: Change AER driver to read UCE fatal status for all CXL PCIe Port devices

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Message-ID: <f9194caf-9dbb-4b2c-b4ac-71bdfda38dc5@amd.com>
Date: Tue, 28 Jan 2025 14:25:54 -0600
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, alucerop@....com,
 Shuai Xue <xueshuai@...ux.alibaba.com>
Subject: Re: [PATCH v5 06/16] PCI/AER: Change AER driver to read UCE fatal
 status for all CXL PCIe Port devices




On 1/14/2025 5:32 AM, Jonathan Cameron wrote:
> On Tue, 7 Jan 2025 08:38:42 -0600
> Terry Bowman <terry.bowman@....com> 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 devices. Make the change such that non-CXL devices
>> are not affected.
>>
>> The fatal error status will be used in future patches implementing
>> CXL PCIe Port uncorrectable error handling and logging.
>>
>> Signed-off-by: Terry Bowman <terry.bowman@....com>
> This clashes with Shuai's series adding link healthy checks.
> Maybe we can reuse that logic to incorporate the condition we
> care about here?
>

Hi Jonathan, et. al,

After looking at this closer and considering the situation I believe
we should remove this patch from the patchset and defer adding these
changes to log USP AER and RAS UCE.

I propose we reintroduce this later as a RFC or RFT in a future patchset.
This will give more needed time for testing.

The only downside to adding later is in the case of CXL USP fatal UCE. AER and
RAS will not be logged but this was the AER driver's existing behavior and as a
result isn't a regression.

Your thoughts?

Regards,
Terry

>> ---
>>  drivers/pci/pcie/aer.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>> index 62be599e3bee..79c828bdcb6d 100644
>> --- a/drivers/pci/pcie/aer.c
>> +++ b/drivers/pci/pcie/aer.c
>> @@ -1253,7 +1253,8 @@ 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,