linux-kernel - Re: [PATCH v2 2/2] PCI/AER: Report fatal errors of RCiEP and EP if link recoverd

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Message-ID: <22d27575-fc68-4a7f-9bce-45b91c7dfb98@linux.alibaba.com>
Date: Sat, 16 Nov 2024 20:44:49 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: "Bowman, Terry" <terry.bowman@....com>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 bhelgaas@...gle.com, kbusch@...nel.org, Lukas Wunner <lukas@...ner.de>
Cc: mahesh@...ux.ibm.com, oohall@...il.com,
 sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH v2 2/2] PCI/AER: Report fatal errors of RCiEP and EP if
 link recoverd



在 2024/11/16 04:20, Bowman, Terry 写道:
> Hi Shuai,
> 
> 
> On 11/12/2024 7:54 AM, Shuai Xue wrote:
>> The AER driver has historically avoided reading the configuration space of
>> an endpoint or RCiEP that reported a fatal error, considering the link to
>> that device unreliable. Consequently, when a fatal error occurs, the AER
>> and DPC drivers do not report specific error types, resulting in logs like:
>>
>>    pcieport 0000:30:03.0: EDR: EDR event received
>>    pcieport 0000:30:03.0: DPC: containment event, status:0x0005 source:0x3400
>>    pcieport 0000:30:03.0: DPC: ERR_FATAL detected
>>    pcieport 0000:30:03.0: AER: broadcast error_detected message
>>    nvme nvme0: frozen state error detected, reset controller
>>    nvme 0000:34:00.0: ready 0ms after DPC
>>    pcieport 0000:30:03.0: AER: broadcast slot_reset message
>>
>> AER status registers are sticky and Write-1-to-clear. If the link recovered
>> after hot reset, we can still safely access AER status of the error device.
>> In such case, report fatal errors which helps to figure out the error root
>> case.
>>
>> After this patch, the logs like:
>>
>>    pcieport 0000:30:03.0: EDR: EDR event received
>>    pcieport 0000:30:03.0: DPC: containment event, status:0x0005 source:0x3400
>>    pcieport 0000:30:03.0: DPC: ERR_FATAL detected
>>    pcieport 0000:30:03.0: AER: broadcast error_detected message
>>    nvme nvme0: frozen state error detected, reset controller
>>    pcieport 0000:30:03.0: waiting 100 ms for downstream link, after activation
>>    nvme 0000:34:00.0: ready 0ms after DPC
>>    nvme 0000:34:00.0: PCIe Bus Error: severity=Uncorrectable (Fatal), type=Data Link Layer, (Receiver ID)
>>    nvme 0000:34:00.0:   device [144d:a804] error status/mask=00000010/00504000
>>    nvme 0000:34:00.0:    [ 4] DLP                    (First)
>>    pcieport 0000:30:03.0: AER: broadcast slot_reset message
>>
>> Signed-off-by: Shuai Xue <xueshuai@...ux.alibaba.com>
>> ---
>>   drivers/pci/pci.h      |  3 ++-
>>   drivers/pci/pcie/aer.c | 11 +++++++----
>>   drivers/pci/pcie/dpc.c |  2 +-
>>   drivers/pci/pcie/err.c |  9 +++++++++
>>   4 files changed, 19 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>> index 0866f79aec54..6f827c313639 100644
>> --- a/drivers/pci/pci.h
>> +++ b/drivers/pci/pci.h
>> @@ -504,7 +504,8 @@ struct aer_err_info {
>>   	struct pcie_tlp_log tlp;	/* TLP Header */
>>   };
>>   
>> -int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info);
>> +int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info,
>> +			      bool link_healthy);
>>   void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);
>>   #endif	/* CONFIG_PCIEAER */
>>   
>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>> index 13b8586924ea..97ec1c17b6f4 100644
>> --- a/drivers/pci/pcie/aer.c
>> +++ b/drivers/pci/pcie/aer.c
>> @@ -1200,12 +1200,14 @@ EXPORT_SYMBOL_GPL(aer_recover_queue);
>>    * aer_get_device_error_info - read error status from dev and store it to info
>>    * @dev: pointer to the device expected to have a error record
>>    * @info: pointer to structure to store the error record
>> + * @link_healthy: link is healthy or not
>>    *
>>    * Return 1 on success, 0 on error.
>>    *
>>    * Note that @info is reused among all error devices. Clear fields properly.
>>    */
>> -int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
>> +int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info,
>> +			      bool link_healthy)
>>   {
>>   	int type = pci_pcie_type(dev);
>>   	int aer = dev->aer_cap;
>> @@ -1229,7 +1231,8 @@ 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 ||
>> +		   (info->severity == AER_FATAL && link_healthy)) {
>>   
>>   		/* Link is still healthy for IO reads */
>>   		pci_read_config_dword(dev, aer + PCI_ERR_UNCOR_STATUS,
>> @@ -1258,11 +1261,11 @@ static inline void aer_process_err_devices(struct aer_err_info *e_info)
>>   
>>   	/* Report all before handle them, not to lost records by reset etc. */
>>   	for (i = 0; i < e_info->error_dev_num && e_info->dev[i]; i++) {
>> -		if (aer_get_device_error_info(e_info->dev[i], e_info))
>> +		if (aer_get_device_error_info(e_info->dev[i], e_info, false))
>>   			aer_print_error(e_info->dev[i], e_info);
>>   	}
> 
> Would it be reasonable to detect if the link is intact and set the aer_get_device_error_info()
> function's 'link_healthy' parameter accordingly? I was thinking the port upstream capability
> link status register could be used to indicate the link viability.
> 
> Regards,
> Terry

Good idea. I think pciehp_check_link_active is a good implementation to check
link_healthy in aer_get_device_error_info().

   int pciehp_check_link_active(struct controller *ctrl)
   {
   	struct pci_dev *pdev = ctrl_dev(ctrl);
   	u16 lnk_status;
   	int ret;
   
   	ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
   	if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status))
   		return -ENODEV;
   
   	ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
   	ctrl_dbg(ctrl, "%s: lnk_status = %x\n", __func__, lnk_status);
   
   	return ret;
   }

Thank you for valuable comments.

Best Regards
Shuai