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

Sathyanarayanan Kuppuswamy
2025-01-23T20:10:47Z

Hi,

On 11/12/24 5:54 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@linux.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);
> }
> 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))
> handle_error_source(e_info->dev[i], e_info);
> }
> }
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 62a68cde4364..b3f157a00405 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -304,7 +304,7 @@ struct pci_dev *dpc_process_error(struct pci_dev *pdev)
> dpc_process_rp_pio_error(pdev);
> else if (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_UNCOR &&
> dpc_get_aer_uncorrect_severity(pdev, &info) &&
> - aer_get_device_error_info(pdev, &info)) {
> + aer_get_device_error_info(pdev, &info, false)) {
> aer_print_error(pdev, &info);
> pci_aer_clear_nonfatal_status(pdev);
> pci_aer_clear_fatal_status(pdev);
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index 31090770fffc..462577b8d75a 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -196,6 +196,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> struct pci_dev *bridge;
> pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
> struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
> + struct aer_err_info info;
>
> /*
> * If the error was detected by a Root Port, Downstream Port, RCEC,
> @@ -223,6 +224,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> pci_warn(bridge, "subordinate device reset failed\n");
> goto failed;
> }
> +
> + info.severity = AER_FATAL;
> + /* Link recovered, report fatal errors of RCiEP or EP */
> + if ((type == PCI_EXP_TYPE_ENDPOINT ||
> + type == PCI_EXP_TYPE_RC_END) &&
> + aer_get_device_error_info(dev, &info, true))
> + aer_print_error(dev, &info);

IMO, error device information is more like a debug info. Can we change
the print level of this info to debug?

> } else {
> pci_walk_bridge(bridge, report_normal_detected, &status);
> }
> @@ -259,6 +267,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> if (host->native_aer || pcie_ports_native) {
> pcie_clear_device_status(dev);
> pci_aer_clear_nonfatal_status(dev);
> + pci_aer_clear_fatal_status(dev);

I think we clear fatal status in DPC driver, why do it again?

> }
>
> pci_walk_bridge(bridge, pci_pm_runtime_put, NULL);

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer