Re: [PATCH 4/4 v3] ACPI: extlog: Trace CPER CXL Protocol Error Section

[Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 6/3/25 8:54 AM, Fabio M. De Francesco wrote:
> When Firmware First is enabled, BIOS handles errors first and then it makes
> them available to the kernel via the Common Platform Error Record (CPER)
> sections (UEFI 2.10 Appendix N). Linux parses the CPER sections via one of
> two similar paths, either ELOG or GHES. The errors managed by ELOG are
> signaled to the BIOS by the I/O Machine Check Architecture (I/O MCA).
>
> Currently, ELOG and GHES show some inconsistencies in how they report to
> userspace via trace events.
>
> Therefore, make the two mentioned paths act similarly by tracing the CPER
> CXL Protocol Error Section (UEFI v2.10, Appendix N.2.13).
>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com>
> ---

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

>   drivers/acpi/acpi_extlog.c | 64 ++++++++++++++++++++++++++++++++++++++
>   drivers/cxl/core/ras.c     |  6 ++++
>   include/cxl/event.h        |  2 ++
>   3 files changed, 72 insertions(+)
>
> diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
> index b2928ff297eda..de4f617f32d49 100644
> --- a/drivers/acpi/acpi_extlog.c
> +++ b/drivers/acpi/acpi_extlog.c
> @@ -12,6 +12,7 @@
>   #include <linux/ratelimit.h>
>   #include <linux/edac.h>
>   #include <linux/ras.h>
> +#include <cxl/event.h>
>   #include <acpi/ghes.h>
>   #include <asm/cpu.h>
>   #include <asm/mce.h>
> @@ -160,6 +161,62 @@ static void extlog_print_pcie(struct cper_sec_pcie *pcie_err,
>   	pci_dev_put(pdev);
>   }
>   
> +static void
> +extlog_cxl_cper_handle_prot_err(struct cxl_cper_sec_prot_err *prot_err,
> +				int severity)
> +{
> +#ifdef CONFIG_ACPI_APEI_PCIEAER
> +	struct cxl_cper_prot_err_work_data wd;
> +	u8 *dvsec_start, *cap_start;
> +
> +	if (!(prot_err->valid_bits & PROT_ERR_VALID_AGENT_ADDRESS)) {
> +		pr_err_ratelimited("CXL CPER invalid agent type\n");
> +		return;
> +	}
> +
> +	if (!(prot_err->valid_bits & PROT_ERR_VALID_ERROR_LOG)) {
> +		pr_err_ratelimited("CXL CPER invalid protocol error log\n");
> +		return;
> +	}
> +
> +	if (prot_err->err_len != sizeof(struct cxl_ras_capability_regs)) {
> +		pr_err_ratelimited("CXL CPER invalid RAS Cap size (%u)\n",
> +				   prot_err->err_len);
> +		return;
> +	}
> +
> +	if ((prot_err->agent_type == RCD || prot_err->agent_type == DEVICE ||
> +	     prot_err->agent_type == LD || prot_err->agent_type == FMLD) &&
> +	    !(prot_err->valid_bits & PROT_ERR_VALID_SERIAL_NUMBER))
> +		pr_warn(FW_WARN "CXL CPER no device serial number\n");
> +
> +	switch (prot_err->agent_type) {
> +	case RCD:
> +	case DEVICE:
> +	case LD:
> +	case FMLD:
> +	case RP:
> +	case DSP:
> +	case USP:
> +		memcpy(&wd.prot_err, prot_err, sizeof(wd.prot_err));
> +
> +		dvsec_start = (u8 *)(prot_err + 1);
> +		cap_start = dvsec_start + prot_err->dvsec_len;
> +
> +		memcpy(&wd.ras_cap, cap_start, sizeof(wd.ras_cap));
> +		wd.severity = cper_severity_to_aer(severity);
> +		break;
> +	default:
> +		pr_err_ratelimited("CXL CPER reserved agent type: %d\n",
> +				   prot_err->agent_type);
> +		return;
> +	}
> +
> +	cxl_cper_ras_handle_prot_err(&wd);
> +
> +#endif
> +}
> +
>   static int extlog_print(struct notifier_block *nb, unsigned long val,
>   			void *data)
>   {
> @@ -211,6 +268,12 @@ static int extlog_print(struct notifier_block *nb, unsigned long val,
>   			if (gdata->error_data_length >= sizeof(*mem))
>   				trace_extlog_mem_event(mem, err_seq, fru_id, fru_text,
>   						       (u8)gdata->error_severity);
> +		} else if (guid_equal(sec_type, &CPER_SEC_CXL_PROT_ERR)) {
> +			struct cxl_cper_sec_prot_err *prot_err =
> +				acpi_hest_get_payload(gdata);
> +
> +			extlog_cxl_cper_handle_prot_err(prot_err,
> +							gdata->error_severity);
>   		} else if (guid_equal(sec_type, &CPER_SEC_PCIE)) {
>   			struct cper_sec_pcie *pcie_err = acpi_hest_get_payload(gdata);
>   
> @@ -378,3 +441,4 @@ module_exit(extlog_exit);
>   MODULE_AUTHOR("Chen, Gong <gong.chen@intel.com>");
>   MODULE_DESCRIPTION("Extended MCA Error Log Driver");
>   MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS("CXL");
> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index 485a831695c70..56db290c88d35 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -98,6 +98,12 @@ static void cxl_cper_handle_prot_err(struct cxl_cper_prot_err_work_data *data)
>   		cxl_cper_trace_uncorr_prot_err(pdev, data->ras_cap);
>   }
>   
> +void cxl_cper_ras_handle_prot_err(struct cxl_cper_prot_err_work_data *wd)
> +{
> +	cxl_cper_handle_prot_err(wd);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_cper_ras_handle_prot_err, "CXL");
> +
>   static void cxl_cper_prot_err_work_fn(struct work_struct *work)
>   {
>   	struct cxl_cper_prot_err_work_data wd;
> diff --git a/include/cxl/event.h b/include/cxl/event.h
> index f9ae1796da85f..aef906e260330 100644
> --- a/include/cxl/event.h
> +++ b/include/cxl/event.h
> @@ -285,4 +285,6 @@ static inline int cxl_cper_prot_err_kfifo_get(struct cxl_cper_prot_err_work_data
>   }
>   #endif
>   
> +void cxl_cper_ras_handle_prot_err(struct cxl_cper_prot_err_work_data *wd);
> +
>   #endif /* _LINUX_CXL_EVENT_H */

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer