Re: [PATCH v6 4/6] acpi/ghes, cper: Recognize and cache CXL Protocol errors

["Luck, Tony" <tony.luck@intel.com>]

On Thu, Jan 23, 2025 at 08:44:19AM +0000, Smita Koralahalli wrote:
> Add support in GHES to detect and process CXL CPER Protocol errors, as
> defined in UEFI v2.10, section N.2.13.
> 
> Define struct cxl_cper_prot_err_work_data to cache CXL protocol error
> information, including RAS capabilities and severity, for further
> handling.
> 
> These cached CXL CPER records will later be processed by workqueues
> within the CXL subsystem.
> 
> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> ---
>  drivers/acpi/apei/ghes.c | 54 ++++++++++++++++++++++++++++++++++++++++
>  include/cxl/event.h      |  6 +++++
>  2 files changed, 60 insertions(+)
> 
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index b72772494655..4d725d988c43 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -674,6 +674,56 @@ static void ghes_defer_non_standard_event(struct acpi_hest_generic_data *gdata,
>  	schedule_work(&entry->work);
>  }
>  
> +static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
> +				   int severity)
> +{
> +#ifdef CONFIG_ACPI_APEI_PCIEAER

#ifdef in ".c" code is ugly. But I don't see a less ugly way to deal
with this. Moving this elsewhere and adding an empty stub function
for when CONFIG_ACPI_APEI_PCIEAER isn't configured doesn't make things
any better.

> +	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->valid_bits & PROT_ERR_VALID_SERIAL_NUMBER))
> +		pr_warn(FW_WARN "CXL CPER no device serial number\n");

Should this be rate limited too? It's not like this device will somehow
acquire a serial number if there is another error.

> +
> +	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 invalid agent type: %d\n",
> +				   prot_err->agent_type);
> +		return;
> +	}
> +#endif
> +}
> +
>  /* Room for 8 entries for each of the 4 event log queues */
>  #define CXL_CPER_FIFO_DEPTH 32
>  DEFINE_KFIFO(cxl_cper_fifo, struct cxl_cper_work_data, CXL_CPER_FIFO_DEPTH);
> @@ -777,6 +827,10 @@ static bool ghes_do_proc(struct ghes *ghes,
>  		}
>  		else if (guid_equal(sec_type, &CPER_SEC_PROC_ARM)) {
>  			queued = ghes_handle_arm_hw_error(gdata, sev, sync);
> +		} else if (guid_equal(sec_type, &CPER_SEC_CXL_PROT_ERR)) {
> +			struct cxl_cper_sec_prot_err *prot_err = acpi_hest_get_payload(gdata);
> +
> +			cxl_cper_post_prot_err(prot_err, gdata->error_severity);
>  		} else if (guid_equal(sec_type, &CPER_SEC_CXL_GEN_MEDIA_GUID)) {
>  			struct cxl_cper_event_rec *rec = acpi_hest_get_payload(gdata);
>  
> diff --git a/include/cxl/event.h b/include/cxl/event.h
> index 66d85fc87701..ee1c3dec62fa 100644
> --- a/include/cxl/event.h
> +++ b/include/cxl/event.h
> @@ -232,6 +232,12 @@ struct cxl_ras_capability_regs {
>  	u32 header_log[16];
>  };
>  
> +struct cxl_cper_prot_err_work_data {
> +	struct cxl_cper_sec_prot_err prot_err;
> +	struct cxl_ras_capability_regs ras_cap;
> +	int severity;
> +};
> +
>  #ifdef CONFIG_ACPI_APEI_GHES
>  int cxl_cper_register_work(struct work_struct *work);
>  int cxl_cper_unregister_work(struct work_struct *work);
> -- 
> 2.17.1
> 

With added ratelimit mentioned above:

Reviewed-by: Tony Luck <tony.luck@intel.com>

-Tony