Re: "invalid agent type: 1" in acpi/ghes, cper: Recognize and cache CXL Protocol errors

[Koralahalli Channabasappa, Smita]

On 7/28/2025 10:41 PM, Marc Herbert wrote:
> On 2025-07-28 09:25, Koralahalli Channabasappa, Smita wrote:
>
> > On 7/22/2025 12:24 PM, Marc Herbert wrote:
>
> > >     The code below triggers the error "invalid agent type: 1" in Intel
> > > validation (internal issue 15018133056)
> > >
> > > It's not clear to anyone we asked why you did not include RCH_DP in
> > > the `switch (prot_err->agent_type)` in cxl_cper_post_prot_err() below.
> > >
> > > I can see how RCH_DP is special in cxl_cper_PRINT_prot_err() and I can
> > > even understand (despite my near-zero CPER knowledge) some of the
> > > special cases there. But in cxl_cper_post_prot_err() here, it's not
> > > clear why RCH_DP would be rejected. Could this be an oversight? If not,
> > > a comment with a short explanation would not hurt.
> >
> > You're right. RCH_DP was excluded because it doesn’t report a valid
> > SBDF in the CPER record. Instead, it provides only the RCRB base
> > address.
> >
> > I haven't thoroughly investigated whether SBDF can be reliably derived
> > from the RCRB base. There might be a platform-specific mechanism for
> > that, but at the time, it seemed non-trivial to implement. Introducing
> > additional infrastructure solely to support RCH_DP felt like it was
> > adding more complexity.
> >
> > I agree that a brief comment explaining this rationale would help. I'm
> > okay if you plan to include a fixup for this along with the one for
> > the device serial number.
>
> If I understood you correctly, I think a different error message
> would be much better than a comment. Like this?

Yeah looks good to me. Thanks for fixing this!

Thanks
Smita

> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -730,6 +730,9 @@ static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
>   		memcpy(&wd.ras_cap, cap_start, sizeof(wd.ras_cap));
>   		wd.severity = cper_severity_to_aer(severity);
>   		break;
> +	case RCH_DP:
> +		pr_err_ratelimited("CXL CPER agent type unsupported: RCH_DP\n");
> +		return;
>   	default:
>   		pr_err_ratelimited("CXL CPER invalid agent type: %d\n",
>   				   prot_err->agent_type);