Re: [PATCH 2/4] acpi/ghes, efi/cper: Recognize and process CXL Protocol Errors.

[Smita Koralahalli]

Hi Alison,

On 5/22/2024 5:03 PM, Alison Schofield wrote:
> On Wed, May 22, 2024 at 03:08:37PM +0000, Smita Koralahalli wrote:
> > UEFI v2.10 section N.2.13 defines a CPER record for CXL Protocol errors.
> >
> > Add GHES support to detect CXL CPER Protocol Error Record and Cache Error
> > Severity, Device ID, Device Serial number and CXL RAS capability struct in
> > struct cxl_cper_prot_err. Include this struct as a member of struct
> > cxl_cper_work_data.
> >
> > Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@xxxxxxx>
> > ---
> >   drivers/acpi/apei/ghes.c        | 10 +++++
> >   drivers/firmware/efi/cper_cxl.c | 66 +++++++++++++++++++++++++++++++++
> >   include/linux/cxl-event.h       | 26 +++++++++++++
> >   3 files changed, 102 insertions(+)
> >
> > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> > index 623cc0cb4a65..1a58032770ee 100644
> > --- a/drivers/acpi/apei/ghes.c
> > +++ b/drivers/acpi/apei/ghes.c
> > @@ -717,6 +717,14 @@ static void cxl_cper_post_event(enum cxl_event_type event_type,
> >   	schedule_work(cxl_cper_work);
> >   }
> >   
> > +static void cxl_cper_handle_prot_err(struct acpi_hest_generic_data *gdata)
> > +{
> > +	struct cxl_cper_work_data wd;
> > +
> > +	if (cxl_cper_handle_prot_err_info(gdata, &wd.p_err))
> > +		return;
> > +}
> > +
> >   int cxl_cper_register_work(struct work_struct *work)
> >   {
> >   	if (cxl_cper_work)
> > @@ -791,6 +799,8 @@ static bool ghes_do_proc(struct ghes *ghes,
> >   			struct cxl_cper_event_rec *rec = acpi_hest_get_payload(gdata);
> >   
> >   			cxl_cper_post_event(CXL_CPER_EVENT_MEM_MODULE, rec);
> > +		} else if (guid_equal(sec_type, &CPER_SEC_CXL_PROT_ERR)) {
> > +			cxl_cper_handle_prot_err(gdata);
> >   		} else {
> >   			void *err = acpi_hest_get_payload(gdata);
> >   
> > diff --git a/drivers/firmware/efi/cper_cxl.c b/drivers/firmware/efi/cper_cxl.c
> > index 4fd8d783993e..03b9839f3b73 100644
> > --- a/drivers/firmware/efi/cper_cxl.c
> > +++ b/drivers/firmware/efi/cper_cxl.c
> > @@ -8,6 +8,7 @@
> >    */
> >   
> >   #include <linux/cper.h>
> > +#include <acpi/ghes.h>
> >   #include "cper_cxl.h"
> >   
> >   #define PROT_ERR_VALID_AGENT_TYPE		BIT_ULL(0)
> > @@ -44,6 +45,17 @@ enum {
> >   	USP,	/* CXL Upstream Switch Port */
> >   };
> >   
> > +static enum cxl_aer_err_type cper_severity_cxl_aer(int cper_severity)
> > +{
> > +	switch (cper_severity) {
> > +	case CPER_SEV_RECOVERABLE:
> > +	case CPER_SEV_FATAL:
> > +		return CXL_AER_UNCORRECTABLE;
> > +	default:
> > +		return CXL_AER_CORRECTABLE;
> > +	}
> > +}
> > +
> >   void cper_print_prot_err(const char *pfx, const struct cper_sec_prot_err *prot_err)
> >   {
> >   	if (prot_err->valid_bits & PROT_ERR_VALID_AGENT_TYPE)
> > @@ -176,3 +188,57 @@ void cper_print_prot_err(const char *pfx, const struct cper_sec_prot_err *prot_e
> >   			       sizeof(cxl_ras->header_log), 0);
> >   	}
> >   }
> > +
> > +int cxl_cper_handle_prot_err_info(struct acpi_hest_generic_data *gdata,
> > +				  struct cxl_cper_prot_err *p_err)
> > +{
> > +	struct cper_sec_prot_err *prot_err = acpi_hest_get_payload(gdata);
> > +	u8 *dvsec_start, *cap_start;
> > +
> > +	if (!(prot_err->valid_bits & PROT_ERR_VALID_DEVICE_ID)) {
> > +		pr_err(FW_WARN "No Device ID\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	/*
> > +	 * The device ID or agent address is required for CXL RCD, CXL
> > +	 * SLD, CXL LD, CXL Fabric Manager Managed LD, CXL Root Port,
> > +	 * CXL Downstream Switch Port and CXL Upstream Switch Port.
> > +	 */
> > +	if (prot_err->agent_type <= 0x7 && prot_err->agent_type != RCH_DP) {
>
> For this check against agent_type, and the similar one below, would a boolean
> array indexed by the agent type work? That would avoid the <= 0x7 and > 0x4
> below. It seems one array would suffice for this case, but naming it isn't obvious
> to me. Maybe it'll be to you.
>
> Something similar to what is done for prot_err_agent_type_strs[]
>
> static const bool agent_requires_id_address_serial[] = {
> 	true,	/* RDC */ 	
> 	false,	/* RCH_DP */
> 	.
> 	.
> 	.
> };

Noted. Will implement it this way!

Thanks
Smita

> > +		p_err->segment = prot_err->agent_addr.segment;
> > +		p_err->bus = prot_err->agent_addr.bus;
> > +		p_err->device = prot_err->agent_addr.device;
> > +		p_err->function = prot_err->agent_addr.function;
> > +	} else {
> > +		pr_err(FW_WARN "Invalid agent type\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!(prot_err->valid_bits & PROT_ERR_VALID_ERROR_LOG)) {
> > +		pr_err(FW_WARN "Invalid Protocol Error log\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	dvsec_start = (u8 *)(prot_err + 1);
> > +	cap_start = dvsec_start + prot_err->dvsec_len;
> > +	p_err->cxl_ras = *(struct cxl_ras_capability_regs *)cap_start;
> > +
> > +	/*
> > +	 * Set device serial number unconditionally.
> > +	 *
> > +	 * Print a warning message if it is not valid. The device serial
> > +	 * number is required for CXL RCD, CXL SLD, CXL LD and CXL Fabric
> > +	 * Manager Managed LD.
> > +	 */
> > +	if (!(prot_err->valid_bits & PROT_ERR_VALID_SERIAL_NUMBER) ||
> > +	      prot_err->agent_type > 0x4 || prot_err->agent_type == RCH_DP)
>
> then this also can be replaced with
> 		agent_requires_id_address_serial[prot_err->agent_type]
>
>
> -- Alison
>
>
> > +		pr_warn(FW_WARN "No Device Serial number\n");
> > +
> > +	p_err->lower_dw = prot_err->dev_serial_num.lower_dw;
> > +	p_err->upper_dw = prot_err->dev_serial_num.upper_dw;
> > +
> > +	p_err->severity = cper_severity_cxl_aer(gdata->error_severity);
> > +
> > +	return 0;
> > +}
>
> snip