Re: [PATCH v5 9/9] cxl/pci: Register for and process CPER events

[Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>]

Hi Ira,

I tested these patches. It works as expected.

Tested-by: Smita-Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Reviewed-by: Smita-Koralahalli <Smita.KoralahalliChannabasappa@amd.com>

Since, the trace support for FW-First Protocol errors are missing I 
wrote a patch for it. I reused the existing registered callback 
cxl_cper_callback making some changes to it. Please take a look and let 
me know what you think. I'm not sure if its appropriate to reuse the 
existing callback or define a new one..

https://lore.kernel.org/linux-cxl/20240102150933.161009-1-Smita.KoralahalliChannabasappa@amd.com/T/#t

Thanks,
Smita

On 12/20/2023 4:17 PM, Ira Weiny wrote:
> If the firmware has configured CXL event support to be firmware first
> the OS can process those events through CPER records.  The CXL layer has
> unique DPA to HPA knowledge and standard event trace parsing in place.
> 
> CPER records contain Bus, Device, Function information which can be used
> to identify the PCI device which is sending the event.
> 
> Change the PCI driver registration to include registration of a CXL
> CPER callback to process events through the trace subsystem.
> 
> Use new scoped based management to simplify the handling of the PCI
> device object.
> 
> NOTE this patch depends on Dan's addition of a device guard[1].
> 
> [1] https://lore.kernel.org/all/170250854466.1522182.17555361077409628655.stgit@dwillia2-xfh.jf.intel.com/
> 
> ---
> Changes for v5:
> [Smita/djbw: trace a generic UUID if the type is unknown]
> [Jonathan: clean up pci and device state error handling]
> [iweiny: consolidate the trace function]
> ---
>   drivers/cxl/core/mbox.c   | 49 ++++++++++++++++++++++++++++-----------
>   drivers/cxl/cxlmem.h      |  4 ++++
>   drivers/cxl/pci.c         | 58 ++++++++++++++++++++++++++++++++++++++++++++++-
>   include/linux/cxl-event.h |  1 +
>   4 files changed, 98 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 06957696247b..b801faaccd45 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -836,21 +836,44 @@ int cxl_enumerate_cmds(struct cxl_memdev_state *mds)
>   }
>   EXPORT_SYMBOL_NS_GPL(cxl_enumerate_cmds, CXL);
>   
> -static void cxl_event_trace_record(const struct cxl_memdev *cxlmd,
> -				   enum cxl_event_log_type type,
> -				   struct cxl_event_record_raw *record)
> +void cxl_event_trace_record(const struct cxl_memdev *cxlmd,
> +			    enum cxl_event_log_type type,
> +			    enum cxl_event_type event_type,
> +			    const uuid_t *uuid, union cxl_event *evt)
>   {
> -	union cxl_event *evt = &record->event;
> -	uuid_t *id = &record->id;
> -
> -	if (uuid_equal(id, &CXL_EVENT_GEN_MEDIA_UUID))
> +	switch (event_type) {
> +	case CXL_CPER_EVENT_GEN_MEDIA:
>   		trace_cxl_general_media(cxlmd, type, &evt->gen_media);
> -	else if (uuid_equal(id, &CXL_EVENT_DRAM_UUID))
> +		break;
> +	case CXL_CPER_EVENT_DRAM:
>   		trace_cxl_dram(cxlmd, type, &evt->dram);
> -	else if (uuid_equal(id, &CXL_EVENT_MEM_MODULE_UUID))
> +		break;
> +	case CXL_CPER_EVENT_MEM_MODULE:
>   		trace_cxl_memory_module(cxlmd, type, &evt->mem_module);
> -	else
> -		trace_cxl_generic_event(cxlmd, type, id, &evt->generic);
> +		break;
> +	case CXL_CPER_EVENT_GENERIC:
> +	default:
> +		trace_cxl_generic_event(cxlmd, type, uuid, &evt->generic);
> +		break;
> +	}
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_event_trace_record, CXL);
> +
> +static void __cxl_event_trace_record(const struct cxl_memdev *cxlmd,
> +				     enum cxl_event_log_type type,
> +				     struct cxl_event_record_raw *record)
> +{
> +	enum cxl_event_type ev_type = CXL_CPER_EVENT_GENERIC;
> +	const uuid_t *uuid = &record->id;
> +
> +	if (uuid_equal(uuid, &CXL_EVENT_GEN_MEDIA_UUID))
> +		ev_type = CXL_CPER_EVENT_GEN_MEDIA;
> +	else if (uuid_equal(uuid, &CXL_EVENT_DRAM_UUID))
> +		ev_type = CXL_CPER_EVENT_DRAM;
> +	else if (uuid_equal(uuid, &CXL_EVENT_MEM_MODULE_UUID))
> +		ev_type = CXL_CPER_EVENT_MEM_MODULE;
> +
> +	cxl_event_trace_record(cxlmd, type, ev_type, uuid, &record->event);
>   }
>   
>   static int cxl_clear_event_record(struct cxl_memdev_state *mds,
> @@ -961,8 +984,8 @@ static void cxl_mem_get_records_log(struct cxl_memdev_state *mds,
>   			break;
>   
>   		for (i = 0; i < nr_rec; i++)
> -			cxl_event_trace_record(cxlmd, type,
> -					       &payload->records[i]);
> +			__cxl_event_trace_record(cxlmd, type,
> +						 &payload->records[i]);
>   
>   		if (payload->flags & CXL_GET_EVENT_FLAG_OVERFLOW)
>   			trace_cxl_overflow(cxlmd, type, payload);
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index e5d770e26e02..80076c235073 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -802,6 +802,10 @@ void set_exclusive_cxl_commands(struct cxl_memdev_state *mds,
>   void clear_exclusive_cxl_commands(struct cxl_memdev_state *mds,
>   				  unsigned long *cmds);
>   void cxl_mem_get_event_records(struct cxl_memdev_state *mds, u32 status);
> +void cxl_event_trace_record(const struct cxl_memdev *cxlmd,
> +			    enum cxl_event_log_type type,
> +			    enum cxl_event_type event_type,
> +			    const uuid_t *uuid, union cxl_event *evt);
>   int cxl_set_timestamp(struct cxl_memdev_state *mds);
>   int cxl_poison_state_init(struct cxl_memdev_state *mds);
>   int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 0155fb66b580..b14237f824cf 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -1,5 +1,6 @@
>   // SPDX-License-Identifier: GPL-2.0-only
>   /* Copyright(c) 2020 Intel Corporation. All rights reserved. */
> +#include <asm-generic/unaligned.h>
>   #include <linux/io-64-nonatomic-lo-hi.h>
>   #include <linux/moduleparam.h>
>   #include <linux/module.h>
> @@ -969,6 +970,61 @@ static struct pci_driver cxl_pci_driver = {
>   	},
>   };
>   
> +#define CXL_EVENT_HDR_FLAGS_REC_SEVERITY GENMASK(1, 0)
> +static void cxl_cper_event_call(enum cxl_event_type ev_type,
> +				struct cxl_cper_event_rec *rec)
> +{
> +	struct cper_cxl_event_devid *device_id = &rec->hdr.device_id;
> +	struct pci_dev *pdev __free(pci_dev_put) = NULL;
> +	enum cxl_event_log_type log_type;
> +	struct cxl_dev_state *cxlds;
> +	unsigned int devfn;
> +	u32 hdr_flags;
> +
> +	devfn = PCI_DEVFN(device_id->device_num, device_id->func_num);
> +	pdev = pci_get_domain_bus_and_slot(device_id->segment_num,
> +					   device_id->bus_num, devfn);
> +	if (!pdev)
> +		return;
> +
> +	guard(device)(&pdev->dev);
> +	if (pdev->driver != &cxl_pci_driver)
> +		return;
> +
> +	cxlds = pci_get_drvdata(pdev);
> +	if (!cxlds)
> +		return;
> +
> +	/* Fabricate a log type */
> +	hdr_flags = get_unaligned_le24(rec->event.generic.hdr.flags);
> +	log_type = FIELD_GET(CXL_EVENT_HDR_FLAGS_REC_SEVERITY, hdr_flags);
> +
> +	cxl_event_trace_record(cxlds->cxlmd, log_type, ev_type,
> +			       &uuid_null, &rec->event);
> +}
> +
> +static int __init cxl_pci_driver_init(void)
> +{
> +	int rc;
> +
> +	rc = pci_register_driver(&cxl_pci_driver);
> +	if (rc)
> +		return rc;
> +
> +	rc = cxl_cper_register_callback(cxl_cper_event_call);
> +	if (rc)
> +		pci_unregister_driver(&cxl_pci_driver);
> +
> +	return rc;
> +}
> +
> +static void __exit cxl_pci_driver_exit(void)
> +{
> +	cxl_cper_unregister_callback(cxl_cper_event_call);
> +	pci_unregister_driver(&cxl_pci_driver);
> +}
> +
> +module_init(cxl_pci_driver_init);
> +module_exit(cxl_pci_driver_exit);
>   MODULE_LICENSE("GPL v2");
> -module_pci_driver(cxl_pci_driver);
>   MODULE_IMPORT_NS(CXL);
> diff --git a/include/linux/cxl-event.h b/include/linux/cxl-event.h
> index 71e3646f7569..17eadee819b6 100644
> --- a/include/linux/cxl-event.h
> +++ b/include/linux/cxl-event.h
> @@ -109,6 +109,7 @@ struct cxl_event_record_raw {
>   } __packed;
>   
>   enum cxl_event_type {
> +	CXL_CPER_EVENT_GENERIC,
>   	CXL_CPER_EVENT_GEN_MEDIA,
>   	CXL_CPER_EVENT_DRAM,
>   	CXL_CPER_EVENT_MEM_MODULE,
>