Re: [PATCH v4 7/7] cxl/memdev: Register for and process CPER events

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

On 12/15/2023 3:26 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 pci driver registration to include registration for a CXL CPER
> notifier to process the events through the trace subsystem.
> 
> Define and use scoped based management to simplify the handling of the
> pci device object.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> 
> ---

[snip]


> +	switch (event_type) {
> +	case CXL_CPER_EVENT_GEN_MEDIA:
> +		trace_cxl_general_media(cxlmd, type, &gen_media_event_uuid,
> +					&event->gen_media);
> +		break;
> +	case CXL_CPER_EVENT_DRAM:
> +		trace_cxl_dram(cxlmd, type, &dram_event_uuid, &event->dram);
> +		break;
> +	case CXL_CPER_EVENT_MEM_MODULE:
> +		trace_cxl_memory_module(cxlmd, type, &mem_mod_event_uuid,
> +					&event->mem_module);
> +		break;
> +	}
> +}

Is default case needed here?

> +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)
>   {
>   	union cxl_event *evt = &record->event;
>   	uuid_t *id = &record->id;
> @@ -965,8 +986,8 @@ 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..e7e9508fecac 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,
> +			    union cxl_event *event);
>   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..638275569d63 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 +970,58 @@ 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;
> +	struct cxl_dev_state *cxlds = NULL;
> +	enum cxl_event_log_type log_type;
> +	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)
> +		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, &rec->event);

Currently, when I run this, I see two trace events printed. One from 
here, and another as a non_standard_event from ghes. I think both should 
be unified?

I remember Dan pointing out to me this when I sent decoding for protocol 
errors and its still pending on me for protocol errors.

Thanks,
Smita

> +}
> +
> +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_notifier(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_notifier(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/pci.h b/include/linux/pci.h
> index 60ca768bc867..290d0a2651b2 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1170,6 +1170,7 @@ int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge);
>   u8 pci_common_swizzle(struct pci_dev *dev, u8 *pinp);
>   struct pci_dev *pci_dev_get(struct pci_dev *dev);
>   void pci_dev_put(struct pci_dev *dev);
> +DEFINE_FREE(pci_dev_put, struct pci_dev *, if (_T) pci_dev_put(_T))
>   void pci_remove_bus(struct pci_bus *b);
>   void pci_stop_and_remove_bus_device(struct pci_dev *dev);
>   void pci_stop_and_remove_bus_device_locked(struct pci_dev *dev);
> @@ -1871,6 +1872,7 @@ void pci_cfg_access_unlock(struct pci_dev *dev);
>   void pci_dev_lock(struct pci_dev *dev);
>   int pci_dev_trylock(struct pci_dev *dev);
>   void pci_dev_unlock(struct pci_dev *dev);
> +DEFINE_GUARD(pci_dev, struct pci_dev *, pci_dev_lock(_T), pci_dev_unlock(_T))
>   
>   /*
>    * PCI domain support.  Sometimes called PCI segment (eg by ACPI),
>