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

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Message-ID: <20240108135005.0000288f@Huawei.com>
Date: Mon, 8 Jan 2024 13:50:05 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Ira Weiny <ira.weiny@...el.com>
CC: Dan Williams <dan.j.williams@...el.com>, Smita Koralahalli
	<Smita.KoralahalliChannabasappa@....com>, Shiju Jose <shiju.jose@...wei.com>,
	Yazen Ghannam <yazen.ghannam@....com>, "Davidlohr Bueso" <dave@...olabs.net>,
	Dave Jiang <dave.jiang@...el.com>, "Alison Schofield"
	<alison.schofield@...el.com>, Vishal Verma <vishal.l.verma@...el.com>, Ard
 Biesheuvel <ardb@...nel.org>, <linux-efi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-cxl@...r.kernel.org>
Subject: Re: [PATCH v5 9/9] cxl/pci: Register for and process CPER events

On Wed, 20 Dec 2023 16:17:36 -0800
Ira Weiny <ira.weiny@...el.com> 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/
> 
One trivial comment inline.
The guard change Dan suggests makes sense.  Otherwise I'm fine with this.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

I'll bolt in the other stuff I need to test it from QEMU this week.
Did the protocol error first, but these are easy to add now I have
that working,

Jonathan
> ---
> 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;

Might as well return directly and save a reviewer having to check if anything else happens
after the switch

> +	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);