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Date:   Tue, 17 Oct 2023 19:37:57 -0700
From:   Ira Weiny <ira.weiny@intel.com>
To:     Ira Weiny <ira.weiny@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Jonathan Cameron <jonathan.cameron@huawei.com>,
        Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
CC:     Yazen Ghannam <yazen.ghannam@amd.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Dave Jiang <dave.jiang@intel.com>,
        Alison Schofield <alison.schofield@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        "Ard Biesheuvel" <ardb@kernel.org>, <linux-efi@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-cxl@vger.kernel.org>,
        Ira Weiny <ira.weiny@intel.com>
Subject: Re: [PATCH RFC 1/2] firmware/efi: Process CXL Component Events
Message-ID: <652f4505231c7_2bb07d29483@iweiny-mobl.notmuch>
References: <20230601-cxl-cper-v1-0-99ba43f8f770@intel.com>
 <20230601-cxl-cper-v1-1-99ba43f8f770@intel.com>
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Ira Weiny wrote:
> BIOS can configure memory devices as firmware first.  This will send CXL
> events to the firmware instead of the OS.  The firmware can then send
> these events to the OS via UEFI.
> 
> UEFI v2.10 section N.2.14 defines a Common Platform Error Record (CPER)
> format for CXL Component Events.  The format is mostly the same as the
> CXL Common Event Record Format.  The only difference is the UUID is
> passed via the Section Type as a GUID and not included as part of the
> record data.
> 
> Add EFI support to detect CXL CPER records and call a notifier chain
> with the record data blobs.
> 
> Note that the format of a GUID and UUID are not the same.  Therefore the
> Section Type GUID must be converted to a UUID prior to being used by the
> CXL code.  Make that conversion and send it along to those registered.
> 
> Not-Yet-Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> 
> ---
> RFC comments:
> I'm still not sure if the 'CXL Component Event Log' portion of the CPER
> record includes the UUID from the CXL Common Event Record Format.
> 
> The 2.10 version of the UEFI spec says:
> 
> "For the CXL Component Event Log: Refer to the Common Event Record field
> (Offset 16) of the Events Record Format for each CXL component."
> 
> This implies that the first 16 bytes (the UUID) is not included.  It
> would be nice if the UUID were included there as a copy of what would
> normally be in the CXL event log.  If so the Section Type GUID could be
> used solely to match for a CXL record and ignored in the CXL code.
> 
> For now convert the GUID to UUID and pass to the notifier users.
> 
> Smita, Another idea I had was to add your cper_print_comp_event()
> function to the dump here to capture that CPER specific data in the EFI
> log.
> ---
>  drivers/firmware/efi/cper.c     | 16 ++++++++++++++
>  drivers/firmware/efi/cper_cxl.c | 39 ++++++++++++++++++++++++++++++++
>  drivers/firmware/efi/cper_cxl.h | 29 ++++++++++++++++++++++++
>  include/linux/efi.h             | 49 +++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 133 insertions(+)
> 
> diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
> index 35c37f667781..af2c59f5e21d 100644
> --- a/drivers/firmware/efi/cper.c
> +++ b/drivers/firmware/efi/cper.c
> @@ -607,6 +607,22 @@ cper_estatus_print_section(const char *pfx, struct acpi_hest_generic_data *gdata
>  			cper_print_prot_err(newpfx, prot_err);
>  		else
>  			goto err_section_too_small;
> +	} else if (guid_equal(sec_type, &gen_media_event_guid) ||
> +		   guid_equal(sec_type, &dram_event_guid) ||
> +		   guid_equal(sec_type, &mem_mod_event_guid)) {
> +		struct cper_cxl_event_rec *rec = acpi_hest_get_payload(gdata);
> +

Smita,

Dan and I were discussing the processing of these GUIDs vs the UUIDs in the
trace prints offline.

Here we could separate out the comparisons and use a token for the events
rather than passing the guid through to be converted into a uuid...

> +		printk("%ssection type: CXL Event\n", newpfx);
> +
> +		if (rec->hdr.length <= sizeof(rec->hdr))
> +			goto err_section_too_small;
> +
> +		if (rec->hdr.length > sizeof(*rec)) {
> +			pr_err(FW_WARN "error section length is too big\n");
> +			return;
> +		}
> +
> +		cper_post_cxl_event(newpfx, sec_type, rec);
>  	} else {
>  		const void *err = acpi_hest_get_payload(gdata);
>  
> diff --git a/drivers/firmware/efi/cper_cxl.c b/drivers/firmware/efi/cper_cxl.c
> index a55771b99a97..9b1a64ed542e 100644
> --- a/drivers/firmware/efi/cper_cxl.c
> +++ b/drivers/firmware/efi/cper_cxl.c
> @@ -187,3 +187,42 @@ void cper_print_prot_err(const char *pfx, const struct cper_sec_prot_err *prot_e
>  			       sizeof(cxl_ras->header_log), 0);
>  	}
>  }
> +
> +/* CXL CPER notifier chain */
> +static BLOCKING_NOTIFIER_HEAD(cxl_cper_chain_head);
> +
> +void cper_post_cxl_event(const char *pfx, guid_t *guid, struct cper_cxl_event_rec *rec)
> +{
> +	struct cxl_cper_notifier_data nd = {
> +		.rec = rec,
> +	};
> +	char guid_str[UUID_STRING_LEN + 1]; /* + trailing NULL */
> +
> +	if (!(rec->hdr.validation_bits & CPER_CXL_COMP_EVENT_LOG_VALID)) {
> +		pr_err(FW_WARN "cxl event no Compoent Event Log present\n");
> +		return;
> +	}
> +
> +	snprintf(guid_str, UUID_STRING_LEN + 1, "%pU", guid);
> +	if (uuid_parse(guid_str, &nd.uuid))
> +		pr_err(FW_WARN "cxl event uuid conversion failed\n");

> +
> +	pr_info("%s cxl event guid %pU, uuid %pU\n", pfx, guid, &nd.uuid);
> +
> +	if (blocking_notifier_call_chain(&cxl_cper_chain_head, 0, (void *)&nd)
> +			== NOTIFY_BAD)
> +		pr_err(FW_WARN "cxl event notifier chain failed\n");
> +}
> +