linux-kernel - Re: [PATCH v2 4/4] EDAC/mce_amd: Add support for FRU Text in MCA

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Date: Wed, 26 Jun 2024 14:04:29 +0200
From: Borislav Petkov <bp@...en8.de>
To: Avadhut Naik <avadhut.naik@....com>
Cc: x86@...nel.org, linux-edac@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, tony.luck@...el.com,
	rafael@...nel.org, tglx@...utronix.de, mingo@...hat.com,
	rostedt@...dmis.org, lenb@...nel.org, mchehab@...nel.org,
	james.morse@....com, airlied@...il.com, yazen.ghannam@....com,
	john.allen@....com, avadnaik@....com
Subject: Re: [PATCH v2 4/4] EDAC/mce_amd: Add support for FRU Text in MCA

On Tue, Jun 25, 2024 at 02:56:24PM -0500, Avadhut Naik wrote:
> From: Yazen Ghannam <yazen.ghannam@....com>
> 
> A new "FRU Text in MCA" feature is defined where the Field Replaceable
> Unit (FRU) Text for a device is represented by a string in the new
> MCA_SYND1 and MCA_SYND2 registers. This feature is supported per MCA
> bank, and it is advertised by the McaFruTextInMca bit (MCA_CONFIG[9]).
> 
> The FRU Text is populated dynamically for each individual error state
> (MCA_STATUS, MCA_ADDR, et al.). This handles the case where an MCA bank
> covers multiple devices, for example, a Unified Memory Controller (UMC)
> bank that manages two DIMMs.
> 

>From here...

> Print the FRU Text string, if available, when decoding an MCA error.
> 
> Also, add field for MCA_CONFIG MSR in struct mce_hw_err as vendor specific
> error information and save the value of the MSR. The very value can then be
> exported through tracepoint for userspace tools like rasdaemon to print FRU
> Text, if available.
> 
>  Note: Checkpatch checks/warnings are ignored to maintain coding style.

... to here goes into the trash can except what MCA_CONFIG is for being logged
as part of the error.

> [Yazen: Add Avadhut as co-developer for wrapper changes. ]
> 
> Co-developed-by: Avadhut Naik <avadhut.naik@....com>
> Signed-off-by: Avadhut Naik <avadhut.naik@....com>
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>

Ditto as for patch 3.

> ---

> @@ -853,8 +850,18 @@ amd_decode_mce(struct notifier_block *nb, unsigned long val, void *data)
>  
>  		if (m->status & MCI_STATUS_SYNDV) {
>  			pr_cont(", Syndrome: 0x%016llx\n", m->synd);
> -			pr_emerg(HW_ERR "Syndrome1: 0x%016llx, Syndrome2: 0x%016llx",
> -				 err->vi.amd.synd1, err->vi.amd.synd2);
> +			if (mca_config & MCI_CONFIG_FRUTEXT) {
> +				char frutext[17];
> +
> +				memset(frutext, 0, sizeof(frutext));

Why are you clearing it if you're overwriting it immediately?

> +				memcpy(&frutext[0], &err->vi.amd.synd1, 8);
> +				memcpy(&frutext[8], &err->vi.amd.synd2, 8);
> +
> +				pr_emerg(HW_ERR "FRU Text: %s", frutext);
> +			} else {
> +				pr_emerg(HW_ERR "Syndrome1: 0x%016llx, Syndrome2: 0x%016llx",
> +					 err->vi.amd.synd1, err->vi.amd.synd2);
> +			}
>  		}
>  
>  		pr_cont("\n");
> -- 
> 2.34.1
> 

-- 
Regards/Gruss,
    Boris.

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