linux-kernel - Re: [PATCH v2 2/2] x86/mce: Add messages to describe panic machine errors on AMD's MCEs grading

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Message-ID: <Ykx+swi/SBjaEzLq@yaz-ubuntu>
Date:   Tue, 5 Apr 2022 17:38:59 +0000
From:   Yazen Ghannam <yazen.ghannam@....com>
To:     Carlos Bilbao <carlos.bilbao@....com>
Cc:     bp@...en8.de, tglx@...utronix.de, mingo@...hat.com,
        dave.hansen@...ux.intel.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
        bilbao@...edu
Subject: Re: [PATCH v2 2/2] x86/mce: Add messages to describe panic machine
 errors on AMD's MCEs grading

On Thu, Mar 31, 2022 at 11:38:50AM -0500, Carlos Bilbao wrote:

...

>  static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)
>  {
>  	int ret;
> +	char *panic_msg;

Order variable lines from longest to shortest.

And the pointer should be initiliazed to NULL like Mike said also.

>  
>  	/*
>  	 * Default return value: Action required, the error must be handled
> @@ -316,6 +317,7 @@ static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **
>  
>  	/* Processor Context Corrupt, no need to fumble too much, die! */
>  	if (m->status & MCI_STATUS_PCC) {
> +		panic_msg = "Processor Context Corrupt";
>  		ret = MCE_PANIC_SEVERITY;
>  		goto amd_severity;
>  	}
> @@ -339,16 +341,21 @@ static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **
>  
>  	if (((m->status & MCI_STATUS_OVER) && !mce_flags.overflow_recov)
>  	     || !mce_flags.succor) {
> +		panic_msg = "Uncorrected unrecoverable error";

So these two cases should definitely be separate. One is "Overflowed
uncorrected error without MCA Overflow Recovery", and the other is
"Uncorrected error without MCA Recovery".

>  		ret = MCE_PANIC_SEVERITY;
>  		goto amd_severity;
>  	}
>  
>  	if (error_context(m, regs) == IN_KERNEL) {
> +		panic_msg = "Uncorrected error in kernel context";

This should be "Uncorrected unrecoverable error in kernel context". There is
the IN_KERNEL_RECOV error context for a recoverable error in kernel context.

Thanks,
Yazen