linux-kernel - [PATCH v1 3/3] x86/MCE/AMD: Handle reassigned bit definitions for CS SMCA

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Date:   Tue, 7 Feb 2023 13:07:55 -0600
From:   Avadhut Naik <avadnaik@....com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-edac@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, bp@...en8.de, tony.luck@...el.com,
        yazen.ghannam@....com
Subject: [PATCH v1 3/3] x86/MCE/AMD: Handle reassigned bit definitions for CS
 SMCA

Hi,

On 1/17/2023 03:23, Ingo Molnar wrote:
> 
> * Avadhut Naik <avadnaik@....com> wrote:
> 
>> @@ -178,6 +178,8 @@ static const struct smca_hwid smca_hwid_mcatypes[] = {
>>  	{ SMCA_CS,	 HWID_MCATYPE(0x2E, 0x0)	},
>>  	{ SMCA_PIE,	 HWID_MCATYPE(0x2E, 0x1)	},
>>  	{ SMCA_CS_V2,	 HWID_MCATYPE(0x2E, 0x2)	},
>> +	/* Software defined SMCA bank type to handle erratum 1384*/
>> +	{ SMCA_CS_V2_QUIRK, HWID_MCATYPE(0x0, 0x1)  },
>>  
>>  	/* Unified Memory Controller MCA type */
>>  	{ SMCA_UMC,	 HWID_MCATYPE(0x96, 0x0)	},
>> @@ -259,6 +261,17 @@ static inline void fixup_hwid(unsigned int *hwid_mcatype)
>>  
>>  	if (c->x86 == 0x19) {
>>  		switch (c->x86_model) {
>> +		/*
>> +		 * Per Genoa's revision guide, erratum 1384, some SMCA Extended
>> +		 * Error Codes and SMCA Control bits are incorrect for SMCA CS
>> +		 * bank type.
>> +		 */
>> +		case 0x10 ... 0x1F:
>> +		case 0x60 ... 0x7B:
>> +		case 0xA0 ... 0xAF:
>> +			if (*hwid_mcatype == HWID_MCATYPE(0x2E, 0x2))
>> +				*hwid_mcatype = HWID_MCATYPE(0x0, 0x1);
> 
> Why are we open-coding these types?
> 
> Why not use smca_hwid_mcatypes[SMCA_CS_V2], etc.?

If I understood correctly (And please rectify me if I didn't), did you mean using something like the below snippet instead of what I have used?

if (*hwid_mcatype == smca_hwid_mcatypes[SMCA_CS_V2].hwid_mcatype)
	*hwid_mcatype = smca_hwid_mcatypes[SMCA_CS_V2_QUIRK].hwid_mcatype;

If yes, then SMCA_CS_V2, SMCA_CS_V2_QUIRK etc. originate from the enum smca_bank_types in arch/x86/include/asm/mce.h.
As the enum stands now, it cannot be used for indexing into the smca_hwid_mcatypes array since it might result in incorrect indexing.

Please advise.

Thanks,
Avadhut Naik
> 
>> +			if (*hwid_mcatype == HWID_MCATYPE(0x2E, 0x2))
>> +				*hwid_mcatype = HWID_MCATYPE(0x0, 0x1);
> 
> Ditto.
> 
> Thanks,
> 
> 	Ingo