linux-kernel - Re: [PATCH V2] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug

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Date:   Tue, 1 Aug 2017 10:05:47 +0800
From:   Liwei Song <liwei.song@...driver.com>
To:     "Zheng, Lv" <lv.zheng@...el.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>
CC:     linux-acpi <linux-acpi@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Moore, Robert" <robert.moore@...el.com>
Subject: Re: [PATCH V2] ACPI, APEI: Fixup incorrect 16-bit access width firmware
 bug



On 07/31/2017 10:09 AM, Zheng, Lv wrote:
> Hi,
> 
>> From: linux-acpi-owner@...r.kernel.org [mailto:linux-acpi-owner@...r.kernel.org] On Behalf Of Song
>> liwei
>> Subject: [PATCH V2] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug
>>
>> From: Liwei Song <liwei.song@...driver.com>
>>
>> This is a follow up to commit f712c71f7b2b ("ACPI, APEI: Fixup common
>> access width firmware bug") fix the following firmware bug:
>>
>> [Firmware Bug]: APEI: Invalid bit width + offset in GAR [0xb2/16/0/1/1]
>>
>> This is due to an 8-bit access width is specified for a 16-bit register,
>> Rearrange the condition and add 8-bit width check.
>>
>> Signed-off-by: Liwei Song <liwei.song@...driver.com>
>> ---
>>  drivers/acpi/apei/apei-base.c | 12 ++++++------
>>  1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
>> index da370e1..eca3d7a 100644
>> --- a/drivers/acpi/apei/apei-base.c
>> +++ b/drivers/acpi/apei/apei-base.c
>> @@ -604,12 +604,12 @@ static int apei_check_gar(struct acpi_generic_address *reg, u64 *paddr,
>>  	*access_bit_width = 1UL << (access_size_code + 2);
>>
>>  	/* Fixup common BIOS bug */
>> -	if (bit_width == 32 && bit_offset == 0 && (*paddr & 0x03) == 0 &&
>> -	    *access_bit_width < 32)
>> -		*access_bit_width = 32;
>> -	else if (bit_width == 64 && bit_offset == 0 && (*paddr & 0x07) == 0 &&
>> -	    *access_bit_width < 64)
>> -		*access_bit_width = 64;
>> +	if (*access_bit_width < bit_width && bit_offset == 0) {
>> +		if ((bit_width == 16 && (*paddr & 0x01) == 0) ||
>> +		    (bit_width == 32 && (*paddr & 0x03) == 0) ||
>> +		    (bit_width == 64 && (*paddr & 0x07) == 0))
>> +			*access_bit_width = bit_width;
>> +	}
>>
>>  	if ((bit_width + bit_offset) > *access_bit_width) {
>>  		pr_warning(FW_BUG APEI_PFX
> 
> IMO, such problem could also be fixed by this commit and a cleanup of APEI
> GAR code to invoke generic ACPICA GAR API - acpi_read()/acpi_write() directly.
> https://github.com/acpica/acpica/pull/209

Hi Lv,

I'm a bit confuse about the commit you said, do you mean this commit can also fix
this common 16-bit access width error, and will check-in to upstream kernel latter?
If so, please ignore this review.

Thanks,
Liwei.


> 
> Thanks and best regards
> Lv
> 
> 
>