Re: [PATCH] ACPI: Pass the same capabilities to the _OSC regardless of the query flag

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 6/8/21 7:10 PM, Hans de Goede wrote:
> Hi,
> 
> On 6/8/21 6:38 PM, Mika Westerberg wrote:
>> Commit 719e1f561afb ("ACPI: Execute platform _OSC also with query bit
>> clear") makes acpi_bus_osc_negotiate_platform_control() not only query
>> the platforms capabilities but it also commits the result back to the
>> firmware to report which capabilities are supported by the OS back to
>> the firmware
>>
>> On certain systems the BIOS loads SSDT tables dynamically based on the
>> capabilities the OS claims to support. However, on these systems the
>> _OSC actually clears some of the bits (under certain conditions) so what
>> happens is that now when we call the _OSC twice the second time we pass
>> the cleared values and that results errors like below to appear on the
>> system log:
>>
>>   ACPI BIOS Error (bug): Could not resolve symbol [\_PR.PR00._CPC], AE_NOT_FOUND (20210105/psargs-330)
>>   ACPI Error: Aborting method \_PR.PR01._CPC due to previous error (AE_NOT_FOUND) (20210105/psparse-529)
>>
>> In addition the ACPI 6.4 spec says following [1]:
>>
>>   If the OS declares support of a feature in the Support Field in one
>>   call to _OSC, then it must preserve the set state of that bit
>>   (declaring support for that feature) in all subsequent calls.
>>
>> Based on the above we can fix the issue by passing the same set of
>> capabilities to the platform wide _OSC in both calls regardless of the
>> query flag.
>>
>> While there drop the context.ret.length check which was wrong to begin
>> with (as the length is number of bytes not elements). This is already
>> checked in acpi_run_osc() that also returns an error in that case.
>>
>> [1] https://uefi.org/specs/ACPI/6.4/06_Device_Configuration/Device_Configuration.html#sequence-of-osc-calls
>>
>> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=213023
>> BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1963717
>> Fixes: 719e1f561afb ("ACPI: Execute platform _OSC also with query bit clear")
>> Cc: Mario Limonciello <mario.limonciello@outlook.com>
>> cc: Hans de Goede <hdegoede@redhat.com>
>> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
>> ---
>>  drivers/acpi/bus.c | 21 +++++++--------------
>>  1 file changed, 7 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
>> index be7da23fad76..61e8c02595ac 100644
>> --- a/drivers/acpi/bus.c
>> +++ b/drivers/acpi/bus.c
>> @@ -336,26 +336,19 @@ static void acpi_bus_osc_negotiate_platform_control(void)
>>  		return;
>>  	}
>>  
>> -	/*
>> -	 * Now run _OSC again with query flag clear and with the caps
>> -	 * supported by both the OS and the platform.
>> -	 */
>> +	/* Now run _OSC again with query flag clear */
>>  	capbuf[OSC_QUERY_DWORD] = 0;
>> -	capbuf[OSC_SUPPORT_DWORD] = capbuf_ret[OSC_SUPPORT_DWORD];
>> -	kfree(context.ret.pointer);
> 
> This kfree needs to be moved up, rather then be completely removed
> and you are still leaving 1 of the unnecessary length checks in place.
> 
> I've added this fixup on top, to fix both these issues:
> 
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -330,11 +330,7 @@ static void acpi_bus_osc_negotiate_platform_control(void)
>  	if (ACPI_FAILURE(acpi_run_osc(handle, &context)))
>  		return;
>  
> -	capbuf_ret = context.ret.pointer;
> -	if (context.ret.length <= OSC_SUPPORT_DWORD) {
> -		kfree(context.ret.pointer);
> -		return;
> -	}
> +	kfree(context.ret.pointer);
>  
>  	/* Now run _OSC again with query flag clear */
>  	capbuf[OSC_QUERY_DWORD] = 0;
> 
> I'll ask the reporters of:
> https://bugzilla.kernel.org/show_bug.cgi?id=213023
> https://bugzilla.redhat.com/show_bug.cgi?id=1963717
> 
> To test the (fixed-up) patch, so that they can confirm if this indeed
> fixes things.

I've received confirmation from 2 users that this patch (with the fixup)
fixes this. Can send a v2 with the fixup squashed in for Rafael to pick up?

Regards,

Hans



>>  
>>  	if (ACPI_FAILURE(acpi_run_osc(handle, &context)))
>>  		return;
>>  
>>  	capbuf_ret = context.ret.pointer;
>> -	if (context.ret.length > OSC_SUPPORT_DWORD) {
>> -		osc_sb_apei_support_acked =
>> -			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;
>> -		osc_pc_lpi_support_confirmed =
>> -			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_PCLPI_SUPPORT;
>> -		osc_sb_native_usb4_support_confirmed =
>> -			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_NATIVE_USB4_SUPPORT;
>> -	}
>> +	osc_sb_apei_support_acked =
>> +		capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;
>> +	osc_pc_lpi_support_confirmed =
>> +		capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_PCLPI_SUPPORT;
>> +	osc_sb_native_usb4_support_confirmed =
>> +		capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_NATIVE_USB4_SUPPORT;
>>  
>>  	kfree(context.ret.pointer);
>>  }
>>