Re: [PATCH v3 3/5] mtrr, x86: Fix MTRR state checks in mtrr_type_lookup()

[Kani, Toshimitsu]

> On Mar 16, 2015, at 3:51 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> 
> 
> * Toshi Kani <toshi.kani@xxxxxx> wrote:
> 
>> 'mtrr_state.enabled' contains FE (fixed MTRRs enabled) and
>> E (MTRRs enabled) flags in MSR_MTRRdefType.  Intel SDM,
>> section 11.11.2.1, defines these flags as follows:
>> - All MTRRs are disabled when the E flag is clear.
>>   The FE flag has no affect when the E flag is clear.
>> - The default type is enabled when the E flag is set.
>> - MTRR variable ranges are enabled when the E flag is set.
>> - MTRR fixed ranges are enabled when both E and FE flags
>>   are set.
>> 
>> MTRR state checks in __mtrr_type_lookup() do not follow the
>> SDM definitions.  Therefore, this patch fixes the MTRR state
>> checks according to the SDM.  This patch defines the flags
>> in mtrr_state.enabled as follows.  print_mtrr_state() is also
>> updated.
>> - FE flag: MTRR_STATE_MTRR_FIXED_ENABLED
>> - E  flag: MTRR_STATE_MTRR_ENABLED
>> 
>> Lastly, this patch fixes the 'else if (start < 0x1000000)',
>> which checks a fixed range but has an extra-zero in the
>> address, to 'else' with no condition.
> 
> Firstly, this does multiple bug fixes in a single patch, which is a 
> no-no: please split it up into separate patches.

Right.  I will split into two patches.

> Secondly, please also outline the differences between the old code and 
> the new code - don't just list the SDM logic and state that we are 
> updating to it.

Yes, I will update the patch log accordingly.

Thanks,
-Toshi

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