linux-kernel - Re: [PATCH 2/6] arm64/cpufeature: Add DIT and CSV2 feature bits in ID

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Date:   Mon, 13 Apr 2020 09:05:28 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Will Deacon <will@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] arm64/cpufeature: Add DIT and CSV2 feature bits in
 ID_PFR0 register



On 04/09/2020 06:25 PM, Will Deacon wrote:
> On Tue, Jan 28, 2020 at 06:09:05PM +0530, Anshuman Khandual wrote:
>> Enable DIT and CSV2 feature bits in ID_PFR0 register as per ARM DDI 0487E.a
>> specification. Except RAS and AMU, all other feature bits are now enabled.
>>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Will Deacon <will@...nel.org>
>> Cc: Suzuki K Poulose <suzuki.poulose@....com>
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
>> ---
>>  arch/arm64/include/asm/sysreg.h | 3 +++
>>  arch/arm64/kernel/cpufeature.c  | 2 ++
>>  2 files changed, 5 insertions(+)
>>
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index 054aab7ebf1b..469d61c8fabf 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -718,6 +718,9 @@
>>  #define ID_ISAR6_DP_SHIFT		4
>>  #define ID_ISAR6_JSCVT_SHIFT		0
>>  
>> +#define ID_PFR0_DIT_SHIFT		24
>> +#define ID_PFR0_CSV2_SHIFT		16
>> +
>>  #define ID_PFR2_SSBS_SHIFT		4
>>  #define ID_PFR2_CSV3_SHIFT		0
>>  
>> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
>> index c1e837fc8f97..9e4dab15c608 100644
>> --- a/arch/arm64/kernel/cpufeature.c
>> +++ b/arch/arm64/kernel/cpufeature.c
>> @@ -341,6 +341,8 @@ static const struct arm64_ftr_bits ftr_id_isar6[] = {
>>  };
>>  
>>  static const struct arm64_ftr_bits ftr_id_pfr0[] = {
>> +	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR0_DIT_SHIFT, 4, 0),
>> +	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR0_CSV2_SHIFT, 4, 0),
> 
> Same comment as CSV3 here. Why is CSV2 being treated as strict here, but not
> in the aa64* register?

Sure, will change.

> 
> Will
>