linux-kernel - Re: [PATCH] arm64: Add support for new control bits CTR_EL0.IDC and CTR_EL0.IDC

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Date:   Mon, 19 Feb 2018 10:36:16 -0600
From:   Shanker Donthineni <shankerd@...eaurora.org>
To:     Will Deacon <will.deacon@....com>
Cc:     Philip Elcan <pelcan@...eaurora.org>,
        Vikram Sethi <vikrams@...eaurora.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kvmarm <kvmarm@...ts.cs.columbia.edu>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] arm64: Add support for new control bits CTR_EL0.IDC and
 CTR_EL0.IDC

Hi Will,

On 02/19/2018 08:43 AM, Will Deacon wrote:
> Hi Shanker,
> 
> On Fri, Feb 16, 2018 at 06:57:46PM -0600, Shanker Donthineni wrote:
>> Two point of unification cache maintenance operations 'DC CVAU' and
>> 'IC IVAU' are optional for implementors as per ARMv8 specification.
>> This patch parses the updated CTR_EL0 register definition and adds
>> the required changes to skip POU operations if the hardware reports
>> CTR_EL0.IDC and/or CTR_EL0.IDC.
>>
>> CTR_EL0.DIC: Instruction cache invalidation requirements for
>>  instruction to data coherence. The meaning of this bit[29].
>>   0: Instruction cache invalidation to the point of unification
>>      is required for instruction to data coherence.
>>   1: Instruction cache cleaning to the point of unification is
>>       not required for instruction to data coherence.
>>
>> CTR_EL0.IDC: Data cache clean requirements for instruction to data
>>  coherence. The meaning of this bit[28].
>>   0: Data cache clean to the point of unification is required for
>>      instruction to data coherence, unless CLIDR_EL1.LoC == 0b000
>>      or (CLIDR_EL1.LoUIS == 0b000 && CLIDR_EL1.LoUU == 0b000).
>>   1: Data cache clean to the point of unification is not required
>>      for instruction to data coherence.
>>
>> Signed-off-by: Philip Elcan <pelcan@...eaurora.org>
>> Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
>> ---
>>  arch/arm64/include/asm/assembler.h | 48 ++++++++++++++++++++++++--------------
>>  arch/arm64/include/asm/cache.h     |  2 ++
>>  arch/arm64/kernel/cpufeature.c     |  2 ++
>>  arch/arm64/mm/cache.S              | 26 ++++++++++++++-------
>>  4 files changed, 51 insertions(+), 27 deletions(-)
> 
> I was looking at our CTR_EL0 code last week but forgot to post the patch I
> wrote fixing up some of the fields. I just send it now, so please can
> you rebase on top of:
> 
> http://lists.infradead.org/pipermail/linux-arm-kernel/2018-February/560488.html
> 
> Also:
> 
>> diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
>> index ea9bb4e..aea533b 100644
>> --- a/arch/arm64/include/asm/cache.h
>> +++ b/arch/arm64/include/asm/cache.h
>> @@ -22,6 +22,8 @@
>>  #define CTR_L1IP_MASK		3
>>  #define CTR_CWG_SHIFT		24
>>  #define CTR_CWG_MASK		15
>> +#define CTR_IDC_SHIFT		28
>> +#define CTR_DIC_SHIFT		29
>>  
>>  #define CTR_L1IP(ctr)		(((ctr) >> CTR_L1IP_SHIFT) & CTR_L1IP_MASK)
>>  
>> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
>> index 29b1f87..f42bb5a 100644
>> --- a/arch/arm64/kernel/cpufeature.c
>> +++ b/arch/arm64/kernel/cpufeature.c
>> @@ -200,6 +200,8 @@ static int __init register_cpu_hwcaps_dumper(void)
>>  
>>  static const struct arm64_ftr_bits ftr_ctr[] = {
>>  	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, 31, 1, 1),	/* RAO */
>> +	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_DIC_SHIFT, 1, 0),	/* DIC */
>> +	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_IDC_SHIFT, 1, 0),	/* IDC */
>>  	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_HIGHER_SAFE, 24, 4, 0),	/* CWG */
>>  	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, 20, 4, 0),	/* ERG */
>>  	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, 16, 4, 1),	/* DminLine */
> 
> Could you update the other table entries here to use the CTR_*_SHIFT values
> as well?
> 

I'll do.

> Thanks,
> 
> Will
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

-- 
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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