linux-kernel - Re: [PATCH v3 15/16] arm64: errata: Advertise the workaround for TSB flush failures

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Message-ID: <982da86b-44ff-b244-33b0-02c95fa2f082@arm.com>
Date:   Mon, 11 Oct 2021 13:32:40 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Will Deacon <will@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        catalin.marinas@....com, mathieu.poirier@...aro.org,
        mike.leach@...aro.org, leo.yan@...aro.org,
        anshuman.khandual@....com, coresight@...ts.linaro.org,
        maz@...nel.org, james.morse@....com, mark.rutland@....com,
        lcherian@...vell.com
Subject: Re: [PATCH v3 15/16] arm64: errata: Advertise the workaround for TSB
 flush failures

On 11/10/2021 11:18, Will Deacon wrote:
> On Fri, Oct 08, 2021 at 07:29:05PM +0100, Suzuki K Poulose wrote:
>> Advertise the workaround for the TSB flush failures via
>> Kconfig entries.
>>
>> Cc: Will Deacon <will@...nel.org>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
>> Cc: Anshuman Khandual <anshuman.khandual@....com>
>> Cc: Marc Zyngier <maz@...nel.org>
>> Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
>> Acked-by: Catalin Marinas <catalin.marinas@....com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>> ---
>> Changes since previous:
>>    - Split the Kconfig/erratum updates to keep the conflicts
>>      minimal with the other Kconfig updates in TRBE errata
>>      I have retained the tags
>> ---
>>   Documentation/arm64/silicon-errata.rst |  4 ++++
>>   arch/arm64/Kconfig                     | 31 ++++++++++++++++++++++++++
>>   2 files changed, 35 insertions(+)
>>
>> diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
>> index 2f99229d993c..569a92411dcd 100644
>> --- a/Documentation/arm64/silicon-errata.rst
>> +++ b/Documentation/arm64/silicon-errata.rst
>> @@ -94,6 +94,8 @@ stable kernels.
>>   +----------------+-----------------+-----------------+-----------------------------+
>>   | ARM            | Cortex-A710     | #2119858        | ARM64_ERRATUM_2119858       |
>>   +----------------+-----------------+-----------------+-----------------------------+
>> +| ARM            | Cortex-A710     | #2054223        | ARM64_ERRATUM_2054223       |
>> ++----------------+-----------------+-----------------+-----------------------------+
>>   | ARM            | Neoverse-N1     | #1188873,1418040| ARM64_ERRATUM_1418040       |
>>   +----------------+-----------------+-----------------+-----------------------------+
>>   | ARM            | Neoverse-N1     | #1349291        | N/A                         |
>> @@ -102,6 +104,8 @@ stable kernels.
>>   +----------------+-----------------+-----------------+-----------------------------+
>>   | ARM            | Neoverse-N2     | #2139208        | ARM64_ERRATUM_2139208       |
>>   +----------------+-----------------+-----------------+-----------------------------+
>> +| ARM            | Neoverse-N2     | #2067961        | ARM64_ERRATUM_2067961       |
>> ++----------------+-----------------+-----------------+-----------------------------+
>>   | ARM            | MMU-500         | #841119,826419  | N/A                         |
>>   +----------------+-----------------+-----------------+-----------------------------+
>>   +----------------+-----------------+-----------------+-----------------------------+
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index eac4030322df..0764774e12bb 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -705,6 +705,37 @@ config ARM64_ERRATUM_2139208
>>   
>>   	  If unsure, say Y.
>>   
>> +config ARM64_WORKAROUND_TSB_FLUSH_FAILURE
>> +	bool
>> +
>> +config ARM64_ERRATUM_2054223
>> +	bool "Cortex-A710: 2054223: workaround TSB instruction failing to flush trace"
>> +	default y
>> +	help
>> +	  Enable workaround for ARM Cortex-A710 erratum 2054223
>> +
>> +	  Affected cores may fail to flush the trace data on a TSB instruction, when
>> +	  the PE is in trace prohibited state. This will cause losing a few bytes
>> +	  of the trace cached.
>> +
>> +	  Workaround is to issue two TSB consecutively on affected cores.
>> +
>> +	  If unsure, say Y.
>> +
>> +config ARM64_ERRATUM_2067961
>> +	bool "Neoverse-N2: 2067961: workaround TSB instruction failing to flush trace"
>> +	default y
>> +	help
>> +	  Enable workaround for ARM Neoverse-N2 erratum 2067961
>> +
>> +	  Affected cores may fail to flush the trace data on a TSB instruction, when
>> +	  the PE is in trace prohibited state. This will cause losing a few bytes
>> +	  of the trace cached.
>> +
>> +	  Workaround is to issue two TSB consecutively on affected cores.
>> +
>> +	  If unsure, say Y.
> 
> Shouldn't these two be selecting the workaround?

doh! I have given myself a slap for this and fixed it locally.


Suzuki