linux-kernel - Re: [PATCH] arm64: Add KRYO{3,4}XX CPU cores to spectre-v2 safe list

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Date:   Thu, 16 Jan 2020 08:42:16 -0700
From:   Jeffrey Hugo <jhugo@...eaurora.org>
To:     Will Deacon <will@...nel.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Cc:     Mark Rutland <mark.rutland@....com>, Marc Zyngier <maz@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andre Przywara <andre.przywara@....com>,
        James Morse <james.morse@....com>,
        Stephen Boyd <swboyd@...omium.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] arm64: Add KRYO{3,4}XX CPU cores to spectre-v2 safe list

On 1/16/2020 8:32 AM, Will Deacon wrote:
> [+Jeffrey]
> 
> On Thu, Jan 16, 2020 at 07:49:12PM +0530, Sai Prakash Ranjan wrote:
>> KRYO3XX silver CPU cores and KRYO4XX silver, gold CPU cores
>> are not affected by Spectre variant 2. Add them to spectre_v2
>> safe list to correct ARM_SMCCC_ARCH_WORKAROUND_1 warning and
>> vulnerability sysfs value.
>>
>> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
>> ---
>>   arch/arm64/include/asm/cputype.h | 6 ++++++
>>   arch/arm64/kernel/cpu_errata.c   | 3 +++
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
>> index aca07c2f6e6e..7219cddeba66 100644
>> --- a/arch/arm64/include/asm/cputype.h
>> +++ b/arch/arm64/include/asm/cputype.h
>> @@ -85,6 +85,9 @@
>>   #define QCOM_CPU_PART_FALKOR_V1		0x800
>>   #define QCOM_CPU_PART_FALKOR		0xC00
>>   #define QCOM_CPU_PART_KRYO		0x200
>> +#define QCOM_CPU_PART_KRYO_3XX_SILVER	0x803
>> +#define QCOM_CPU_PART_KRYO_4XX_GOLD	0x804
>> +#define QCOM_CPU_PART_KRYO_4XX_SILVER	0x805
> 
> Jeffrey is the only person I know who understands the CPU naming here, so
> I've added him in case this needs either renaming or extending to cover
> other CPUs. I wouldn't be at all surprised if we need a function call
> rather than a bunch of table entries...

The added lines look sane to me, from a naming and MIDR perspective.  I 
don't know off hand if these CPUs are really fixed or not.

I wonder why a "KRYO_3XX_GOLD  0x802" line is not being added.  Sai?

> 
> That said, the internet claims that KRYO4XX gold is based on Cortex-A76,
> and so CSV2 should be set...
> 
> Will
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

-- 
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

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