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

[Jeffrey Hugo]

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