Re: [PATCH 02/16] arm64: Move errata work around check on boot CPU

[Suzuki K Poulose]

On 23/01/18 14:59, Dave Martin wrote:
> On Tue, Jan 23, 2018 at 12:27:55PM +0000, Suzuki K Poulose wrote:
> > We trigger CPU errata work around check on the boot CPU from
> > smp_prepare_boot_cpu() to make sure that we run the checks only
> > after the CPU feature infrastructure is initialised.
>
> On the surface of it, this sounds like a bug fix.

No, this is not. It is just moving the code to cpufeature.c

Earlier it was :

smp_prepare_boot_cpu()  -> cpuinfo_store_boot_cpu() -> init_cpu_features()

and then we did update_cpu_errata_workarounds() after we have done
cpuinfo_store_boot_cpu(). With this change we do :

smp_prepare_boot_cpu()  -> cpuinfo_store_boot_cpu() -> init_cpu_features() -> update_cpu_errata_workarounds()


> Should there be a Fixes tag if so?
>
> If this reordering doesn't matter for upstream, it would be good to have
> a quick explanation here as to why not.

Sure, will make it clearer.

Cheers
Suzuki

> Cheers
> ---Dave
>
> > We can do this from init_cpu_features() which is called only
> > on the boot CPU and does the initilisation of the infrastructure.
> > As we are consolidating the cpu capability handling, let us
> > move this to where it should belong. No functional changes.
> >
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > ---
> >   arch/arm64/kernel/cpufeature.c | 6 ++++++
> >   arch/arm64/kernel/smp.c        | 6 ------
> >   2 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> > index 6a8dfdc532b1..ebb467340b9c 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -545,6 +545,12 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
> >   		init_cpu_ftr_reg(SYS_ZCR_EL1, info->reg_zcr);
> >   		sve_init_vq_map();
> >   	}
> > +
> > +	/*
> > +	 * Run the errata work around checks on the boot CPU, once we have
> > +	 * initialised the cpu feature infrastructure.
> > +	 */
> > +	update_cpu_errata_workarounds();
> >   }
> >   
> >   static void update_cpu_ftr_reg(struct arm64_ftr_reg *reg, u64 new)
> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> > index 3b8ad7be9c33..5cef11450183 100644
> > --- a/arch/arm64/kernel/smp.c
> > +++ b/arch/arm64/kernel/smp.c
> > @@ -448,12 +448,6 @@ void __init smp_prepare_boot_cpu(void)
> >   	jump_label_init();
> >   	cpuinfo_store_boot_cpu();
> >   	save_boot_cpu_run_el();
> > -	/*
> > -	 * Run the errata work around checks on the boot CPU, once we have
> > -	 * initialised the cpu feature infrastructure from
> > -	 * cpuinfo_store_boot_cpu() above.
> > -	 */
> > -	update_cpu_errata_workarounds();
> >   }
> >   
> >   static u64 __init of_get_cpu_mpidr(struct device_node *dn)
> > --
> > 2.13.6
> >
> >
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