linux-kernel - Re: [PATCH 14/24] RISC-V: ACPI: smpboot: Add function to retrieve the hartid

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Date:   Mon, 13 Feb 2023 22:30:33 +0530
From:   Sunil V L <sunilvl@...tanamicro.com>
To:     Conor Dooley <conor@...nel.org>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Anup Patel <apatel@...tanamicro.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Atish Patra <atishp@...osinc.com>
Subject: Re: [PATCH 14/24] RISC-V: ACPI: smpboot: Add function to retrieve
 the hartid

On Thu, Feb 09, 2023 at 08:30:40PM +0000, Conor Dooley wrote:
> Hey Sunil, Drew,
> 
> @drew, a question below that I'm sorta aiming at you...
> 
> On Mon, Jan 30, 2023 at 11:52:15PM +0530, Sunil V L wrote:
> > hartid is in RINTC structuire in MADT table. Instead of parsing
> 
> Nit: missing articles before RINTC and MADT. Also typo "structure".
> 
> Perhaps you'd benefit from a spell checker in your git editor.
> 
Okay.

> > the ACPI table every time we need for a cpu, cache it and provide
> > a function to read it.
> > 
> > This is similar to acpi_get_madt_gicc() in arm64.
> 
> -ENOTFOUND, do you mean acpi_cpu_get_madt_gicc()?
>
Yes. Will update.

> > 
> > Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
> > ---
> >  arch/riscv/include/asm/acpi.h | 14 +++++++++++++-
> >  arch/riscv/kernel/smpboot.c   | 21 +++++++++++++++++++++
> >  2 files changed, 34 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
> > index d1f1e53ec657..69a880b7257a 100644
> > --- a/arch/riscv/include/asm/acpi.h
> > +++ b/arch/riscv/include/asm/acpi.h
> > @@ -65,6 +65,18 @@ int acpi_numa_get_nid(unsigned int cpu);
> >  static inline int acpi_numa_get_nid(unsigned int cpu) { return NUMA_NO_NODE; }
> >  #endif /* CONFIG_ACPI_NUMA */
> >  
> > -#endif
> > +struct acpi_madt_rintc *acpi_get_madt_rintc(int cpu);
> > +struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu);
> > +static inline u32 get_acpi_id_for_cpu(int cpu)
> > +{
> > +	return	acpi_cpu_get_madt_rintc(cpu)->uid;
> > +}
> > +#else
> > +static inline u32 get_acpi_id_for_cpu(int cpu)
> > +{
> > +	return -1;
> > +}
> > +
> > +#endif /* CONFIG_ACPI */
> >  
> >  #endif /*_ASM_ACPI_H*/
> > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> > index e48cf88d0bc1..3a8b7a9eb5ac 100644
> > --- a/arch/riscv/kernel/smpboot.c
> > +++ b/arch/riscv/kernel/smpboot.c
> > @@ -73,6 +73,25 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> >  
> >  #ifdef CONFIG_ACPI
> >  static unsigned int cpu_count = 1;
> > +static unsigned int intc_count;
> > +static struct acpi_madt_rintc cpu_madt_rintc[NR_CPUS];
> > +
> > +struct acpi_madt_rintc *acpi_get_madt_rintc(int cpu)
> > +{
> > +	return &cpu_madt_rintc[cpu];
> > +}
> > +
> > +struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
> > +{
> > +	int i;
> 
> Since we are C11 now, you don't even need to declare this outside of the
> loop, right?
>
Okay.
 
> > +
> > +	for (i = 0; i < NR_CPUS; i++) {
> 
> @drew, perhaps you know since you were fiddling not too long ago with
> cpumask stuff - at what point does for_each_possible_cpu() become
> usable?
> I had a bit of a poke & couldn't immediately tell if it'd be okay to use
> it here.
>
It should be possible. Thanks!
 
> > +		if (riscv_hartid_to_cpuid(cpu_madt_rintc[i].hart_id) == cpu)
> > +			return &cpu_madt_rintc[i];
> > +	}
> > +	return NULL;
> 
> Another nit: newline before return please :)
>
Sure.

Thanks,
Sunil