linux-kernel - Re: [PATCH V3 10/20] RISC-V: smpboot: Add ACPI support in smp

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Date:   Fri, 3 Mar 2023 23:24:21 +0530
From:   Sunil V L <sunilvl@...tanamicro.com>
To:     Andrew Jones <ajones@...tanamicro.com>
Cc:     linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        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>,
        Anup Patel <apatel@...tanamicro.com>,
        Atish Patra <atishp@...osinc.com>,
        'Conor Dooley ' <conor.dooley@...rochip.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH V3 10/20] RISC-V: smpboot: Add ACPI support in smp_setup()

On Fri, Mar 03, 2023 at 04:49:20PM +0100, Andrew Jones wrote:
> On Fri, Mar 03, 2023 at 07:06:37PM +0530, Sunil V L wrote:
> > Enable SMP boot on ACPI based platforms by using the RINTC
> > structures in the MADT table.
> > 
> > Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
> > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
> > ---
> >  arch/riscv/kernel/smpboot.c | 72 ++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 71 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> > index 26214ddefaa4..27047322d3bb 100644
> > --- a/arch/riscv/kernel/smpboot.c
> > +++ b/arch/riscv/kernel/smpboot.c
> > @@ -8,6 +8,7 @@
> >   * Copyright (C) 2017 SiFive
> >   */
> >  
> > +#include <linux/acpi.h>
> >  #include <linux/arch_topology.h>
> >  #include <linux/module.h>
> >  #include <linux/init.h>
> > @@ -70,6 +71,72 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> >  	}
> >  }
> >  
> > +#ifdef CONFIG_ACPI
> > +static unsigned int cpu_count = 1;
> > +
> > +static int __init acpi_parse_rintc(union acpi_subtable_headers *header, const unsigned long end)
> > +{
> > +	unsigned long hart;
> > +	static bool found_boot_cpu;
> > +	struct acpi_madt_rintc *processor = (struct acpi_madt_rintc *)header;
> > +
> > +	/*
> > +	 * Each RINTC structure in MADT will have a flag. If ACPI_MADT_ENABLED
> > +	 * bit in the flag is not enabled, it means OS should not try to enable
> > +	 * the cpu to which RINTC belongs.
> > +	 */
> > +	if (!(processor->flags & ACPI_MADT_ENABLED))
> > +		return 0;
> > +
> > +	if (BAD_MADT_ENTRY(processor, end))
> > +		return -EINVAL;
> > +
> > +	acpi_table_print_madt_entry(&header->common);
> > +
> > +	hart = processor->hart_id;
> > +	if (hart == INVALID_HARTID) {
> > +		pr_warn("Invalid hartid\n");
> > +		return 0;
> > +	}
> > +
> > +	if (hart == cpuid_to_hartid_map(0)) {
> > +		BUG_ON(found_boot_cpu);
> > +		found_boot_cpu = true;
> > +		early_map_cpu_to_node(0, NUMA_NO_NODE);
> 
> We should have kept
> 
>  static inline int acpi_numa_get_nid(unsigned int cpu) { return NUMA_NO_NODE; }
> 
> and only dropped the
> 
>  #ifdef CONFIG_ACPI_NUMA
>  int acpi_numa_get_nid(unsigned int cpu);
>  #else
>  ...
>  #endif
> 
Okay, I thought we better add it when we enable NUMA with ACPI. 

> > +		return 0;
> > +	}
> > +
> > +	if (cpu_count >= NR_CPUS) {
> > +		pr_warn("NR_CPUS is too small for the number of ACPI tables.\n");
> > +		return 0;
> > +	}
> > +
> > +	cpuid_to_hartid_map(cpu_count) = hart;
> > +	early_map_cpu_to_node(cpu_count, NUMA_NO_NODE);
> > +	cpu_count++;
> > +
> > +	return 0;
> > +}
> > +
> > +static void __init acpi_parse_and_init_cpus(void)
> > +{
> > +	int cpuid;
> > +
> > +	cpu_set_ops(0);
> > +
> > +	acpi_table_parse_madt(ACPI_MADT_TYPE_RINTC, acpi_parse_rintc, 0);
> > +
> > +	for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
> > +		if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
> > +			cpu_set_ops(cpuid);
> > +			set_cpu_possible(cpuid, true);
> > +		}
> > +	}
> > +}
> > +#else
> > +#define acpi_parse_and_init_cpus(...)	do { } while (0)
> > +#endif
> > +
> >  static void __init of_parse_and_init_cpus(void)
> >  {
> >  	struct device_node *dn;
> > @@ -118,7 +185,10 @@ static void __init of_parse_and_init_cpus(void)
> >  
> >  void __init setup_smp(void)
> >  {
> > -	of_parse_and_init_cpus();
> > +	if (acpi_disabled)
> > +		of_parse_and_init_cpus();
> > +	else
> > +		acpi_parse_and_init_cpus();
> >  }
> >  
> >  static int start_secondary_cpu(int cpu, struct task_struct *tidle)
> > -- 
> > 2.34.1
> >
> 
> Thanks,
> drew