Re: [PATCH 11/20] ARM64 / ACPI: Get the enable method for SMP initialization

[Hanjun Guo]

Hi Catalin,

On 2014å01æ24æ 01:50, Catalin Marinas wrote:
> On Fri, Jan 17, 2014 at 12:25:05PM +0000, Hanjun Guo wrote:
> > --- a/arch/arm64/kernel/smp.c
> > +++ b/arch/arm64/kernel/smp.c
> > @@ -48,6 +48,7 @@
> >   #include <asm/sections.h>
> >   #include <asm/tlbflush.h>
> >   #include <asm/ptrace.h>
> > +#include <asm/acpi.h>
> >   
> >   /*
> >    * as from 2.5, kernels no longer have an init_tasks structure
> > @@ -280,7 +281,7 @@ static void (*smp_cross_call)(const struct cpumask *, unsigned int);
> >    * cpu logical map array containing MPIDR values related to logical
> >    * cpus. Assumes that cpu_logical_map(0) has already been initialized.
> >    */
> > -void __init smp_init_cpus(void)
> > +static int __init of_smp_init_cpus(void)
> >   {
> >   	struct device_node *dn = NULL;
> >   	unsigned int i, cpu = 1;
> > @@ -364,6 +365,10 @@ next:
> >   		cpu++;
> >   	}
> >   
> > +	/* No device tree or no CPU node in DT */
> > +	if (cpu == 1 && !bootcpu_valid)
> > +		return -ENODEV;
> > +
> >   	/* sanity check */
> >   	if (cpu > NR_CPUS)
> >   		pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
> > @@ -371,7 +376,7 @@ next:
> >   
> >   	if (!bootcpu_valid) {
> >   		pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
> > -		return;
> > +		return -EINVAL;
> >   	}
> >   
> >   	/*
> > @@ -381,6 +386,39 @@ next:
> >   	for (i = 0; i < NR_CPUS; i++)
> >   		if (cpu_logical_map(i) != INVALID_HWID)
> >   			set_cpu_possible(i, true);
> > +
> > +	return 0;
> > +}
> > +
> > +/*
> > + * In ACPI mode, the cpu possible map was enumerated before SMP
> > + * initialization when MADT table was parsed, so we can get the
> > + * possible map here to initialize CPUs.
> > + */
> > +static void __init acpi_smp_init_cpus(void)
> > +{
> > +	int cpu;
> > +	const char *enable_method;
> > +
> > +	for_each_possible_cpu(cpu) {
> > +		enable_method = acpi_get_enable_method(cpu);
> > +		if (!enable_method)
> > +			continue;
> > +
> > +		cpu_ops[cpu] = cpu_get_ops(enable_method);
> > +		if (!cpu_ops[cpu])
> > +			continue;
> > +
> > +		cpu_ops[cpu]->cpu_init(NULL, cpu);
> > +	}
> > +}
> > +
> > +void __init smp_init_cpus(void)
> > +{
> > +	if (!of_smp_init_cpus())
> > +		return;
> > +
> > +	acpi_smp_init_cpus();
> >   }
> With DT we initialise the cpu_ops[0] via cpu_read_bootcpu_ops() called
> from setup_arch(). This is needed because with PSCI we use cpu_ops for
> power management even if it's a UP system. Do you get a some kernel
> warning about device node for the boot cpu not found?

Thanks for pointing this out, actually we didn't find a dts file with
spin-table method for SMP initialization, and this patch is not fully
tested (only spin-table method is supported in ACPI now), we are
working on that and get this patch fully tested.

I will review the code carefully in your comments, and update
the code accordingly.

> > --- a/drivers/acpi/plat/arm-core.c
> > +++ b/drivers/acpi/plat/arm-core.c
> > @@ -367,6 +367,32 @@ static void __init acpi_process_madt(void)
> >   }
> >   
> >   /*
> > + * To see PCSI is enabled or not.
> > + *
> > + * PSCI is not available for ACPI 5.0, return FALSE for now.
> > + *
> > + * FIXME: should we introduce early_param("psci", func) for test purpose?
> > + */
> > +static bool acpi_psci_smp_available(int cpu)
> > +{
> > +	return FALSE;
> > +}
> > +
> > +static const char *enable_method[] = {
> > +	"psci",
> > +	"spin-table",
> > +	NULL
> > +};
> > +
> > +const char *acpi_get_enable_method(int cpu)
> > +{
> > +	if (acpi_psci_smp_available(cpu))
> > +		return enable_method[0];
> > +	else
> > +		return enable_method[1];
> > +}
> You could just use literal strings here, actually even ignoring PSCI
> until available.

Ok.

Thanks
Hanjun

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