Re: [PATCH 07/19] ARM64 / ACPI: Parse MADT to map logical cpu to MPIDR and get cpu_possible/present_map

[Naresh Bhat]

On 24 July 2014 18:30, Hanjun Guo <hanjun.guo@xxxxxxxxxx> wrote:
> MADT contains the information for MPIDR which is essential for
> SMP initialization, parse the GIC cpu interface structures to
> get the MPIDR value and map it to cpu_logical_map(), and add
> enabled cpu with valid MPIDR into cpu_possible_map and
> cpu_present_map.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/acpi.h |    2 +
>  arch/arm64/kernel/acpi.c      |  127 +++++++++++++++++++++++++++++++++++++++++
>  arch/arm64/kernel/smp.c       |   10 +++-
>  3 files changed, 138 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 67dac90..5ce85f8 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -50,6 +50,8 @@ static inline bool acpi_has_cpu_in_madt(void)
>  extern int (*acpi_suspend_lowlevel)(void);
>  #define acpi_wakeup_address 0
>
> +#define MAX_GIC_CPU_INTERFACE 65535
> +
>  #endif /* CONFIG_ACPI */
>
>  #endif /*_ASM_ACPI_H*/
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index 374926f..801e268 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -22,6 +22,9 @@
>  #include <linux/bootmem.h>
>  #include <linux/smp.h>
>
> +#include <asm/smp_plat.h>
> +#include <asm/cputype.h>
> +
>  /*
>   * We never plan to use RSDT on arm/arm64 as its deprecated in spec but this
>   * variable is still required by the ACPI core
> @@ -42,6 +45,9 @@ int acpi_psci_present;
>  /* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
>  int acpi_psci_use_hvc;
>
> +/* Processors (GICC) with enabled flag in MADT */
> +static int enabled_cpus;
> +
>  /*
>   * __acpi_map_table() will be called before page_init(), so early_ioremap()
>   * or early_memremap() should be called here to for ACPI table mapping.
> @@ -62,6 +68,122 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
>         early_iounmap(map, size);
>  }
>
> +/**
> + * acpi_register_gic_cpu_interface - register a gic cpu interface and
> + * generates a logic cpu number

logic - logical

> + * @mpidr: CPU's hardware id to register, MPIDR represented in MADT
> + * @enabled: this cpu is enabled or not
> + *
> + * Returns the logic cpu number which maps to the gic cpu interface

logic - logical

> + */
> +static int acpi_register_gic_cpu_interface(u64 mpidr, u8 enabled)
> +{
> +       int cpu;
> +
> +       if (mpidr == INVALID_HWID) {
> +               pr_info("Skip invalid cpu hardware ID\n");
> +               return -EINVAL;
> +       }
> +
> +       total_cpus++;
> +       if (!enabled)
> +               return -EINVAL;
> +
> +       if (enabled_cpus >=  NR_CPUS) {
> +               pr_warn("NR_CPUS limit of %d reached, Processor %d/0x%llx ignored.\n",
> +                       NR_CPUS, total_cpus, mpidr);
> +               return -EINVAL;
> +       }
> +
> +       /* If it is the first CPU, no need to check duplicate MPIDRs */
> +       if (!enabled_cpus)
> +               goto skip_mpidr_check;
> +
> +       /*
> +        * Duplicate MPIDRs are a recipe for disaster. Scan
> +        * all initialized entries and check for
> +        * duplicates. If any is found just ignore the CPU.
> +        */
> +       for_each_present_cpu(cpu) {
> +               if (cpu_logical_map(cpu) == mpidr) {
> +                       pr_err("Firmware bug, duplicate CPU MPIDR: 0x%llx in MADT\n",
> +                              mpidr);
> +                       return -EINVAL;
> +               }
> +       }
> +
> +skip_mpidr_check:
> +       enabled_cpus++;
> +
> +       /* allocate a logic cpu id for the new comer */

logic - logical

> +       if (cpu_logical_map(0) == mpidr) {
> +               /*
> +                * boot_cpu_init() already hold bit 0 in cpu_present_mask
> +                * for BSP, no need to allocte again.

allocte - allocate

> +                */
> +               cpu = 0;
> +       } else {
> +               cpu = cpumask_next_zero(-1, cpu_present_mask);
> +       }
> +
> +       /* map the logic cpu id to cpu MPIDR */

logic - logical

> +       cpu_logical_map(cpu) = mpidr;
> +
> +       set_cpu_possible(cpu, true);
> +       set_cpu_present(cpu, true);
> +
> +       return cpu;
> +}
> +
> +static int __init
> +acpi_parse_gic_cpu_interface(struct acpi_subtable_header *header,
> +                               const unsigned long end)
> +{
> +       struct acpi_madt_generic_interrupt *processor;
> +
> +       processor = (struct acpi_madt_generic_interrupt *)header;
> +
> +       if (BAD_MADT_ENTRY(processor, end))
> +               return -EINVAL;
> +
> +       acpi_table_print_madt_entry(header);
> +
> +       acpi_register_gic_cpu_interface(processor->mpidr,
> +               processor->flags & ACPI_MADT_ENABLED);
> +
> +       return 0;
> +}
> +
> +/*
> + * Parse GIC cpu interface related entries in MADT
> + * returns 0 on success, < 0 on error
> + */
> +static int __init acpi_parse_madt_gic_cpu_interface_entries(void)
> +{
> +       int count;
> +
> +       /*
> +        * do a partial walk of MADT to determine how many CPUs
> +        * we have including disabled CPUs, and get information
> +        * we need for SMP init
> +        */
> +       count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
> +                       acpi_parse_gic_cpu_interface, MAX_GIC_CPU_INTERFACE);
> +
> +       if (!count) {
> +               pr_err("No GIC CPU interface entries present\n");
> +               return -ENODEV;
> +       } else if (count < 0) {
> +               pr_err("Error parsing GIC CPU interface entry\n");
> +               return count;
> +       }
> +
> +       /* Make boot-up look pretty */
> +       pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus);
> +
> +       return 0;
> +}
> +
>  static int __init acpi_parse_fadt(struct acpi_table_header *table)
>  {
>         struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
> @@ -122,6 +244,11 @@ int __init acpi_boot_init(void)
>         if (err)
>                 pr_err("Can't find FADT\n");
>
> +       /* Get the boot CPU's MPIDR before MADT parsing */
> +       cpu_logical_map(0) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
> +
> +       err = acpi_parse_madt_gic_cpu_interface_entries();
> +
>         return err;
>  }
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 40f38f4..8f1d37c 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -36,6 +36,7 @@
>  #include <linux/completion.h>
>  #include <linux/of.h>
>  #include <linux/irq_work.h>
> +#include <linux/acpi.h>
>
>  #include <asm/atomic.h>
>  #include <asm/cacheflush.h>
> @@ -458,7 +459,14 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
>                 if (err)
>                         continue;
>
> -               set_cpu_present(cpu, true);
> +               /*
> +                * In ACPI mode, cpu_present_map was initialised when
> +                * MADT table was parsed which before this function
> +                * is called.
> +                */
> +               if (acpi_disabled)
> +                       set_cpu_present(cpu, true);
> +
>                 max_cpus--;
>         }
>  }
> --
> 1.7.9.5
>
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