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

[Sudeep Holla]

On 24/07/14 14:00, Hanjun Guo 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
> +

Can this me made something like MAX_MADT_INTERRUPT_CONTROLLER_ENTRIES ?
And assuming each entry to be at-least 4 or 8 bytes, it can be reduced.

>   #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
> + * @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
> + */
> +static int acpi_register_gic_cpu_interface(u64 mpidr, u8 enabled)

Honestly this function doesn't deal anything with GIC cpu interface.

> +{
> +	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 */
> +	if (cpu_logical_map(0) == mpidr) {
> +		/*
> +		 * boot_cpu_init() already hold bit 0 in cpu_present_mask
> +		 * for BSP, no need to allocte again.
> +		 */
> +		cpu = 0;
> +	} else {
> +		cpu = cpumask_next_zero(-1, cpu_present_mask);
> +	}
> +
> +	/* map the logic cpu id to cpu MPIDR */
> +	cpu_logical_map(cpu) = mpidr;
> +
> +	set_cpu_possible(cpu, true);
> +	set_cpu_present(cpu, true);
> +

I need to think more about this function and will comment later but I
think these cpumasks should be set only if SMP and probably belong to smp.c

> +	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;
> +

As Mark suggested better to move this prior to ACPI changes.

> +	err = acpi_parse_madt_gic_cpu_interface_entries();
> +

OK, so now you ignore if there was any FADT error if MADT is
successfully parsed ?

>   	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);
> +

This is what I said above, it belongs here and we need to see how we do
that. I will give it a thought.

Regards,
Sudeep

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