On 2014-8-18 22:27, Catalin Marinas wrote:
> On Mon, Aug 04, 2014 at 04:28:13PM +0100, Hanjun Guo wrote:
>> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
>> index 6e04868..e877967 100644
>> --- a/arch/arm64/include/asm/acpi.h
>> +++ b/arch/arm64/include/asm/acpi.h
>> @@ -64,6 +64,8 @@ static inline void arch_fix_phys_package_id(int num, u32
>> slot) { }
>> extern int (*acpi_suspend_lowlevel)(void);
>> #define acpi_wakeup_address 0
>>
>> +#define MAX_GIC_CPU_INTERFACE 65535
>
> Does this need to be more than NR_CPUS?
Sometimes yes, CPU structure entries in MADT just like CPU nodes in
device tree, the number of them may more than NR_CPUS.
>
>> +/**
>> + * acpi_register_gic_cpu_interface - register a gic cpu interface and
>> + * generates a logical cpu number
>> + * @mpidr: CPU's hardware id to register, MPIDR represented in MADT
>> + * @enabled: this cpu is enabled or not
>> + *
>> + * Returns the logical cpu number which maps to the gic cpu interface
>> + */
>> +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 logical 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 allocate again.
>> + */
>> + cpu = 0;
>> + } else {
>> + cpu = cpumask_next_zero(-1, cpu_present_mask);
>> + }
>> +
>> + /* map the logical cpu id to cpu MPIDR */
>> + cpu_logical_map(cpu) = mpidr;
>> +
>> + set_cpu_possible(cpu, true);
>> + set_cpu_present(cpu, true);
>> +
>> + return cpu;
>> +}
>
> Why not only set the cpu possible here (with the additional mpidr
> validity checks changed to for_each_possible_cpu)...
>
>> 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--;
>
> ... and don't touch this at all.
the original intent was to support CPU hotplug, I will update the patch
as you suggested and introduce the change when CPU hotplug patch is upstreamed,
then it will make the patch less confusing.
Thanks
Hanjun
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