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SubjectRe: [RFC PATCH v2 2/3] arm64: mark all the GICC nodes in MADT as possible cpu
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On 2019/6/29 10:42, Xiongfeng Wang wrote:
> We set 'cpu_possible_mask' based on the enabled GICC node in MADT. If
> the GICC node is disabled, we will skip initializing the kernel data
> structure for that CPU.
>
> To support CPU hotplug, we need to initialize some CPU related data
> structure in advance. This patch mark all the GICC nodes as possible CPU
> and only these enabled GICC nodes as present CPU.
>
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
> ---
> arch/arm64/kernel/setup.c | 2 +-
> arch/arm64/kernel/smp.c | 11 +++++------
> 2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 7e541f9..7f4d12a 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -359,7 +359,7 @@ static int __init topology_init(void)
> for_each_online_node(i)
> register_one_node(i);
>
> - for_each_possible_cpu(i) {
> + for_each_online_cpu(i) {

Have you considered the case in non-acpi mode? and setting "maxcpus=n" in host
kernel boot

parameters?

---
Cheers,
Justin (Jia He)


> struct cpu *cpu = &per_cpu(cpu_data.cpu, i);
> cpu->hotpluggable = 1;
> register_cpu(cpu, i);
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 6dcf960..6d9983c 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -525,16 +525,14 @@ struct acpi_madt_generic_interrupt *acpi_cpu_get_madt_gicc(int cpu)
> {
> u64 hwid = processor->arm_mpidr;
>
> - if (!(processor->flags & ACPI_MADT_ENABLED)) {
> - pr_debug("skipping disabled CPU entry with 0x%llx MPIDR\n", hwid);
> - return;
> - }
> -
> if (hwid & ~MPIDR_HWID_BITMASK || hwid == INVALID_HWID) {
> pr_err("skipping CPU entry with invalid MPIDR 0x%llx\n", hwid);
> return;
> }
>
> + if (!(processor->flags & ACPI_MADT_ENABLED))
> + pr_debug("disabled CPU entry with 0x%llx MPIDR\n", hwid);
> +
> if (is_mpidr_duplicate(cpu_count, hwid)) {
> pr_err("duplicate CPU MPIDR 0x%llx in MADT\n", hwid);
> return;
> @@ -755,7 +753,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> if (err)
> continue;
>
> - set_cpu_present(cpu, true);
> + if ((cpu_madt_gicc[cpu].flags & ACPI_MADT_ENABLED))
> + set_cpu_present(cpu, true);
> numa_store_cpu_info(cpu);
> }
> }

--

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