linux-kernel - [RFC PATCH v2 2/3] arm64: mark all the GICC nodes in MADT as possible cpu

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Date:   Sat, 29 Jun 2019 10:42:34 +0800
From:   Xiongfeng Wang <wangxiongfeng2@...wei.com>
To:     <rjw@...ysocki.net>, <catalin.marinas@....com>,
        <james.morse@....com>
CC:     <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <guohanjun@...wei.com>,
        <xiexiuqi@...wei.com>, <huawei.libin@...wei.com>,
        <john.garry@...wei.com>, <jonathan.cameron@...wei.com>,
        <wangxiongfeng2@...wei.com>
Subject: [RFC PATCH v2 2/3] arm64: mark all the GICC nodes in MADT as possible cpu

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@...wei.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) {
 		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);
 	}
 }
-- 
1.7.12.4