[PATCH RFC 2/4] arm64: kernel: Bound the total(present+disabled) cpus with nr_cpu_ids

[Salil Mehta]

Bound the total number of identified cpus(including disabled cpus) by
maximum allowed limit by the kernel. Max value is either specified as
part of the kernel parameters 'nr_cpus' or specified during compile
time using CONFIG_NR_CPUS.

Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
---
 arch/arm64/kernel/smp.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 51a707928302..864ccd3da419 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -513,6 +513,7 @@ static int __init smp_cpu_setup(int cpu)
 }
 
 static bool bootcpu_valid __initdata;
+static bool cpus_clipped __initdata = false;
 static unsigned int cpu_count = 1;
 static unsigned int disabled_cpu_count;
 
@@ -536,6 +537,11 @@ acpi_map_gic_cpu_interface(struct 
acpi_madt_generic_interrupt *processor)
        unsigned int total_cpu_count = disabled_cpu_count + cpu_count;
        u64 hwid = processor->arm_mpidr;
 
+       if (total_cpu_count > nr_cpu_ids) {
+               cpus_clipped = true;
+               return;
+       }
+
        if (!(processor->flags & ACPI_MADT_ENABLED)) {
 #ifndef CONFIG_ACPI_HOTPLUG_CPU
                pr_debug("skipping disabled CPU entry with 0x%llx MPIDR\n", 
hwid);
@@ -569,9 +575,6 @@ acpi_map_gic_cpu_interface(struct 
acpi_madt_generic_interrupt *processor)
                return;
        }
 
-       if (cpu_count >= NR_CPUS)
-               return;
-
        /* map the logical cpu id to cpu MPIDR */
        cpu_logical_map(total_cpu_count) = hwid;
 
@@ -688,8 +691,10 @@ static void __init of_parse_and_init_cpus(void)
                        continue;
                }
 
-               if (cpu_count >= NR_CPUS)
+               if (cpu_count >= NR_CPUS) {
+                       cpus_clipped = true;
                        goto next;
+               }
 
                pr_debug("cpu logical map 0x%llx\n", hwid);
                cpu_logical_map(cpu_count) = hwid;
@@ -710,6 +715,7 @@ static void __init of_parse_and_init_cpus(void)
  */
 void __init smp_init_cpus(void)
 {
+       unsigned int total_cpu_count = disabled_cpu_count + cpu_count;
        int i;
 
        if (acpi_disabled)
@@ -717,9 +723,9 @@ void __init smp_init_cpus(void)
        else
                acpi_parse_and_init_cpus();
 
-       if (cpu_count > nr_cpu_ids)
+       if (cpus_clipped)
                pr_warn("Number of cores (%d) exceeds configured maximum of %u 
- clipping\n",
-                       cpu_count, nr_cpu_ids);
+                       total_cpu_count, nr_cpu_ids);
 
        if (!bootcpu_valid) {
                pr_err("missing boot CPU MPIDR, not enabling secondaries\n");
-- 
2.17.1