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

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