summaryrefslogtreecommitdiffstats
path: root/drivers/base
diff options
context:
space:
mode:
authorJames Morse <james.morse@arm.com>2024-05-29 15:34:46 +0200
committerCatalin Marinas <catalin.marinas@arm.com>2024-06-28 19:38:33 +0200
commit4e1a7df4548003fc081360b0f4edce3f7a991bfc (patch)
treecf94859fea1576cf6f9c0e691e680212f1960994 /drivers/base
parentarm64: document virtual CPU hotplug's expectations (diff)
downloadlinux-4e1a7df4548003fc081360b0f4edce3f7a991bfc.tar.xz
linux-4e1a7df4548003fc081360b0f4edce3f7a991bfc.zip
cpumask: Add enabled cpumask for present CPUs that can be brought online
The 'offline' file in sysfs shows all offline CPUs, including those that aren't present. User-space is expected to remove not-present CPUs from this list to learn which CPUs could be brought online. CPUs can be present but not-enabled. These CPUs can't be brought online until the firmware policy changes, which comes with an ACPI notification that will register the CPUs. With only the offline and present files, user-space is unable to determine which CPUs it can try to bring online. Add a new CPU mask that shows this based on all the registered CPUs. Signed-off-by: James Morse <james.morse@arm.com> Tested-by: Miguel Luis <miguel.luis@oracle.com> Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com> Tested-by: Jianyong Wu <jianyong.wu@arm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Reviewed-by: Gavin Shan <gshan@redhat.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: https://lore.kernel.org/r/20240529133446.28446-20-Jonathan.Cameron@huawei.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/cpu.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 1487cd9761a4..b57326fd48d4 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -95,6 +95,7 @@ void unregister_cpu(struct cpu *cpu)
{
int logical_cpu = cpu->dev.id;
+ set_cpu_enabled(logical_cpu, false);
unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
device_unregister(&cpu->dev);
@@ -273,6 +274,13 @@ static ssize_t print_cpus_offline(struct device *dev,
}
static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
+static ssize_t print_cpus_enabled(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_enabled_mask));
+}
+static DEVICE_ATTR(enabled, 0444, print_cpus_enabled, NULL);
+
static ssize_t print_cpus_isolated(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -413,6 +421,7 @@ int register_cpu(struct cpu *cpu, int num)
register_cpu_under_node(num, cpu_to_node(num));
dev_pm_qos_expose_latency_limit(&cpu->dev,
PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
+ set_cpu_enabled(num, true);
return 0;
}
@@ -494,6 +503,7 @@ static struct attribute *cpu_root_attrs[] = {
&cpu_attrs[2].attr.attr,
&dev_attr_kernel_max.attr,
&dev_attr_offline.attr,
+ &dev_attr_enabled.attr,
&dev_attr_isolated.attr,
#ifdef CONFIG_NO_HZ_FULL
&dev_attr_nohz_full.attr,