ACPI: processor: Simplify initial onlining to use same path for cold and hotplug

Separate code paths, combined with a flag set in acpi_processor.c to
indicate a struct acpi_processor was for a hotplugged CPU ensured that
per CPU data was only set up the first time that a CPU was initialized.
This appears to be unnecessary as the paths can be combined by letting
the online logic also handle any CPUs online at the time of driver load.

Motivation for this change, beyond simplification, is that ARM64
virtual CPU HP uses the same code paths for hotplug and cold path in
acpi_processor.c so had no easy way to set the flag for hotplug only.
Removing this necessity will enable ARM64 vCPU HP to reuse the existing
code paths.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Miguel Luis <miguel.luis@oracle.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240529133446.28446-2-Jonathan.Cameron@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index 7a0dd35d62c94779a51389eec6f44cc6407b2e15..b2f0b6c194828f13be20ba68ea1fcdbd95fdabf3 100644 (file)
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -211,12 +211,11 @@ static int acpi_processor_hotadd_init(struct acpi_processor *pr)
        }
 
        /*
-        * CPU got hot-added, but cpu_data is not initialized yet.  Set a flag
-        * to delay cpu_idle/throttling initialization and do it when the CPU
-        * gets online for the first time.
+        * CPU got hot-added, but cpu_data is not initialized yet. Do
+        * cpu_idle/throttling initialization when the CPU gets online for
+        * the first time.
         */
        pr_info("CPU%d has been hot-added\n", pr->id);
-       pr->flags.need_hotplug_init = 1;
 
 out:
        cpus_write_unlock();

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 67db60eda3707dfda8d0f90585cc710b81e7ee26..cb52dd000b9587ed4c3e4595cf4776f3c709023c 100644 (file)
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -33,7 +33,6 @@ MODULE_AUTHOR("Paul Diefenbaugh");
 MODULE_DESCRIPTION("ACPI Processor Driver");
 MODULE_LICENSE("GPL");
 
-static int acpi_processor_start(struct device *dev);
 static int acpi_processor_stop(struct device *dev);
 
 static const struct acpi_device_id processor_device_ids[] = {
@@ -47,7 +46,6 @@ static struct device_driver acpi_processor_driver = {
        .name = "processor",
        .bus = &cpu_subsys,
        .acpi_match_table = processor_device_ids,
-       .probe = acpi_processor_start,
        .remove = acpi_processor_stop,
 };
 
@@ -115,12 +113,9 @@ static int acpi_soft_cpu_online(unsigned int cpu)
         * CPU got physically hotplugged and onlined for the first time:
         * Initialize missing things.
         */
-       if (pr->flags.need_hotplug_init) {
+       if (!pr->flags.previously_online) {
                int ret;
 
-               pr_info("Will online and init hotplugged CPU: %d\n",
-                       pr->id);
-               pr->flags.need_hotplug_init = 0;
                ret = __acpi_processor_start(device);
                WARN(ret, "Failed to start CPU: %d\n", pr->id);
        } else {
@@ -167,9 +162,6 @@ static int __acpi_processor_start(struct acpi_device *device)
        if (!pr)
                return -ENODEV;
 
-       if (pr->flags.need_hotplug_init)
-               return 0;
-
        result = acpi_cppc_processor_probe(pr);
        if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
                dev_dbg(&device->dev, "CPPC data invalid or not present\n");
@@ -185,32 +177,21 @@ static int __acpi_processor_start(struct acpi_device *device)
 
        status = acpi_install_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
                                             acpi_processor_notify, device);
-       if (ACPI_SUCCESS(status))
-               return 0;
+       if (!ACPI_SUCCESS(status)) {
+               result = -ENODEV;
+               goto err_thermal_exit;
+       }
+       pr->flags.previously_online = 1;
 
-       result = -ENODEV;
-       acpi_processor_thermal_exit(pr, device);
+       return 0;
 
+err_thermal_exit:
+       acpi_processor_thermal_exit(pr, device);
 err_power_exit:
        acpi_processor_power_exit(pr);
        return result;
 }
 
-static int acpi_processor_start(struct device *dev)
-{
-       struct acpi_device *device = ACPI_COMPANION(dev);
-       int ret;
-
-       if (!device)
-               return -ENODEV;
-
-       /* Protect against concurrent CPU hotplug operations */
-       cpu_hotplug_disable();
-       ret = __acpi_processor_start(device);
-       cpu_hotplug_enable();
-       return ret;
-}
-
 static int acpi_processor_stop(struct device *dev)
 {
        struct acpi_device *device = ACPI_COMPANION(dev);
@@ -279,9 +260,9 @@ static int __init acpi_processor_driver_init(void)
        if (result < 0)
                return result;
 
-       result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
-                                          "acpi/cpu-drv:online",
-                                          acpi_soft_cpu_online, NULL);
+       result = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+                                  "acpi/cpu-drv:online",
+                                  acpi_soft_cpu_online, NULL);
        if (result < 0)
                goto err;
        hp_online = result;

diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 3f34ebb275253e281fbecaad602a0531b1e6e55d..e6f6074eadbf3c2acc083c246401cf0346937c7f 100644 (file)
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -217,7 +217,7 @@ struct acpi_processor_flags {
        u8 has_lpi:1;
        u8 power_setup_done:1;
        u8 bm_rld_set:1;
-       u8 need_hotplug_init:1;
+       u8 previously_online:1;
 };
 
 struct acpi_processor {