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authorJames Morse <james.morse@arm.com>2021-07-02 17:11:07 +0100
committerRussell King (Oracle) <rmk+kernel@armlinux.org.uk>2023-11-27 10:58:02 +0000
commit446dc5105cb03b71341c7979c6252221f34e54d8 (patch)
tree3ed718a6237de050bcc3023d6360233c8e3500a4
parentb7858c3dab276047ca805ab8411f490a093f5eab (diff)
ACPI: add support to register CPUs based on the _STA enabled bit
acpi_processor_get_info() registers all present CPUs. Registering a CPU is what creates the sysfs entries and triggers the udev notifications. arm64 virtual machines that support 'virtual cpu hotplug' use the enabled bit to indicate whether the CPU can be brought online, as the existing ACPI tables require all hardware to be described and present. If firmware describes a CPU as present, but disabled, skip the registration. Such CPUs are present, but can't be brought online for whatever reason. (e.g. firmware/hypervisor policy). Once firmware sets the enabled bit, the CPU can be registered and brought online by user-space. Online CPUs, or CPUs that are missing an _STA method must always be registered. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Gavin Shan <gshan@redhat.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
-rw-r--r--drivers/acpi/acpi_processor.c31
1 files changed, 30 insertions, 1 deletions
diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index b7a94c1348b0..5dabb426481f 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -228,6 +228,32 @@ out:
return ret;
}
+static int acpi_processor_make_enabled(struct acpi_processor *pr)
+{
+ unsigned long long sta;
+ acpi_status status;
+ bool present, enabled;
+
+ if (!acpi_has_method(pr->handle, "_STA"))
+ return arch_register_cpu(pr->id);
+
+ status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta);
+ if (ACPI_FAILURE(status))
+ return -ENODEV;
+
+ present = sta & ACPI_STA_DEVICE_PRESENT;
+ enabled = sta & ACPI_STA_DEVICE_ENABLED;
+
+ if (cpu_online(pr->id) && (!present || !enabled)) {
+ pr_err_once(FW_BUG "CPU %u is online, but described as not present or disabled!\n", pr->id);
+ add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+ } else if (!present || !enabled) {
+ return -ENODEV;
+ }
+
+ return arch_register_cpu(pr->id);
+}
+
static int acpi_processor_get_info(struct acpi_device *device)
{
union acpi_object object = { 0 };
@@ -318,7 +344,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
*/
if (!invalid_logical_cpuid(pr->id) && cpu_present(pr->id) &&
!get_cpu_device(pr->id)) {
- int ret = arch_register_cpu(pr->id);
+ int ret = acpi_processor_make_enabled(pr);
if (ret)
return ret;
@@ -526,6 +552,9 @@ static void acpi_processor_post_eject(struct acpi_device *device)
acpi_processor_make_not_present(device);
return;
}
+
+ if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_ENABLED))
+ arch_unregister_cpu(pr->id);
}
#ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC