On 9/14/23 02:38, James Morse wrote:
When called acpi_processor_post_eject() unconditionally make a CPU
not-present and unregisters it.
To add support for AML events where the CPU has become disabled, but
remains present, the _STA method should be checked before calling
acpi_processor_remove().
Rename acpi_processor_post_eject() acpi_processor_remove_possible(), and
check the _STA before calling.
Adding the function prototype for arch_unregister_cpu() allows the
preprocessor guards to be removed.
After this change CPUs will remain registered and visible to
user-space as offline if buggy firmware triggers an eject-request,
but doesn't clear the corresponding _STA bits after _EJ0 has been
called.
Signed-off-by: James Morse <james.morse@xxxxxxx>
---
drivers/acpi/acpi_processor.c | 31 +++++++++++++++++++++++++------
include/linux/cpu.h | 1 +
2 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index 00dcc23d49a8..2cafea1edc24 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -457,13 +457,12 @@ static int acpi_processor_add(struct acpi_device *device,
return result;
}
-#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
/* Removal */
-static void acpi_processor_post_eject(struct acpi_device *device)
+static void acpi_processor_make_not_present(struct acpi_device *device)
{
struct acpi_processor *pr;
- if (!device || !acpi_driver_data(device))
+ if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
return;
In order to use IS_ENABLED(),
pr = acpi_driver_data(device);
@@ -501,7 +500,29 @@ static void acpi_processor_post_eject(struct acpi_device *device)
free_cpumask_var(pr->throttling.shared_cpu_map);
kfree(pr);
}
-#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
+
+static void acpi_processor_post_eject(struct acpi_device *device)
+{
+ struct acpi_processor *pr;
+ unsigned long long sta;
+ acpi_status status;
+
+ if (!device)
+ return;
+
+ pr = acpi_driver_data(device);
+ if (!pr || pr->id >= nr_cpu_ids || invalid_phys_cpuid(pr->phys_id))
+ return;
+
Do we really need to validate the logic and hardware CPU IDs here? I think
the ACPI processor device can't be added successfully if one of them is
invalid.
+ status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta);
+ if (ACPI_FAILURE(status))
+ return;
+
+ if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_PRESENT)) {
+ acpi_processor_make_not_present(device);
+ return;
+ }
+}
#ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC
bool __init processor_physically_present(acpi_handle handle)
@@ -626,9 +647,7 @@ static const struct acpi_device_id processor_device_ids[] = {
static struct acpi_scan_handler processor_handler = {
.ids = processor_device_ids,
.attach = acpi_processor_add,
-#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
.post_eject = acpi_processor_post_eject,
-#endif
.hotplug = {
.enabled = true,
},
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index a71691d7c2ca..e117c06e0c6b 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -81,6 +81,7 @@ struct device *cpu_device_create(struct device *parent, void *drvdata,
const struct attribute_group **groups,
const char *fmt, ...);
extern int arch_register_cpu(int cpu);
+extern void arch_unregister_cpu(int cpu);
arch_unregister_cpu() is protected by CONFIG_HOTPLUG_CPU in the individual architectures,
for example arch/ia64/kernel/topology.c
#ifdef CONFIG_HOTPLUG_CPU
extern void unregister_cpu(struct cpu *cpu);
extern ssize_t arch_cpu_probe(const char *, size_t);
Thanks,
Gavin
