HOTPLUG: Add CPU_DYING notifier
KVM wants a notification when a cpu is about to die, so it can disable
hardware extensions, but at a time when user processes cannot be scheduled
on the cpu, so it doesn't try to use virtualization extensions after they
have been disabled.
This adds a CPU_DYING notification. The notification is called in atomic
context on the doomed cpu.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 9431101..576f2bb 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -196,6 +196,8 @@
#define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */
#define CPU_LOCK_ACQUIRE 0x0008 /* Acquire all hotcpu locks */
#define CPU_LOCK_RELEASE 0x0009 /* Release all hotcpu locks */
+#define CPU_DYING 0x000A /* CPU (unsigned)v not running any task,
+ * not handling interrupts, soon dead */
/* Used for CPU hotplug events occuring while tasks are frozen due to a suspend
* operation in progress
@@ -208,6 +210,7 @@
#define CPU_DOWN_PREPARE_FROZEN (CPU_DOWN_PREPARE | CPU_TASKS_FROZEN)
#define CPU_DOWN_FAILED_FROZEN (CPU_DOWN_FAILED | CPU_TASKS_FROZEN)
#define CPU_DEAD_FROZEN (CPU_DEAD | CPU_TASKS_FROZEN)
+#define CPU_DYING_FROZEN (CPU_DYING | CPU_TASKS_FROZEN)
#endif /* __KERNEL__ */
#endif /* _LINUX_NOTIFIER_H */