forked from Minki/linux
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>
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@ -196,6 +196,8 @@ extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
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#define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */
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#define CPU_LOCK_ACQUIRE 0x0008 /* Acquire all hotcpu locks */
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#define CPU_LOCK_RELEASE 0x0009 /* Release all hotcpu locks */
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#define CPU_DYING 0x000A /* CPU (unsigned)v not running any task,
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* not handling interrupts, soon dead */
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/* Used for CPU hotplug events occuring while tasks are frozen due to a suspend
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* operation in progress
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@ -208,6 +210,7 @@ extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
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#define CPU_DOWN_PREPARE_FROZEN (CPU_DOWN_PREPARE | CPU_TASKS_FROZEN)
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#define CPU_DOWN_FAILED_FROZEN (CPU_DOWN_FAILED | CPU_TASKS_FROZEN)
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#define CPU_DEAD_FROZEN (CPU_DEAD | CPU_TASKS_FROZEN)
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#define CPU_DYING_FROZEN (CPU_DYING | CPU_TASKS_FROZEN)
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#endif /* __KERNEL__ */
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#endif /* _LINUX_NOTIFIER_H */
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16
kernel/cpu.c
16
kernel/cpu.c
@ -103,11 +103,19 @@ static inline void check_for_tasks(int cpu)
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write_unlock_irq(&tasklist_lock);
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}
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struct take_cpu_down_param {
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unsigned long mod;
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void *hcpu;
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};
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/* Take this CPU down. */
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static int take_cpu_down(void *unused)
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static int take_cpu_down(void *_param)
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{
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struct take_cpu_down_param *param = _param;
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int err;
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raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
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param->hcpu);
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/* Ensure this CPU doesn't handle any more interrupts. */
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err = __cpu_disable();
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if (err < 0)
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@ -127,6 +135,10 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen)
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cpumask_t old_allowed, tmp;
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void *hcpu = (void *)(long)cpu;
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unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
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struct take_cpu_down_param tcd_param = {
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.mod = mod,
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.hcpu = hcpu,
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};
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if (num_online_cpus() == 1)
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return -EBUSY;
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@ -153,7 +165,7 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen)
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set_cpus_allowed(current, tmp);
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mutex_lock(&cpu_bitmask_lock);
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p = __stop_machine_run(take_cpu_down, NULL, cpu);
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p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
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mutex_unlock(&cpu_bitmask_lock);
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if (IS_ERR(p) || cpu_online(cpu)) {
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