[patch 48/66] arm: kvm: arch_timer: Convert to hotplug state machine

[Anna-Maria Gleixner]

From: Richard Cochran <rcoch...@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Richard Cochran <rcoch...@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Cc: Christoffer Dall <christoffer.d...@linaro.org>
Cc: Marc Zyngier <marc.zyng...@arm.com>
Cc: Gleb Natapov <g...@kernel.org>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: kvm...@lists.cs.columbia.edu
Cc: k...@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-ma...@linutronix.de>
---
 include/linux/cpuhotplug.h |    1 +
 virt/kvm/arm/arch_timer.c  |   35 +++++++++++------------------------
 2 files changed, 12 insertions(+), 24 deletions(-)

--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -48,6 +48,7 @@ enum cpuhp_state {
        CPUHP_AP_MIPS_GIC_TIMER_STARTING,
        CPUHP_AP_KVM_STARTING,
        CPUHP_AP_KVM_ARM_VGIC_STARTING,
+       CPUHP_AP_KVM_ARM_TIMER_STARTING,
        CPUHP_AP_LEDTRIG_STARTING,
        CPUHP_AP_NOTIFY_STARTING,
        CPUHP_AP_ONLINE,
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -405,26 +405,17 @@ u64 kvm_arm_timer_get_reg(struct kvm_vcp
        return (u64)-1;
 }
 
-static int kvm_timer_cpu_notify(struct notifier_block *self,
-                               unsigned long action, void *cpu)
+static int kvm_timer_starting_cpu(unsigned int cpu)
 {
-       switch (action) {
-       case CPU_STARTING:
-       case CPU_STARTING_FROZEN:
-               kvm_timer_init_interrupt(NULL);
-               break;
-       case CPU_DYING:
-       case CPU_DYING_FROZEN:
-               disable_percpu_irq(host_vtimer_irq);
-               break;
-       }
-
-       return NOTIFY_OK;
+       kvm_timer_init_interrupt(NULL);
+       return 0;
 }
 
-static struct notifier_block kvm_timer_cpu_nb = {
-       .notifier_call = kvm_timer_cpu_notify,
-};
+static int kvm_timer_dying_cpu(unsigned int cpu)
+{
+       disable_percpu_irq(host_vtimer_irq);
+       return 0;
+}
 
 int kvm_timer_hyp_init(void)
 {
@@ -449,12 +440,6 @@ int kvm_timer_hyp_init(void)
                goto out;
        }
 
-       err = __register_cpu_notifier(&kvm_timer_cpu_nb);
-       if (err) {
-               kvm_err("Cannot register timer CPU notifier\n");
-               goto out_free;
-       }
-
        wqueue = create_singlethread_workqueue("kvm_arch_timer");
        if (!wqueue) {
                err = -ENOMEM;
@@ -462,8 +447,10 @@ int kvm_timer_hyp_init(void)
        }
 
        kvm_info("virtual timer IRQ%d\n", host_vtimer_irq);
-       on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
 
+       cpuhp_setup_state(CPUHP_AP_KVM_ARM_TIMER_STARTING,
+                         "AP_KVM_ARM_TIMER_STARTING", kvm_timer_starting_cpu,
+                         kvm_timer_dying_cpu);
        goto out;
 out_free:
        free_percpu_irq(host_vtimer_irq, kvm_get_running_vcpus());