arm/kvm/arch_timer: Convert to hotplug state machine

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

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-arm-kernel@lists.infradead.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153336.634155707@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 12 insertions, 24 deletions

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index ff37caccafce..88986c979b0f 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -43,6 +43,7 @@ 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,
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index e2d5b6f988fb..4fde8c7dfcfe 100644
--- 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_vcpu *vcpu, u64 regid)
         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());