KVM: PIT: stop vpit before freeing irq_routing

Fix:
general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
......
Call Trace:
 [<ffffffffa0159bd1>] ? kvm_set_irq+0xdd/0x24b [kvm]
 [<ffffffff8106ea8b>] ? trace_hardirqs_off_caller+0x1f/0x10e
 [<ffffffff813ad17f>] ? sub_preempt_count+0xe/0xb6
 [<ffffffff8106d273>] ? put_lock_stats+0xe/0x27
...
RIP  [<ffffffffa0159c72>] kvm_set_irq+0x17e/0x24b [kvm]

This bug is triggered when guest is shutdown, is because we freed
irq_routing before pit thread stopped

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2 files changed, 4 insertions, 1 deletions

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 70db4d435393..0fd6378981f4 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -752,6 +752,9 @@ void kvm_free_pit(struct kvm *kvm)
         struct hrtimer *timer;
 
         if (kvm->arch.vpit) {
+                kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev);
+                kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,
+                                              &kvm->arch.vpit->speaker_dev);
                 kvm_unregister_irq_mask_notifier(kvm, 0,
                                                &kvm->arch.vpit->mask_notifier);
                 kvm_unregister_irq_ack_notifier(kvm,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d51eed239b47..d721e2d81a53 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5523,12 +5523,12 @@ static void kvm_free_vcpus(struct kvm *kvm)
 void kvm_arch_sync_events(struct kvm *kvm)
 {
         kvm_free_all_assigned_devices(kvm);
+        kvm_free_pit(kvm);
 }
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
         kvm_iommu_unmap_guest(kvm);
-        kvm_free_pit(kvm);
         kfree(kvm->arch.vpic);
         kfree(kvm->arch.vioapic);
         kvm_free_vcpus(kvm);