From: Radim Krčmář Date: Mon, 10 Jul 2017 18:53:28 +0000 (+0200) Subject: KVM: x86: take slots_lock in kvm_free_pit X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=fb5307298e49ec1668c3a9ec888c1b9da4347395;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git KVM: x86: take slots_lock in kvm_free_pit kvm_vm_release() did not have slots_lock when calling kvm_io_bus_unregister_dev() and this went unnoticed until 4a12f9517728 ("KVM: mark kvm->busses as rcu protected") added dynamic checks. Luckily, there should be no race at that point: ============================= WARNING: suspicious RCU usage 4.12.0.kvm+ #0 Not tainted ----------------------------- ./include/linux/kvm_host.h:479 suspicious rcu_dereference_check() usage! lockdep_rcu_suspicious+0xc5/0x100 kvm_io_bus_unregister_dev+0x173/0x190 [kvm] kvm_free_pit+0x28/0x80 [kvm] kvm_arch_sync_events+0x2d/0x30 [kvm] kvm_put_kvm+0xa7/0x2a0 [kvm] kvm_vm_release+0x21/0x30 [kvm] Reviewed-by: David Hildenbrand Signed-off-by: Radim Krčmář --- diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index a78b445ce411..af192895b1fc 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -724,8 +724,10 @@ void kvm_free_pit(struct kvm *kvm) struct kvm_pit *pit = kvm->arch.vpit; if (pit) { + mutex_lock(&kvm->slots_lock); kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev); kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->speaker_dev); + mutex_unlock(&kvm->slots_lock); kvm_pit_set_reinject(pit, false); hrtimer_cancel(&pit->pit_state.timer); kthread_destroy_worker(pit->worker);