This is a note to let you know that I've just added the patch titled KVM: x86/xen: Initialize Xen timer only once to the 5.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-x86-xen-initialize-xen-timer-only-once.patch and it can be found in the queue-5.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From af735db31285fa699384c649be72a9f32ecbb665 Mon Sep 17 00:00:00 2001 From: Coleman Dietsch <dietschc@xxxxxxx> Date: Mon, 8 Aug 2022 14:06:06 -0500 Subject: KVM: x86/xen: Initialize Xen timer only once From: Coleman Dietsch <dietschc@xxxxxxx> commit af735db31285fa699384c649be72a9f32ecbb665 upstream. Add a check for existing xen timers before initializing a new one. Currently kvm_xen_init_timer() is called on every KVM_XEN_VCPU_ATTR_TYPE_TIMER, which is causing the following ODEBUG crash when vcpu->arch.xen.timer is already set. ODEBUG: init active (active state 0) object type: hrtimer hint: xen_timer_callbac0 RIP: 0010:debug_print_object+0x16e/0x250 lib/debugobjects.c:502 Call Trace: __debug_object_init debug_hrtimer_init debug_init hrtimer_init kvm_xen_init_timer kvm_xen_vcpu_set_attr kvm_arch_vcpu_ioctl kvm_vcpu_ioctl vfs_ioctl Fixes: 536395260582 ("KVM: x86/xen: handle PV timers oneshot mode") Cc: stable@xxxxxxxxxxxxxxx Link: https://syzkaller.appspot.com/bug?id=8234a9dfd3aafbf092cc5a7cd9842e3ebc45fc42 Reported-by: syzbot+e54f930ed78eb0f85281@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Coleman Dietsch <dietschc@xxxxxxx> Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx> Message-Id: <20220808190607.323899-2-dietschc@xxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kvm/xen.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -713,7 +713,9 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcp break; } vcpu->arch.xen.timer_virq = data->u.timer.port; - kvm_xen_init_timer(vcpu); + + if (!vcpu->arch.xen.timer.function) + kvm_xen_init_timer(vcpu); /* Restart the timer if it's set */ if (data->u.timer.expires_ns) Patches currently in stable-queue which might be from dietschc@xxxxxxx are queue-5.19/kvm-x86-xen-initialize-xen-timer-only-once.patch queue-5.19/kvm-x86-xen-stop-xen-timer-before-changing-irq.patch