linux-kernel - Re: [PATCH v3 1/2] KVM: x86/xen: Initialize Xen timer only once

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Message-ID: <397d670c-69c0-8686-e492-06063b7f6621@redhat.com>
Date:   Tue, 9 Aug 2022 14:59:34 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Coleman Dietsch <dietschc@....edu>
Cc:     kvm@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        skhan@...uxfoundation.org, Pavel Skripkin <paskripkin@...il.com>,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        stable@...r.kernel.org,
        syzbot+e54f930ed78eb0f85281@...kaller.appspotmail.com
Subject: Re: [PATCH v3 1/2] KVM: x86/xen: Initialize Xen timer only once

On 8/9/22 02:32, Sean Christopherson wrote:
> On Mon, Aug 08, 2022, Coleman Dietsch wrote:
>> 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@...r.kernel.org
>> Link: https://syzkaller.appspot.com/bug?id=8234a9dfd3aafbf092cc5a7cd9842e3ebc45fc42
>> Reported-by: syzbot+e54f930ed78eb0f85281@...kaller.appspotmail.com
>> Signed-off-by: Coleman Dietsch <dietschc@....edu>
>> ---
> 
> Reviewed-by: Sean Christopherson <seanjc@...gle.com>
> 

Queued both (pending resolution of David's question), thanks.

Paolo