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From: Wanpeng Li <kernellwp@gmail.com>
Date: Fri, 15 Dec 2017 17:58:41 +0800
Message-ID: <CANRm+Cy_=ZO9eJGk2HzgN0by_c_uoEPFNa850+GvsYvJAw0DwA@mail.gmail.com>
Subject: Re: BUG: unable to handle kernel paging request in __switch_to
To: David Hildenbrand <david@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        syzbot 
        <bot+1f445b1009b8eeededa30fe62ccf685f2ec9d155@syzkaller.appspotmail.com>,
        Borislav Petkov <bp@suse.de>, Dmitry Safonov <dsafonov@virtuozzo.com>,
        Peter Anvin <hpa@zytor.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Kyle Huey <me@kylehuey.com>, Ingo Molnar <mingo@redhat.com>,
        syzkaller-bugs@googlegroups.com,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        KVM list <kvm@vger.kernel.org>, "Lan, Tianyu" <tianyu.lan@intel.com>,
        James Mattson <jmattson@google.com>
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2017-12-15 17:51 GMT+08:00 David Hildenbrand <david@redhat.com>:
>
>> int main()
>> {
>>   int fd = open("/dev/kvm", 0x80102ul);
>>   int vm = ioctl(fd, KVM_CREATE_VM, 0);
>>   int  cpu = ioctl(vm, KVM_CREATE_VCPU, 4);
>
> Not even a memory region :) So maybe the first memory access directly
> triggers a fault?
>
>>   ioctl(cpu, KVM_RUN, 0);
>>   return 0;
>> }
>>
>> And, yes, this in fact triggers instant reboot of kernel (running in qemu).
>> Am I missing something here?
>>
>> +kvm maintainers, you can see full thread here:
>> https://groups.google.com/forum/#!topic/syzkaller-bugs/_oveOKGm3jw

I didn't see any issue after running the test.

Regards,
Wanpeng Li