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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        Paul McKenney <paulmck@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        "Joel Fernandes \(Google\)" <joel@joelfernandes.org>,
        "Steven Rostedt \(VMware\)" <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Brian Gerst <brgerst@gmail.com>,
        Juergen Gross <jgross@suse.com>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org,
        Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [RESEND][patch V3 19/23] x86/kvm/vmx: Add hardirq tracing to guest enter/exit
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Date:   Wed, 25 Mar 2020 00:21:38 +0100
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Peter Zijlstra <peterz@infradead.org> writes:

> On Fri, Mar 20, 2020 at 07:00:15PM +0100, Thomas Gleixner wrote:
>> The VMX code does not track hard interrupt state correctly. The state in
>> tracing and lockdep is 'OFF' all the way during guest mode. From the host
>> point of view this is wrong because the VMENTER reenables interrupts like a
>> return to user space and VMENTER disables them again like an entry from
>> user space.
>> 
>> Make it do exactly the same thing as enter/exit user mode does.
>> 
>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>
> This patch (and the SVM counterpart) result in:
>
> ERROR: "lockdep_hardirqs_on" [arch/x86/kvm/kvm-amd.ko] undefined!
> ERROR: "lockdep_hardirqs_off" [arch/x86/kvm/kvm-amd.ko] undefined!
> ERROR: "__trace_hardirqs_off" [arch/x86/kvm/kvm-amd.ko] undefined!
> ERROR: "lockdep_hardirqs_on_prepare" [arch/x86/kvm/kvm-amd.ko] undefined!
> ERROR: "__trace_hardirqs_on" [arch/x86/kvm/kvm-amd.ko] undefined!
> ERROR: "lockdep_hardirqs_on" [arch/x86/kvm/kvm-intel.ko] undefined!
> ERROR: "lockdep_hardirqs_off" [arch/x86/kvm/kvm-intel.ko] undefined!
> ERROR: "__trace_hardirqs_off" [arch/x86/kvm/kvm-intel.ko] undefined!
> ERROR: "lockdep_hardirqs_on_prepare" [arch/x86/kvm/kvm-intel.ko] undefined!
> ERROR: "__trace_hardirqs_on" [arch/x86/kvm/kvm-intel.ko] undefined!
>
> on allmodconfig.
>
> I suppose them things need an EXPORT_SYMBOL_GPL() on them.

Indeed.