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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     x86@kernel.org, "Paul E. McKenney" <paulmck@kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Juergen Gross <jgross@suse.com>,
        Brian Gerst <brgerst@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Will Deacon <will@kernel.org>
Subject: Re: [patch V4 part 5 05/31] x86/entry: Switch XEN/PV hypercall entry to IDTENTRY
In-Reply-To: <5418e98e-b293-bff3-2c74-c7f932c09c55@oracle.com>
References: <20200505135341.730586321@linutronix.de> <20200505135828.592598658@linutronix.de> <5418e98e-b293-bff3-2c74-c7f932c09c55@oracle.com>
Date:   Thu, 07 May 2020 10:30:05 +0200
Message-ID: <874kssjgfm.fsf@nanos.tec.linutronix.de>
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Boris Ostrovsky <boris.ostrovsky@oracle.com> writes:
>> -	if (register_callback(CALLBACKTYPE_event, xen_hypervisor_callback) ||
>> +	if (register_callback(CALLBACKTYPE_event,
>> +			      asm_exc_xen_hypervisor_callback) ||
>
>
> This ...
>
>
>>  	    register_callback(CALLBACKTYPE_failsafe, xen_failsafe_callback))
>>  		BUG();
...
>> @@ -347,7 +348,7 @@ cpu_initialize_context(unsigned int cpu,
>>  	ctxt->gs_base_kernel = per_cpu_offset(cpu);
>>  #endif
>>  	ctxt->event_callback_eip    =
>> -		(unsigned long)xen_hypervisor_callback;
>> +		(unsigned long)asm_exc_xen_hypervisor_callback;
>
>
> ... and this should be xen_asm_exc_xen_hypervisor_callback (we need to
> pop %rcx and %r11).
>
>
> And then Xen PV guest boots.

Ooops. Thanks for tracking this down!