linux-kernel - Re: [patch V4 part 5 05/31] x86/entry: Switch XEN/PV hypercall entry to IDTENTRY

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Date:   Thu, 07 May 2020 10:30:05 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>
Subject: Re: [patch V4 part 5 05/31] x86/entry: Switch XEN/PV hypercall entry to IDTENTRY

Boris Ostrovsky <boris.ostrovsky@...cle.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!