x86/init: Add intr_mode_init to x86_init_ops

X86 and XEN initialize interrupt delivery mode in different way.

To avoid conditionals, add a new x86_init_ops function which defaults to
the standard function and can be overridden by the early XEN platform code.

[ tglx: Folded the XEN part which was a separate patch to preserve
  	bisectability ]
Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: yinghai@kernel.org
Cc: bhe@redhat.com
Link: https://lkml.kernel.org/r/1505293975-26005-10-git-send-email-douly.fnst@cn.fujitsu.com

arch/x86/include/asm/x86_init.h

@@ -50,11 +50,13 @@ struct x86_init_resources {
  *				are set up.
  * @intr_init:			interrupt init code
  * @trap_init:			platform specific trap setup
+ * @intr_mode_init:		interrupt delivery mode setup
  */
 struct x86_init_irqs {
 	void (*pre_vector_init)(void);
 	void (*intr_init)(void);
 	void (*trap_init)(void);
+	void (*intr_mode_init)(void);
 };
 
 /**

arch/x86/kernel/apic/apic.c

@@ -2423,7 +2423,7 @@ void __init apic_bsp_setup(bool upmode)
 #ifdef CONFIG_UP_LATE_INIT
 void __init up_late_init(void)
 {
-	apic_intr_mode_init();
+	x86_init.irqs.intr_mode_init();
 
 	if (apic_intr_mode == APIC_PIC)
 		return;

arch/x86/kernel/smpboot.c

@@ -1296,7 +1296,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 
 	set_cpu_sibling_map(0);
 
-	apic_intr_mode_init();
+	x86_init.irqs.intr_mode_init();
 
 	smp_sanity_check();
 

arch/x86/kernel/x86_init.c

@@ -55,6 +55,7 @@ struct x86_init_ops x86_init __initdata = {
 		.pre_vector_init	= init_ISA_irqs,
 		.intr_init		= native_init_IRQ,
 		.trap_init		= x86_init_noop,
+		.intr_mode_init		= apic_intr_mode_init
 	},
 
 	.oem = {

arch/x86/xen/enlighten_pv.c

@@ -1230,6 +1230,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 	x86_platform.get_nmi_reason = xen_get_nmi_reason;
 
 	x86_init.resources.memory_setup = xen_memory_setup;
+	x86_init.irqs.intr_mode_init	= x86_init_noop;
 	x86_init.oem.arch_setup = xen_arch_setup;
 	x86_init.oem.banner = xen_banner;