X86/Hyper-V: Enlighten APIC access

Hyper-V supports MSR based APIC access; implement
the enlightenment.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: olaf@aepfle.de
Cc: sthemmin@microsoft.com
Cc: gregkh@linuxfoundation.org
Cc: jasowang@redhat.com
Cc: Michael.H.Kelley@microsoft.com
Cc: hpa@zytor.com
Cc: apw@canonical.com
Cc: devel@linuxdriverproject.org
Cc: vkuznets@redhat.com
Link: https://lkml.kernel.org/r/20180516215334.6547-1-kys@linuxonhyperv.com

arch/x86/hyperv/hv_init.c

@@ -242,8 +242,9 @@ static int hv_cpu_die(unsigned int cpu)
  *
  * 1. Setup the hypercall page.
  * 2. Register Hyper-V specific clocksource.
+ * 3. Setup Hyper-V specific APIC entry points.
  */
-void hyperv_init(void)
+void __init hyperv_init(void)
 {
 	u64 guest_id, required_msrs;
 	union hv_x64_msr_hypercall_contents hypercall_msr;
@@ -298,6 +299,8 @@ void hyperv_init(void)
 
 	hyper_alloc_mmu();
 
+	hv_apic_init();
+
 	/*
 	 * Register Hyper-V specific clocksource.
 	 */