x86/apic: Get rid of apic_phys

No need for an extra variable to find out whether the APIC has been mapped
or is accessible (X2APIC mode).

Provide an inline for this and check apic_mmio_base which is only set when
the local APIC has been mapped.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)

arch/x86/kernel/apic/apic.c

@@ -99,6 +99,11 @@ static bool virt_ext_dest_id __ro_after_init;
 /* For parallel bootup. */
 unsigned long apic_mmio_base __ro_after_init;
 
+static inline bool apic_accessible(void)
+{
+	return x2apic_mode || apic_mmio_base;
+}
+
 /*
  * Map cpu index to physical APIC ID
  */
@@ -199,8 +204,6 @@ unsigned int lapic_timer_period = 0;
 
 static void apic_pm_activate(void);
 
-static unsigned long apic_phys __ro_after_init;
-
 /*
  * Get the LAPIC version
  */
@@ -1127,8 +1130,7 @@ void clear_local_APIC(void)
 	int maxlvt;
 	u32 v;
 
-	/* APIC hasn't been mapped yet */
-	if (!x2apic_mode && !apic_phys)
+	if (!apic_accessible())
 		return;
 
 	maxlvt = lapic_get_maxlvt();
@@ -1218,8 +1220,7 @@ void apic_soft_disable(void)
  */
 void disable_local_APIC(void)
 {
-	/* APIC hasn't been mapped yet */
-	if (!x2apic_mode && !apic_phys)
+	if (!apic_accessible())
 		return;
 
 	apic_soft_disable();
@@ -2142,7 +2143,7 @@ void __init init_apic_mappings(void)
 static __init void apic_set_fixmap(void)
 {
 	set_fixmap_nocache(FIX_APIC_BASE, mp_lapic_addr);
-	apic_phys = apic_mmio_base = APIC_BASE;
+	apic_mmio_base = APIC_BASE;
 	apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
 		    apic_mmio_base, mp_lapic_addr);
 	apic_read_boot_cpu_id(false);
@@ -2896,11 +2897,11 @@ early_param("apic", apic_set_verbosity);
 
 static int __init lapic_insert_resource(void)
 {
-	if (!apic_phys)
+	if (!apic_mmio_base)
 		return -1;
 
 	/* Put local APIC into the resource map. */
-	lapic_resource.start = apic_phys;
+	lapic_resource.start = apic_mmio_base;
 	lapic_resource.end = lapic_resource.start + PAGE_SIZE - 1;
 	insert_resource(&iomem_resource, &lapic_resource);