Move logic into check_x2apic_preenabled() (to make sure
generic_apic_probe() doesn't see genapic already set) and disable dead
code on ix86.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -71,10 +71,12 @@ static int enable_local_apic __initdata 
  */
 int apic_verbosity;
 
+#ifndef __i386__
 static bool_t __initdata opt_x2apic = 1;
 boolean_param("x2apic", opt_x2apic);
 
 bool_t __read_mostly x2apic_enabled = 0;
+#endif
 bool_t __read_mostly directed_eoi_enabled = 0;
 
 /*
@@ -962,20 +964,8 @@ void __init x2apic_bsp_setup(void)
         return;
 
 #ifdef __i386__
-    clear_bit(X86_FEATURE_X2APIC, boot_cpu_data.x86_capability);
-    if ( x2apic_enabled )
-    {
-        uint64_t msr_content;
-        rdmsrl(MSR_IA32_APICBASE, msr_content);
-        msr_content &= ~(MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD);
-        wrmsrl(MSR_IA32_APICBASE, msr_content);
-        msr_content |= MSR_IA32_APICBASE_ENABLE;
-        wrmsrl(MSR_IA32_APICBASE, msr_content);
-        x2apic_enabled = 0;
-    }
-    printk("x2APIC disabled permanently on x86_32.\n");
-    return;
-#endif
+    BUG();
+#else
 
     if ( !opt_x2apic )
     {
@@ -1038,6 +1028,7 @@ restore_out:
     unmask_8259A();
 
 out:
+#endif /* !__i386__ */
     if ( ioapic_entries )
         free_ioapic_entries(ioapic_entries);
 }
--- a/xen/arch/x86/genapic/x2apic.c
+++ b/xen/arch/x86/genapic/x2apic.c
@@ -29,6 +29,8 @@
 #include <xen/smp.h>
 #include <asm/mach-default/mach_mpparse.h>
 
+#ifndef __i386__
+
 static bool_t __initdata x2apic_phys; /* By default we use logical cluster mode. */
 boolean_param("x2apic_phys", x2apic_phys);
 
@@ -126,6 +128,8 @@ const struct genapic *__init apic_x2apic
     return x2apic_phys ? &apic_x2apic_phys : &apic_x2apic_cluster;
 }
 
+#endif /* !__i386__ */
+
 void __init check_x2apic_preenabled(void)
 {
     u32 lo, hi;
@@ -138,7 +142,19 @@ void __init check_x2apic_preenabled(void
     if ( lo & MSR_IA32_APICBASE_EXTD )
     {
         printk("x2APIC mode is already enabled by BIOS.\n");
+#ifndef __i386__
         x2apic_enabled = 1;
         genapic = apic_x2apic_probe();
+#else
+        lo &= ~(MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD);
+        wrmsr(MSR_IA32_APICBASE, lo, hi);
+        lo |= MSR_IA32_APICBASE_ENABLE;
+        wrmsr(MSR_IA32_APICBASE, lo, hi);
+        printk("x2APIC disabled permanently on x86_32.\n");
+#endif
     }
+
+#ifdef __i386__
+    clear_bit(X86_FEATURE_X2APIC, boot_cpu_data.x86_capability);
+#endif
 }
--- a/xen/include/asm-x86/apic.h
+++ b/xen/include/asm-x86/apic.h
@@ -22,7 +22,11 @@
 #define IO_APIC_REDIR_DEST_PHYSICAL	0x00000
 
 extern int apic_verbosity;
+#ifdef __i386__
+#define x2apic_enabled 0
+#else
 extern bool_t x2apic_enabled;
+#endif
 extern bool_t directed_eoi_enabled;
 
 void check_x2apic_preenabled(void);