x86/apic: Make disable x2apic work really

If x2apic_preenabled is not enabled, then disable_x2apic() is not
called from various places which results in x2apic_disabled not being
set. So other code pathes can happily reenable the x2apic.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20150115211702.621431109@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 5 insertions, 9 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 08144f5c1236..fdc6c60faa6b 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1479,8 +1479,6 @@ static bool nox2apic __initdata;
 
 #ifdef CONFIG_X86_X2APIC
 int x2apic_mode;
-/* x2apic enabled before OS handover */
-static int x2apic_preenabled;
 static int x2apic_disabled;
 static int __init setup_nox2apic(char *str)
 {
@@ -1535,18 +1533,19 @@ static __init void disable_x2apic(void)
                         setup_clear_cpu_cap(X86_FEATURE_X2APIC);
                 }
 
-                x2apic_disabled = 1;
                 x2apic_mode = 0;
 
                 register_lapic_address(mp_lapic_addr);
         }
+
+        x2apic_disabled = 1;
 }
 
 void check_x2apic(void)
 {
         if (x2apic_enabled()) {
                 pr_info("x2apic enabled by BIOS, switching to x2apic ops\n");
-                x2apic_preenabled = x2apic_mode = 1;
+                x2apic_mode = 1;
         }
 }
 
@@ -1569,8 +1568,6 @@ void enable_x2apic(void)
                 wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
         }
 }
-#else
-#define x2apic_preenabled       (0)
 #endif /* CONFIG_X86_X2APIC */
 
 static int __init try_to_enable_IR(void)
@@ -1599,8 +1596,7 @@ static __init void try_to_enable_x2apic(int ir_stat)
                     (IS_ENABLED(CONFIG_HYPERVISOR_GUEST) &&
                      !hypervisor_x2apic_available())) {
                         pr_info("IRQ remapping doesn't support X2APIC mode, disable x2apic.\n");
-                        if (x2apic_preenabled)
-                                disable_x2apic();
+                        disable_x2apic();
                         return;
                 }
 
@@ -1643,7 +1639,7 @@ void __init enable_IR_x2apic(void)
         legacy_pic->mask_all();
         mask_ioapic_entries();
 
-        if (x2apic_preenabled && nox2apic)
+        if (nox2apic)
                 disable_x2apic();
         /* If irq_remapping_prepare() succeded, try to enable it */
         if (ir_stat >= 0)