[tip:x86/urgent] x86/apic: Do not init irq remapping if ioapic is disabled

[tip-bot for Wanpeng Li]

Commit-ID:  2e63ad4bd5dd583871e6602f9d398b9322d358d9
Gitweb:     http://git.kernel.org/tip/2e63ad4bd5dd583871e6602f9d398b9322d358d9
Author:     Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
AuthorDate: Tue, 23 Aug 2016 20:07:19 +0800
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 24 Aug 2016 09:45:40 +0200

x86/apic: Do not init irq remapping if ioapic is disabled

native_smp_prepare_cpus
  -> default_setup_apic_routing
    -> enable_IR_x2apic
      -> irq_remapping_prepare
        -> intel_prepare_irq_remapping
          -> intel_setup_irq_remapping		  

So IR table is setup even if "noapic" boot parameter is added. As a result we
crash later when the interrupt affinity is set due to a half initialized
remapping infrastructure.

Prevent remap initialization when IOAPIC is disabled.

Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1471954039-3942-1-git-send-email-wanpeng.li@xxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

---
 arch/x86/kernel/apic/apic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index cea4fc1..50c95af 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1623,6 +1623,9 @@ void __init enable_IR_x2apic(void)
 	unsigned long flags;
 	int ret, ir_stat;
 
+	if (skip_ioapic_setup)
+		return;
+
 	ir_stat = irq_remapping_prepare();
 	if (ir_stat < 0 && !x2apic_supported())
 		return;