linux-kernel - [PATCH 4.7 43/59] x86/apic: Do not init irq remapping if ioapic is disabled

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Message-Id: <20160912152130.587290561@linuxfoundation.org>
Date:   Mon, 12 Sep 2016 17:30:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wanpeng Li <wanpeng.li@...mail.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 4.7 43/59] x86/apic: Do not init irq remapping if ioapic is disabled

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wanpeng Li <wanpeng.li@...mail.com>

commit 2e63ad4bd5dd583871e6602f9d398b9322d358d9 upstream.

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@...mail.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Joerg Roedel <joro@...tes.org>
Link: http://lkml.kernel.org/r/1471954039-3942-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1597,6 +1597,9 @@ 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;