linux-kernel - [PATCH 3.16 217/346] x86/apic: Do not init irq remapping if ioapic is disabled

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Message-ID: <lsq.1479082460.565407462@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Wanpeng Li" <wanpeng.li@...mail.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Joerg Roedel" <joro@...tes.org>,
        "Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 3.16 217/346] x86/apic: Do not init irq remapping if
 ioapic is disabled

3.16.39-rc1 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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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
@@ -1615,6 +1615,9 @@ void __init enable_IR_x2apic(void)
 	int ret, x2apic_enabled = 0;
 	int hardware_init_ret;
 
+	if (skip_ioapic_setup)
+		return;
+
 	/* Make sure irq_remap_ops are initialized */
 	setup_irq_remapping_ops();