Patch "x86/idt: Load idt early in start_secondary" has been added to the 4.14-stable tree

Patch "x86/idt: Load idt early in start_secondary" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    x86/idt: Load idt early in start_secondary

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-idt-load-idt-early-in-start_secondary.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 55d2d0ad2fb4325f615d1950486fbc5e6fba1769 Mon Sep 17 00:00:00 2001
From: Chunyu Hu <chuhu@redhat.com>
Date: Mon, 27 Nov 2017 22:21:39 +0800
Subject: x86/idt: Load idt early in start_secondary

From: Chunyu Hu <chuhu@redhat.com>

commit 55d2d0ad2fb4325f615d1950486fbc5e6fba1769 upstream.

On a secondary, idt is first loaded in cpu_init() with load_current_idt(),
i.e. no exceptions can be handled before that point.

The conversion of WARN() to use UD requires the IDT being loaded earlier as
any warning between start_secondary() and load_curren_idt() in cpu_init()
will result in an unhandled @UD exception and therefore fail the bringup of
the CPU.

Install the IDT handlers right in start_secondary() before calling cpu_init().

[ tglx: Massaged changelog ]

Fixes: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0")
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Cc: bp@alien8.de
Cc: rostedt@goodmis.org
Cc: luto@kernel.org
Link: https://lkml.kernel.org/r/1511792499-4073-1-git-send-email-chuhu@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/smpboot.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -239,7 +239,7 @@ static void notrace start_secondary(void
 	load_cr3(swapper_pg_dir);
 	__flush_tlb_all();
 #endif
-
+	load_current_idt();
 	cpu_init();
 	x86_cpuinit.early_percpu_clock_init();
 	preempt_disable();


Patches currently in stable-queue which might be from chuhu@redhat.com are

queue-4.14/x86-idt-load-idt-early-in-start_secondary.patch