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%3Ba=su...

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