Patch "x86/boot/smp: Don't try to poke disabled/non-existent APIC" has been added to the 4.8-stable tree

[<gregkh@linuxfoundation.org>]

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

    x86/boot/smp: Don't try to poke disabled/non-existent APIC

to the 4.8-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-boot-smp-don-t-try-to-poke-disabled-non-existent-apic.patch
and it can be found in the queue-4.8 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 ff8560512b8d4b7ca3ef4fd69166634ac30b2525 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Sat, 22 Oct 2016 05:18:04 +0300
Subject: x86/boot/smp: Don't try to poke disabled/non-existent APIC
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

commit ff8560512b8d4b7ca3ef4fd69166634ac30b2525 upstream.

Apparently trying to poke a disabled or non-existent APIC
leads to a box that doesn't even boot. Let's not do that.

No real clue if this is the right fix, but at least my
P3 machine boots again.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: dyoung@redhat.com
Cc: kexec@lists.infradead.org
Fixes: 2a51fe083eba ("arch/x86: Handle non enumerated CPU after physical hotplug")
Link: http://lkml.kernel.org/r/1477102684-5092-1-git-send-email-ville.syrjala@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/smpboot.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1408,15 +1408,17 @@ __init void prefill_possible_map(void)
 
 	/* No boot processor was found in mptable or ACPI MADT */
 	if (!num_processors) {
-		int apicid = boot_cpu_physical_apicid;
-		int cpu = hard_smp_processor_id();
+		if (boot_cpu_has(X86_FEATURE_APIC)) {
+			int apicid = boot_cpu_physical_apicid;
+			int cpu = hard_smp_processor_id();
 
-		pr_warn("Boot CPU (id %d) not listed by BIOS\n", cpu);
+			pr_warn("Boot CPU (id %d) not listed by BIOS\n", cpu);
 
-		/* Make sure boot cpu is enumerated */
-		if (apic->cpu_present_to_apicid(0) == BAD_APICID &&
-		    apic->apic_id_valid(apicid))
-			generic_processor_info(apicid, boot_cpu_apic_version);
+			/* Make sure boot cpu is enumerated */
+			if (apic->cpu_present_to_apicid(0) == BAD_APICID &&
+			    apic->apic_id_valid(apicid))
+				generic_processor_info(apicid, boot_cpu_apic_version);
+		}
 
 		if (!num_processors)
 			num_processors = 1;


Patches currently in stable-queue which might be from ville.syrjala@linux.intel.com are

queue-4.8/x86-boot-smp-don-t-try-to-poke-disabled-non-existent-apic.patch
queue-4.8/pinctrl-baytrail-fix-lockdep.patch