From ff8560512b8d4b7ca3ef4fd69166634ac30b2525 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Sat, 22 Oct 2016 05:18:04 +0300 Subject: [PATCH] x86/boot/smp: Don't try to poke disabled/non-existent APIC MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Eric Biederman Cc: H. Peter Anvin Cc: Jiri Olsa Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Len Brown Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Cc: Yinghai Lu Cc: dyoung@redhat.com Cc: kexec@lists.infradead.org Cc: stable@vger.kernel.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 --- arch/x86/kernel/smpboot.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 951f093a96fe..42f5eb7b4f6c 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1409,15 +1409,17 @@ __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; -- 2.20.1