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From: ville.syrjala@linux.intel.com
To: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org, "Ingo Molnar" <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, "Prarit Bhargava" <prarit@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Len Brown" <len.brown@intel.com>, "Borislav Petkov" <bp@suse.de>,
	"Andi Kleen" <ak@linux.intel.com>, "Jiri Olsa" <jolsa@redhat.com>,
	"Juergen Gross" <jgross@suse.com>,
	dyoung@redhat.com, "Eric Biederman" <ebiederm@xmission.com>,
	kexec@lists.infradead.org, "Thomas Gleixner" <tglx@linutronix.de>,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>
Subject: [PATCH] arch/x86: Don't try to poke disabled/non-existent APIC
Date: Sat, 22 Oct 2016 05:18:04 +0300
Message-ID: <1477102684-5092-1-git-send-email-ville.syrjala@linux.intel.com> (raw)

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

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.

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: dyoung@redhat.com
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 2a51fe083eba ("arch/x86: Handle non enumerated CPU after physical hotplug")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 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;
-- 
2.7.4

             reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-22  2:18 ville.syrjala [this message]
2016-10-25 18:32 ` Prarit Bhargava

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