x86: Fix vSMP boot crash

2.6.31-rc7 does not boot on vSMP systems:

[    8.501108] CPU31: Thermal monitoring enabled (TM1)
[    8.501127] CPU 31 MCA banks SHD:2 SHD:3 SHD:5 SHD:6 SHD:8
[    8.650254] CPU31: Intel(R) Xeon(R) CPU           E5540  @ 2.53GHz stepping 04
[    8.710324] Brought up 32 CPUs
[    8.713916] Total of 32 processors activated (162314.96 BogoMIPS).
[    8.721489] ERROR: parent span is not a superset of domain->span
[    8.727686] ERROR: domain->groups does not contain CPU0
[    8.733091] ERROR: groups don't span domain->span
[    8.737975] ERROR: domain->cpu_power not set
[    8.742416]

Ravikiran Thirumalai bisected it to:

| commit 2759c3287d
| x86: don't call read_apic_id if !cpu_has_apic

The problem is that on vSMP systems the CPUID derived
initial-APICIDs are overlapping - so we need to fall
back on hard_smp_processor_id() which reads the local
APIC.

Both come from the hardware (influenced by firmware
though) so it's a tough call which one to trust.

Doing the quirk expresses the vSMP property properly
and also does not affect other systems, so we go for
this solution instead of a revert.

Reported-and-Tested-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Shai Fultheim <shai@scalex86.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <4A944D3C.5030100@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/apic/probe_64.c

@@ -44,6 +44,11 @@ static struct apic *apic_probe[] __initdata = {
 	NULL,
 };
 
+static int apicid_phys_pkg_id(int initial_apic_id, int index_msb)
+{
+	return hard_smp_processor_id() >> index_msb;
+}
+
 /*
  * Check the APIC IDs in bios_cpu_apicid and choose the APIC mode.
  */
@@ -69,6 +74,11 @@ void __init default_setup_apic_routing(void)
 		printk(KERN_INFO "Setting APIC routing to %s\n", apic->name);
 	}
 
+	if (is_vsmp_box()) {
+		/* need to update phys_pkg_id */
+		apic->phys_pkg_id = apicid_phys_pkg_id;
+	}
+
 	/*
 	 * Now that apic routing model is selected, configure the
 	 * fault handling for intr remapping.