[PATCH] x86-64: fix sibling map again

Recent x86-64 sibling map fix for clustered mode by James
(http://linux.bkbits.net:8080/linux-2.6/cset@414b34a6jkiHQ5AnhA269av76y3ZAw?nav=index.html)
is not the recommended way of fixing it.

That patch assumes BIOS for non-clustered systems accept the HW assigned
value.  Why make this assumption when we can fix it in a better
fashion(which is also used by x86 kernel's today)

Basically use HW assigned apic_id's(returned by cpuid) for non clustered
systems and for clustered use BIOS provided apic_id's.  Appended patch does
this.

Note: Similar issue was earlier disussed in context of x86 approx an year
back and James then backed out his changes.
http://www.ussg.iu.edu/hypermail/linux/kernel/0312.2/0167.htmlSigned-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/genapic_cluster.c

@@ -103,6 +103,16 @@ static unsigned int cluster_cpu_mask_to_apicid(cpumask_t cpumask)
 		return BAD_APICID;
 }
 
+/* cpuid returns the value latched in the HW at reset, not the APIC ID
+ * register's value.  For any box whose BIOS changes APIC IDs, like
+ * clustered APIC systems, we must use hard_smp_processor_id.
+ *
+ * See Intel's IA-32 SW Dev's Manual Vol2 under CPUID.
+ */
+static unsigned int phys_pkg_id(int index_msb)
+{
+	return hard_smp_processor_id() >> index_msb;
+}
 
 struct genapic apic_cluster = {
 	.name = "clustered",
@@ -116,4 +126,5 @@ struct genapic apic_cluster = {
 	.send_IPI_allbutself = cluster_send_IPI_allbutself,
 	.send_IPI_mask = cluster_send_IPI_mask,
 	.cpu_mask_to_apicid = cluster_cpu_mask_to_apicid,
+	.phys_pkg_id = phys_pkg_id,
 };

arch/x86_64/kernel/genapic_flat.c

@@ -103,6 +103,13 @@ static unsigned int flat_cpu_mask_to_apicid(cpumask_t cpumask)
 	return cpus_addr(cpumask)[0] & APIC_ALL_CPUS;
 }
 
+static unsigned int phys_pkg_id(int index_msb)
+{
+	u32 ebx;
+
+	ebx = cpuid_ebx(1);
+	return ((ebx >> 24) & 0xFF) >> index_msb;
+}
 
 struct genapic apic_flat =  {
 	.name = "flat",
@@ -116,4 +123,5 @@ struct genapic apic_flat =  {
 	.send_IPI_allbutself = flat_send_IPI_allbutself,
 	.send_IPI_mask = flat_send_IPI_mask,
 	.cpu_mask_to_apicid = flat_cpu_mask_to_apicid,
+	.phys_pkg_id = phys_pkg_id,
 };

arch/x86_64/kernel/setup.c

@@ -56,6 +56,7 @@
 #include <asm/smp.h>
 #include <asm/proto.h>
 #include <asm/setup.h>
+#include <asm/mach_apic.h>
 
 /*
  * Machine setup..
@@ -710,7 +711,6 @@ static void __init detect_ht(struct cpuinfo_x86 *c)
 #ifdef CONFIG_SMP
 	u32 	eax, ebx, ecx, edx;
 	int 	index_lsb, index_msb, tmp;
-	int	initial_apic_id;
 	int 	cpu = smp_processor_id();
 	
 	if (!cpu_has(c, X86_FEATURE_HT))
@@ -745,8 +745,7 @@ static void __init detect_ht(struct cpuinfo_x86 *c)
 		}
 		if (index_lsb != index_msb )
 			index_msb++;
-		initial_apic_id = hard_smp_processor_id();
-		phys_proc_id[cpu] = initial_apic_id >> index_msb;
+		phys_proc_id[cpu] = phys_pkg_id(index_msb);
 		
 		printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
 		       phys_proc_id[cpu]);

include/asm-x86_64/genapic.h

@@ -26,6 +26,7 @@ struct genapic {
 	void (*send_IPI_all)(int vector);
 	/* */
 	unsigned int (*cpu_mask_to_apicid)(cpumask_t cpumask);
+	unsigned int (*phys_pkg_id)(int index_msb);
 };
 
 

include/asm-x86_64/mach_apic.h

@@ -24,5 +24,6 @@
 #define send_IPI_allbutself (genapic->send_IPI_allbutself)
 #define send_IPI_all (genapic->send_IPI_all)
 #define cpu_mask_to_apicid (genapic->cpu_mask_to_apicid)
+#define phys_pkg_id	(genapic->phys_pkg_id)
 
 #endif /* __ASM_MACH_APIC_H */