Index: trunk/linux-2.6-xen-sparse/arch/i386/kernel/cpu/intel_cacheinfo-xen.c
===================================================================
--- trunk/linux-2.6-xen-sparse/arch/i386/kernel/cpu/intel_cacheinfo-xen.c	(revision 10421)
+++ trunk/linux-2.6-xen-sparse/arch/i386/kernel/cpu/intel_cacheinfo-xen.c	(working copy)
@@ -418,7 +418,7 @@
 
 /* pointer to _cpuid4_info array (for each cache leaf) */
 static struct _cpuid4_info *cpuid4_info[NR_CPUS];
-#define CPUID4_INFO_IDX(x,y)    (&((cpuid4_info[x])[y]))
+#define CPUID4_INFO_IDX(x,y)    (cpuid4_info[x]?(&((cpuid4_info[x])[y])):NULL)
 
 #ifdef CONFIG_SMP
 static void __cpuinit cache_shared_cpu_map_setup(unsigned int cpu, int index)
@@ -429,20 +429,23 @@
 	struct cpuinfo_x86 *c = cpu_data;
 
 	this_leaf = CPUID4_INFO_IDX(cpu, index);
-	num_threads_sharing = 1 + this_leaf->eax.split.num_threads_sharing;
+	if (this_leaf) {
+		num_threads_sharing = 1 + this_leaf->eax.split.num_threads_sharing;
 
-	if (num_threads_sharing == 1)
-		cpu_set(cpu, this_leaf->shared_cpu_map);
-	else {
-		index_msb = get_count_order(num_threads_sharing);
+		if (num_threads_sharing == 1)
+			cpu_set(cpu, this_leaf->shared_cpu_map);
+		else {
+			index_msb = get_count_order(num_threads_sharing);
 
-		for_each_online_cpu(i) {
-			if (c[i].apicid >> index_msb ==
-			    c[cpu].apicid >> index_msb) {
-				cpu_set(i, this_leaf->shared_cpu_map);
-				if (i != cpu && cpuid4_info[i])  {
-					sibling_leaf = CPUID4_INFO_IDX(i, index);
-					cpu_set(cpu, sibling_leaf->shared_cpu_map);
+			for_each_online_cpu(i) {
+				if (c[i].apicid >> index_msb ==
+				    c[cpu].apicid >> index_msb) {
+					cpu_set(i, this_leaf->shared_cpu_map);
+					if (i != cpu && cpuid4_info[i])  {
+						sibling_leaf = CPUID4_INFO_IDX(i, index);
+						if (sibling_leaf)
+							cpu_set(cpu, sibling_leaf->shared_cpu_map);
+					}
 				}
 			}
 		}
@@ -454,9 +457,11 @@
 	int sibling;
 
 	this_leaf = CPUID4_INFO_IDX(cpu, index);
-	for_each_cpu_mask(sibling, this_leaf->shared_cpu_map) {
-		sibling_leaf = CPUID4_INFO_IDX(sibling, index);	
-		cpu_clear(cpu, sibling_leaf->shared_cpu_map);
+	if (this_leaf) {
+		for_each_cpu_mask(sibling, this_leaf->shared_cpu_map) {
+			sibling_leaf = CPUID4_INFO_IDX(sibling, index);	
+			cpu_clear(cpu, sibling_leaf->shared_cpu_map);
+		}
 	}
 }
 #else
@@ -496,10 +501,12 @@
 	retval = 0;
 	for (j = 0; j < num_cache_leaves; j++) {
 		this_leaf = CPUID4_INFO_IDX(cpu, j);
-		retval = cpuid4_cache_lookup(j, this_leaf);
-		if (unlikely(retval < 0))
-			break;
-		cache_shared_cpu_map_setup(cpu, j);
+		if (this_leaf) {
+			retval = cpuid4_cache_lookup(j, this_leaf);
+			if (unlikely(retval < 0))
+				break;
+			cache_shared_cpu_map_setup(cpu, j);
+		}
 	}
 	set_cpus_allowed(current, oldmask);
 
@@ -527,7 +534,7 @@
 
 /* pointer to array of kobjects for cpuX/cache/indexY */
 static struct _index_kobject *index_kobject[NR_CPUS];
-#define INDEX_KOBJECT_PTR(x,y)    (&((index_kobject[x])[y]))
+#define INDEX_KOBJECT_PTR(x,y)    (index_kobject[x]?(&((index_kobject[x])[y])):NULL)
 
 #define show_one_plus(file_name, object, val)				\
 static ssize_t show_##file_name						\
@@ -608,12 +615,14 @@
 static ssize_t show(struct kobject * kobj, struct attribute * attr, char * buf)
 {
 	struct _cache_attr *fattr = to_attr(attr);
-	struct _index_kobject *this_leaf = to_object(kobj);
+	struct _index_kobject *this_leaf_obj = to_object(kobj);
+	struct _cpuid4_info *this_leaf = CPUID4_INFO_IDX(this_leaf_obj->cpu,
+							 this_leaf_obj->index);
+
 	ssize_t ret;
 
-	ret = fattr->show ?
-		fattr->show(CPUID4_INFO_IDX(this_leaf->cpu, this_leaf->index),
-			buf) :
+	ret = fattr->show && this_leaf?
+		fattr->show(this_leaf,buf) :
 	       	0;
 	return ret;
 }
@@ -696,6 +705,9 @@
 
 	for (i = 0; i < num_cache_leaves; i++) {
 		this_object = INDEX_KOBJECT_PTR(cpu,i);
+		if (!this_object)
+			continue;
+
 		this_object->cpu = cpu;
 		this_object->index = i;
 		this_object->kobj.parent = cache_kobject[cpu];
@@ -704,8 +716,10 @@
 		retval = kobject_register(&(this_object->kobj));
 		if (unlikely(retval)) {
 			for (j = 0; j < i; j++) {
-				kobject_unregister(
-					&(INDEX_KOBJECT_PTR(cpu,j)->kobj));
+				struct _index_kobject *robj = 
+					INDEX_KOBJECT_PTR(cpu,j);
+				if (robj)
+					kobject_unregister(&robj->kobj);
 			}
 			kobject_unregister(cache_kobject[cpu]);
 			cpuid4_cache_sysfs_exit(cpu);
@@ -719,12 +733,16 @@
 {
 	unsigned int cpu = sys_dev->id;
 	unsigned long i;
+	struct _index_kobject *this_object;
 
 	for (i = 0; i < num_cache_leaves; i++) {
 		cache_remove_shared_cpu_map(cpu, i);
-		kobject_unregister(&(INDEX_KOBJECT_PTR(cpu,i)->kobj));
+		this_object = INDEX_KOBJECT_PTR(cpu,i);
+		if (this_object)
+			kobject_unregister(&this_object->kobj);
 	}
-	kobject_unregister(cache_kobject[cpu]);
+	if (cache_kobject[cpu])
+		kobject_unregister(cache_kobject[cpu]);
 	cpuid4_cache_sysfs_exit(cpu);
 	return;
 }