Index: xen-3.3.0-testing/xen/arch/x86/microcode.c
===================================================================
--- xen-3.3.0-testing.orig/xen/arch/x86/microcode.c
+++ xen-3.3.0-testing/xen/arch/x86/microcode.c
@@ -98,7 +98,7 @@ MODULE_LICENSE("GPL");
 static int verbose;
 boolean_param("microcode.verbose", verbose);
 
-#define MICROCODE_VERSION 	"1.14a"
+#define MICROCODE_VERSION 	"1.14b"
 
 #define DEFAULT_UCODE_DATASIZE 	(2000) 	  /* 2000 bytes */
 #define MC_HEADER_SIZE		(sizeof (microcode_header_t))  	  /* 48 bytes */
@@ -118,9 +118,6 @@ boolean_param("microcode.verbose", verbo
 
 #define exttable_size(et) ((et)->count * EXT_SIGNATURE_SIZE + EXT_HEADER_SIZE)
 
-/* serialize access to the physical write to MSR 0x79 */
-static DEFINE_SPINLOCK(microcode_update_lock);
-
 /* no concurrent ->write()s are allowed on /dev/cpu/microcode */
 static DEFINE_MUTEX(microcode_mutex);
 
@@ -376,25 +373,10 @@ out:
 
 static void do_update_one (void * unused)
 {
-	unsigned long flags;
 	unsigned int val[2];
 	int cpu_num = smp_processor_id();
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
 
-	if (uci->mc == NULL) {
-		if (verbose) {
-			if (uci->err == MC_SUCCESS)
-				printk(KERN_INFO "microcode: CPU%d already at revision 0x%x\n",
-					cpu_num, uci->rev);
-			else
-				printk(KERN_INFO "microcode: No new microcode data for CPU%d\n", cpu_num);
-		}
-		return;
-	}
-
-	/* serialize access to the physical write to MSR 0x79 */
-	spin_lock_irqsave(&microcode_update_lock, flags);          
-
 	/* write microcode via MSR 0x79 */
 	wrmsr(MSR_IA32_UCODE_WRITE,
 		(unsigned long) uci->mc->bits, 
@@ -409,7 +391,6 @@ static void do_update_one (void * unused
 
 	/* notify the caller of success on this cpu */
 	uci->err = MC_SUCCESS;
-	spin_unlock_irqrestore(&microcode_update_lock, flags);
 	printk(KERN_INFO "microcode: CPU%d updated from revision "
 	       "0x%x to 0x%x, date = %08x \n", 
 	       cpu_num, uci->rev, val[1], uci->mc->hdr.date);
@@ -418,40 +399,65 @@ static void do_update_one (void * unused
 
 static int do_microcode_update (void)
 {
-	int i, error;
+	int i, j, error;
+	cpumask_t cpu_mask = cpu_online_map;
 
-	if (on_each_cpu(collect_cpu_info, NULL, 1, 1) != 0) {
-		printk(KERN_ERR "microcode: Error! Could not run on all processors\n");
-		error = -EIO;
-		goto out;
+	for_each_cpu_mask(i, cpu_mask) {
+		if (on_selected_cpus(cpumask_of_cpu(i), collect_cpu_info, NULL, 1, 1) != 0) {
+			printk(KERN_ERR "microcode: Error! Could not run on all processors\n");
+			return -EIO;
+		}
 	}
 
 	if ((error = find_matching_ucodes())) {
 		printk(KERN_ERR "microcode: Error in the microcode data\n");
-		goto out_free;
+		cpus_clear(cpu_mask);
 	}
 
-	if (on_each_cpu(do_update_one, NULL, 1, 1) != 0) {
-		printk(KERN_ERR "microcode: Error! Could not run on all processors\n");
-		error = -EIO;
+	for (; (i = any_online_cpu(cpu_mask)) < NR_CPUS; cpu_clear(i, cpu_mask)) {
+		if (ucode_cpu_info[i].mc == NULL) {
+			if (verbose) {
+				switch (ucode_cpu_info[i].err) {
+				case MC_SUCCESS:
+					printk(KERN_INFO "microcode: CPU%d already at revision 0x%x\n",
+					       i, ucode_cpu_info[i].rev);
+					break;
+				case MC_IGNORED:
+					printk(KERN_WARNING "microcode: CPU%d not 'upgrading' to earlier revision"
+					       " 0x%x (current=0x%x)\n", i, ucode_cpu_info[i].cksum, ucode_cpu_info[i].rev);
+					break;
+				default:
+					printk(KERN_INFO "microcode: No new microcode data for CPU%d\n", i);
+					break;
+				}
+			}
+		} else if (on_selected_cpus(cpumask_of_cpu(i), do_update_one, NULL, 1, 1) != 0) {
+			printk(KERN_ERR "microcode: Error! Could not run on processor %d\n", i);
+			error = -EIO;
+		} else if (ucode_cpu_info[i].err == MC_SUCCESS) {
+			cpus_andnot(cpu_mask, cpu_mask, cpu_sibling_map[i]);
+			for_each_cpu_mask(j, cpu_sibling_map[i]) {
+				if (j != i) {
+					ucode_cpu_info[j].err = MC_SUCCESS;
+					ASSERT(ucode_cpu_info[j].mc == ucode_cpu_info[i].mc);
+					ucode_cpu_info[j].mc = NULL;
+				}
+			}
+		}
 	}
 
-out_free:
-	for_each_online_cpu(i) {
+	for (i = 0; i < NR_CPUS; i++) {
 		if (ucode_cpu_info[i].mc) {
-			int j;
 			void *tmp = ucode_cpu_info[i].mc;
-			vfree(tmp);
-			for_each_online_cpu(j) {
+
+			for (j = 0; j < NR_CPUS; j++) {
 				if (ucode_cpu_info[j].mc == tmp)
 					ucode_cpu_info[j].mc = NULL;
 			}
+			vfree(tmp);
 		}
-		if (ucode_cpu_info[i].err == MC_IGNORED && verbose)
-			printk(KERN_WARNING "microcode: CPU%d not 'upgrading' to earlier revision"
-			       " 0x%x (current=0x%x)\n", i, ucode_cpu_info[i].cksum, ucode_cpu_info[i].rev);
 	}
-out:
+
 	return error;
 }