diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index a111ed6ac1..e60929daa2 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -162,13 +162,13 @@ static inline u32 _phys_pkg_id(u32 cpuid_apic, int index_msb)
 /*
  * 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.
+ * clustered APIC systems, we must use get_apic_id().
  *
  * See Intel's IA-32 SW Dev's Manual Vol2 under CPUID.
  */
 static inline u32 phys_pkg_id(u32 cpuid_apic, int index_msb)
 {
-	return _phys_pkg_id(hard_smp_processor_id(), index_msb);
+	return _phys_pkg_id(get_apic_id(), index_msb);
 }
 
 /* Do minimum CPU detection early.
diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 08cd3f2cdd..d746d0e361 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -20,6 +20,7 @@
 
 #include <asm/processor.h>
 #include <asm/system.h>
+#include <asm/apic.h>
 #include <asm/msr.h>
 #include <asm/p2m.h>
 
@@ -980,7 +981,7 @@ static void do_mc_get_cpu_info(void *v)
         cpuid(1, &junk, &ebx, &junk, &junk);
         xcp->mc_clusterid = (ebx >> 24) & 0xff;
     } else
-        xcp->mc_clusterid = hard_smp_processor_id();
+        xcp->mc_clusterid = get_apic_id();
 }
 
 
diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c
index f8c8e559d0..11a0e5d714 100644
--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -1039,7 +1039,7 @@ static void __init setup_IO_APIC_irqs(void)
                 disable_8259A_irq(irq_to_desc(irq));
 
             desc = irq_to_desc(irq);
-            SET_DEST(entry, logical, cpu_mask_to_apicid(desc->arch.cpu_mask));
+            SET_DEST(entry, logical, get_apic_id());
             spin_lock_irqsave(&ioapic_lock, flags);
             __ioapic_write_entry(apic, pin, 0, entry);
             set_native_irq_info(irq, TARGET_CPUS);
@@ -1843,7 +1843,7 @@ static void __init unlock_ExtINT_logic(void)
 
     entry1.dest_mode = 0;			/* physical delivery */
     entry1.mask = 0;			/* unmask IRQ now */
-    SET_DEST(entry1, physical, hard_smp_processor_id());
+    SET_DEST(entry1, physical, get_apic_id());
     entry1.delivery_mode = dest_ExtINT;
     entry1.polarity = entry0.polarity;
     entry1.trigger = 0;
@@ -2201,6 +2201,7 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
 {
     struct irq_desc *desc = irq_to_desc(irq);
     struct IO_APIC_route_entry entry;
+    cpumask_t mask;
     unsigned long flags;
     int vector;
 
@@ -2220,7 +2221,6 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
 
     entry.delivery_mode = INT_DELIVERY_MODE;
     entry.dest_mode = INT_DEST_MODE;
-    SET_DEST(entry, logical, cpu_mask_to_apicid(TARGET_CPUS));
     entry.trigger = edge_level;
     entry.polarity = active_high_low;
     entry.mask  = 1;
@@ -2236,6 +2236,12 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
         return vector;
     entry.vector = vector;
 
+    cpumask_copy(&mask, TARGET_CPUS);
+    /* Don't chance ending up with an empty mask. */
+    if (cpumask_intersects(&mask, desc->arch.cpu_mask))
+        cpumask_and(&mask, &mask, desc->arch.cpu_mask);
+    SET_DEST(entry, logical, cpu_mask_to_apicid(&mask));
+
     apic_printk(APIC_DEBUG, KERN_DEBUG "IOAPIC[%d]: Set PCI routing entry "
 		"(%d-%d -> %#x -> IRQ %d Mode:%i Active:%i)\n", ioapic,
 		mp_ioapics[ioapic].mpc_apicid, pin, entry.vector, irq,
diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index f1397d6653..5f515a09f9 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -563,21 +563,26 @@ int assign_irq_vector(int irq, const cpumask_t *mask)
  * Initialize vector_irq on a new cpu. This function must be called
  * with vector_lock held.
  */
-void __setup_vector_irq(int cpu)
+void setup_vector_irq(unsigned int cpu)
 {
-    int irq, vector;
+    unsigned int irq, vector;
 
     /* Clear vector_irq */
-    for (vector = 0; vector < NR_VECTORS; ++vector)
+    for ( vector = 0; vector < NR_VECTORS; ++vector )
         per_cpu(vector_irq, cpu)[vector] = INT_MIN;
     /* Mark the inuse vectors */
-    for (irq = 0; irq < nr_irqs; ++irq) {
+    for ( irq = 0; irq < nr_irqs; ++irq )
+    {
         struct irq_desc *desc = irq_to_desc(irq);
 
-        if (!irq_desc_initialized(desc) ||
-            !cpumask_test_cpu(cpu, desc->arch.cpu_mask))
+        if ( !irq_desc_initialized(desc) )
             continue;
         vector = irq_to_vector(irq);
+        if ( vector >= FIRST_HIPRIORITY_VECTOR &&
+             vector <= LAST_HIPRIORITY_VECTOR )
+            cpumask_set_cpu(cpu, desc->arch.cpu_mask);
+        else if ( !cpumask_test_cpu(cpu, desc->arch.cpu_mask) )
+            continue;
         per_cpu(vector_irq, cpu)[vector] = irq;
     }
 }
@@ -2334,8 +2339,8 @@ void fixup_irqs(void)
 
     for ( irq = 0; irq < nr_irqs; irq++ )
     {
-        int break_affinity = 0;
-        int set_affinity = 1;
+        bool_t break_affinity = 0, set_affinity = 1;
+        unsigned int vector;
         cpumask_t affinity;
 
         if ( irq == 2 )
@@ -2347,6 +2352,12 @@ void fixup_irqs(void)
 
         spin_lock(&desc->lock);
 
+        vector = irq_to_vector(irq);
+        if ( vector >= FIRST_HIPRIORITY_VECTOR &&
+             vector <= LAST_HIPRIORITY_VECTOR )
+            cpumask_and(desc->arch.cpu_mask, desc->arch.cpu_mask,
+                        &cpu_online_map);
+
         cpumask_copy(&affinity, desc->affinity);
         if ( !desc->action || cpumask_subset(&affinity, &cpu_online_map) )
         {
diff --git a/xen/arch/x86/smp.c b/xen/arch/x86/smp.c
index 8caa0bce33..50ff6c2efd 100644
--- a/xen/arch/x86/smp.c
+++ b/xen/arch/x86/smp.c
@@ -23,11 +23,6 @@
 #include <asm/hvm/support.h>
 #include <mach_apic.h>
 
-int hard_smp_processor_id(void)
-{
-    return get_apic_id();
-}
-
 /*
  * send_IPI_mask(cpumask, vector): sends @vector IPI to CPUs in @cpumask,
  * excluding the local CPU. @cpumask may be empty.
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index dabc929d4c..5d48bac1ca 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -387,7 +387,7 @@ void start_secondary(void *unused)
      * this lock ensures we don't half assign or remove an irq from a cpu.
      */
     lock_vector_lock();
-    __setup_vector_irq(cpu);
+    setup_vector_irq(cpu);
     cpumask_set_cpu(cpu, &cpu_online_map);
     unlock_vector_lock();
 
@@ -854,7 +854,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
     {
         printk("weird, boot CPU (#%d) not listed by the BIOS.\n",
                boot_cpu_physical_apicid);
-        physid_set(hard_smp_processor_id(), phys_cpu_present_map);
+        physid_set(get_apic_id(), phys_cpu_present_map);
     }
 
     /* If we couldn't find a local APIC, then get out of here now! */
diff --git a/xen/include/asm-x86/irq.h b/xen/include/asm-x86/irq.h
index a44305e9a4..fcf37a3a48 100644
--- a/xen/include/asm-x86/irq.h
+++ b/xen/include/asm-x86/irq.h
@@ -167,7 +167,7 @@ extern struct irq_desc *irq_desc;
 void lock_vector_lock(void);
 void unlock_vector_lock(void);
 
-void __setup_vector_irq(int cpu);
+void setup_vector_irq(unsigned int cpu);
 
 void move_native_irq(struct irq_desc *);
 void move_masked_irq(struct irq_desc *);
diff --git a/xen/include/asm-x86/smp.h b/xen/include/asm-x86/smp.h
index fb0f42a6a7..64f510b6ba 100644
--- a/xen/include/asm-x86/smp.h
+++ b/xen/include/asm-x86/smp.h
@@ -54,8 +54,6 @@ int cpu_add(uint32_t apic_id, uint32_t acpi_id, uint32_t pxm);
  */
 #define raw_smp_processor_id() (get_processor_id())
 
-int hard_smp_processor_id(void);
-
 void __stop_this_cpu(void);
 
 long cpu_up_helper(void *data);