x86: irq_move_cleanup_interrupt() must ignore legacy vectors

Since the main loop in the function includes legacy vectors, and since
vector_irq[] gets set up for legacy vectors regardless of whether those
get handled through the IO-APIC, it must not do anything on this vector
range. In fact, we should never get here for IRQs not handled through
the IO-APIC, so add a respective assertion at once. For that assertion
to not have false positives we however need to suppress setting up IRQ2
as an 8259A interrupt (which wasn't correct anyway).

Furthermore, there's no point iterating over the vectors past
LAST_HIPRIORITY_VECTOR, so terminate the loop accordingly.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/i8259.c
+++ b/xen/arch/x86/i8259.c
@@ -416,6 +416,8 @@ void __init init_IRQ(void)
     for (irq = 0; platform_legacy_irq(irq); irq++) {
         struct irq_desc *desc = irq_to_desc(irq);
         
+        if ( irq == 2 ) /* IRQ2 doesn't exist */
+            continue;
         desc->handler = &i8259A_irq_type;
         per_cpu(vector_irq, cpu)[FIRST_LEGACY_VECTOR + irq] = irq;
         cpumask_copy(desc->arch.cpu_mask, cpumask_of(cpu));
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -616,7 +616,9 @@ void irq_move_cleanup_interrupt(struct c
     ack_APIC_irq();
 
     me = smp_processor_id();
-    for (vector = FIRST_DYNAMIC_VECTOR; vector < NR_VECTORS; vector++) {
+    for ( vector = FIRST_DYNAMIC_VECTOR;
+          vector <= LAST_HIPRIORITY_VECTOR; vector++)
+    {
         unsigned int irq;
         unsigned int irr;
         struct irq_desc *desc;
@@ -625,6 +627,12 @@ void irq_move_cleanup_interrupt(struct c
         if ((int)irq < 0)
             continue;
 
+        if ( vector >= FIRST_LEGACY_VECTOR && vector <= LAST_LEGACY_VECTOR )
+        {
+            ASSERT(IO_APIC_IRQ(irq));
+            continue;
+        }
+
         desc = irq_to_desc(irq);
         if (!desc)
             continue;