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 past the move_cleanup_count check
for IRQs not handled through the IO-APIC. Adding a respective assertion
woulkd make those iterations more expensive (due to the lock acquire).

For such an assertion to not have false positives we however ought to
suppress setting up IRQ2 as an 8259A interrupt (which wasn't correct
anyway), which is being done here despite the assertion not actually
getting added.

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

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>
master commit: af699220ad6d111ba76fc3040342184e423cc9a1
master date: 2013-04-02 08:30:03 +0200

2 files changed, 8 insertions, 1 deletions

diff --git a/xen/arch/x86/i8259.c b/xen/arch/x86/i8259.c
index 9cfbca87ff..1ff2a8cbad 100644
--- a/xen/arch/x86/i8259.c
+++ b/xen/arch/x86/i8259.c
@@ -406,6 +406,8 @@ 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));
diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 0964c762fd..5833612cfb 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -616,7 +616,9 @@ void irq_move_cleanup_interrupt(struct cpu_user_regs *regs)
     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 +627,9 @@ void irq_move_cleanup_interrupt(struct cpu_user_regs *regs)
         if (irq == -1)
             continue;
 
+        if ( vector >= FIRST_LEGACY_VECTOR && vector <= LAST_LEGACY_VECTOR )
+            continue;
+
         desc = irq_to_desc(irq);
         if (!desc)
             continue;