x86: add handle_irq() to allow interrupt injection

Xen uses a different interrupt path, so introduce handle_irq() to
allow interrupts to be inserted into the normal interrupt path.  This
is handled slightly differently on 32 and 64-bit.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 16 insertions, 7 deletions

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 018963aa6ee3..a93f3b0dc7f2 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -48,6 +48,20 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 #endif
 }
 
+bool handle_irq(unsigned irq, struct pt_regs *regs)
+{
+	struct irq_desc *desc;
+
+	stack_overflow_check(regs);
+
+	desc = irq_to_desc(irq);
+	if (unlikely(!desc))
+		return false;
+
+	generic_handle_irq_desc(irq, desc);
+	return true;
+}
+
 /*
  * do_IRQ handles all normal device IRQ's (the special
  * SMP cross-CPU interrupts have their own specific
@@ -56,7 +70,6 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 asmlinkage unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
-	struct irq_desc *desc;
 
 	/* high bit used in ret_from_ code  */
 	unsigned vector = ~regs->orig_ax;
@@ -64,14 +77,10 @@ asmlinkage unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
 
 	exit_idle();
 	irq_enter();
-	irq = __get_cpu_var(vector_irq)[vector];
 
-	stack_overflow_check(regs);
+	irq = __get_cpu_var(vector_irq)[vector];
 
-	desc = irq_to_desc(irq);
-	if (likely(desc))
-		generic_handle_irq_desc(irq, desc);
-	else {
+	if (!handle_irq(irq, regs)) {
 		if (!disable_apic)
 			ack_APIC_irq();