x86-64 linux: properly exit idle mode from evtchn_do_upcall()

Add a call to exit_idle() when evtchn_do_upcall() calls
evtchn_device_upcall() instead of do_IRQ().

From: Jan Beulich <JBeulich@novell.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>

linux-2.6-xen-sparse/drivers/xen/core/evtchn.c

@@ -123,8 +123,10 @@ static void init_evtchn_cpu_bindings(void)
 #ifdef CONFIG_X86
 extern fastcall unsigned int do_IRQ(struct pt_regs *regs);
 #if defined (__i386__)
+static inline void exit_idle(void) {}
 #define IRQ_REG orig_eax
 #elif defined (__x86_64__)
+#include <asm/idle.h>
 #define IRQ_REG orig_rax
 #endif
 #define do_IRQ(irq, regs) do {			\
@@ -170,8 +172,10 @@ asmlinkage void evtchn_do_upcall(struct pt_regs *regs)
 			port = (l1i * BITS_PER_LONG) + l2i;
 			if ((irq = evtchn_to_irq[port]) != -1)
 				do_IRQ(irq, regs);
-			else
+			else {
+				exit_idle();
 				evtchn_device_upcall(port);
+			}
 		}
 	}
 }