powerpc/powernv: Machine check and other system interrupts

OPAL can handle various interrupt for us such as Machine Checks (it
performs all sorts of recovery tasks and passes back control to us with
informations about the error), Hardware Management Interrupts and Softpatch
interrupts.

This wires up the mechanisms and prints out specific informations returned
by HAL when a machine check occurs.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/paca.h

@@ -43,6 +43,7 @@ extern unsigned int debug_smp_processor_id(void); /* from linux/smp.h */
 #define get_slb_shadow()	(get_paca()->slb_shadow_ptr)
 
 struct task_struct;
+struct opal_machine_check_event;
 
 /*
  * Defines the layout of the paca.
@@ -135,6 +136,13 @@ struct paca_struct {
 	u8 io_sync;			/* writel() needs spin_unlock sync */
 	u8 irq_work_pending;		/* IRQ_WORK interrupt while soft-disable */
 
+#ifdef CONFIG_PPC_POWERNV
+	/* Pointer to OPAL machine check event structure set by the
+	 * early exception handler for use by high level C handler
+	 */
+	struct opal_machine_check_event *opal_mc_evt;
+#endif
+
 	/* Stuff for accurate time accounting */
 	u64 user_time;			/* accumulated usermode TB ticks */
 	u64 system_time;		/* accumulated system TB ticks */