xive: Increase the interrupt "gap" on debug builds

We normally allocate IPIs from 0x10. Make that 0x1000 on debug
builds to limit the chances of overlapping with Linux interrupt
numbers which makes debugging code that confuses them easier.

Also add a warning in emulation if we get an interrupt in the
queue whose number is below the gap.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

hw/xive.c

@@ -46,12 +46,14 @@
 #define XIVE_DEBUG_INIT_CACHE_UPDATES
 #define XIVE_EXTRA_CHECK_INIT_CACHE
 #define XIVE_CHECK_LOCKS
+#define XIVE_INT_SAFETY_GAP 0x1000
 #else
 #undef  XIVE_DEBUG_DUPLICATES
 #undef  XIVE_PERCPU_LOG
 #undef  XIVE_DEBUG_INIT_CACHE_UPDATES
 #undef  XIVE_EXTRA_CHECK_INIT_CACHE
 #undef  XIVE_CHECK_LOCKS
+#define XIVE_INT_SAFETY_GAP 0x10
 #endif
 
 /*
@@ -2756,8 +2758,8 @@ static struct xive *init_one_xive(struct dt_node *np)
 	/* Make sure we never hand out "2" as it's reserved for XICS emulation
 	 * IPI returns. Generally start handing out at 0x10
 	 */
-	if (x->int_ipi_top < 0x10)
-		x->int_ipi_top = 0x10;
+	if (x->int_ipi_top < XIVE_INT_SAFETY_GAP)
+		x->int_ipi_top = XIVE_INT_SAFETY_GAP;
 
 	/* Allocate a few bitmaps */
 	x->eq_map = zalloc(BITMAP_BYTES(MAX_EQ_COUNT >> 3));
@@ -3540,6 +3542,9 @@ static int64_t opal_xive_get_xirr(uint32_t *out_xirr, bool just_poll)
 		/* XXX Use "p" to select queue */
 		val = xive_read_eq(xs, just_poll);
 
+		if (val && val < XIVE_INT_SAFETY_GAP)
+			xive_cpu_err(c, "Bogus interrupt 0x%x received !\n", val);
+
 		/* Convert to magic IPI if needed */
 		if (val == xs->ipi_irq)
 			val = 2;