[PATCH V2 12/13] xen: introduce xen_event_channel_register_nlevel

[Wei Liu <wei.liu2@citrix.com>]

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 drivers/xen/events.c |   55 ++++++++++++++++++++++++++++++++++++++++++++------
 include/xen/events.h |    7 +++++++
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 6e0283c..6a0307c 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -2217,17 +2217,60 @@ err:
 	return rc;
 }
 
+void xen_event_channel_register_nlevel(unsigned int highest_level)
+{
+	int rc;
+
+	switch (highest_level) {
+	case 3:
+		rc = xen_event_channel_register_3level();
+		if (rc == 0) {
+			printk(KERN_INFO "Register 3-level event channel succeed.\n");
+			xen_set_event_channel_nlevel(3);
+			break;
+		} else {
+			printk(KERN_INFO "Regsiter 3-level event channel failed with %d\n",
+			       rc);
+		}
+		/* fall through */
+	case 2:
+		printk(KERN_INFO "Using 2-level event channel\n");
+		xen_set_event_channel_nlevel(2);
+		break;
+	default:
+		printk(KERN_INFO "Trying to register unsupported %d-level event channel\n",
+		       highest_level);
+	}
+}
+
+void xen_set_event_channel_nlevel(unsigned int level)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	switch (level) {
+	case 2:
+		evtchn_pending = s->evtchn_pending;
+		evtchn_mask = s->evtchn_mask;
+		evtchn_level = 2;
+		nr_event_channels = NR_EVENT_CHANNELS_L2;
+		break;
+	case 3:
+		/* evtchn_pending/mask already set */
+		evtchn_level = 3;
+		nr_event_channels = NR_EVENT_CHANNELS_L3;
+		break;
+	default:
+		printk(KERN_EMERG "Trying to set unsupported %d-level event channel\n",
+		       level);
+		BUG();
+	}
+}
+
 void __init xen_init_IRQ(void)
 {
 	int i, rc;
 	int cpu;
-	struct shared_info *s = HYPERVISOR_shared_info;
-
-	evtchn_pending = s->evtchn_pending;
-	evtchn_mask = s->evtchn_mask;
 
-	evtchn_level = 2;
-	nr_event_channels = NR_EVENT_CHANNELS_L2;
+	xen_set_event_channel_nlevel(2);
 
 	evtchn_to_irq = kcalloc(nr_event_channels, sizeof(*evtchn_to_irq),
 				    GFP_KERNEL);
diff --git a/include/xen/events.h b/include/xen/events.h
index 6b117ac..6b6c4fb 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -111,4 +111,11 @@ int xen_test_irq_shared(int irq);
 
 extern unsigned int nr_event_channels;
 
+/* Register N-level event channel. If register N-level fails, it will try to
+ * register N-1 level, until it reaches the default 2-level event channel. */
+void xen_event_channel_register_nlevel(unsigned int highest_level);
+
+/* Set event channel to N-level if registration succeed */
+void xen_set_event_channel_nlevel(unsigned int level);
+
 #endif	/* _XEN_EVENTS_H */
-- 
1.7.10.4