From: Marc Zyngier <marc.zyngier@arm.com>
Date: Fri, 4 Aug 2017 17:45:50 +0100
Subject: irqchip/gic-v3-its: Add post-mortem info on command timeout
Patch-mainline: v4.15-rc1
Git-commit: a19b462f044b1bc5327f0bc871b46a03efb84363
References: bsc#1077761

If the ITS stops processing commands, we're pretty much toasted
as we cannot update the configuration anymore (and we're not
even sure that the ITS still translates interrups).

If that happens, let's dump some basic information about the
state of affairs before moving on.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Alexander Graf <agraf@suse.de>
---
 drivers/irqchip/irq-gic-v3-its.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -694,9 +694,9 @@
 		dsb(ishst);
 }
 
-static void its_wait_for_range_completion(struct its_node *its,
-					  struct its_cmd_block *from,
-					  struct its_cmd_block *to)
+static int its_wait_for_range_completion(struct its_node *its,
+					 struct its_cmd_block *from,
+					 struct its_cmd_block *to)
 {
 	u64 rd_idx, from_idx, to_idx;
 	u32 count = 1000000;	/* 1s! */
@@ -717,12 +717,15 @@
 
 		count--;
 		if (!count) {
-			pr_err_ratelimited("ITS queue timeout\n");
-			return;
+			pr_err_ratelimited("ITS queue timeout (%llu %llu %llu)\n",
+					   from_idx, to_idx, rd_idx);
+			return -1;
 		}
 		cpu_relax();
 		udelay(1);
 	}
+
+	return 0;
 }
 
 /* Warning, macro hell follows */
@@ -758,7 +761,8 @@
 	next_cmd = its_post_commands(its);				\
 	raw_spin_unlock_irqrestore(&its->lock, flags);			\
 									\
-	its_wait_for_range_completion(its, cmd, next_cmd);		\
+	if (its_wait_for_range_completion(its, cmd, next_cmd))		\
+		pr_err_ratelimited("ITS cmd %ps failed\n", builder);	\
 }
 
 static void its_build_sync_cmd(struct its_cmd_block *sync_cmd,