[Skiboot] [PATCH 13/13] xive: Fix failure to lower CPPR in opal_xive_get_xirr()

[Benjamin Herrenschmidt]

There is a theorical possibility that if we don't get any
pending interrupt in the queue in opal_xive_get_xirr() due
to a spurious notification we leave the CPPR elevated.

Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
 hw/xive.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/xive.c b/hw/xive.c
index 2db73d8..363c7f0 100644
--- a/hw/xive.c
+++ b/hw/xive.c
@@ -3102,7 +3102,7 @@ static int64_t opal_xive_get_xirr(uint32_t *out_xirr, bool just_poll)
 		break;
 	case TM_QW3_NSR_HE_PHYS:
 		/* Mark pending and keep track of the CPPR update */
-		if (!just_poll) {
+		if (!just_poll && (ack & 0xff) != 0xff) {
 			xs->cppr = ack & 0xff;
 			xs->pending |= 1 << xs->cppr;
 		}
@@ -3158,6 +3158,12 @@ static int64_t opal_xive_get_xirr(uint32_t *out_xirr, bool just_poll)
 		if (val)
 			xive_cpu_vdbg(c, "  found irq, prio=%d\n", prio);
 
+	} else {
+		/* Nothing was active, this is a fluke, restore CPPR */
+		xs->cppr = old_cppr;
+		out_8(xs->tm_ring1 + TM_QW3_HV_PHYS + TM_CPPR, old_cppr);
+		xive_cpu_vdbg(c, "  nothing active, restored CPPR to %d\n",
+			      old_cppr);
 	}
  skip:
 
-- 
2.9.3